diff --git a/cranelift/codegen/src/machinst/mod.rs b/cranelift/codegen/src/machinst/mod.rs
index 072c32a9d0..28738c9e61 100644
--- a/cranelift/codegen/src/machinst/mod.rs
+++ b/cranelift/codegen/src/machinst/mod.rs
@@ -354,49 +354,57 @@ impl<T: CompilePhase> CompiledCodeBase<T> {
 
         let relocs = self.buffer.relocs();
         let traps = self.buffer.traps();
-        let labels = self.bb_starts.as_slice();
 
-        let insns = cs.disasm_all(self.buffer.data(), 0x0).map_err(map_caperr)?;
-        for i in insns.iter() {
-            if let Some((n, off)) = labels
-                .iter()
-                .copied()
-                .enumerate()
-                .find(|(_, val)| *val == i.address() as u32)
-            {
-                writeln!(buf, "block{}: ; offset 0x{:x}", n, off)?;
-            }
+        // Normalize the block starts to include an initial block of offset 0.
+        let mut block_starts = Vec::new();
+        if self.bb_starts.first().copied() != Some(0) {
+            block_starts.push(0);
+        }
+        block_starts.extend_from_slice(&self.bb_starts);
+        block_starts.push(self.buffer.data().len() as u32);
 
-            write!(buf, "  ")?;
+        // Iterate over block regions, to ensure that we always produce block labels
+        for (n, (&start, &end)) in block_starts
+            .iter()
+            .zip(block_starts.iter().skip(1))
+            .enumerate()
+        {
+            writeln!(buf, "block{}: ; offset 0x{:x}", n, start)?;
 
-            let op_str = i.op_str().unwrap_or("");
-            if let Some(s) = i.mnemonic() {
-                write!(buf, "{}", s)?;
-                if !op_str.is_empty() {
-                    write!(buf, " ")?;
+            let buffer = &self.buffer.data()[start as usize..end as usize];
+            let insns = cs.disasm_all(buffer, start as u64).map_err(map_caperr)?;
+            for i in insns.iter() {
+                write!(buf, "  ")?;
+
+                let op_str = i.op_str().unwrap_or("");
+                if let Some(s) = i.mnemonic() {
+                    write!(buf, "{}", s)?;
+                    if !op_str.is_empty() {
+                        write!(buf, " ")?;
+                    }
                 }
+
+                write!(buf, "{}", op_str)?;
+
+                let end = i.address() + i.bytes().len() as u64;
+                let contains = |off| i.address() <= off && off < end;
+
+                if let Some(reloc) = relocs.iter().find(|reloc| contains(reloc.offset as u64)) {
+                    write!(
+                        buf,
+                        " ; reloc_external {} {} {}",
+                        reloc.kind,
+                        reloc.name.display(params),
+                        reloc.addend,
+                    )?;
+                }
+
+                if let Some(trap) = traps.iter().find(|trap| contains(trap.offset as u64)) {
+                    write!(buf, " ; trap: {}", trap.code)?;
+                }
+
+                writeln!(buf)?;
             }
-
-            write!(buf, "{}", op_str)?;
-
-            let end = i.address() + i.bytes().len() as u64;
-            let contains = |off| i.address() <= off && off < end;
-
-            if let Some(reloc) = relocs.iter().find(|reloc| contains(reloc.offset as u64)) {
-                write!(
-                    buf,
-                    " ; reloc_external {} {} {}",
-                    reloc.kind,
-                    reloc.name.display(params),
-                    reloc.addend,
-                )?;
-            }
-
-            if let Some(trap) = traps.iter().find(|trap| contains(trap.offset as u64)) {
-                write!(buf, " ; trap: {}", trap.code)?;
-            }
-
-            writeln!(buf)?;
         }
 
         return Ok(buf);
diff --git a/cranelift/filetests/filetests/egraph/multivalue.clif b/cranelift/filetests/filetests/egraph/multivalue.clif
index 9c664643dc..65c34c477c 100644
--- a/cranelift/filetests/filetests/egraph/multivalue.clif
+++ b/cranelift/filetests/filetests/egraph/multivalue.clif
@@ -26,9 +26,10 @@ function u0:359(i64) -> i8, i8 system_v {
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   callq 9 ; reloc_external CallPCRel4 u0:521 -4
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/egraph/not_a_load.clif b/cranelift/filetests/filetests/egraph/not_a_load.clif
index 0e5b46f14d..6f40dfecf6 100644
--- a/cranelift/filetests/filetests/egraph/not_a_load.clif
+++ b/cranelift/filetests/filetests/egraph/not_a_load.clif
@@ -24,9 +24,10 @@ function u0:1302(i64) -> i64 system_v {
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq (%rdi), %rax ; trap: heap_oob
 ;   movq %rax, %rcx
 ;   addq %rdi, %rcx
diff --git a/cranelift/filetests/filetests/isa/aarch64/atomic-cas.clif b/cranelift/filetests/filetests/isa/aarch64/atomic-cas.clif
index 58fe258746..5869e0af94 100644
--- a/cranelift/filetests/filetests/isa/aarch64/atomic-cas.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/atomic-cas.clif
@@ -30,12 +30,13 @@ block0(v0: i64, v1: i32, v2: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   mov x28, x2
diff --git a/cranelift/filetests/filetests/isa/aarch64/atomic-rmw-lse.clif b/cranelift/filetests/filetests/isa/aarch64/atomic-rmw-lse.clif
index 22cd655462..97df31507b 100644
--- a/cranelift/filetests/filetests/isa/aarch64/atomic-rmw-lse.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/atomic-rmw-lse.clif
@@ -232,12 +232,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -274,12 +275,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -316,12 +318,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -358,12 +361,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
diff --git a/cranelift/filetests/filetests/isa/aarch64/atomic-rmw.clif b/cranelift/filetests/filetests/isa/aarch64/atomic-rmw.clif
index 5887aa7167..7d13e32321 100644
--- a/cranelift/filetests/filetests/isa/aarch64/atomic-rmw.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/atomic-rmw.clif
@@ -24,12 +24,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -65,12 +66,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -106,12 +108,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -147,12 +150,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
@@ -188,12 +192,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -229,12 +234,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -270,12 +276,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -311,12 +318,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
@@ -352,12 +360,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -393,12 +402,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -434,12 +444,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -475,12 +486,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
@@ -516,12 +528,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -558,12 +571,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -600,12 +614,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -642,12 +657,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
@@ -684,12 +700,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -725,12 +742,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -766,12 +784,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -807,12 +826,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
@@ -848,12 +868,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -889,12 +910,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -930,12 +952,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -971,12 +994,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
@@ -1012,12 +1036,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -1054,12 +1079,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -1096,12 +1122,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -1139,12 +1166,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
@@ -1182,12 +1210,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -1224,12 +1253,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -1266,12 +1296,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -1308,12 +1339,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
@@ -1350,12 +1382,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -1392,12 +1425,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -1434,12 +1468,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -1477,12 +1512,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
@@ -1520,12 +1556,13 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr x27, [x25]
@@ -1562,12 +1599,13 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxr w27, [x25]
@@ -1604,12 +1642,13 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrh w27, [x25]
@@ -1646,12 +1685,13 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x26, x27, [sp, #-0x10]!
 ;   stp x24, x25, [sp, #-0x10]!
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x25, x0
 ;   mov x26, x1
 ;   ldaxrb w27, [x25]
diff --git a/cranelift/filetests/filetests/isa/aarch64/bti.clif b/cranelift/filetests/filetests/isa/aarch64/bti.clif
index 86f7fcdd76..bd32884750 100644
--- a/cranelift/filetests/filetests/isa/aarch64/bti.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/bti.clif
@@ -61,8 +61,9 @@ block5(v5: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   hint #0x22
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmp w0, #3
 ;   b.hs #0x30
 ;   csel x15, xzr, x0, hs
@@ -74,24 +75,24 @@ block5(v5: i32):
 ;   .byte 0x14, 0x00, 0x00, 0x00
 ;   .byte 0x20, 0x00, 0x00, 0x00
 ;   .byte 0x2c, 0x00, 0x00, 0x00
-; block1: ; offset 0x30
+; block2: ; offset 0x30
 ;   mov w5, #4
-; block2: ; offset 0x34
+; block3: ; offset 0x34
 ;   b #0x58
-; block3: ; offset 0x38
+; block4: ; offset 0x38
 ;   hint #0x24
 ;   mov w5, #1
-; block4: ; offset 0x40
+; block5: ; offset 0x40
 ;   b #0x58
-; block5: ; offset 0x44
+; block6: ; offset 0x44
 ;   hint #0x24
 ;   mov w5, #2
-; block6: ; offset 0x4c
+; block7: ; offset 0x4c
 ;   b #0x58
-; block7: ; offset 0x50
+; block8: ; offset 0x50
 ;   hint #0x24
 ;   mov w5, #3
-; block8: ; offset 0x58
+; block9: ; offset 0x58
 ;   add w0, w0, w5
 ;   ret
 
@@ -128,8 +129,9 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   hint #0x22
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   ldr x5, [x0]
 ;   mov x8, x5
 ;   cmp w0, #1
@@ -141,10 +143,10 @@ block2:
 ;   add x6, x6, x7
 ;   br x6
 ;   .byte 0x0c, 0x00, 0x00, 0x00
-; block1: ; offset 0x30
+; block2: ; offset 0x30
 ;   mov x0, x8
 ;   ret
-; block2: ; offset 0x38
+; block3: ; offset 0x38
 ;   hint #0x24
 ;   mov x0, x8
 ;   add x0, x0, #0x2a
@@ -169,10 +171,11 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   hint #0x22
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   ldr x3, #0x14
 ;   b #0x1c
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; reloc_external Abs8 %g 0
diff --git a/cranelift/filetests/filetests/isa/aarch64/call-indirect.clif b/cranelift/filetests/filetests/isa/aarch64/call-indirect.clif
index 05b54c2403..77c0d20ba4 100644
--- a/cranelift/filetests/filetests/isa/aarch64/call-indirect.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/call-indirect.clif
@@ -18,9 +18,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   blr x1
 ;   ldp x29, x30, [sp], #0x10
 ;   ret
diff --git a/cranelift/filetests/filetests/isa/aarch64/call-pauth.clif b/cranelift/filetests/filetests/isa/aarch64/call-pauth.clif
index c38c69d700..706c2211e3 100644
--- a/cranelift/filetests/filetests/isa/aarch64/call-pauth.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/call-pauth.clif
@@ -21,10 +21,11 @@ block0(v0: i64):
 ;   autiasp ; ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   paciasp
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   ldr x3, #0x14
 ;   b #0x1c
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; reloc_external Abs8 %g 0
diff --git a/cranelift/filetests/filetests/isa/aarch64/call.clif b/cranelift/filetests/filetests/isa/aarch64/call.clif
index bae501abf7..8566175afc 100644
--- a/cranelift/filetests/filetests/isa/aarch64/call.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/call.clif
@@ -21,9 +21,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   ldr x3, #0x10
 ;   b #0x18
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; reloc_external Abs8 %g 0
@@ -50,9 +51,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   ldr x3, #0x10
 ;   b #0x18
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; reloc_external Abs8 %g 0
@@ -92,9 +94,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   ldr x3, #0x10
 ;   b #0x18
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; reloc_external Abs8 %g 0
@@ -149,9 +152,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   mov x8, x0
 ;   sub sp, sp, #0x10
 ;   mov w0, #0x2a
@@ -256,10 +260,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x30
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   ldr x9, #0x14
 ;   b #0x1c
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; reloc_external Abs8 %g0 0
@@ -351,10 +356,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x30
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   ldr x9, #0x14
 ;   b #0x1c
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; reloc_external Abs8 %g0 0
@@ -450,10 +456,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x30
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   ldr x9, #0x14
 ;   b #0x1c
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; reloc_external Abs8 %g0 0
@@ -538,9 +545,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   mov x1, x0
 ;   mov x0, #0x2a
 ;   mov x2, #0x2a
@@ -591,9 +599,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   mov x2, x0
 ;   mov x3, #0x2a
 ;   mov x0, #0x2a
@@ -644,9 +653,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   mov x1, x0
 ;   mov x2, #0x2a
 ;   mov x0, #0x2a
@@ -673,9 +683,10 @@ block0(v0: i128, v1: i128, v2: i128, v3: i64, v4: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   ldur x0, [x29, #0x10]
 ;   ldur x1, [x29, #0x18]
 ;   ldp x29, x30, [sp], #0x10
@@ -712,9 +723,10 @@ block0(v0: i128, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   mov x6, x2
 ;   sub sp, sp, #0x10
 ;   stur x0, [sp]
@@ -749,9 +761,10 @@ block0(v0: i128, v1: i128, v2: i128, v3: i64, v4: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   ldur x0, [x29, #0x10]
 ;   ldur x1, [x29, #0x18]
 ;   ldp x29, x30, [sp], #0x10
@@ -788,9 +801,10 @@ block0(v0: i128, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   mov x6, x2
 ;   sub sp, sp, #0x10
 ;   stur x0, [sp]
@@ -873,9 +887,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   mov x8, x0
 ;   ldr x3, #0x14
 ;   b #0x1c
@@ -907,10 +922,11 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x24, [sp, #-0x10]!
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x24, x8
 ;   ldr x4, #0x18
 ;   b #0x20
diff --git a/cranelift/filetests/filetests/isa/aarch64/dynamic-slot.clif b/cranelift/filetests/filetests/isa/aarch64/dynamic-slot.clif
index 2284a0bb55..0d6f3dc524 100644
--- a/cranelift/filetests/filetests/isa/aarch64/dynamic-slot.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/dynamic-slot.clif
@@ -24,10 +24,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x1, sp
 ;   mov x2, #1
 ;   str x2, [x1]
@@ -58,10 +59,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x1, sp
 ;   mov x2, #1
 ;   str x2, [x1]
@@ -93,10 +95,11 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   dup v3.4s, w0
 ;   mov x3, sp
 ;   str q3, [x3]
@@ -127,10 +130,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x2, sp
 ;   ldr q0, [x2]
 ;   add sp, sp, #0x10
@@ -161,10 +165,11 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   dup v3.4s, w0
 ;   mov x3, sp
 ;   str q3, [x3]
@@ -193,10 +198,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x0, sp
 ;   add sp, sp, #0x10
 ;   ldp x29, x30, [sp], #0x10
diff --git a/cranelift/filetests/filetests/isa/aarch64/fp_sp_pc-pauth.clif b/cranelift/filetests/filetests/isa/aarch64/fp_sp_pc-pauth.clif
index f320c6aec0..d7ac248a07 100644
--- a/cranelift/filetests/filetests/isa/aarch64/fp_sp_pc-pauth.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/fp_sp_pc-pauth.clif
@@ -18,10 +18,11 @@ block0:
 ;   autiasp ; ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   paciasp
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x0, x29
 ;   ldp x29, x30, [sp], #0x10
 ;   autiasp
@@ -43,10 +44,11 @@ block0:
 ;   autiasp ; ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   paciasp
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x0, sp
 ;   ldp x29, x30, [sp], #0x10
 ;   autiasp
@@ -70,10 +72,11 @@ block0:
 ;   autiasp ; ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   paciasp
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   ldur x30, [x29, #8]
 ;   xpaclri
 ;   mov x0, x30
diff --git a/cranelift/filetests/filetests/isa/aarch64/fp_sp_pc.clif b/cranelift/filetests/filetests/isa/aarch64/fp_sp_pc.clif
index 82cb9bf484..409f24d6cd 100644
--- a/cranelift/filetests/filetests/isa/aarch64/fp_sp_pc.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/fp_sp_pc.clif
@@ -17,9 +17,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   mov x0, x29
 ;   ldp x29, x30, [sp], #0x10
 ;   ret
@@ -39,9 +40,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   mov x0, sp
 ;   ldp x29, x30, [sp], #0x10
 ;   ret
@@ -61,9 +63,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   ldur x0, [x29, #8]
 ;   ldp x29, x30, [sp], #0x10
 ;   ret
diff --git a/cranelift/filetests/filetests/isa/aarch64/inline-probestack.clif b/cranelift/filetests/filetests/isa/aarch64/inline-probestack.clif
index d18b96a961..3a2fca9636 100644
--- a/cranelift/filetests/filetests/isa/aarch64/inline-probestack.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/inline-probestack.clif
@@ -26,10 +26,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x800
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x0, sp
 ;   add sp, sp, #0x800
 ;   ldp x29, x30, [sp], #0x10
@@ -57,6 +58,7 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   mov x16, #-0x1000
@@ -66,7 +68,7 @@ block0:
 ;   mov x16, #-0x3000
 ;   str wzr, [sp, x16, sxtx]
 ;   sub sp, sp, #3, lsl #12
-; block0: ; offset 0x24
+; block1: ; offset 0x24
 ;   mov x0, sp
 ;   add sp, sp, #3, lsl #12
 ;   ldp x29, x30, [sp], #0x10
@@ -99,6 +101,7 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   mov x16, #0
@@ -111,7 +114,7 @@ block0:
 ;   mov w16, #0x86a0
 ;   movk w16, #1, lsl #16
 ;   sub sp, sp, x16
-; block0: ; offset 0x30
+; block1: ; offset 0x30
 ;   mov x0, sp
 ;   mov w16, #0x86a0
 ;   movk w16, #1, lsl #16
diff --git a/cranelift/filetests/filetests/isa/aarch64/leaf_with_preserve_frame_pointers.clif b/cranelift/filetests/filetests/isa/aarch64/leaf_with_preserve_frame_pointers.clif
index 8b662ade04..82605ceeb7 100644
--- a/cranelift/filetests/filetests/isa/aarch64/leaf_with_preserve_frame_pointers.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/leaf_with_preserve_frame_pointers.clif
@@ -18,9 +18,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
-; block0: ; offset 0x8
+; block1: ; offset 0x8
 ;   ldp x29, x30, [sp], #0x10
 ;   ret
 
diff --git a/cranelift/filetests/filetests/isa/aarch64/prologue.clif b/cranelift/filetests/filetests/isa/aarch64/prologue.clif
index 420ac5365b..136b4d3e86 100644
--- a/cranelift/filetests/filetests/isa/aarch64/prologue.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/prologue.clif
@@ -153,13 +153,14 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   stp d14, d15, [sp, #-0x10]!
 ;   stp d12, d13, [sp, #-0x10]!
 ;   stp d10, d11, [sp, #-0x10]!
 ;   stp d8, d9, [sp, #-0x10]!
-; block0: ; offset 0x18
+; block1: ; offset 0x18
 ;   fadd d23, d0, d0
 ;   fadd d24, d0, d0
 ;   fadd d25, d0, d0
@@ -323,11 +324,12 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x28, [sp, #-0x10]!
 ;   stp x21, x27, [sp, #-0x10]!
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   add x5, x0, x0
 ;   add x6, x0, x5
 ;   add x7, x0, x6
diff --git a/cranelift/filetests/filetests/isa/aarch64/reftypes.clif b/cranelift/filetests/filetests/isa/aarch64/reftypes.clif
index e4c7825a7f..0c425b94cf 100644
--- a/cranelift/filetests/filetests/isa/aarch64/reftypes.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/reftypes.clif
@@ -121,10 +121,11 @@ block3(v7: r64, v8: r64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x20
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   stur x0, [sp, #8]
 ;   stur x1, [sp, #0x10]
 ;   ldr x1, #0x1c
@@ -137,14 +138,14 @@ block3(v7: r64, v8: r64):
 ;   str x6, [x15]
 ;   uxtb w0, w0
 ;   cbz x0, #0x48
-; block1: ; offset 0x3c
+; block2: ; offset 0x3c
 ;   mov x0, x6
 ;   ldur x1, [sp, #0x10]
 ;   b #0x50
-; block2: ; offset 0x48
+; block3: ; offset 0x48
 ;   mov x1, x6
 ;   ldur x0, [sp, #0x10]
-; block3: ; offset 0x50
+; block4: ; offset 0x50
 ;   mov x2, sp
 ;   ldr x2, [x2]
 ;   add sp, sp, #0x20
diff --git a/cranelift/filetests/filetests/isa/aarch64/stack-limit.clif b/cranelift/filetests/filetests/isa/aarch64/stack-limit.clif
index beb04d9c08..e938e155a6 100644
--- a/cranelift/filetests/filetests/isa/aarch64/stack-limit.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/stack-limit.clif
@@ -64,12 +64,13 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   cmp sp, x0
 ;   b.hs #0x14
 ;   .byte 0x1f, 0xc1, 0x00, 0x00 ; trap: stk_ovf
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   ldr x2, #0x1c
 ;   b #0x24
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; reloc_external Abs8 %foo 0
@@ -103,6 +104,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   ldur x16, [x0]
@@ -110,7 +112,7 @@ block0(v0: i64):
 ;   cmp sp, x16
 ;   b.hs #0x1c
 ;   .byte 0x1f, 0xc1, 0x00, 0x00 ; trap: stk_ovf
-; block0: ; offset 0x1c
+; block1: ; offset 0x1c
 ;   ldr x2, #0x24
 ;   b #0x2c
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; reloc_external Abs8 %foo 0
@@ -138,6 +140,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   add x16, x0, #0xb0
@@ -145,7 +148,7 @@ block0(v0: i64):
 ;   b.hs #0x18
 ;   .byte 0x1f, 0xc1, 0x00, 0x00 ; trap: stk_ovf
 ;   sub sp, sp, #0xb0
-; block0: ; offset 0x1c
+; block1: ; offset 0x1c
 ;   add sp, sp, #0xb0
 ;   ldp x29, x30, [sp], #0x10
 ;   ret
@@ -177,6 +180,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   cmp sp, x0
@@ -191,7 +195,7 @@ block0(v0: i64):
 ;   mov w16, #0x1a80
 ;   movk w16, #6, lsl #16
 ;   sub sp, sp, x16
-; block0: ; offset 0x38
+; block1: ; offset 0x38
 ;   mov w16, #0x1a80
 ;   movk w16, #6, lsl #16
 ;   add sp, sp, x16
@@ -223,6 +227,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   ldur x16, [x0]
@@ -232,7 +237,7 @@ block0(v0: i64):
 ;   b.hs #0x20
 ;   .byte 0x1f, 0xc1, 0x00, 0x00 ; trap: stk_ovf
 ;   sub sp, sp, #0x20
-; block0: ; offset 0x24
+; block1: ; offset 0x24
 ;   add sp, sp, #0x20
 ;   ldp x29, x30, [sp], #0x10
 ;   ret
@@ -270,6 +275,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   ldur x16, [x0]
@@ -286,7 +292,7 @@ block0(v0: i64):
 ;   mov w16, #0x1a80
 ;   movk w16, #6, lsl #16
 ;   sub sp, sp, x16
-; block0: ; offset 0x40
+; block1: ; offset 0x40
 ;   mov w16, #0x1a80
 ;   movk w16, #6, lsl #16
 ;   add sp, sp, x16
@@ -316,6 +322,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   mov w16, #0x1a80
@@ -326,7 +333,7 @@ block0(v0: i64):
 ;   b.hs #0x24
 ;   .byte 0x1f, 0xc1, 0x00, 0x00 ; trap: stk_ovf
 ;   sub sp, sp, #0x20
-; block0: ; offset 0x28
+; block1: ; offset 0x28
 ;   add sp, sp, #0x20
 ;   ldp x29, x30, [sp], #0x10
 ;   ret
diff --git a/cranelift/filetests/filetests/isa/aarch64/stack.clif b/cranelift/filetests/filetests/isa/aarch64/stack.clif
index aceed5e669..5753b0ef92 100644
--- a/cranelift/filetests/filetests/isa/aarch64/stack.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/stack.clif
@@ -21,10 +21,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x0, sp
 ;   add sp, sp, #0x10
 ;   ldp x29, x30, [sp], #0x10
@@ -54,12 +55,13 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   mov w16, #0x86b0
 ;   movk w16, #1, lsl #16
 ;   sub sp, sp, x16
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x0, sp
 ;   mov w16, #0x86b0
 ;   movk w16, #1, lsl #16
@@ -87,10 +89,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x1, sp
 ;   ldr x0, [x1]
 ;   add sp, sp, #0x10
@@ -122,12 +125,13 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   mov w16, #0x86b0
 ;   movk w16, #1, lsl #16
 ;   sub sp, sp, x16
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x1, sp
 ;   ldr x0, [x1]
 ;   mov w16, #0x86b0
@@ -156,10 +160,11 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x2, sp
 ;   str x0, [x2]
 ;   add sp, sp, #0x10
@@ -191,12 +196,13 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   mov w16, #0x86b0
 ;   movk w16, #1, lsl #16
 ;   sub sp, sp, x16
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x2, sp
 ;   str x0, [x2]
 ;   mov w16, #0x86b0
@@ -514,6 +520,7 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   stp x27, x28, [sp, #-0x10]!
@@ -522,7 +529,7 @@ block0(v0: i8):
 ;   stp x21, x22, [sp, #-0x10]!
 ;   stp x19, x20, [sp, #-0x10]!
 ;   sub sp, sp, #0x480
-; block0: ; offset 0x20
+; block1: ; offset 0x20
 ;   str x0, [sp, #0x3e8]
 ;   mov x6, #2
 ;   add x9, x6, #1
@@ -690,10 +697,11 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x3, sp
 ;   stp x0, x1, [x3]
 ;   add sp, sp, #0x10
@@ -721,10 +729,11 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x20
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   add x3, sp, #0x20
 ;   stp x0, x1, [x3]
 ;   add sp, sp, #0x20
@@ -756,12 +765,13 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   mov w16, #0x86b0
 ;   movk w16, #1, lsl #16
 ;   sub sp, sp, x16
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x3, sp
 ;   stp x0, x1, [x3]
 ;   mov w16, #0x86b0
@@ -790,10 +800,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x10
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   mov x2, sp
 ;   ldp x0, x1, [x2]
 ;   add sp, sp, #0x10
@@ -821,10 +832,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   sub sp, sp, #0x20
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   add x2, sp, #0x20
 ;   ldp x0, x1, [x2]
 ;   add sp, sp, #0x20
@@ -856,12 +868,13 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   mov w16, #0x86b0
 ;   movk w16, #1, lsl #16
 ;   sub sp, sp, x16
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mov x2, sp
 ;   ldp x0, x1, [x2]
 ;   mov w16, #0x86b0
diff --git a/cranelift/filetests/filetests/isa/aarch64/tls-elf-gd.clif b/cranelift/filetests/filetests/isa/aarch64/tls-elf-gd.clif
index cc7fcd1ebb..674e83516a 100644
--- a/cranelift/filetests/filetests/isa/aarch64/tls-elf-gd.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/tls-elf-gd.clif
@@ -32,6 +32,7 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stp x29, x30, [sp, #-0x10]!
 ;   mov x29, sp
 ;   str x24, [sp, #-0x10]!
@@ -39,7 +40,7 @@ block0(v0: i32):
 ;   stp d12, d13, [sp, #-0x10]!
 ;   stp d10, d11, [sp, #-0x10]!
 ;   stp d8, d9, [sp, #-0x10]!
-; block0: ; offset 0x1c
+; block1: ; offset 0x1c
 ;   mov x24, x0
 ;   adrp x0, #0 ; reloc_external Aarch64TlsGdAdrPage21 u1:0 0
 ;   add x0, x0, #0 ; reloc_external Aarch64TlsGdAddLo12Nc u1:0 0
diff --git a/cranelift/filetests/filetests/isa/riscv64/call-indirect.clif b/cranelift/filetests/filetests/isa/riscv64/call-indirect.clif
index 0f1e6f3c8d..5acc0bb5b6 100644
--- a/cranelift/filetests/filetests/isa/riscv64/call-indirect.clif
+++ b/cranelift/filetests/filetests/isa/riscv64/call-indirect.clif
@@ -22,11 +22,12 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   jalr a1
 ;   ld ra, 8(sp)
 ;   ld s0, 0(sp)
diff --git a/cranelift/filetests/filetests/isa/riscv64/call.clif b/cranelift/filetests/filetests/isa/riscv64/call.clif
index 0e77140a51..63135ed045 100644
--- a/cranelift/filetests/filetests/isa/riscv64/call.clif
+++ b/cranelift/filetests/filetests/isa/riscv64/call.clif
@@ -24,11 +24,12 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   auipc a1, 0
 ;   ld a1, 0xc(a1)
 ;   j 0xc
@@ -63,11 +64,12 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   slli a0, a0, 0x20
 ;   srli a0, a0, 0x20
 ;   auipc a2, 0
@@ -120,11 +122,12 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   slli a0, a0, 0x20
 ;   srai a0, a0, 0x20
 ;   auipc a2, 0
@@ -192,11 +195,12 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   ori t3, a0, 0
 ;   addi sp, sp, -0x10
 ;   addi a0, zero, 0x2a
@@ -335,6 +339,7 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -343,7 +348,7 @@ block0:
 ;   fsd fs3, -0x10(sp)
 ;   fsd fs11, -0x18(sp)
 ;   addi sp, sp, -0x20
-; block0: ; offset 0x20
+; block1: ; offset 0x20
 ;   auipc a6, 0
 ;   ld a6, 0xc(a6)
 ;   j 0xc
@@ -445,11 +450,12 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   ori a5, a0, 0
 ;   addi a0, zero, 0x2a
 ;   ori a1, a5, 0
@@ -510,11 +516,12 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   ori a1, a0, 0
 ;   addi a2, zero, 0x2a
 ;   addi a0, zero, 0x2a
@@ -574,11 +581,12 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   ori a1, a0, 0
 ;   addi a2, zero, 0x2a
 ;   addi a0, zero, 0x2a
@@ -612,11 +620,12 @@ block0(v0: i128, v1: i128, v2: i128, v3: i64, v4: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   ori a0, a7, 0
 ;   ld a1, 0x10(s0)
 ;   ld ra, 8(sp)
@@ -659,11 +668,12 @@ block0(v0: i128, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   ori a7, a0, 0
 ;   ori a6, a2, 0
 ;   addi sp, sp, -0x10
@@ -705,11 +715,12 @@ block0(v0: i128, v1: i128, v2: i128, v3: i64, v4: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   ori a0, a7, 0
 ;   ld a1, 0x10(s0)
 ;   ld ra, 8(sp)
@@ -752,11 +763,12 @@ block0(v0: i128, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
-; block0: ; offset 0x10
+; block1: ; offset 0x10
 ;   ori a7, a0, 0
 ;   ori a6, a2, 0
 ;   addi sp, sp, -0x10
diff --git a/cranelift/filetests/filetests/isa/riscv64/prologue.clif b/cranelift/filetests/filetests/isa/riscv64/prologue.clif
index 08c7db5583..0f2e4dafe8 100644
--- a/cranelift/filetests/filetests/isa/riscv64/prologue.clif
+++ b/cranelift/filetests/filetests/isa/riscv64/prologue.clif
@@ -173,6 +173,7 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -189,7 +190,7 @@ block0(v0: f64):
 ;   fsd fs10, -0x50(sp)
 ;   fsd fs11, -0x58(sp)
 ;   addi sp, sp, -0x60
-; block0: ; offset 0x40
+; block1: ; offset 0x40
 ;   fadd.d ft3, fa0, fa0
 ;   fadd.d ft4, fa0, fa0
 ;   fadd.d ft5, fa0, fa0
@@ -377,6 +378,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -388,7 +390,7 @@ block0(v0: i64):
 ;   sd s9, -0x28(sp)
 ;   sd s10, -0x30(sp)
 ;   addi sp, sp, -0x30
-; block0: ; offset 0x2c
+; block1: ; offset 0x2c
 ;   add t3, a0, a0
 ;   add t4, a0, t3
 ;   add t0, a0, t4
diff --git a/cranelift/filetests/filetests/isa/riscv64/reftypes.clif b/cranelift/filetests/filetests/isa/riscv64/reftypes.clif
index b9db2ff6c8..8ea6e9625c 100644
--- a/cranelift/filetests/filetests/isa/riscv64/reftypes.clif
+++ b/cranelift/filetests/filetests/isa/riscv64/reftypes.clif
@@ -132,13 +132,14 @@ block3(v7: r64, v8: r64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
 ;   sd s7, -8(sp)
 ;   addi sp, sp, -0x30
-; block0: ; offset 0x18
+; block1: ; offset 0x18
 ;   sd a0, 8(sp)
 ;   sd a1, 0x10(sp)
 ;   ori s7, a2, 0
@@ -153,14 +154,14 @@ block3(v7: r64, v8: r64):
 ;   sd t4, 0(a1)
 ;   andi a1, a0, 0xff
 ;   beqz a1, 0x10
-; block1: ; offset 0x50
+; block2: ; offset 0x50
 ;   ori a0, t4, 0
 ;   ld a1, 0x10(sp)
 ;   j 0xc
-; block2: ; offset 0x5c
+; block3: ; offset 0x5c
 ;   ori a1, t4, 0
 ;   ld a0, 0x10(sp)
-; block3: ; offset 0x64
+; block4: ; offset 0x64
 ;   mv a2, sp
 ;   ld a2, 0(a2)
 ;   ori a3, s7, 0
diff --git a/cranelift/filetests/filetests/isa/riscv64/stack-limit.clif b/cranelift/filetests/filetests/isa/riscv64/stack-limit.clif
index 1edc46acbc..ec6b1383c2 100644
--- a/cranelift/filetests/filetests/isa/riscv64/stack-limit.clif
+++ b/cranelift/filetests/filetests/isa/riscv64/stack-limit.clif
@@ -68,13 +68,14 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
 ;   bgeu sp, a0, 8
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; trap: stk_ovf
-; block0: ; offset 0x18
+; block1: ; offset 0x18
 ;   auipc t2, 0
 ;   ld t2, 0xc(t2)
 ;   j 0xc
@@ -114,6 +115,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -122,7 +124,7 @@ block0(v0: i64):
 ;   ld t6, 4(t6)
 ;   bgeu sp, t6, 8
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; trap: stk_ovf
-; block0: ; offset 0x20
+; block1: ; offset 0x20
 ;   auipc t2, 0
 ;   ld t2, 0xc(t2)
 ;   j 0xc
@@ -156,6 +158,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -164,7 +167,7 @@ block0(v0: i64):
 ;   bgeu sp, t6, 8
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; trap: stk_ovf
 ;   addi sp, sp, -0xb0
-; block0: ; offset 0x20
+; block1: ; offset 0x20
 ;   addi sp, sp, 0xb0
 ;   ld ra, 8(sp)
 ;   ld s0, 0(sp)
@@ -199,6 +202,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -221,7 +225,7 @@ block0(v0: i64):
 ;   lui t6, 0xfff9e
 ;   addi t6, t6, 0x580
 ;   add sp, t6, sp
-; block0: ; offset 0x58
+; block1: ; offset 0x58
 ;   lui t6, 0x62
 ;   addi t6, t6, -0x580
 ;   add sp, t6, sp
@@ -258,6 +262,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -268,7 +273,7 @@ block0(v0: i64):
 ;   bgeu sp, t6, 8
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; trap: stk_ovf
 ;   addi sp, sp, -0x20
-; block0: ; offset 0x28
+; block1: ; offset 0x28
 ;   addi sp, sp, 0x20
 ;   ld ra, 8(sp)
 ;   ld s0, 0(sp)
@@ -309,6 +314,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -333,7 +339,7 @@ block0(v0: i64):
 ;   lui t6, 0xfff9e
 ;   addi t6, t6, 0x580
 ;   add sp, t6, sp
-; block0: ; offset 0x60
+; block1: ; offset 0x60
 ;   lui t6, 0x62
 ;   addi t6, t6, -0x580
 ;   add sp, t6, sp
@@ -368,6 +374,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -383,7 +390,7 @@ block0(v0: i64):
 ;   bgeu sp, t6, 8
 ;   .byte 0x00, 0x00, 0x00, 0x00 ; trap: stk_ovf
 ;   addi sp, sp, -0x20
-; block0: ; offset 0x3c
+; block1: ; offset 0x3c
 ;   addi sp, sp, 0x20
 ;   ld ra, 8(sp)
 ;   ld s0, 0(sp)
diff --git a/cranelift/filetests/filetests/isa/riscv64/stack.clif b/cranelift/filetests/filetests/isa/riscv64/stack.clif
index 4e83ecdbfd..6ad38bb1ec 100644
--- a/cranelift/filetests/filetests/isa/riscv64/stack.clif
+++ b/cranelift/filetests/filetests/isa/riscv64/stack.clif
@@ -26,12 +26,13 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
 ;   addi sp, sp, -0x10
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mv a0, sp
 ;   addi sp, sp, 0x10
 ;   ld ra, 8(sp)
@@ -66,6 +67,7 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -81,7 +83,7 @@ block0:
 ;   lui t6, 0xfffe8
 ;   addi t6, t6, -0x6b0
 ;   add sp, t6, sp
-; block0: ; offset 0x3c
+; block1: ; offset 0x3c
 ;   mv a0, sp
 ;   lui t6, 0x18
 ;   addi t6, t6, 0x6b0
@@ -115,12 +117,13 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
 ;   addi sp, sp, -0x10
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mv t1, sp
 ;   ld a0, 0(t1)
 ;   addi sp, sp, 0x10
@@ -157,6 +160,7 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -172,7 +176,7 @@ block0:
 ;   lui t6, 0xfffe8
 ;   addi t6, t6, -0x6b0
 ;   add sp, t6, sp
-; block0: ; offset 0x3c
+; block1: ; offset 0x3c
 ;   mv t1, sp
 ;   ld a0, 0(t1)
 ;   lui t6, 0x18
@@ -207,12 +211,13 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
 ;   addi sp, sp, -0x10
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mv t2, sp
 ;   sd a0, 0(t2)
 ;   addi sp, sp, 0x10
@@ -249,6 +254,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -264,7 +270,7 @@ block0(v0: i64):
 ;   lui t6, 0xfffe8
 ;   addi t6, t6, -0x6b0
 ;   add sp, t6, sp
-; block0: ; offset 0x3c
+; block1: ; offset 0x3c
 ;   mv t2, sp
 ;   sd a0, 0(t2)
 ;   lui t6, 0x18
@@ -610,6 +616,7 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -626,7 +633,7 @@ block0(v0: i8):
 ;   sd s10, -0x50(sp)
 ;   sd s11, -0x58(sp)
 ;   addi sp, sp, -0x500
-; block0: ; offset 0x40
+; block1: ; offset 0x40
 ;   sd a0, 0x3e8(sp)
 ;   addi t3, zero, 2
 ;   addi t1, t3, 1
@@ -818,12 +825,13 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
 ;   addi sp, sp, -0x10
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   ori a2, a0, 0
 ;   mv a0, sp
 ;   sd a2, 0(a0)
@@ -861,12 +869,13 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
 ;   addi sp, sp, -0x20
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   ori a2, a0, 0
 ;   addi a0, sp, 0x20
 ;   sd a2, 0(a0)
@@ -907,6 +916,7 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -922,7 +932,7 @@ block0(v0: i128):
 ;   lui t6, 0xfffe8
 ;   addi t6, t6, -0x6b0
 ;   add sp, t6, sp
-; block0: ; offset 0x3c
+; block1: ; offset 0x3c
 ;   ori a2, a0, 0
 ;   mv a0, sp
 ;   sd a2, 0(a0)
@@ -960,12 +970,13 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
 ;   addi sp, sp, -0x10
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   mv t2, sp
 ;   ld a0, 0(t2)
 ;   ld a1, 8(t2)
@@ -1001,12 +1012,13 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
 ;   ori s0, sp, 0
 ;   addi sp, sp, -0x20
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   addi t2, sp, 0x20
 ;   ld a0, 0(t2)
 ;   ld a1, 8(t2)
@@ -1045,6 +1057,7 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   addi sp, sp, -0x10
 ;   sd ra, 8(sp)
 ;   sd s0, 0(sp)
@@ -1060,7 +1073,7 @@ block0:
 ;   lui t6, 0xfffe8
 ;   addi t6, t6, -0x6b0
 ;   add sp, t6, sp
-; block0: ; offset 0x3c
+; block1: ; offset 0x3c
 ;   mv t2, sp
 ;   ld a0, 0(t2)
 ;   ld a1, 8(t2)
diff --git a/cranelift/filetests/filetests/isa/s390x/arithmetic.clif b/cranelift/filetests/filetests/isa/s390x/arithmetic.clif
index c87f584377..8803998743 100644
--- a/cranelift/filetests/filetests/isa/s390x/arithmetic.clif
+++ b/cranelift/filetests/filetests/isa/s390x/arithmetic.clif
@@ -967,8 +967,9 @@ block0(v0: i128, v1: i128):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r7, %r15, 0x38(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r10, %r2
 ;   vl %v1, 0(%r3)
 ;   vl %v3, 0(%r4)
@@ -1555,8 +1556,9 @@ block0(v0: i32, v1: i32):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r7, %r15, 0x38(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r7, %r3
 ;   lgfr %r3, %r2
 ;   iilf %r4, 0x7fffffff
@@ -1826,8 +1828,9 @@ block0(v0: i16, v1: i16):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r8, %r15, 0x40(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r4, %r3
 ;   lhi %r5, 0
 ;   lgr %r8, %r5
@@ -1891,8 +1894,9 @@ block0(v0: i8, v1: i8):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r8, %r15, 0x40(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r4, %r3
 ;   lhi %r5, 0
 ;   lgr %r8, %r5
@@ -2089,8 +2093,9 @@ block0(v0: i16, v1: i16):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r8, %r15, 0x40(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r4, %r3
 ;   lhi %r5, 0
 ;   lgr %r8, %r5
@@ -2123,8 +2128,9 @@ block0(v0: i8, v1: i8):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r8, %r15, 0x40(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r4, %r3
 ;   lhi %r5, 0
 ;   lgr %r8, %r5
diff --git a/cranelift/filetests/filetests/isa/s390x/atomic_cas-little.clif b/cranelift/filetests/filetests/isa/s390x/atomic_cas-little.clif
index fc1fc1686a..a236eb4409 100644
--- a/cranelift/filetests/filetests/isa/s390x/atomic_cas-little.clif
+++ b/cranelift/filetests/filetests/isa/s390x/atomic_cas-little.clif
@@ -70,8 +70,9 @@ block0(v0: i64, v1: i16, v2: i16, v3: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r11, %r15, 0x58(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   sllk %r11, %r5, 3
 ;   nill %r5, 0xfffc
 ;   lrvr %r2, %r3
@@ -109,8 +110,9 @@ block0(v0: i64, v1: i8, v2: i8, v3: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r10, %r15, 0x50(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r10, %r3
 ;   sllk %r3, %r5, 3
 ;   nill %r5, 0xfffc
diff --git a/cranelift/filetests/filetests/isa/s390x/atomic_cas.clif b/cranelift/filetests/filetests/isa/s390x/atomic_cas.clif
index 78b80aaa41..935a349242 100644
--- a/cranelift/filetests/filetests/isa/s390x/atomic_cas.clif
+++ b/cranelift/filetests/filetests/isa/s390x/atomic_cas.clif
@@ -89,8 +89,9 @@ block0(v0: i64, v1: i8, v2: i8, v3: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r10, %r15, 0x50(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r10, %r3
 ;   sllk %r3, %r5, 3
 ;   nill %r5, 0xfffc
diff --git a/cranelift/filetests/filetests/isa/s390x/call.clif b/cranelift/filetests/filetests/isa/s390x/call.clif
index 9fabef2c92..88044bd38a 100644
--- a/cranelift/filetests/filetests/isa/s390x/call.clif
+++ b/cranelift/filetests/filetests/isa/s390x/call.clif
@@ -24,9 +24,10 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   bras %r1, 0x16
 ;   .byte 0x00, 0x00 ; reloc_external Abs8 %g 0
 ;   .byte 0x00, 0x00
@@ -57,9 +58,10 @@ block0(v0: i32):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   llgfr %r2, %r2
 ;   bras %r1, 0x1a
 ;   .byte 0x00, 0x00 ; reloc_external Abs8 %g 0
@@ -106,9 +108,10 @@ block0(v0: i32):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   lgfr %r2, %r2
 ;   bras %r1, 0x1a
 ;   .byte 0x00, 0x00 ; reloc_external Abs8 %g 0
@@ -153,9 +156,10 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   brasl %r14, 0xa ; reloc_external PLTRel32Dbl %g 2
 ;   lmg %r14, %r15, 0x110(%r15)
 ;   br %r14
@@ -180,9 +184,10 @@ block0(v0: i32):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   llgfr %r2, %r2
 ;   bras %r1, 0x1a
 ;   .byte 0x00, 0x00 ; reloc_external Abs8 %g 0
@@ -211,9 +216,10 @@ block0(v0: i64, v1: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   basr %r14, %r3
 ;   lmg %r14, %r15, 0x110(%r15)
 ;   br %r14
@@ -271,8 +277,9 @@ block0(v0: i64, v1: i32, v2: i32, v3: i32, v4: i16, v5: i16, v6: i16, v7: i8, v8
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r6, %r15, 0x30(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lg %r12, 0xa0(%r15)
 ;   lg %r14, 0xa8(%r15)
 ;   llgc %r7, 0xb7(%r15)
@@ -378,9 +385,10 @@ block0:
 ;   trap
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   lghi %r2, 0
 ;   brasl %r14, 0xe ; reloc_external PLTRel32Dbl %g 2
 ;   .byte 0x00, 0x00 ; trap: user0
diff --git a/cranelift/filetests/filetests/isa/s390x/div-traps.clif b/cranelift/filetests/filetests/isa/s390x/div-traps.clif
index b1d98a43d0..5b776de46c 100644
--- a/cranelift/filetests/filetests/isa/s390x/div-traps.clif
+++ b/cranelift/filetests/filetests/isa/s390x/div-traps.clif
@@ -92,8 +92,9 @@ block0(v0: i32, v1: i32):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r7, %r15, 0x38(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgfr %r5, %r2
 ;   lgr %r7, %r5
 ;   cite %r3, 0 ; trap: int_divz
@@ -379,8 +380,9 @@ block0(v0: i16, v1: i16):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r8, %r15, 0x40(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r4, %r3
 ;   lhi %r5, 0
 ;   lgr %r8, %r5
@@ -446,8 +448,9 @@ block0(v0: i8, v1: i8):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r8, %r15, 0x40(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r4, %r3
 ;   lhi %r5, 0
 ;   lgr %r8, %r5
@@ -670,8 +673,9 @@ block0(v0: i16, v1: i16):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r8, %r15, 0x40(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r4, %r3
 ;   lhi %r5, 0
 ;   lgr %r8, %r5
@@ -706,8 +710,9 @@ block0(v0: i8, v1: i8):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r8, %r15, 0x40(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lgr %r4, %r3
 ;   lhi %r5, 0
 ;   lgr %r8, %r5
diff --git a/cranelift/filetests/filetests/isa/s390x/fp_sp_pc.clif b/cranelift/filetests/filetests/isa/s390x/fp_sp_pc.clif
index 62a8425e08..e96993ec6d 100644
--- a/cranelift/filetests/filetests/isa/s390x/fp_sp_pc.clif
+++ b/cranelift/filetests/filetests/isa/s390x/fp_sp_pc.clif
@@ -20,11 +20,12 @@ block0:
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   lgr %r1, %r15
 ;   aghi %r15, -0xa0
 ;   stg %r1, 0(%r15)
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   lg %r2, 0(%r15)
 ;   lmg %r14, %r15, 0x110(%r15)
 ;   br %r14
@@ -47,11 +48,12 @@ block0:
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   lgr %r1, %r15
 ;   aghi %r15, -0xa0
 ;   stg %r1, 0(%r15)
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   lgr %r2, %r15
 ;   lmg %r14, %r15, 0x110(%r15)
 ;   br %r14
@@ -74,11 +76,12 @@ block0:
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   lgr %r1, %r15
 ;   aghi %r15, -0xa0
 ;   stg %r1, 0(%r15)
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   lg %r2, 0x110(%r15)
 ;   lmg %r14, %r15, 0x110(%r15)
 ;   br %r14
diff --git a/cranelift/filetests/filetests/isa/s390x/leaf_with_preserve_frame_pointers.clif b/cranelift/filetests/filetests/isa/s390x/leaf_with_preserve_frame_pointers.clif
index d7a1de8204..c11d1b5e23 100644
--- a/cranelift/filetests/filetests/isa/s390x/leaf_with_preserve_frame_pointers.clif
+++ b/cranelift/filetests/filetests/isa/s390x/leaf_with_preserve_frame_pointers.clif
@@ -21,11 +21,12 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   lgr %r1, %r15
 ;   aghi %r15, -0xa0
 ;   stg %r1, 0(%r15)
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   lmg %r14, %r15, 0x110(%r15)
 ;   br %r14
 
diff --git a/cranelift/filetests/filetests/isa/s390x/multivalue-ret.clif b/cranelift/filetests/filetests/isa/s390x/multivalue-ret.clif
index b88bc92702..546d60c90f 100644
--- a/cranelift/filetests/filetests/isa/s390x/multivalue-ret.clif
+++ b/cranelift/filetests/filetests/isa/s390x/multivalue-ret.clif
@@ -54,8 +54,9 @@ block1:
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r7, %r15, 0x38(%r15)
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   lghi %r4, 1
 ;   lgr %r14, %r4
 ;   lghi %r3, 2
diff --git a/cranelift/filetests/filetests/isa/s390x/reftypes.clif b/cranelift/filetests/filetests/isa/s390x/reftypes.clif
index 11e5824a9d..03e0a72dda 100644
--- a/cranelift/filetests/filetests/isa/s390x/reftypes.clif
+++ b/cranelift/filetests/filetests/isa/s390x/reftypes.clif
@@ -126,9 +126,10 @@ block3(v7: r64, v8: r64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xb8
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   stg %r2, 0xa8(%r15)
 ;   stg %r3, 0xb0(%r15)
 ;   bras %r1, 0x22
@@ -144,14 +145,14 @@ block3(v7: r64, v8: r64):
 ;   lbr %r2, %r2
 ;   chi %r2, 0
 ;   jgnlh 0x58
-; block1: ; offset 0x48
+; block2: ; offset 0x48
 ;   lgr %r2, %r4
 ;   lg %r3, 0xb0(%r15)
 ;   jg 0x62
-; block2: ; offset 0x58
+; block3: ; offset 0x58
 ;   lgr %r3, %r4
 ;   lg %r2, 0xb0(%r15)
-; block3: ; offset 0x62
+; block4: ; offset 0x62
 ;   la %r4, 0xa0(%r15)
 ;   lg %r4, 0(%r4)
 ;   lmg %r14, %r15, 0x128(%r15)
diff --git a/cranelift/filetests/filetests/isa/s390x/stack-limit.clif b/cranelift/filetests/filetests/isa/s390x/stack-limit.clif
index 0d01c49ca2..93387a5dca 100644
--- a/cranelift/filetests/filetests/isa/s390x/stack-limit.clif
+++ b/cranelift/filetests/filetests/isa/s390x/stack-limit.clif
@@ -63,10 +63,11 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   clgrtle %r15, %r2 ; trap: stk_ovf
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xe
+; block1: ; offset 0xe
 ;   bras %r1, 0x1a
 ;   .byte 0x00, 0x00 ; reloc_external Abs8 %foo 0
 ;   .byte 0x00, 0x00
@@ -102,12 +103,13 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   lg %r1, 0(%r2)
 ;   lg %r1, 4(%r1)
 ;   clgrtle %r15, %r1 ; trap: stk_ovf
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0x1a
+; block1: ; offset 0x1a
 ;   bras %r1, 0x26
 ;   .byte 0x00, 0x00 ; reloc_external Abs8 %foo 0
 ;   .byte 0x00, 0x00
@@ -133,10 +135,11 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   la %r1, 0xa8(%r2)
 ;   clgrtle %r15, %r1 ; trap: stk_ovf
 ;   aghi %r15, -0xa8
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   aghi %r15, 0xa8
 ;   br %r14
 
@@ -156,11 +159,12 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   clgrtle %r15, %r2 ; trap: stk_ovf
 ;   lay %r1, 0x61a80(%r2)
 ;   clgrtle %r15, %r1 ; trap: stk_ovf
 ;   agfi %r15, -0x61a80
-; block0: ; offset 0x14
+; block1: ; offset 0x14
 ;   agfi %r15, 0x61a80
 ;   br %r14
 
@@ -181,12 +185,13 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   clgrtle %r15, %r2 ; trap: stk_ovf
 ;   lgr %r1, %r2
 ;   algfi %r1, 0x3d0900
 ;   clgrtle %r15, %r1 ; trap: stk_ovf
 ;   agfi %r15, -0x3d0900
-; block0: ; offset 0x18
+; block1: ; offset 0x18
 ;   agfi %r15, 0x3d0900
 ;   br %r14
 
@@ -211,12 +216,13 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   lg %r1, 0(%r2)
 ;   lg %r1, 4(%r1)
 ;   la %r1, 0x18(%r1)
 ;   clgrtle %r15, %r1 ; trap: stk_ovf
 ;   aghi %r15, -0x18
-; block0: ; offset 0x18
+; block1: ; offset 0x18
 ;   aghi %r15, 0x18
 ;   br %r14
 
@@ -242,13 +248,14 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   lg %r1, 0(%r2)
 ;   lg %r1, 4(%r1)
 ;   clgrtle %r15, %r1 ; trap: stk_ovf
 ;   lay %r1, 0x61a80(%r1)
 ;   clgrtle %r15, %r1 ; trap: stk_ovf
 ;   agfi %r15, -0x61a80
-; block0: ; offset 0x20
+; block1: ; offset 0x20
 ;   agfi %r15, 0x61a80
 ;   br %r14
 
@@ -274,13 +281,14 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   lg %r1, 0(%r2)
 ;   lg %r1, 4(%r1)
 ;   clgrtle %r15, %r1 ; trap: stk_ovf
 ;   algfi %r1, 0x3d0900
 ;   clgrtle %r15, %r1 ; trap: stk_ovf
 ;   agfi %r15, -0x3d0900
-; block0: ; offset 0x20
+; block1: ; offset 0x20
 ;   agfi %r15, 0x3d0900
 ;   br %r14
 
@@ -303,12 +311,13 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   lgfi %r1, 0xf4240
 ;   lg %r1, 0(%r1, %r2)
 ;   la %r1, 0x18(%r1)
 ;   clgrtle %r15, %r1 ; trap: stk_ovf
 ;   aghi %r15, -0x18
-; block0: ; offset 0x18
+; block1: ; offset 0x18
 ;   aghi %r15, 0x18
 ;   br %r14
 
diff --git a/cranelift/filetests/filetests/isa/s390x/stack.clif b/cranelift/filetests/filetests/isa/s390x/stack.clif
index 708bd69837..cc7fa045eb 100644
--- a/cranelift/filetests/filetests/isa/s390x/stack.clif
+++ b/cranelift/filetests/filetests/isa/s390x/stack.clif
@@ -19,8 +19,9 @@ block0:
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   aghi %r15, -8
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   la %r2, 0(%r15)
 ;   aghi %r15, 8
 ;   br %r14
@@ -42,8 +43,9 @@ block0:
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   agfi %r15, -0x186a8
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   la %r2, 0(%r15)
 ;   agfi %r15, 0x186a8
 ;   br %r14
@@ -65,8 +67,9 @@ block0:
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   aghi %r15, -8
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   la %r3, 0(%r15)
 ;   lg %r2, 0(%r3)
 ;   aghi %r15, 8
@@ -90,8 +93,9 @@ block0:
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   agfi %r15, -0x186a8
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   la %r3, 0(%r15)
 ;   lg %r2, 0(%r3)
 ;   agfi %r15, 0x186a8
@@ -114,8 +118,9 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   aghi %r15, -8
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   la %r4, 0(%r15)
 ;   stg %r2, 0(%r4)
 ;   aghi %r15, 8
@@ -139,8 +144,9 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   agfi %r15, -0x186a8
-; block0: ; offset 0x6
+; block1: ; offset 0x6
 ;   la %r4, 0(%r15)
 ;   stg %r2, 0(%r4)
 ;   agfi %r15, 0x186a8
diff --git a/cranelift/filetests/filetests/isa/s390x/struct-arg.clif b/cranelift/filetests/filetests/isa/s390x/struct-arg.clif
index 6f4bfc7843..026047adb7 100644
--- a/cranelift/filetests/filetests/isa/s390x/struct-arg.clif
+++ b/cranelift/filetests/filetests/isa/s390x/struct-arg.clif
@@ -59,9 +59,10 @@ block0(v0: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xe0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   mvc 0xa0(0x40, %r15), 0(%r2)
 ;   la %r2, 0xa0(%r15)
 ;   brasl %r14, 0x14 ; reloc_external PLTRel32Dbl u0:0 2
@@ -88,9 +89,10 @@ block0(v0: i64, v1: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xe0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   mvc 0xa0(0x40, %r15), 0(%r3)
 ;   la %r3, 0xa0(%r15)
 ;   brasl %r14, 0x14 ; reloc_external PLTRel32Dbl u0:0 2
@@ -143,9 +145,10 @@ block0(v0: i64, v1: i64, v2: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0x1e0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   mvc 0xa0(0x100, %r15), 0(%r3)
 ;   mvc 0x1a0(0x40, %r15), 0(%r4)
 ;   la %r3, 0xa0(%r15)
@@ -183,9 +186,10 @@ block0(v0: i64, v1: i64, v2: i64):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r7, %r15, 0x38(%r15)
 ;   aghi %r15, -0x4e0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   lgr %r7, %r2
 ;   lgr %r9, %r4
 ;   la %r2, 0xa0(%r15)
diff --git a/cranelift/filetests/filetests/isa/s390x/tls_elf.clif b/cranelift/filetests/filetests/isa/s390x/tls_elf.clif
index f895bbd0b0..8370a6f9df 100644
--- a/cranelift/filetests/filetests/isa/s390x/tls_elf.clif
+++ b/cranelift/filetests/filetests/isa/s390x/tls_elf.clif
@@ -26,9 +26,10 @@ block0(v0: i32):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r12, %r15, 0x60(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   larl %r12, 0xa ; reloc_external PCRel32Dbl %ElfGlobalOffsetTable 2
 ;   bras %r1, 0x1c
 ;   .byte 0x00, 0x00 ; reloc_external TlsGd64 u1:0 0
diff --git a/cranelift/filetests/filetests/isa/s390x/vec-abi.clif b/cranelift/filetests/filetests/isa/s390x/vec-abi.clif
index ee2d06c0aa..124ee25acd 100644
--- a/cranelift/filetests/filetests/isa/s390x/vec-abi.clif
+++ b/cranelift/filetests/filetests/isa/s390x/vec-abi.clif
@@ -20,9 +20,10 @@ block0(v0: i64x2, v1: i32x4, v2: i16x8, v3: i8x16):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   bras %r1, 0x16
 ;   .byte 0x00, 0x00 ; reloc_external Abs8 %callee_be 0
 ;   .byte 0x00, 0x00
@@ -80,6 +81,7 @@ block0(v0: i64x2, v1: i32x4, v2: i16x8, v3: i8x16):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xe0
 ;   std %f8, 0xa0(%r15)
@@ -90,7 +92,7 @@ block0(v0: i64x2, v1: i32x4, v2: i16x8, v3: i8x16):
 ;   std %f13, 0xc8(%r15)
 ;   std %f14, 0xd0(%r15)
 ;   std %f15, 0xd8(%r15)
-; block0: ; offset 0x2a
+; block1: ; offset 0x2a
 ;   vpdi %v24, %v24, %v24, 4
 ;   vpdi %v7, %v25, %v25, 4
 ;   verllg %v25, %v7, 0x20
@@ -168,6 +170,7 @@ block0(v0: i64x2, v1: i32x4, v2: i16x8, v3: i8x16):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xe0
 ;   std %f8, 0xa0(%r15)
@@ -178,7 +181,7 @@ block0(v0: i64x2, v1: i32x4, v2: i16x8, v3: i8x16):
 ;   std %f13, 0xc8(%r15)
 ;   std %f14, 0xd0(%r15)
 ;   std %f15, 0xd8(%r15)
-; block0: ; offset 0x2a
+; block1: ; offset 0x2a
 ;   vpdi %v24, %v24, %v24, 4
 ;   vpdi %v7, %v25, %v25, 4
 ;   verllg %v25, %v7, 0x20
@@ -228,9 +231,10 @@ block0(v0: i64x2, v1: i32x4, v2: i16x8, v3: i8x16):
 ;   br %r14
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   stmg %r14, %r15, 0x70(%r15)
 ;   aghi %r15, -0xa0
-; block0: ; offset 0xa
+; block1: ; offset 0xa
 ;   bras %r1, 0x16
 ;   .byte 0x00, 0x00 ; reloc_external Abs8 %callee_le 0
 ;   .byte 0x00, 0x00
diff --git a/cranelift/filetests/filetests/isa/x64/amode-opt.clif b/cranelift/filetests/filetests/isa/x64/amode-opt.clif
index a842be4514..2de9483263 100644
--- a/cranelift/filetests/filetests/isa/x64/amode-opt.clif
+++ b/cranelift/filetests/filetests/isa/x64/amode-opt.clif
@@ -18,9 +18,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq (%rdi, %rsi), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -44,9 +45,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq 0x2a(%rdi), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -70,9 +72,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq 0x2a(%rdi), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -97,9 +100,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq 0x2a(%rdi), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -124,9 +128,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq 0x140(%rdi, %rsi), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -151,9 +156,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq -1(%rdi, %rsi), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -179,9 +185,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq -1(%rdi, %rsi, 8), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -209,9 +216,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl %esi, %ecx
 ;   movq -1(%rdi, %rcx, 8), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
@@ -242,9 +250,10 @@ block0(v0: i64, v1: i32, v2: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %r8
 ;   addl %edx, %r8d
 ;   movq -1(%rdi, %r8, 4), %rax ; trap: heap_oob
diff --git a/cranelift/filetests/filetests/isa/x64/band_not_bmi1.clif b/cranelift/filetests/filetests/isa/x64/band_not_bmi1.clif
index 2c93ffb4cd..3a687ccfcc 100644
--- a/cranelift/filetests/filetests/isa/x64/band_not_bmi1.clif
+++ b/cranelift/filetests/filetests/isa/x64/band_not_bmi1.clif
@@ -18,9 +18,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   andnl %edi, %esi, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -43,9 +44,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   andnl %esi, %edi, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/basic.clif b/cranelift/filetests/filetests/isa/x64/basic.clif
index 9af3478b52..d10885cd07 100644
--- a/cranelift/filetests/filetests/isa/x64/basic.clif
+++ b/cranelift/filetests/filetests/isa/x64/basic.clif
@@ -18,9 +18,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   addl %esi, %eax
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/bitcast.clif b/cranelift/filetests/filetests/isa/x64/bitcast.clif
index cf804009b1..72a5008fcd 100644
--- a/cranelift/filetests/filetests/isa/x64/bitcast.clif
+++ b/cranelift/filetests/filetests/isa/x64/bitcast.clif
@@ -17,9 +17,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movd %xmm0, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movd %edi, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -65,9 +67,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %xmm0, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -89,9 +92,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/bmask.clif b/cranelift/filetests/filetests/isa/x64/bmask.clif
index 6e3504fd34..20f3419328 100644
--- a/cranelift/filetests/filetests/isa/x64/bmask.clif
+++ b/cranelift/filetests/filetests/isa/x64/bmask.clif
@@ -22,9 +22,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negq %rax
 ;   movq %rdi, %rax
@@ -52,9 +53,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negq %rax
 ;   movq %rdi, %rax
@@ -82,9 +84,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negq %rax
 ;   movq %rdi, %rax
@@ -112,9 +115,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negq %rax
 ;   movq %rdi, %rax
@@ -142,9 +146,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negl %eax
 ;   movq %rdi, %rax
@@ -172,9 +177,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negl %eax
 ;   movq %rdi, %rax
@@ -202,9 +208,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negl %eax
 ;   movq %rdi, %rax
@@ -232,9 +239,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negl %eax
 ;   movq %rdi, %rax
@@ -262,9 +270,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negw %ax
 ;   movq %rdi, %rax
@@ -292,9 +301,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negw %ax
 ;   movq %rdi, %rax
@@ -322,9 +332,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negw %ax
 ;   movq %rdi, %rax
@@ -352,9 +363,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negw %ax
 ;   movq %rdi, %rax
@@ -382,9 +394,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negb %al
 ;   movq %rdi, %rax
@@ -412,9 +425,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negb %al
 ;   movq %rdi, %rax
@@ -442,9 +456,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negb %al
 ;   movq %rdi, %rax
@@ -472,9 +487,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negb %al
 ;   movq %rdi, %rax
@@ -504,9 +520,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rdx
 ;   orq %rsi, %rdx
 ;   movq %rdx, %r8
@@ -537,9 +554,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   orq %rsi, %rax
 ;   movq %rax, %r8
@@ -569,9 +587,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   orq %rsi, %rax
 ;   movq %rax, %r8
@@ -601,9 +620,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   orq %rsi, %rax
 ;   movq %rax, %r8
@@ -633,9 +653,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   orq %rsi, %rax
 ;   movq %rax, %r8
@@ -665,9 +686,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negq %rax
 ;   movq %rdi, %rdx
@@ -697,9 +719,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negl %eax
 ;   movq %rdi, %rdx
@@ -729,9 +752,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negw %ax
 ;   movq %rdi, %rdx
@@ -761,9 +785,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negb %al
 ;   movq %rdi, %rdx
diff --git a/cranelift/filetests/filetests/isa/x64/branches.clif b/cranelift/filetests/filetests/isa/x64/branches.clif
index 22b6635364..666e8e2abd 100644
--- a/cranelift/filetests/filetests/isa/x64/branches.clif
+++ b/cranelift/filetests/filetests/isa/x64/branches.clif
@@ -33,17 +33,18 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpl %esi, %edi
 ;   jne 0x16
-; block1: ; offset 0xc
+; block2: ; offset 0xc
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x16
+; block3: ; offset 0x16
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -81,17 +82,18 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpl %esi, %edi
 ;   jne 0x16
-; block1: ; offset 0xc
+; block2: ; offset 0xc
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x16
+; block3: ; offset 0x16
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -129,17 +131,18 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpl %esi, %edi
 ;   jne 0x16
-; block1: ; offset 0xc
+; block2: ; offset 0xc
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x16
+; block3: ; offset 0x16
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -178,18 +181,19 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   ucomiss %xmm1, %xmm0
 ;   jp 0x1d
 ;   jne 0x1d
-; block1: ; offset 0x13
+; block2: ; offset 0x13
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x1d
+; block3: ; offset 0x1d
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -226,18 +230,19 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   ucomiss %xmm1, %xmm0
 ;   jp 0x1a
 ;   jne 0x1a
-; block1: ; offset 0x13
+; block2: ; offset 0x13
 ;   xorl %eax, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x1a
+; block3: ; offset 0x1a
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -274,18 +279,19 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   ucomiss %xmm1, %xmm0
 ;   jp 0x13
 ;   je 0x1a
-; block1: ; offset 0x13
+; block2: ; offset 0x13
 ;   xorl %eax, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x1a
+; block3: ; offset 0x1a
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -326,9 +332,10 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpl $2, %edi
 ;   jae 0x34
 ;   movl %edi, %r9d
@@ -342,12 +349,12 @@ block2:
 ;   addb %al, (%rax)
 ;   adcb (%rax), %al
 ;   addb %al, (%rax)
-; block1: ; offset 0x34
+; block2: ; offset 0x34
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x3e
+; block3: ; offset 0x3e
 ;   xorl %eax, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -384,17 +391,18 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpq $0, %rdi
 ;   jge 0x18
-; block1: ; offset 0xe
+; block2: ; offset 0xe
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x18
+; block3: ; offset 0x18
 ;   xorl %eax, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -431,17 +439,18 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpl $0, %edi
 ;   jge 0x17
-; block1: ; offset 0xd
+; block2: ; offset 0xd
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x17
+; block3: ; offset 0x17
 ;   xorl %eax, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -493,22 +502,23 @@ block202:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0x42500000, %edx
 ;   movd %edx, %xmm6
 ;   ucomiss %xmm6, %xmm0
 ;   jp 0x1c
 ;   je 0x33
-; block1: ; offset 0x1c
+; block2: ; offset 0x1c
 ;   movl $0x42500000, %r11d
 ;   movd %r11d, %xmm10
 ;   ucomiss %xmm10, %xmm0
 ;   jp 0x33
-; block2: ; offset 0x31
+; block3: ; offset 0x31
 ;   ud2 ; trap: heap_oob
-; block3: ; offset 0x33
+; block4: ; offset 0x33
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
@@ -546,17 +556,18 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpl %esi, %edi
 ;   jne 0x16
-; block1: ; offset 0xc
+; block2: ; offset 0xc
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x16
+; block3: ; offset 0x16
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -596,18 +607,19 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   ucomiss %xmm1, %xmm0
 ;   jp 0x1d
 ;   jne 0x1d
-; block1: ; offset 0x13
+; block2: ; offset 0x13
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x1d
+; block3: ; offset 0x1d
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -646,17 +658,18 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpl %esi, %edi
 ;   jne 0x16
-; block1: ; offset 0xc
+; block2: ; offset 0xc
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x16
+; block3: ; offset 0x16
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -696,18 +709,19 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   ucomiss %xmm1, %xmm0
 ;   jp 0x1d
 ;   jne 0x1d
-; block1: ; offset 0x13
+; block2: ; offset 0x13
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x1d
+; block3: ; offset 0x1d
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/bswap.clif b/cranelift/filetests/filetests/isa/x64/bswap.clif
index 65d73157af..2e5663691d 100644
--- a/cranelift/filetests/filetests/isa/x64/bswap.clif
+++ b/cranelift/filetests/filetests/isa/x64/bswap.clif
@@ -18,9 +18,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   bswapq %rax
 ;   movq %rbp, %rsp
@@ -44,9 +45,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   bswapl %eax
 ;   movq %rbp, %rsp
@@ -70,9 +72,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   rolw $8, %ax
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/call-conv.clif b/cranelift/filetests/filetests/isa/x64/call-conv.clif
index 351c6ca283..e3a34a7e3a 100644
--- a/cranelift/filetests/filetests/isa/x64/call-conv.clif
+++ b/cranelift/filetests/filetests/isa/x64/call-conv.clif
@@ -24,9 +24,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rcx
 ;   subq $0x20, %rsp
 ;   callq *%rcx
@@ -64,9 +65,10 @@ block0(v0: i32, v1: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm6
 ;   subq $0x20, %rsp
 ;   movq %rdi, %rcx
@@ -124,6 +126,7 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0xb0, %rsp
@@ -139,7 +142,7 @@ block0(v0: i32):
 ;   movdqu %xmm13, 0x80(%rsp)
 ;   movdqu %xmm14, 0x90(%rsp)
 ;   movdqu %xmm15, 0xa0(%rsp)
-; block0: ; offset 0x61
+; block1: ; offset 0x61
 ;   callq *%rcx
 ;   movq (%rsp), %rsi
 ;   movq 8(%rsp), %rdi
@@ -228,9 +231,10 @@ block0(
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rcx, %rax
 ;   movq %rdx, %rcx
 ;   movq %rsi, %rdx
@@ -296,9 +300,10 @@ block0(v0: i64, v1:i64, v2:i64, v3:i64, v4:i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %r11
 ;   movq %rcx, %r9
 ;   movq %rsi, %rdx
@@ -347,9 +352,10 @@ block0(v0: i32, v1: f32, v2: i64, v3: f64, v4: i32, v5: i32, v6: i32, v7: f32, v
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %r9
 ;   movq %rdi, %rsi
 ;   movdqa %xmm1, %xmm12
@@ -388,9 +394,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   callq *%rdi
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -413,9 +420,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   callq *%rdi
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -446,9 +454,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $1, %esi
 ;   subq $0x10, %rsp
 ;   leaq (%rsp), %rdi
@@ -485,11 +494,12 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x10, %rsp
 ;   movq %rbx, (%rsp)
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   movq %rdi, %rbx
 ;   movl $1, %eax
 ;   callq *%rax
@@ -534,11 +544,12 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x10, %rsp
 ;   movq %r13, (%rsp)
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   movq %rdi, %r13
 ;   movl $1, %eax
 ;   subq $0x10, %rsp
@@ -583,11 +594,12 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x10, %rsp
 ;   movq %r13, (%rsp)
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   movq %rdi, %r13
 ;   movl $1, %eax
 ;   callq *%rax
@@ -629,11 +641,12 @@ block0(v0: f32, v1: i64, v2: i32, v3: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x10, %rsp
 ;   movq %r12, (%rsp)
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   movq %rdx, %r12
 ;   movl $1, %r9d
 ;   callq *%r9
diff --git a/cranelift/filetests/filetests/isa/x64/ceil-libcall.clif b/cranelift/filetests/filetests/isa/x64/ceil-libcall.clif
index e3c28f1aa9..075bab6a5c 100644
--- a/cranelift/filetests/filetests/isa/x64/ceil-libcall.clif
+++ b/cranelift/filetests/filetests/isa/x64/ceil-libcall.clif
@@ -18,9 +18,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %rcx ; reloc_external Abs8 %CeilF32 0
 ;   callq *%rcx
 ;   movq %rbp, %rsp
@@ -44,9 +45,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %rcx ; reloc_external Abs8 %CeilF64 0
 ;   callq *%rcx
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/ceil.clif b/cranelift/filetests/filetests/isa/x64/ceil.clif
index f16eb297a1..cbd1e32d94 100644
--- a/cranelift/filetests/filetests/isa/x64/ceil.clif
+++ b/cranelift/filetests/filetests/isa/x64/ceil.clif
@@ -17,9 +17,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundss $2, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundsd $2, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -65,9 +67,10 @@ block0(v0: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundps $2, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -89,9 +92,10 @@ block0(v0: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundpd $2, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/clz-lzcnt.clif b/cranelift/filetests/filetests/isa/x64/clz-lzcnt.clif
index 6f6cf79d8d..300236167d 100644
--- a/cranelift/filetests/filetests/isa/x64/clz-lzcnt.clif
+++ b/cranelift/filetests/filetests/isa/x64/clz-lzcnt.clif
@@ -17,9 +17,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   lzcntq %rdi, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   lzcntl %edi, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/cmp-mem-bug.clif b/cranelift/filetests/filetests/isa/x64/cmp-mem-bug.clif
index 8ed9d5b84e..459302bebb 100644
--- a/cranelift/filetests/filetests/isa/x64/cmp-mem-bug.clif
+++ b/cranelift/filetests/filetests/isa/x64/cmp-mem-bug.clif
@@ -26,9 +26,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq (%rsi), %r9 ; trap: heap_oob
 ;   cmpq %r9, %rdi
 ;   sete %r10b
@@ -68,9 +69,10 @@ block0(v0: f64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movsd (%rdi), %xmm9 ; trap: heap_oob
 ;   ucomisd %xmm9, %xmm0
 ;   setnp %dil
diff --git a/cranelift/filetests/filetests/isa/x64/conditional-values.clif b/cranelift/filetests/filetests/isa/x64/conditional-values.clif
index 82f6c3bee8..6426d95ec7 100644
--- a/cranelift/filetests/filetests/isa/x64/conditional-values.clif
+++ b/cranelift/filetests/filetests/isa/x64/conditional-values.clif
@@ -19,9 +19,10 @@ block0(v0: i8, v1: i32, v2: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   testb %dil, %dil
 ;   movq %rdx, %rax
 ;   cmovnel %esi, %eax
@@ -58,17 +59,18 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   testb %dil, %dil
 ;   je 0x17
-; block1: ; offset 0xd
+; block2: ; offset 0xd
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x17
+; block3: ; offset 0x17
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -103,17 +105,18 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   testb %dil, %dil
 ;   je 0x17
-; block1: ; offset 0xd
+; block2: ; offset 0xd
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x17
+; block3: ; offset 0x17
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -152,18 +155,19 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl (%rdi), %edx ; trap: heap_oob
 ;   cmpl $1, %edx
 ;   jne 0x19
-; block1: ; offset 0xf
+; block2: ; offset 0xf
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x19
+; block3: ; offset 0x19
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -202,18 +206,19 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl (%rdi), %edx ; trap: heap_oob
 ;   cmpl $1, %edx
 ;   jne 0x19
-; block1: ; offset 0xf
+; block2: ; offset 0xf
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x19
+; block3: ; offset 0x19
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -237,9 +242,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shrq $0x3f, %rax
 ;   movq %rbp, %rsp
@@ -264,9 +270,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shrl $0x1f, %eax
 ;   movq %rbp, %rsp
@@ -291,9 +298,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shrq $0x3f, %rax
 ;   movq %rbp, %rsp
@@ -318,9 +326,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shrl $0x1f, %eax
 ;   movq %rbp, %rsp
@@ -346,9 +355,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   notq %rax
 ;   shrq $0x3f, %rax
@@ -375,9 +385,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   notq %rax
 ;   shrl $0x1f, %eax
@@ -404,9 +415,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   notq %rax
 ;   shrq $0x3f, %rax
@@ -433,9 +445,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   notq %rax
 ;   shrl $0x1f, %eax
diff --git a/cranelift/filetests/filetests/isa/x64/ctz-bmi1.clif b/cranelift/filetests/filetests/isa/x64/ctz-bmi1.clif
index d41e68cb2c..47bae4fb80 100644
--- a/cranelift/filetests/filetests/isa/x64/ctz-bmi1.clif
+++ b/cranelift/filetests/filetests/isa/x64/ctz-bmi1.clif
@@ -17,9 +17,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   tzcntq %rdi, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   tzcntl %edi, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/div-checks.clif b/cranelift/filetests/filetests/isa/x64/div-checks.clif
index 173c01beaa..b147c49dca 100644
--- a/cranelift/filetests/filetests/isa/x64/div-checks.clif
+++ b/cranelift/filetests/filetests/isa/x64/div-checks.clif
@@ -27,9 +27,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   xorl %edx, %edx
 ;   cmpb $0, %sil
@@ -66,9 +67,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   xorl %edx, %edx
 ;   cmpw $0, %si
@@ -105,9 +107,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   xorl %edx, %edx
 ;   cmpl $0, %esi
@@ -144,9 +147,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   xorl %edx, %edx
 ;   cmpq $0, %rsi
diff --git a/cranelift/filetests/filetests/isa/x64/extractlane.clif b/cranelift/filetests/filetests/isa/x64/extractlane.clif
index 9459a09d34..abe9882d36 100644
--- a/cranelift/filetests/filetests/isa/x64/extractlane.clif
+++ b/cranelift/filetests/filetests/isa/x64/extractlane.clif
@@ -17,9 +17,10 @@ block0(v0: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pextrb $1, %xmm0, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pextrw $1, %xmm0, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -65,9 +67,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pextrd $1, %xmm0, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -89,9 +92,10 @@ block0(v0: i64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pextrq $1, %xmm0, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -113,9 +117,10 @@ block0(v0: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pshufd $1, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -137,9 +142,10 @@ block0(v0: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pshufd $0xee, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/fabs.clif b/cranelift/filetests/filetests/isa/x64/fabs.clif
index 5ef0e0d3be..574d34cc12 100644
--- a/cranelift/filetests/filetests/isa/x64/fabs.clif
+++ b/cranelift/filetests/filetests/isa/x64/fabs.clif
@@ -19,9 +19,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0x7fffffff, %eax
 ;   movd %eax, %xmm4
 ;   andps %xmm4, %xmm0
@@ -47,9 +48,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0x7fffffffffffffff, %rax
 ;   movq %rax, %xmm4
 ;   andpd %xmm4, %xmm0
@@ -75,9 +77,10 @@ block0(v0: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pcmpeqd %xmm3, %xmm3
 ;   psrld $1, %xmm3
 ;   andps %xmm3, %xmm0
@@ -103,9 +106,10 @@ block0(v0: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pcmpeqd %xmm3, %xmm3
 ;   psrlq $1, %xmm3
 ;   andpd %xmm3, %xmm0
diff --git a/cranelift/filetests/filetests/isa/x64/fastcall.clif b/cranelift/filetests/filetests/isa/x64/fastcall.clif
index f6c97c1cef..cdb178f133 100644
--- a/cranelift/filetests/filetests/isa/x64/fastcall.clif
+++ b/cranelift/filetests/filetests/isa/x64/fastcall.clif
@@ -20,9 +20,10 @@ block0(v0: i64, v1: i64, v2: i64, v3: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rcx, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -45,9 +46,10 @@ block0(v0: i64, v1: i64, v2: i64, v3: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -70,9 +72,10 @@ block0(v0: i64, v1: i64, v2: i64, v3: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %r8, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -95,9 +98,10 @@ block0(v0: i64, v1: i64, v2: i64, v3: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %r9, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -120,9 +124,10 @@ block0(v0: i64, v1: i64, v2: f64, v3: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm2, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -145,9 +150,10 @@ block0(v0: i64, v1: i64, v2: f64, v3: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %r9, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -181,9 +187,10 @@ block0(v0: i64, v1: i64, v2: i64, v3: i64, v4: i64, v5: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq 0x30(%rbp), %r8
 ;   movq 0x38(%rbp), %rax
 ;   movq %rbp, %rsp
@@ -209,9 +216,10 @@ block0(v0: i128, v1: i64, v2: i128, v3: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq 0x30(%rbp), %r8
 ;   movq 0x38(%rbp), %rax
 ;   movq 0x40(%rbp), %rdx
@@ -252,9 +260,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvtsi2sdq %rcx, %xmm3
 ;   subq $0x30, %rsp
 ;   movq %rcx, 0x20(%rsp)
@@ -413,6 +422,7 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x100, %rsp
@@ -426,7 +436,7 @@ block0(v0: i64):
 ;   movdqu %xmm13, 0xd0(%rsp)
 ;   movdqu %xmm14, 0xe0(%rsp)
 ;   movdqu %xmm15, 0xf0(%rsp)
-; block0: ; offset 0x67
+; block1: ; offset 0x67
 ;   movsd (%rcx), %xmm0 ; trap: heap_oob
 ;   movsd 8(%rcx), %xmm10 ; trap: heap_oob
 ;   movdqu %xmm10, 0x50(%rsp)
diff --git a/cranelift/filetests/filetests/isa/x64/fcopysign.clif b/cranelift/filetests/filetests/isa/x64/fcopysign.clif
index 243dc5612a..83441825eb 100644
--- a/cranelift/filetests/filetests/isa/x64/fcopysign.clif
+++ b/cranelift/filetests/filetests/isa/x64/fcopysign.clif
@@ -23,9 +23,10 @@ block0(v0: f32, v1: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0x80000000, %ecx
 ;   movd %ecx, %xmm7
 ;   movdqa %xmm0, %xmm10
@@ -59,9 +60,10 @@ block0(v0: f64, v1: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $9223372036854775808, %rcx
 ;   movq %rcx, %xmm7
 ;   movdqa %xmm0, %xmm10
diff --git a/cranelift/filetests/filetests/isa/x64/fcvt-simd.clif b/cranelift/filetests/filetests/isa/x64/fcvt-simd.clif
index 5f38389e65..fb7baa7536 100644
--- a/cranelift/filetests/filetests/isa/x64/fcvt-simd.clif
+++ b/cranelift/filetests/filetests/isa/x64/fcvt-simd.clif
@@ -18,9 +18,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   vcvtudq2ps %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/fcvt.clif b/cranelift/filetests/filetests/isa/x64/fcvt.clif
index b6ca34f51e..40d570cce9 100644
--- a/cranelift/filetests/filetests/isa/x64/fcvt.clif
+++ b/cranelift/filetests/filetests/isa/x64/fcvt.clif
@@ -18,9 +18,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movsbl %dil, %eax
 ;   cvtsi2ssl %eax, %xmm0
 ;   movq %rbp, %rsp
@@ -44,9 +45,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movswl %di, %eax
 ;   cvtsi2ssl %eax, %xmm0
 ;   movq %rbp, %rsp
@@ -69,9 +71,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvtsi2ssl %edi, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -93,9 +96,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvtsi2ssq %rdi, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -118,9 +122,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movsbl %dil, %eax
 ;   cvtsi2sdl %eax, %xmm0
 ;   movq %rbp, %rsp
@@ -144,9 +149,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movswl %di, %eax
 ;   cvtsi2sdl %eax, %xmm0
 ;   movq %rbp, %rsp
@@ -169,9 +175,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvtsi2sdl %edi, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -193,9 +200,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvtsi2sdq %rdi, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -217,9 +225,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvtdq2pd %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -256,9 +265,10 @@ block0(v0: i8, v1: i16, v2: i32, v3: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movzbq %dil, %r9
 ;   cvtsi2ssq %r9, %xmm0
 ;   movzwq %si, %r9
@@ -303,9 +313,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0x14(%rip), %xmm2
 ;   unpcklps %xmm2, %xmm0
 ;   movdqu 0x19(%rip), %xmm6
@@ -353,9 +364,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm3
 ;   pslld $0x10, %xmm3
 ;   psrld $0x10, %xmm3
@@ -386,9 +398,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0x4f000000, %r8d
 ;   movd %r8d, %xmm3
 ;   ucomiss %xmm3, %xmm0
@@ -426,9 +439,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0x5f000000, %r8d
 ;   movd %r8d, %xmm3
 ;   ucomiss %xmm3, %xmm0
@@ -467,9 +481,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0x41e0000000000000, %r8
 ;   movq %r8, %xmm3
 ;   ucomisd %xmm3, %xmm0
@@ -507,9 +522,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0x43e0000000000000, %r8
 ;   movq %r8, %xmm3
 ;   ucomisd %xmm3, %xmm0
@@ -548,9 +564,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0x4f000000, %r8d
 ;   movd %r8d, %xmm3
 ;   ucomiss %xmm3, %xmm0
@@ -591,9 +608,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0x5f000000, %r8d
 ;   movd %r8d, %xmm3
 ;   ucomiss %xmm3, %xmm0
@@ -635,9 +653,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0x41e0000000000000, %r8
 ;   movq %r8, %xmm3
 ;   ucomisd %xmm3, %xmm0
@@ -678,9 +697,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0x43e0000000000000, %r8
 ;   movq %r8, %xmm3
 ;   ucomisd %xmm3, %xmm0
@@ -722,9 +742,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvttss2si %xmm0, %eax
 ;   cmpl $1, %eax
 ;   jno 0x3f
@@ -760,9 +781,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvttss2si %xmm0, %rax
 ;   cmpq $1, %rax
 ;   jno 0x41
@@ -798,9 +820,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvttsd2si %xmm0, %eax
 ;   cmpl $1, %eax
 ;   jno 0x48
@@ -836,9 +859,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvttsd2si %xmm0, %rax
 ;   cmpq $1, %rax
 ;   jno 0x4a
@@ -874,9 +898,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvttss2si %xmm0, %eax
 ;   cmpl $1, %eax
 ;   jno 0x33
@@ -908,9 +933,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvttss2si %xmm0, %rax
 ;   cmpq $1, %rax
 ;   jno 0x3b
@@ -942,9 +968,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvttsd2si %xmm0, %eax
 ;   cmpl $1, %eax
 ;   jno 0x35
@@ -976,9 +1003,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cvttsd2si %xmm0, %rax
 ;   cmpq $1, %rax
 ;   jno 0x3d
@@ -1023,9 +1051,10 @@ block0(v0: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pxor %xmm2, %xmm2
 ;   movdqa %xmm0, %xmm9
 ;   maxps %xmm2, %xmm9
@@ -1069,9 +1098,10 @@ block0(v0: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm4
 ;   cmpeqps %xmm0, %xmm4
 ;   movdqa %xmm0, %xmm5
diff --git a/cranelift/filetests/filetests/isa/x64/floating-point.clif b/cranelift/filetests/filetests/isa/x64/floating-point.clif
index 02ce7b853e..61c7b1953a 100644
--- a/cranelift/filetests/filetests/isa/x64/floating-point.clif
+++ b/cranelift/filetests/filetests/isa/x64/floating-point.clif
@@ -19,9 +19,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0x7fffffffffffffff, %rax
 ;   movq %rax, %xmm4
 ;   andpd %xmm4, %xmm0
@@ -49,9 +50,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movsd (%rdi), %xmm0 ; trap: heap_oob
 ;   movabsq $0x7fffffffffffffff, %rcx
 ;   movq %rcx, %xmm5
diff --git a/cranelift/filetests/filetests/isa/x64/floor-libcall.clif b/cranelift/filetests/filetests/isa/x64/floor-libcall.clif
index 4753232aab..98dc9f8c43 100644
--- a/cranelift/filetests/filetests/isa/x64/floor-libcall.clif
+++ b/cranelift/filetests/filetests/isa/x64/floor-libcall.clif
@@ -18,9 +18,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %rcx ; reloc_external Abs8 %FloorF32 0
 ;   callq *%rcx
 ;   movq %rbp, %rsp
@@ -44,9 +45,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %rcx ; reloc_external Abs8 %FloorF64 0
 ;   callq *%rcx
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/floor.clif b/cranelift/filetests/filetests/isa/x64/floor.clif
index 173a92197d..9eb8ca6265 100644
--- a/cranelift/filetests/filetests/isa/x64/floor.clif
+++ b/cranelift/filetests/filetests/isa/x64/floor.clif
@@ -17,9 +17,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundss $1, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundsd $1, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -65,9 +67,10 @@ block0(v0: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundps $1, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -89,9 +92,10 @@ block0(v0: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundpd $1, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/fma-call.clif b/cranelift/filetests/filetests/isa/x64/fma-call.clif
index 3ab3b3a805..25b62371b6 100644
--- a/cranelift/filetests/filetests/isa/x64/fma-call.clif
+++ b/cranelift/filetests/filetests/isa/x64/fma-call.clif
@@ -18,9 +18,10 @@ block0(v0: f32, v1: f32, v2: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %r8 ; reloc_external Abs8 %FmaF32 0
 ;   callq *%r8
 ;   movq %rbp, %rsp
@@ -44,9 +45,10 @@ block0(v0: f64, v1: f64, v2: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %r8 ; reloc_external Abs8 %FmaF64 0
 ;   callq *%r8
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/fma-inst.clif b/cranelift/filetests/filetests/isa/x64/fma-inst.clif
index aa90421a28..16f6ca2267 100644
--- a/cranelift/filetests/filetests/isa/x64/fma-inst.clif
+++ b/cranelift/filetests/filetests/isa/x64/fma-inst.clif
@@ -17,9 +17,10 @@ block0(v0: f32, v1: f32, v2: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   vfmadd213ss %xmm2, %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: f64, v1: f64, v2: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   vfmadd213sd %xmm2, %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/fneg.clif b/cranelift/filetests/filetests/isa/x64/fneg.clif
index 90da792850..d990c31c14 100644
--- a/cranelift/filetests/filetests/isa/x64/fneg.clif
+++ b/cranelift/filetests/filetests/isa/x64/fneg.clif
@@ -19,9 +19,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0x80000000, %eax
 ;   movd %eax, %xmm4
 ;   xorps %xmm4, %xmm0
@@ -47,9 +48,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $9223372036854775808, %rax
 ;   movq %rax, %xmm4
 ;   xorpd %xmm4, %xmm0
@@ -75,9 +77,10 @@ block0(v0: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pcmpeqd %xmm3, %xmm3
 ;   pslld $0x1f, %xmm3
 ;   xorps %xmm3, %xmm0
@@ -103,9 +106,10 @@ block0(v0: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pcmpeqd %xmm3, %xmm3
 ;   psllq $0x3f, %xmm3
 ;   xorpd %xmm3, %xmm0
diff --git a/cranelift/filetests/filetests/isa/x64/fp_sp_pc.clif b/cranelift/filetests/filetests/isa/x64/fp_sp_pc.clif
index b129c8bf83..89731b4520 100644
--- a/cranelift/filetests/filetests/isa/x64/fp_sp_pc.clif
+++ b/cranelift/filetests/filetests/isa/x64/fp_sp_pc.clif
@@ -18,9 +18,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rbp, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -42,9 +43,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsp, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -67,9 +69,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rbp, %rsi
 ;   movq 8(%rsi), %rax
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/i128.clif b/cranelift/filetests/filetests/isa/x64/i128.clif
index 62346303ea..53b1e9b3f2 100644
--- a/cranelift/filetests/filetests/isa/x64/i128.clif
+++ b/cranelift/filetests/filetests/isa/x64/i128.clif
@@ -21,9 +21,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   addq %rdx, %rax
 ;   movq %rsi, %rdx
@@ -51,9 +52,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   subq %rdx, %rax
 ;   movq %rsi, %rdx
@@ -81,9 +83,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   andq %rdx, %rax
 ;   movq %rsi, %rdx
@@ -111,9 +114,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   orq %rdx, %rax
 ;   movq %rsi, %rdx
@@ -141,9 +145,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   xorq %rdx, %rax
 ;   movq %rsi, %rdx
@@ -171,9 +176,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   notq %rax
 ;   movq %rsi, %rdx
@@ -210,9 +216,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rax
 ;   movq %rdi, %rdx
 ;   imulq %rcx, %rdx
@@ -247,9 +254,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rdx
 ;   movq %rdi, %rax
 ;   movq %rbp, %rsp
@@ -273,9 +281,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rdx
 ;   movq %rdi, %rax
 ;   movq %rbp, %rsp
@@ -424,6 +433,7 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x40, %rsp
@@ -432,7 +442,7 @@ block0(v0: i128, v1: i128):
 ;   movq %r13, 0x20(%rsp)
 ;   movq %r14, 0x28(%rsp)
 ;   movq %r15, 0x30(%rsp)
-; block0: ; offset 0x21
+; block1: ; offset 0x21
 ;   cmpq %rdx, %rdi
 ;   sete %r9b
 ;   cmpq %rcx, %rsi
@@ -575,21 +585,22 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpq $0, %rdi
 ;   sete %r9b
 ;   cmpq $0, %rsi
 ;   sete %sil
 ;   testb %r9b, %sil
 ;   jne 0x27
-; block1: ; offset 0x1d
+; block2: ; offset 0x1d
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x27
+; block3: ; offset 0x27
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -630,21 +641,22 @@ block2:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpq $0, %rdi
 ;   sete %r9b
 ;   cmpq $0, %rsi
 ;   sete %sil
 ;   testb %r9b, %sil
 ;   jne 0x27
-; block1: ; offset 0x1d
+; block2: ; offset 0x1d
 ;   movl $1, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x27
+; block3: ; offset 0x27
 ;   movl $2, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -667,9 +679,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   xorq %rdx, %rdx
 ;   movq %rbp, %rsp
@@ -694,9 +707,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rdx
 ;   sarq $0x3f, %rdx
 ;   movq %rdi, %rax
@@ -722,9 +736,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movsbq %dil, %rax
 ;   movq %rax, %rdx
 ;   sarq $0x3f, %rdx
@@ -749,9 +764,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movzbq %dil, %rax
 ;   xorq %rdx, %rdx
 ;   movq %rbp, %rsp
@@ -774,9 +790,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -798,9 +815,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -823,9 +841,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movzbq %dil, %rax
 ;   xorq %rdx, %rdx
 ;   movq %rbp, %rsp
@@ -889,9 +908,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shrq $1, %rax
 ;   movabsq $0x7777777777777777, %r8
@@ -1037,9 +1057,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0x5555555555555555, %rcx
 ;   movq %rsi, %rdx
 ;   andq %rcx, %rdx
@@ -1145,9 +1166,10 @@ block0(v0: i128, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, (%rdx) ; trap: heap_oob
 ;   movq %rsi, 8(%rdx) ; trap: heap_oob
 ;   movq %rbp, %rsp
@@ -1171,9 +1193,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq (%rdi), %rax ; trap: heap_oob
 ;   movq 8(%rdi), %rdx ; trap: heap_oob
 ;   movq %rbp, %rsp
@@ -1227,14 +1250,15 @@ block2(v8: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   xorq %rax, %rax
 ;   xorq %r9, %r9
 ;   testb %dl, %dl
 ;   je 0x29
-; block1: ; offset 0x12
+; block2: ; offset 0x12
 ;   movl $1, %r8d
 ;   xorq %r10, %r10
 ;   addq %r8, %rax
@@ -1243,7 +1267,7 @@ block2(v8: i128):
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x29
+; block3: ; offset 0x29
 ;   movq %r9, %rdx
 ;   movl $2, %r9d
 ;   xorq %r11, %r11
@@ -1308,6 +1332,7 @@ block0(v0: i128, v1: i128, v2: i64, v3: i128, v4: i128, v5: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x20, %rsp
@@ -1315,7 +1340,7 @@ block0(v0: i128, v1: i128, v2: i64, v3: i128, v4: i128, v5: i128):
 ;   movq %r12, 8(%rsp)
 ;   movq %r14, 0x10(%rsp)
 ;   movq %r15, 0x18(%rsp)
-; block0: ; offset 0x1b
+; block1: ; offset 0x1b
 ;   movq %r8, %r14
 ;   movq %rcx, %rbx
 ;   movq %rdx, %rcx
@@ -1375,9 +1400,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, (%rdx)
 ;   movq %rsi, 8(%rdx)
 ;   movq %rdi, 0x10(%rdx)
@@ -1426,11 +1452,12 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x10, %rsp
 ;   movq %r13, (%rsp)
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   movq %r8, %r13
 ;   subq $0x10, %rsp
 ;   leaq (%rsp), %r8
@@ -1478,9 +1505,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %r8
 ;   movq $18446744073709551615, %rcx
 ;   bsrq %rsi, %r9
@@ -1525,9 +1553,10 @@ block0(v0: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0x40, %ecx
 ;   bsfq %rdi, %rax
 ;   cmoveq %rcx, %rax
@@ -1561,9 +1590,10 @@ block0(v0: i8, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -1605,9 +1635,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %rdx
 ;   shlq %cl, %rdx
@@ -1663,9 +1694,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r8
 ;   shrq %cl, %r8
@@ -1723,9 +1755,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r8
 ;   shrq %cl, %r8
@@ -1805,9 +1838,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %rdx
 ;   shlq %cl, %rdx
@@ -1908,9 +1942,10 @@ block0(v0: i128, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r8
 ;   shrq %cl, %r8
diff --git a/cranelift/filetests/filetests/isa/x64/iabs.clif b/cranelift/filetests/filetests/isa/x64/iabs.clif
index 02bea8d040..f9eed8f12d 100644
--- a/cranelift/filetests/filetests/isa/x64/iabs.clif
+++ b/cranelift/filetests/filetests/isa/x64/iabs.clif
@@ -19,9 +19,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negb %al
 ;   cmovsl %edi, %eax
@@ -47,9 +48,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negw %ax
 ;   cmovsl %edi, %eax
@@ -75,9 +77,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negl %eax
 ;   cmovsl %edi, %eax
@@ -103,9 +106,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   negq %rax
 ;   cmovsq %rdi, %rax
diff --git a/cranelift/filetests/filetests/isa/x64/immediates.clif b/cranelift/filetests/filetests/isa/x64/immediates.clif
index 9283cd8bce..bdbd7ece6a 100644
--- a/cranelift/filetests/filetests/isa/x64/immediates.clif
+++ b/cranelift/filetests/filetests/isa/x64/immediates.clif
@@ -35,9 +35,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %r9
 ;   addq 0x32(%rip), %r9
 ;   movq %r9, (%rsi) ; trap: heap_oob
diff --git a/cranelift/filetests/filetests/isa/x64/inline-probestack-large.clif b/cranelift/filetests/filetests/isa/x64/inline-probestack-large.clif
index 57785bb04c..85fea2fcb8 100644
--- a/cranelift/filetests/filetests/isa/x64/inline-probestack-large.clif
+++ b/cranelift/filetests/filetests/isa/x64/inline-probestack-large.clif
@@ -28,10 +28,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x2000, %rsp
-; block0: ; offset 0xb
+; block1: ; offset 0xb
 ;   leaq (%rsp), %rax
 ;   addq $0x2000, %rsp
 ;   movq %rbp, %rsp
@@ -61,13 +62,14 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   movl %esp, -0x10000(%rsp)
 ;   movl %esp, -0x20000(%rsp)
 ;   movl %esp, -0x30000(%rsp)
 ;   subq $0x30000, %rsp
-; block0: ; offset 0x20
+; block1: ; offset 0x20
 ;   leaq (%rsp), %rax
 ;   addq $0x30000, %rsp
 ;   movq %rbp, %rsp
@@ -95,6 +97,7 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   movq %rsp, %r11
@@ -105,7 +108,7 @@ block0:
 ;   jne 0xe
 ;   addq $0x200000, %rsp
 ;   subq $0x200000, %rsp
-; block0: ; offset 0x2f
+; block1: ; offset 0x2f
 ;   leaq (%rsp), %rax
 ;   addq $0x200000, %rsp
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/inline-probestack.clif b/cranelift/filetests/filetests/isa/x64/inline-probestack.clif
index ddb042ea2e..a8f95b7f12 100644
--- a/cranelift/filetests/filetests/isa/x64/inline-probestack.clif
+++ b/cranelift/filetests/filetests/isa/x64/inline-probestack.clif
@@ -27,10 +27,11 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x800, %rsp
-; block0: ; offset 0xb
+; block1: ; offset 0xb
 ;   leaq (%rsp), %rax
 ;   addq $0x800, %rsp
 ;   movq %rbp, %rsp
@@ -60,13 +61,14 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   movl %esp, -0x1000(%rsp)
 ;   movl %esp, -0x2000(%rsp)
 ;   movl %esp, -0x3000(%rsp)
 ;   subq $0x3000, %rsp
-; block0: ; offset 0x20
+; block1: ; offset 0x20
 ;   leaq (%rsp), %rax
 ;   addq $0x3000, %rsp
 ;   movq %rbp, %rsp
@@ -94,6 +96,7 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   movq %rsp, %r11
@@ -104,7 +107,7 @@ block0:
 ;   jne 0xe
 ;   addq $0x19000, %rsp
 ;   subq $0x186a0, %rsp
-; block0: ; offset 0x2f
+; block1: ; offset 0x2f
 ;   leaq (%rsp), %rax
 ;   addq $0x186a0, %rsp
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/ishl.clif b/cranelift/filetests/filetests/isa/x64/ishl.clif
index 04aa692a9b..73cb469a9e 100644
--- a/cranelift/filetests/filetests/isa/x64/ishl.clif
+++ b/cranelift/filetests/filetests/isa/x64/ishl.clif
@@ -41,9 +41,10 @@ block0(v0: i128, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movzbq %dl, %rcx
 ;   movq %rdi, %rdx
 ;   shlq %cl, %rdx
@@ -99,9 +100,10 @@ block0(v0: i128, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %rdx
 ;   shlq %cl, %rdx
@@ -157,9 +159,10 @@ block0(v0: i128, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %rdx
 ;   shlq %cl, %rdx
@@ -215,9 +218,10 @@ block0(v0: i128, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %rdx
 ;   shlq %cl, %rdx
@@ -273,9 +277,10 @@ block0(v0: i128, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %rdx
 ;   shlq %cl, %rdx
@@ -316,9 +321,10 @@ block0(v0: i64, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shlq %cl, %rax
@@ -344,9 +350,10 @@ block0(v0: i32, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shll %cl, %eax
@@ -373,9 +380,10 @@ block0(v0: i16, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -403,9 +411,10 @@ block0(v0: i8, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -432,9 +441,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shlq %cl, %rax
@@ -460,9 +470,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shlq %cl, %rax
@@ -488,9 +499,10 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shlq %cl, %rax
@@ -516,9 +528,10 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shlq %cl, %rax
@@ -544,9 +557,10 @@ block0(v0: i32, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shll %cl, %eax
@@ -572,9 +586,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shll %cl, %eax
@@ -600,9 +615,10 @@ block0(v0: i32, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shll %cl, %eax
@@ -628,9 +644,10 @@ block0(v0: i32, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shll %cl, %eax
@@ -657,9 +674,10 @@ block0(v0: i16, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -687,9 +705,10 @@ block0(v0: i16, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -717,9 +736,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -747,9 +767,10 @@ block0(v0: i16, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -777,9 +798,10 @@ block0(v0: i8, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -807,9 +829,10 @@ block0(v0: i8, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -837,9 +860,10 @@ block0(v0: i8, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -867,9 +891,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -895,9 +920,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shlq $1, %rax
 ;   movq %rbp, %rsp
@@ -921,9 +947,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shll $1, %eax
 ;   movq %rbp, %rsp
@@ -947,9 +974,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shlw $1, %ax
 ;   movq %rbp, %rsp
@@ -973,9 +1001,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shlb $1, %al
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/leaf.clif b/cranelift/filetests/filetests/isa/x64/leaf.clif
index b90c34b535..dd249331a4 100644
--- a/cranelift/filetests/filetests/isa/x64/leaf.clif
+++ b/cranelift/filetests/filetests/isa/x64/leaf.clif
@@ -20,9 +20,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/leaf_with_preserve_frame_pointers.clif b/cranelift/filetests/filetests/isa/x64/leaf_with_preserve_frame_pointers.clif
index c1ae3e7ed4..7186f567b0 100644
--- a/cranelift/filetests/filetests/isa/x64/leaf_with_preserve_frame_pointers.clif
+++ b/cranelift/filetests/filetests/isa/x64/leaf_with_preserve_frame_pointers.clif
@@ -20,9 +20,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/load-op-store.clif b/cranelift/filetests/filetests/isa/x64/load-op-store.clif
index 7fe8e95859..0d8df4c6c1 100644
--- a/cranelift/filetests/filetests/isa/x64/load-op-store.clif
+++ b/cranelift/filetests/filetests/isa/x64/load-op-store.clif
@@ -19,9 +19,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   addl %esi, 0x20(%rdi) ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -45,9 +46,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   addl %esi, 0x20(%rdi) ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -71,9 +73,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   subl %esi, 0x20(%rdi) ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -97,9 +100,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   andl %esi, 0x20(%rdi) ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -123,9 +127,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   andl %esi, 0x20(%rdi) ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -149,9 +154,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   orl %esi, 0x20(%rdi) ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -175,9 +181,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   orl %esi, 0x20(%rdi) ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -201,9 +208,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   xorl %esi, 0x20(%rdi) ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -227,9 +235,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   xorl %esi, 0x20(%rdi) ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/load-op.clif b/cranelift/filetests/filetests/isa/x64/load-op.clif
index 1ee29c3148..ab140cb5fe 100644
--- a/cranelift/filetests/filetests/isa/x64/load-op.clif
+++ b/cranelift/filetests/filetests/isa/x64/load-op.clif
@@ -19,9 +19,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rax
 ;   addl (%rdi), %eax ; trap: heap_oob
 ;   movq %rbp, %rsp
@@ -46,9 +47,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rax
 ;   addl (%rdi), %eax ; trap: heap_oob
 ;   movq %rbp, %rsp
@@ -73,9 +75,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rax
 ;   addq (%rdi), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
@@ -100,9 +103,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rax
 ;   addq (%rdi), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
@@ -127,9 +131,10 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movzbq (%rdi), %rax ; trap: heap_oob
 ;   addl %esi, %eax
 ;   movq %rbp, %rsp
@@ -159,9 +164,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq (%rdi), %r8 ; trap: heap_oob
 ;   movq %r8, %r9
 ;   addq %rdi, %r9
@@ -193,11 +199,12 @@ block1:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movss (%rdi), %xmm0 ; trap: heap_oob
-; block1: ; offset 0x8
+; block2: ; offset 0x8
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
@@ -222,9 +229,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpq (%rdi), %rdi ; trap: heap_oob
 ;   sete %dl
 ;   movzbq %dl, %rax
diff --git a/cranelift/filetests/filetests/isa/x64/move-elision.clif b/cranelift/filetests/filetests/isa/x64/move-elision.clif
index 48cea6f7af..899ddb0205 100644
--- a/cranelift/filetests/filetests/isa/x64/move-elision.clif
+++ b/cranelift/filetests/filetests/isa/x64/move-elision.clif
@@ -22,9 +22,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
diff --git a/cranelift/filetests/filetests/isa/x64/narrowing.clif b/cranelift/filetests/filetests/isa/x64/narrowing.clif
index 2357bcb4c1..2e9025d5e7 100644
--- a/cranelift/filetests/filetests/isa/x64/narrowing.clif
+++ b/cranelift/filetests/filetests/isa/x64/narrowing.clif
@@ -17,9 +17,10 @@ block0(v0: i16x8, v1: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   packsswb %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   packssdw %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -73,9 +75,10 @@ block0(v0: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm4
 ;   cmpeqpd %xmm0, %xmm4
 ;   movupd 0x1b(%rip), %xmm5
@@ -107,9 +110,10 @@ block0(v0: i16x8, v1: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   packuswb %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -131,9 +135,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   packusdw %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/nearest-libcall.clif b/cranelift/filetests/filetests/isa/x64/nearest-libcall.clif
index 8a5f0d9e1c..c4ad2ad451 100644
--- a/cranelift/filetests/filetests/isa/x64/nearest-libcall.clif
+++ b/cranelift/filetests/filetests/isa/x64/nearest-libcall.clif
@@ -18,9 +18,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %rcx ; reloc_external Abs8 %NearestF32 0
 ;   callq *%rcx
 ;   movq %rbp, %rsp
@@ -44,9 +45,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %rcx ; reloc_external Abs8 %NearestF64 0
 ;   callq *%rcx
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/nearest.clif b/cranelift/filetests/filetests/isa/x64/nearest.clif
index b3e2a625ce..f4af299995 100644
--- a/cranelift/filetests/filetests/isa/x64/nearest.clif
+++ b/cranelift/filetests/filetests/isa/x64/nearest.clif
@@ -17,9 +17,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundss $0, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundsd $0, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -65,9 +67,10 @@ block0(v0: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundps $0, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -89,9 +92,10 @@ block0(v0: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundpd $0, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/pinned-reg.clif b/cranelift/filetests/filetests/isa/x64/pinned-reg.clif
index 5f86e3abba..26bc0b280f 100644
--- a/cranelift/filetests/filetests/isa/x64/pinned-reg.clif
+++ b/cranelift/filetests/filetests/isa/x64/pinned-reg.clif
@@ -22,9 +22,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %r15, %rsi
 ;   addq $1, %rsi
 ;   movq %rsi, %r15
@@ -56,11 +57,12 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x10, %rsp
 ;   movq %rsi, (%rsp)
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   movq %r15, %rsi
 ;   addq $1, %rsi
 ;   movq %rsi, %r15
diff --git a/cranelift/filetests/filetests/isa/x64/popcnt-use-popcnt.clif b/cranelift/filetests/filetests/isa/x64/popcnt-use-popcnt.clif
index f3fc404705..3fc7a69565 100644
--- a/cranelift/filetests/filetests/isa/x64/popcnt-use-popcnt.clif
+++ b/cranelift/filetests/filetests/isa/x64/popcnt-use-popcnt.clif
@@ -17,9 +17,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   popcntq %rdi, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   popcntl %edi, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/popcnt.clif b/cranelift/filetests/filetests/isa/x64/popcnt.clif
index ee14b91573..1718b7518c 100644
--- a/cranelift/filetests/filetests/isa/x64/popcnt.clif
+++ b/cranelift/filetests/filetests/isa/x64/popcnt.clif
@@ -36,9 +36,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rcx
 ;   shrq $1, %rdi
 ;   movq %rcx, %r8
@@ -99,9 +100,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq (%rdi), %rdx ; trap: heap_oob
 ;   movq %rdx, %rcx
 ;   shrq $1, %rcx
@@ -159,9 +161,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shrl $1, %edi
 ;   movl $0x77777777, %edx
@@ -218,9 +221,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl (%rdi), %edx ; trap: heap_oob
 ;   movq %rdx, %rcx
 ;   shrl $1, %ecx
diff --git a/cranelift/filetests/filetests/isa/x64/probestack.clif b/cranelift/filetests/filetests/isa/x64/probestack.clif
index dcf3db1324..2989ea65c4 100644
--- a/cranelift/filetests/filetests/isa/x64/probestack.clif
+++ b/cranelift/filetests/filetests/isa/x64/probestack.clif
@@ -24,12 +24,13 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   movl $0x186a0, %eax
 ;   callq 0xe ; reloc_external CallPCRel4 %Probestack -4
 ;   subq $0x186a0, %rsp
-; block0: ; offset 0x15
+; block1: ; offset 0x15
 ;   leaq (%rsp), %rax
 ;   addq $0x186a0, %rsp
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/sdiv.clif b/cranelift/filetests/filetests/isa/x64/sdiv.clif
index 6307bc90bd..17c79168dc 100644
--- a/cranelift/filetests/filetests/isa/x64/sdiv.clif
+++ b/cranelift/filetests/filetests/isa/x64/sdiv.clif
@@ -19,9 +19,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   cbtw
 ;   idivb %sil ; trap: int_divz
@@ -47,9 +48,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   cwtd
 ;   idivw %si ; trap: int_divz
@@ -75,9 +77,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   cltd
 ;   idivl %esi ; trap: int_divz
@@ -103,9 +106,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   cqto
 ;   idivq %rsi ; trap: int_divz
diff --git a/cranelift/filetests/filetests/isa/x64/select-i128.clif b/cranelift/filetests/filetests/isa/x64/select-i128.clif
index e95dd22e3f..89576c873f 100644
--- a/cranelift/filetests/filetests/isa/x64/select-i128.clif
+++ b/cranelift/filetests/filetests/isa/x64/select-i128.clif
@@ -25,9 +25,10 @@ block0(v0: i32, v1: i128, v2: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpl $0x2a, %edi
 ;   movq %rcx, %rax
 ;   cmoveq %rsi, %rax
@@ -61,9 +62,10 @@ block0(v0: f32, v1: i128, v2: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   ucomiss %xmm0, %xmm0
 ;   movq %rdi, %rax
 ;   cmovneq %rdx, %rax
diff --git a/cranelift/filetests/filetests/isa/x64/select.clif b/cranelift/filetests/filetests/isa/x64/select.clif
index 18ca1fb446..674a01e5fc 100644
--- a/cranelift/filetests/filetests/isa/x64/select.clif
+++ b/cranelift/filetests/filetests/isa/x64/select.clif
@@ -21,9 +21,10 @@ block0(v0: i32, v1: i32, v2: i64, v3: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpl %esi, %edi
 ;   movq %rcx, %rax
 ;   cmoveq %rdx, %rax
@@ -52,9 +53,10 @@ block0(v0: f32, v1: f32, v2: i64, v3: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   ucomiss %xmm0, %xmm1
 ;   movq %rdi, %rax
 ;   cmovneq %rsi, %rax
diff --git a/cranelift/filetests/filetests/isa/x64/sextend.clif b/cranelift/filetests/filetests/isa/x64/sextend.clif
index 814594dcdb..48686505b1 100644
--- a/cranelift/filetests/filetests/isa/x64/sextend.clif
+++ b/cranelift/filetests/filetests/isa/x64/sextend.clif
@@ -17,9 +17,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movsbq %dil, %rax
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/shuffle-avx512.clif b/cranelift/filetests/filetests/isa/x64/shuffle-avx512.clif
index 665c0bb8d9..c7bbf96e44 100644
--- a/cranelift/filetests/filetests/isa/x64/shuffle-avx512.clif
+++ b/cranelift/filetests/filetests/isa/x64/shuffle-avx512.clif
@@ -22,9 +22,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm5
 ;   movdqu 0x10(%rip), %xmm0
 ;   movdqa %xmm5, %xmm6
@@ -65,9 +66,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm7
 ;   movdqu 0x30(%rip), %xmm0
 ;   movdqu 0x18(%rip), %xmm6
@@ -108,9 +110,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm5
 ;   movdqu 0x10(%rip), %xmm0
 ;   movdqa %xmm5, %xmm6
diff --git a/cranelift/filetests/filetests/isa/x64/simd-bitselect.clif b/cranelift/filetests/filetests/isa/x64/simd-bitselect.clif
index 39b6e08436..ea1f1f913c 100644
--- a/cranelift/filetests/filetests/isa/x64/simd-bitselect.clif
+++ b/cranelift/filetests/filetests/isa/x64/simd-bitselect.clif
@@ -25,9 +25,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm4
 ;   pcmpeqb %xmm1, %xmm4
 ;   movdqa %xmm0, %xmm7
@@ -59,9 +60,10 @@ block0(v0: f32x4, v1: f32x4, v2: i32x4, v3: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   cmpeqps %xmm1, %xmm0
 ;   movdqa %xmm3, %xmm6
 ;   pblendvb %xmm0, %xmm2, %xmm6
@@ -91,9 +93,10 @@ block0(v0: i8x16, v1: i8x16, v2: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm4
 ;   pand %xmm2, %xmm4
 ;   movdqa %xmm2, %xmm0
@@ -125,9 +128,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm5
 ;   movdqu 0x20(%rip), %xmm0
 ;   movdqa %xmm5, %xmm6
@@ -173,9 +177,10 @@ block0(v0: i16x8, v1: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm5
 ;   movdqu 0x20(%rip), %xmm0
 ;   movdqa %xmm5, %xmm6
@@ -218,9 +223,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm8
 ;   movdqu 0x1f(%rip), %xmm0
 ;   movdqa %xmm8, %xmm4
diff --git a/cranelift/filetests/filetests/isa/x64/simd-bitwise-compile.clif b/cranelift/filetests/filetests/isa/x64/simd-bitwise-compile.clif
index f9d020d878..056f256013 100644
--- a/cranelift/filetests/filetests/isa/x64/simd-bitwise-compile.clif
+++ b/cranelift/filetests/filetests/isa/x64/simd-bitwise-compile.clif
@@ -18,9 +18,10 @@ block0(v0: f32x4, v1: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   andps %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -42,9 +43,10 @@ block0(v0: f64x2, v1: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   andpd %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -66,9 +68,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pand %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -90,9 +93,10 @@ block0(v0: f32x4, v1: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   orps %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -114,9 +118,10 @@ block0(v0: f64x2, v1: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   orpd %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -138,9 +143,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   por %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -162,9 +168,10 @@ block0(v0: f32x4, v1: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   xorps %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -186,9 +193,10 @@ block0(v0: f64x2, v1: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   xorpd %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -210,9 +218,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pxor %xmm1, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -236,9 +245,10 @@ block0(v0: i16x8, v1: i16x8, v2: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm2, %xmm4
 ;   pblendvb %xmm0, %xmm1, %xmm4
 ;   movdqa %xmm4, %xmm0
@@ -264,9 +274,10 @@ block0(v0: i32x4, v1: f32x4, v2: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm2, %xmm4
 ;   blendvps %xmm0, %xmm1, %xmm4
 ;   movdqa %xmm4, %xmm0
@@ -292,9 +303,10 @@ block0(v0: i64x2, v1: f64x2, v2: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm2, %xmm4
 ;   blendvpd %xmm0, %xmm1, %xmm4
 ;   movdqa %xmm4, %xmm0
@@ -327,9 +339,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0xb4(%rip), %xmm0
 ;   movq %rdi, %r10
 ;   andq $7, %r10
@@ -373,9 +386,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0xb4(%rip), %xmm0
 ;   movl $1, %r9d
 ;   andq $7, %r9
@@ -419,9 +433,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0x33(%rip), %xmm8
 ;   movq %rdi, %r9
 ;   andq $7, %r9
@@ -468,9 +483,10 @@ block0(v0: i8x16, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $3, %r10d
 ;   andq $7, %r10
 ;   movdqa %xmm0, %xmm13
@@ -511,9 +527,10 @@ block0(v0: i64x2, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pextrq $0, %xmm0, %r8
 ;   pextrq $1, %xmm0, %r10
 ;   movq %rdi, %rcx
diff --git a/cranelift/filetests/filetests/isa/x64/simd-comparison-legalize.clif b/cranelift/filetests/filetests/isa/x64/simd-comparison-legalize.clif
index 66402bda54..a7fce09551 100644
--- a/cranelift/filetests/filetests/isa/x64/simd-comparison-legalize.clif
+++ b/cranelift/filetests/filetests/isa/x64/simd-comparison-legalize.clif
@@ -20,9 +20,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pcmpeqd %xmm1, %xmm0
 ;   pcmpeqd %xmm5, %xmm5
 ;   pxor %xmm5, %xmm0
@@ -49,9 +50,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmaxud %xmm1, %xmm0
 ;   pcmpeqd %xmm1, %xmm0
 ;   pcmpeqd %xmm7, %xmm7
@@ -78,9 +80,10 @@ block0(v0: i16x8, v1: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm3
 ;   pmaxsw %xmm1, %xmm3
 ;   pcmpeqw %xmm3, %xmm0
@@ -106,9 +109,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm3
 ;   pmaxub %xmm1, %xmm3
 ;   pcmpeqb %xmm3, %xmm0
diff --git a/cranelift/filetests/filetests/isa/x64/simd-lane-access-compile.clif b/cranelift/filetests/filetests/isa/x64/simd-lane-access-compile.clif
index fe8925c816..790fde063f 100644
--- a/cranelift/filetests/filetests/isa/x64/simd-lane-access-compile.clif
+++ b/cranelift/filetests/filetests/isa/x64/simd-lane-access-compile.clif
@@ -28,9 +28,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0x64(%rip), %xmm0
 ;   movdqu 0x4c(%rip), %xmm4
 ;   movdqu 0x24(%rip), %xmm2
@@ -90,9 +91,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0x24(%rip), %xmm0
 ;   movdqu 0xc(%rip), %xmm1
 ;   pshufb %xmm1, %xmm0
@@ -138,9 +140,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0x34(%rip), %xmm0
 ;   movdqu 0x2c(%rip), %xmm2
 ;   movdqu 0x14(%rip), %xmm3
@@ -183,9 +186,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pinsrb $0, %edi, %xmm0
 ;   pxor %xmm6, %xmm6
 ;   pshufb %xmm6, %xmm0
@@ -214,9 +218,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0xffffffff, %esi
 ;   pinsrw $0, %esi, %xmm4
 ;   pinsrw $1, %esi, %xmm4
@@ -243,9 +248,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pinsrd $0, %edi, %xmm3
 ;   pshufd $0, %xmm3, %xmm0
 ;   movq %rbp, %rsp
@@ -272,9 +278,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm5
 ;   movdqa %xmm5, %xmm6
 ;   movsd %xmm6, %xmm0
@@ -300,9 +307,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movss (%rdi), %xmm0 ; trap: heap_oob
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -324,9 +332,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movd %edi, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -347,9 +356,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
diff --git a/cranelift/filetests/filetests/isa/x64/simd-logical-compile.clif b/cranelift/filetests/filetests/isa/x64/simd-logical-compile.clif
index 520ae43e2d..4d07e7912b 100644
--- a/cranelift/filetests/filetests/isa/x64/simd-logical-compile.clif
+++ b/cranelift/filetests/filetests/isa/x64/simd-logical-compile.clif
@@ -19,9 +19,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pcmpeqd %xmm2, %xmm2
 ;   pxor %xmm2, %xmm0
 ;   movq %rbp, %rsp
@@ -45,9 +46,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   ptest %xmm0, %xmm0
 ;   setne %al
 ;   movq %rbp, %rsp
@@ -74,9 +76,10 @@ block0(v0: i64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pxor %xmm2, %xmm2
 ;   movdqa %xmm0, %xmm4
 ;   pcmpeqq %xmm2, %xmm4
diff --git a/cranelift/filetests/filetests/isa/x64/simd-pairwise-add.clif b/cranelift/filetests/filetests/isa/x64/simd-pairwise-add.clif
index a195d97549..6f3698c61b 100644
--- a/cranelift/filetests/filetests/isa/x64/simd-pairwise-add.clif
+++ b/cranelift/filetests/filetests/isa/x64/simd-pairwise-add.clif
@@ -22,9 +22,10 @@ block0(v0: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm4
 ;   movdqu 0x10(%rip), %xmm0
 ;   movdqa %xmm4, %xmm5
@@ -61,9 +62,10 @@ block0(v0: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0x14(%rip), %xmm2
 ;   pmaddwd %xmm2, %xmm0
 ;   movq %rbp, %rsp
@@ -102,9 +104,10 @@ block0(v0: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0x14(%rip), %xmm2
 ;   pmaddubsw %xmm2, %xmm0
 ;   movq %rbp, %rsp
@@ -147,9 +150,10 @@ block0(v0: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0x24(%rip), %xmm2
 ;   pxor %xmm2, %xmm0
 ;   movdqu 0x28(%rip), %xmm6
diff --git a/cranelift/filetests/filetests/isa/x64/simd-widen-mul.clif b/cranelift/filetests/filetests/isa/x64/simd-widen-mul.clif
index 2b4969847a..e31b6f133f 100644
--- a/cranelift/filetests/filetests/isa/x64/simd-widen-mul.clif
+++ b/cranelift/filetests/filetests/isa/x64/simd-widen-mul.clif
@@ -28,9 +28,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm3
 ;   palignr $8, %xmm0, %xmm3
 ;   pmovsxbw %xmm3, %xmm0
@@ -66,9 +67,10 @@ block0(v0: i16x8, v1: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm5
 ;   pmullw %xmm1, %xmm5
 ;   movdqa %xmm5, %xmm6
@@ -100,9 +102,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pshufd $0xfa, %xmm0, %xmm0
 ;   pshufd $0xfa, %xmm1, %xmm5
 ;   pmuldq %xmm5, %xmm0
@@ -130,9 +133,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmovsxbw %xmm0, %xmm0
 ;   pmovsxbw %xmm1, %xmm5
 ;   pmullw %xmm5, %xmm0
@@ -164,9 +168,10 @@ block0(v0: i16x8, v1: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm5
 ;   pmullw %xmm1, %xmm5
 ;   movdqa %xmm5, %xmm6
@@ -198,9 +203,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pshufd $0x50, %xmm0, %xmm0
 ;   pshufd $0x50, %xmm1, %xmm5
 ;   pmuldq %xmm5, %xmm0
@@ -232,9 +238,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm3
 ;   palignr $8, %xmm0, %xmm3
 ;   pmovzxbw %xmm3, %xmm0
@@ -270,9 +277,10 @@ block0(v0: i16x8, v1: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm5
 ;   pmullw %xmm1, %xmm5
 ;   movdqa %xmm5, %xmm6
@@ -304,9 +312,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pshufd $0xfa, %xmm0, %xmm0
 ;   pshufd $0xfa, %xmm1, %xmm5
 ;   pmuludq %xmm5, %xmm0
@@ -334,9 +343,10 @@ block0(v0: i8x16, v1: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmovzxbw %xmm0, %xmm0
 ;   pmovzxbw %xmm1, %xmm5
 ;   pmullw %xmm5, %xmm0
@@ -368,9 +378,10 @@ block0(v0: i16x8, v1: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm5
 ;   pmullw %xmm1, %xmm5
 ;   movdqa %xmm5, %xmm6
@@ -402,9 +413,10 @@ block0(v0: i32x4, v1: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pshufd $0x50, %xmm0, %xmm0
 ;   pshufd $0x50, %xmm1, %xmm5
 ;   pmuludq %xmm5, %xmm0
diff --git a/cranelift/filetests/filetests/isa/x64/smulhi.clif b/cranelift/filetests/filetests/isa/x64/smulhi.clif
index e456a6732c..8d3cdbf401 100644
--- a/cranelift/filetests/filetests/isa/x64/smulhi.clif
+++ b/cranelift/filetests/filetests/isa/x64/smulhi.clif
@@ -19,9 +19,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   imulw %si
 ;   movq %rdx, %rax
@@ -47,9 +48,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   imull %esi
 ;   movq %rdx, %rax
@@ -75,9 +77,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   imulq %rsi
 ;   movq %rdx, %rax
diff --git a/cranelift/filetests/filetests/isa/x64/sqmul_round_sat.clif b/cranelift/filetests/filetests/isa/x64/sqmul_round_sat.clif
index b5f0c25904..d9241b6047 100644
--- a/cranelift/filetests/filetests/isa/x64/sqmul_round_sat.clif
+++ b/cranelift/filetests/filetests/isa/x64/sqmul_round_sat.clif
@@ -20,9 +20,10 @@ block0(v0: i16x8, v1: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0x14(%rip), %xmm5
 ;   pmulhrsw %xmm1, %xmm0
 ;   pcmpeqw %xmm0, %xmm5
diff --git a/cranelift/filetests/filetests/isa/x64/srem.clif b/cranelift/filetests/filetests/isa/x64/srem.clif
index 38123c09d8..e7fd115784 100644
--- a/cranelift/filetests/filetests/isa/x64/srem.clif
+++ b/cranelift/filetests/filetests/isa/x64/srem.clif
@@ -20,9 +20,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   xorl %edx, %edx
 ;   cmpb $0, %sil
@@ -58,9 +59,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   xorl %edx, %edx
 ;   cmpw $0, %si
@@ -96,9 +98,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   xorl %edx, %edx
 ;   cmpl $0, %esi
@@ -134,9 +137,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   xorl %edx, %edx
 ;   cmpq $0, %rsi
diff --git a/cranelift/filetests/filetests/isa/x64/sshr.clif b/cranelift/filetests/filetests/isa/x64/sshr.clif
index b6df919ac3..79a4d46e50 100644
--- a/cranelift/filetests/filetests/isa/x64/sshr.clif
+++ b/cranelift/filetests/filetests/isa/x64/sshr.clif
@@ -43,9 +43,10 @@ block0(v0: i128, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movzbq %dl, %rcx
 ;   movq %rdi, %r8
 ;   shrq %cl, %r8
@@ -106,9 +107,10 @@ block0(v0: i128, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r11
 ;   shrq %cl, %r11
@@ -168,9 +170,10 @@ block0(v0: i128, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r11
 ;   shrq %cl, %r11
@@ -230,9 +233,10 @@ block0(v0: i128, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r11
 ;   shrq %cl, %r11
@@ -292,9 +296,10 @@ block0(v0: i128, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r11
 ;   shrq %cl, %r11
@@ -337,9 +342,10 @@ block0(v0: i64, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   sarq %cl, %rax
@@ -365,9 +371,10 @@ block0(v0: i32, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   sarl %cl, %eax
@@ -394,9 +401,10 @@ block0(v0: i16, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -424,9 +432,10 @@ block0(v0: i8, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -453,9 +462,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   sarq %cl, %rax
@@ -481,9 +491,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   sarq %cl, %rax
@@ -509,9 +520,10 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   sarq %cl, %rax
@@ -537,9 +549,10 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   sarq %cl, %rax
@@ -565,9 +578,10 @@ block0(v0: i32, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   sarl %cl, %eax
@@ -593,9 +607,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   sarl %cl, %eax
@@ -621,9 +636,10 @@ block0(v0: i32, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   sarl %cl, %eax
@@ -649,9 +665,10 @@ block0(v0: i32, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   sarl %cl, %eax
@@ -678,9 +695,10 @@ block0(v0: i16, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -708,9 +726,10 @@ block0(v0: i16, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -738,9 +757,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -768,9 +788,10 @@ block0(v0: i16, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -798,9 +819,10 @@ block0(v0: i8, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -828,9 +850,10 @@ block0(v0: i8, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -858,9 +881,10 @@ block0(v0: i8, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -888,9 +912,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -916,9 +941,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   sarq $1, %rax
 ;   movq %rbp, %rsp
@@ -942,9 +968,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   sarl $1, %eax
 ;   movq %rbp, %rsp
@@ -968,9 +995,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   sarw $1, %ax
 ;   movq %rbp, %rsp
@@ -994,9 +1022,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   sarb $1, %al
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/struct-arg.clif b/cranelift/filetests/filetests/isa/x64/struct-arg.clif
index 5766f116f3..0039857fcc 100644
--- a/cranelift/filetests/filetests/isa/x64/struct-arg.clif
+++ b/cranelift/filetests/filetests/isa/x64/struct-arg.clif
@@ -18,9 +18,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   leaq 0x10(%rbp), %rsi
 ;   movzbq (%rsi), %rax ; trap: heap_oob
 ;   movq %rbp, %rsp
@@ -48,9 +49,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   leaq 0x10(%rbp), %rcx
 ;   movzbq (%rdi), %rax ; trap: heap_oob
 ;   movzbq (%rcx), %r9 ; trap: heap_oob
@@ -86,9 +88,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rsi
 ;   subq $0x40, %rsp
 ;   leaq (%rsp), %rdi
@@ -133,11 +136,12 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x10, %rsp
 ;   movq %r13, (%rsp)
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   movq %rdi, %r13
 ;   subq $0x40, %rsp
 ;   leaq (%rsp), %rdi
@@ -175,9 +179,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   leaq 0x10(%rbp), %rsi
 ;   leaq 0x90(%rbp), %rcx
 ;   movzbq (%rsi), %rax ; trap: heap_oob
@@ -227,12 +232,13 @@ block0(v0: i64, v1: i64, v2: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x10, %rsp
 ;   movq %r12, (%rsp)
 ;   movq %r14, 8(%rsp)
-; block0: ; offset 0x11
+; block1: ; offset 0x11
 ;   movq %rdx, %r14
 ;   movq %rdi, %r12
 ;   subq $0xc0, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/struct-ret.clif b/cranelift/filetests/filetests/isa/x64/struct-ret.clif
index cfeb4fcd10..59c0d681f0 100644
--- a/cranelift/filetests/filetests/isa/x64/struct-ret.clif
+++ b/cranelift/filetests/filetests/isa/x64/struct-ret.clif
@@ -20,9 +20,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movl $0x2a, %edx
 ;   movq %rdx, (%rdi) ; trap: heap_oob
@@ -51,9 +52,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rdi
 ;   movabsq $0, %rdx ; reloc_external Abs8 %f2 0
 ;   callq *%rdx
@@ -87,11 +89,12 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
 ;   subq $0x10, %rsp
 ;   movq %r15, (%rsp)
-; block0: ; offset 0xc
+; block1: ; offset 0xc
 ;   movq %rdi, %r15
 ;   movabsq $0, %rdx ; reloc_external Abs8 %f4 0
 ;   callq *%rdx
diff --git a/cranelift/filetests/filetests/isa/x64/symbols.clif b/cranelift/filetests/filetests/isa/x64/symbols.clif
index ceb423d175..c7468d666a 100644
--- a/cranelift/filetests/filetests/isa/x64/symbols.clif
+++ b/cranelift/filetests/filetests/isa/x64/symbols.clif
@@ -19,9 +19,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %rax ; reloc_external Abs8 %func0 0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -45,9 +46,10 @@ block0:
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %rax ; reloc_external Abs8 %global0 0
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/table.clif b/cranelift/filetests/filetests/isa/x64/table.clif
index bd769a6cd7..f562a3ccce 100644
--- a/cranelift/filetests/filetests/isa/x64/table.clif
+++ b/cranelift/filetests/filetests/isa/x64/table.clif
@@ -38,13 +38,14 @@ block0(v0: i32, v1: r64, v2: i64):
 ;   ud2 table_oob
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl 8(%rdx), %r11d
 ;   cmpl %r11d, %edi
 ;   jae 0x2b
-; block1: ; offset 0x11
+; block2: ; offset 0x11
 ;   movl %edi, %ecx
 ;   movq (%rdx), %rax
 ;   movq %rax, %rdx
@@ -55,6 +56,6 @@ block0(v0: i32, v1: r64, v2: i64):
 ;   movq %rbp, %rsp
 ;   popq %rbp
 ;   retq
-; block2: ; offset 0x2b
+; block3: ; offset 0x2b
 ;   ud2 ; trap: table_oob
 
diff --git a/cranelift/filetests/filetests/isa/x64/tls_coff.clif b/cranelift/filetests/filetests/isa/x64/tls_coff.clif
index 05e583d151..a2c69dfffc 100644
--- a/cranelift/filetests/filetests/isa/x64/tls_coff.clif
+++ b/cranelift/filetests/filetests/isa/x64/tls_coff.clif
@@ -21,9 +21,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl (%rip), %eax ; reloc_external PCRel4 %CoffTlsIndex -4
 ;   movq %gs:0x58, %rcx
 ;   movq (%rcx, %rax, 8), %rax
diff --git a/cranelift/filetests/filetests/isa/x64/tls_elf.clif b/cranelift/filetests/filetests/isa/x64/tls_elf.clif
index 6449740f56..6442f3b2fa 100644
--- a/cranelift/filetests/filetests/isa/x64/tls_elf.clif
+++ b/cranelift/filetests/filetests/isa/x64/tls_elf.clif
@@ -20,9 +20,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   leaq (%rip), %rdi ; reloc_external ElfX86_64TlsGd u1:0 -4
 ;   callq 0x14 ; reloc_external CallPLTRel4 %ElfTlsGetAddr -4
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/traps.clif b/cranelift/filetests/filetests/isa/x64/traps.clif
index 243935119d..2a5da8413f 100644
--- a/cranelift/filetests/filetests/isa/x64/traps.clif
+++ b/cranelift/filetests/filetests/isa/x64/traps.clif
@@ -13,9 +13,10 @@ block0:
 ;   ud2 user0
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   ud2 ; trap: user0
 
 function %trap_iadd_ifcout(i64, i64) {
@@ -36,9 +37,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rcx
 ;   addq %rsi, %rcx
 ;   jae 0x12
diff --git a/cranelift/filetests/filetests/isa/x64/trunc-libcall.clif b/cranelift/filetests/filetests/isa/x64/trunc-libcall.clif
index f422e0522d..95e2a6ab68 100644
--- a/cranelift/filetests/filetests/isa/x64/trunc-libcall.clif
+++ b/cranelift/filetests/filetests/isa/x64/trunc-libcall.clif
@@ -18,9 +18,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %rcx ; reloc_external Abs8 %TruncF32 0
 ;   callq *%rcx
 ;   movq %rbp, %rsp
@@ -44,9 +45,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movabsq $0, %rcx ; reloc_external Abs8 %TruncF64 0
 ;   callq *%rcx
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/trunc.clif b/cranelift/filetests/filetests/isa/x64/trunc.clif
index 3cbaeb9488..02dfd7d5bc 100644
--- a/cranelift/filetests/filetests/isa/x64/trunc.clif
+++ b/cranelift/filetests/filetests/isa/x64/trunc.clif
@@ -17,9 +17,10 @@ block0(v0: f32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundss $3, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: f64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundsd $3, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -65,9 +67,10 @@ block0(v0: f32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundps $3, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -89,9 +92,10 @@ block0(v0: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   roundpd $3, %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/uadd_overflow_trap.clif b/cranelift/filetests/filetests/isa/x64/uadd_overflow_trap.clif
index 094af916fa..a47db9ee11 100644
--- a/cranelift/filetests/filetests/isa/x64/uadd_overflow_trap.clif
+++ b/cranelift/filetests/filetests/isa/x64/uadd_overflow_trap.clif
@@ -20,9 +20,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   addl $0x7f, %eax
 ;   jae 0x12
@@ -50,9 +51,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   addl $0x7f, %eax
 ;   jae 0x12
@@ -79,9 +81,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   addl %esi, %eax
 ;   jae 0x11
@@ -109,9 +112,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   addq $0x7f, %rax
 ;   jae 0x13
@@ -139,9 +143,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   addq $0x7f, %rax
 ;   jae 0x13
@@ -168,9 +173,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   addq %rsi, %rax
 ;   jae 0x12
diff --git a/cranelift/filetests/filetests/isa/x64/udiv.clif b/cranelift/filetests/filetests/isa/x64/udiv.clif
index ecd7bf622c..b0affd746d 100644
--- a/cranelift/filetests/filetests/isa/x64/udiv.clif
+++ b/cranelift/filetests/filetests/isa/x64/udiv.clif
@@ -18,9 +18,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movzbl %dil, %eax
 ;   divb %sil ; trap: int_divz
 ;   movq %rbp, %rsp
@@ -45,9 +46,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movl $0, %edx
 ;   divw %si ; trap: int_divz
@@ -73,9 +75,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movl $0, %edx
 ;   divl %esi ; trap: int_divz
@@ -101,9 +104,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movl $0, %edx
 ;   divq %rsi ; trap: int_divz
diff --git a/cranelift/filetests/filetests/isa/x64/udivrem.clif b/cranelift/filetests/filetests/isa/x64/udivrem.clif
index 9540502a61..9385c4b870 100644
--- a/cranelift/filetests/filetests/isa/x64/udivrem.clif
+++ b/cranelift/filetests/filetests/isa/x64/udivrem.clif
@@ -27,9 +27,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movzbl %dil, %eax
 ;   divb %sil ; trap: int_divz
 ;   movq %rax, %rcx
@@ -67,9 +68,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0, %edx
 ;   movq %rdi, %rax
 ;   divw %si ; trap: int_divz
@@ -108,9 +110,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0, %edx
 ;   movq %rdi, %rax
 ;   divl %esi ; trap: int_divz
@@ -149,9 +152,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl $0, %edx
 ;   movq %rdi, %rax
 ;   divq %rsi ; trap: int_divz
diff --git a/cranelift/filetests/filetests/isa/x64/uextend-elision.clif b/cranelift/filetests/filetests/isa/x64/uextend-elision.clif
index 35bd0020e2..faf3a6763b 100644
--- a/cranelift/filetests/filetests/isa/x64/uextend-elision.clif
+++ b/cranelift/filetests/filetests/isa/x64/uextend-elision.clif
@@ -19,9 +19,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   addl %esi, %eax
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/umax-bug.clif b/cranelift/filetests/filetests/isa/x64/umax-bug.clif
index 9b67e5ad5c..320f360f93 100644
--- a/cranelift/filetests/filetests/isa/x64/umax-bug.clif
+++ b/cranelift/filetests/filetests/isa/x64/umax-bug.clif
@@ -21,9 +21,10 @@ block0(v1: i32, v2: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movl (%rsi), %edx
 ;   cmpl %edi, %edx
 ;   movq %rdi, %rax
diff --git a/cranelift/filetests/filetests/isa/x64/umulhi.clif b/cranelift/filetests/filetests/isa/x64/umulhi.clif
index 09442e8173..51afdd5695 100644
--- a/cranelift/filetests/filetests/isa/x64/umulhi.clif
+++ b/cranelift/filetests/filetests/isa/x64/umulhi.clif
@@ -19,9 +19,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   mulw %si
 ;   movq %rdx, %rax
@@ -47,9 +48,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   mull %esi
 ;   movq %rdx, %rax
@@ -75,9 +77,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   mulq %rsi
 ;   movq %rdx, %rax
diff --git a/cranelift/filetests/filetests/isa/x64/urem.clif b/cranelift/filetests/filetests/isa/x64/urem.clif
index fa4396fa4d..05b8949432 100644
--- a/cranelift/filetests/filetests/isa/x64/urem.clif
+++ b/cranelift/filetests/filetests/isa/x64/urem.clif
@@ -19,9 +19,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movzbl %dil, %eax
 ;   divb %sil ; trap: int_divz
 ;   shrq $8, %rax
@@ -48,9 +49,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movl $0, %edx
 ;   divw %si ; trap: int_divz
@@ -78,9 +80,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movl $0, %edx
 ;   divl %esi ; trap: int_divz
@@ -108,9 +111,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   movl $0, %edx
 ;   divq %rsi ; trap: int_divz
diff --git a/cranelift/filetests/filetests/isa/x64/ushr.clif b/cranelift/filetests/filetests/isa/x64/ushr.clif
index 1ce022b62f..6514cbd12d 100644
--- a/cranelift/filetests/filetests/isa/x64/ushr.clif
+++ b/cranelift/filetests/filetests/isa/x64/ushr.clif
@@ -40,9 +40,10 @@ block0(v0: i128, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movzbq %dl, %rcx
 ;   movq %rdi, %r8
 ;   shrq %cl, %r8
@@ -99,9 +100,10 @@ block0(v0: i128, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r8
 ;   shrq %cl, %r8
@@ -157,9 +159,10 @@ block0(v0: i128, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r8
 ;   shrq %cl, %r8
@@ -215,9 +218,10 @@ block0(v0: i128, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r8
 ;   shrq %cl, %r8
@@ -273,9 +277,10 @@ block0(v0: i128, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdx, %rcx
 ;   movq %rdi, %r8
 ;   shrq %cl, %r8
@@ -316,9 +321,10 @@ block0(v0: i64, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shrq %cl, %rax
@@ -345,9 +351,10 @@ block0(v0: i32, v1: i64, v2: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shrl %cl, %eax
@@ -374,9 +381,10 @@ block0(v0: i16, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -404,9 +412,10 @@ block0(v0: i8, v1: i128):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -433,9 +442,10 @@ block0(v0: i64, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shrq %cl, %rax
@@ -461,9 +471,10 @@ block0(v0: i64, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shrq %cl, %rax
@@ -489,9 +500,10 @@ block0(v0: i64, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shrq %cl, %rax
@@ -517,9 +529,10 @@ block0(v0: i64, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shrq %cl, %rax
@@ -545,9 +558,10 @@ block0(v0: i32, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shrl %cl, %eax
@@ -573,9 +587,10 @@ block0(v0: i32, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shrl %cl, %eax
@@ -601,9 +616,10 @@ block0(v0: i32, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shrl %cl, %eax
@@ -629,9 +645,10 @@ block0(v0: i32, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   movq %rdi, %rax
 ;   shrl %cl, %eax
@@ -658,9 +675,10 @@ block0(v0: i16, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -688,9 +706,10 @@ block0(v0: i16, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -718,9 +737,10 @@ block0(v0: i16, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -748,9 +768,10 @@ block0(v0: i16, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $0xf, %rcx
 ;   movq %rdi, %rax
@@ -778,9 +799,10 @@ block0(v0: i8, v1: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -808,9 +830,10 @@ block0(v0: i8, v1: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -838,9 +861,10 @@ block0(v0: i8, v1: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -868,9 +892,10 @@ block0(v0: i8, v1: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rsi, %rcx
 ;   andq $7, %rcx
 ;   movq %rdi, %rax
@@ -896,9 +921,10 @@ block0(v0: i64):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shrq $1, %rax
 ;   movq %rbp, %rsp
@@ -922,9 +948,10 @@ block0(v0: i32):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shrl $1, %eax
 ;   movq %rbp, %rsp
@@ -948,9 +975,10 @@ block0(v0: i16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shrw $1, %ax
 ;   movq %rbp, %rsp
@@ -974,9 +1002,10 @@ block0(v0: i8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movq %rdi, %rax
 ;   shrb $1, %al
 ;   movq %rbp, %rsp
diff --git a/cranelift/filetests/filetests/isa/x64/uunarrow.clif b/cranelift/filetests/filetests/isa/x64/uunarrow.clif
index 604908f502..b65eb2643a 100644
--- a/cranelift/filetests/filetests/isa/x64/uunarrow.clif
+++ b/cranelift/filetests/filetests/isa/x64/uunarrow.clif
@@ -27,9 +27,10 @@ block0(v0: f64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   xorpd %xmm2, %xmm2
 ;   movdqa %xmm0, %xmm6
 ;   maxpd %xmm2, %xmm6
diff --git a/cranelift/filetests/filetests/isa/x64/vhigh_bits.clif b/cranelift/filetests/filetests/isa/x64/vhigh_bits.clif
index 6be6db07d4..44759d3110 100644
--- a/cranelift/filetests/filetests/isa/x64/vhigh_bits.clif
+++ b/cranelift/filetests/filetests/isa/x64/vhigh_bits.clif
@@ -17,9 +17,10 @@ block0(v0: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmovmskb %xmm0, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmovmskb %xmm0, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -68,9 +70,10 @@ block0(v0: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm2
 ;   packsswb %xmm0, %xmm2
 ;   pmovmskb %xmm2, %eax
@@ -95,9 +98,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movmskps %xmm0, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -119,9 +123,10 @@ block0(v0: i64x2):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movmskpd %xmm0, %eax
 ;   movq %rbp, %rsp
 ;   popq %rbp
diff --git a/cranelift/filetests/filetests/isa/x64/widen-high-bug.clif b/cranelift/filetests/filetests/isa/x64/widen-high-bug.clif
index 95532db790..9aa77be46c 100644
--- a/cranelift/filetests/filetests/isa/x64/widen-high-bug.clif
+++ b/cranelift/filetests/filetests/isa/x64/widen-high-bug.clif
@@ -20,9 +20,10 @@ block0(v0: i64, v2: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqu 0x50(%rdi), %xmm3
 ;   palignr $8, %xmm3, %xmm3
 ;   pmovzxbw %xmm3, %xmm0
diff --git a/cranelift/filetests/filetests/isa/x64/widening.clif b/cranelift/filetests/filetests/isa/x64/widening.clif
index 2cfaaa38e6..44377ad041 100644
--- a/cranelift/filetests/filetests/isa/x64/widening.clif
+++ b/cranelift/filetests/filetests/isa/x64/widening.clif
@@ -17,9 +17,10 @@ block0(v0: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmovsxbw %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -41,9 +42,10 @@ block0(v0: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmovsxwd %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -65,9 +67,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmovsxdq %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -91,9 +94,10 @@ block0(v0: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm2
 ;   palignr $8, %xmm0, %xmm2
 ;   pmovsxbw %xmm2, %xmm0
@@ -119,9 +123,10 @@ block0(v0: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm2
 ;   palignr $8, %xmm0, %xmm2
 ;   pmovsxwd %xmm2, %xmm0
@@ -146,9 +151,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pshufd $0xee, %xmm0, %xmm2
 ;   pmovsxdq %xmm2, %xmm0
 ;   movq %rbp, %rsp
@@ -171,9 +177,10 @@ block0(v0: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmovzxbw %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -195,9 +202,10 @@ block0(v0: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmovzxwd %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -219,9 +227,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pmovzxdq %xmm0, %xmm0
 ;   movq %rbp, %rsp
 ;   popq %rbp
@@ -245,9 +254,10 @@ block0(v0: i8x16):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm2
 ;   palignr $8, %xmm0, %xmm2
 ;   pmovzxbw %xmm2, %xmm0
@@ -273,9 +283,10 @@ block0(v0: i16x8):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   movdqa %xmm0, %xmm2
 ;   palignr $8, %xmm0, %xmm2
 ;   pmovzxwd %xmm2, %xmm0
@@ -300,9 +311,10 @@ block0(v0: i32x4):
 ;   ret
 ; 
 ; Disassembled:
+; block0: ; offset 0x0
 ;   pushq %rbp
 ;   movq %rsp, %rbp
-; block0: ; offset 0x4
+; block1: ; offset 0x4
 ;   pshufd $0xee, %xmm0, %xmm2
 ;   pmovzxdq %xmm2, %xmm0
 ;   movq %rbp, %rsp