diff --git a/Cargo.lock b/Cargo.lock
index 5f6b37c2fc..388927fd8a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1692,9 +1692,9 @@ dependencies = [
 
 [[package]]
 name = "regalloc"
-version = "0.0.30"
+version = "0.0.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2041c2d34f6ff346d6f428974f03d8bf12679b0c816bb640dc5eb1d48848d8d1"
+checksum = "571f7f397d61c4755285cd37853fe8e03271c243424a907415909379659381c5"
 dependencies = [
  "log",
  "rustc-hash",
diff --git a/cranelift/codegen/Cargo.toml b/cranelift/codegen/Cargo.toml
index 3ac7f27171..2be771738c 100644
--- a/cranelift/codegen/Cargo.toml
+++ b/cranelift/codegen/Cargo.toml
@@ -28,7 +28,7 @@ byteorder = { version = "1.3.2", default-features = false }
 peepmatic = { path = "../peepmatic", optional = true, version = "0.67.0" }
 peepmatic-traits = { path = "../peepmatic/crates/traits", optional = true, version = "0.67.0" }
 peepmatic-runtime = { path = "../peepmatic/crates/runtime", optional = true, version = "0.67.0" }
-regalloc = "0.0.30"
+regalloc = { version = "0.0.31" }
 souper-ir = { version = "1", optional = true }
 wast = { version = "25.0.0", optional = true }
 # It is a goal of the cranelift-codegen crate to have minimal external dependencies.
diff --git a/cranelift/codegen/src/isa/aarch64/abi.rs b/cranelift/codegen/src/isa/aarch64/abi.rs
index 03c6622f12..b897352ebe 100644
--- a/cranelift/codegen/src/isa/aarch64/abi.rs
+++ b/cranelift/codegen/src/isa/aarch64/abi.rs
@@ -510,7 +510,7 @@ impl ABIMachineSpec for AArch64MachineDeps {
         fixed_frame_storage_size: u32,
     ) -> (u64, SmallVec<[Inst; 16]>) {
         let mut insts = SmallVec::new();
-        let (clobbered_int, clobbered_vec) = get_callee_saves(call_conv, clobbers);
+        let (clobbered_int, clobbered_vec) = get_regs_saved_in_prologue(call_conv, clobbers);
 
         let (int_save_bytes, vec_save_bytes) = saved_reg_stack_size(&clobbered_int, &clobbered_vec);
         let total_save_bytes = (vec_save_bytes + int_save_bytes) as i32;
@@ -561,7 +561,7 @@ impl ABIMachineSpec for AArch64MachineDeps {
         clobbers: &Set<Writable<RealReg>>,
     ) -> SmallVec<[Inst; 16]> {
         let mut insts = SmallVec::new();
-        let (clobbered_int, clobbered_vec) = get_callee_saves(call_conv, clobbers);
+        let (clobbered_int, clobbered_vec) = get_regs_saved_in_prologue(call_conv, clobbers);
 
         let (int_save_bytes, vec_save_bytes) = saved_reg_stack_size(&clobbered_int, &clobbered_vec);
         for (i, reg_pair) in clobbered_int.chunks(2).enumerate() {
@@ -629,6 +629,8 @@ impl ABIMachineSpec for AArch64MachineDeps {
         loc: SourceLoc,
         opcode: ir::Opcode,
         tmp: Writable<Reg>,
+        callee_conv: isa::CallConv,
+        caller_conv: isa::CallConv,
     ) -> SmallVec<[(InstIsSafepoint, Inst); 2]> {
         let mut insts = SmallVec::new();
         match &dest {
@@ -641,6 +643,8 @@ impl ABIMachineSpec for AArch64MachineDeps {
                         defs,
                         loc,
                         opcode,
+                        caller_callconv: caller_conv,
+                        callee_callconv: callee_conv,
                     }),
                 },
             )),
@@ -663,6 +667,8 @@ impl ABIMachineSpec for AArch64MachineDeps {
                             defs,
                             loc,
                             opcode,
+                            caller_callconv: caller_conv,
+                            callee_callconv: callee_conv,
                         }),
                     },
                 ));
@@ -676,6 +682,8 @@ impl ABIMachineSpec for AArch64MachineDeps {
                         defs,
                         loc,
                         opcode,
+                        caller_callconv: caller_conv,
+                        callee_callconv: callee_conv,
                     }),
                 },
             )),
@@ -704,17 +712,17 @@ impl ABIMachineSpec for AArch64MachineDeps {
         s.nominal_sp_to_fp
     }
 
-    fn get_caller_saves(call_conv: isa::CallConv) -> Vec<Writable<Reg>> {
+    fn get_regs_clobbered_by_call(call_conv_of_callee: isa::CallConv) -> Vec<Writable<Reg>> {
         let mut caller_saved = Vec::new();
         for i in 0..29 {
             let x = writable_xreg(i);
-            if is_caller_save_reg(call_conv, x.to_reg().to_real_reg()) {
+            if is_reg_clobbered_by_call(call_conv_of_callee, x.to_reg().to_real_reg()) {
                 caller_saved.push(x);
             }
         }
         for i in 0..32 {
             let v = writable_vreg(i);
-            if is_caller_save_reg(call_conv, v.to_reg().to_real_reg()) {
+            if is_reg_clobbered_by_call(call_conv_of_callee, v.to_reg().to_real_reg()) {
                 caller_saved.push(v);
             }
         }
@@ -731,7 +739,9 @@ fn legal_type_for_machine(ty: Type) -> bool {
     }
 }
 
-fn is_callee_save_reg(call_conv: isa::CallConv, r: RealReg) -> bool {
+/// Is the given register saved in the prologue if clobbered, i.e., is it a
+/// callee-save?
+fn is_reg_saved_in_prologue(call_conv: isa::CallConv, r: RealReg) -> bool {
     if call_conv.extends_baldrdash() {
         match r.get_class() {
             RegClass::I64 => {
@@ -759,14 +769,17 @@ fn is_callee_save_reg(call_conv: isa::CallConv, r: RealReg) -> bool {
     }
 }
 
-fn get_callee_saves(
+/// Return the set of all integer and vector registers that must be saved in the
+/// prologue and restored in the epilogue, given the set of all registers
+/// written by the function's body.
+fn get_regs_saved_in_prologue(
     call_conv: isa::CallConv,
     regs: &Set<Writable<RealReg>>,
 ) -> (Vec<Writable<RealReg>>, Vec<Writable<RealReg>>) {
     let mut int_saves = vec![];
     let mut vec_saves = vec![];
     for &reg in regs.iter() {
-        if is_callee_save_reg(call_conv, reg.to_reg()) {
+        if is_reg_saved_in_prologue(call_conv, reg.to_reg()) {
             match reg.to_reg().get_class() {
                 RegClass::I64 => int_saves.push(reg),
                 RegClass::V128 => vec_saves.push(reg),
@@ -781,8 +794,8 @@ fn get_callee_saves(
     (int_saves, vec_saves)
 }
 
-fn is_caller_save_reg(call_conv: isa::CallConv, r: RealReg) -> bool {
-    if call_conv.extends_baldrdash() {
+fn is_reg_clobbered_by_call(call_conv_of_callee: isa::CallConv, r: RealReg) -> bool {
+    if call_conv_of_callee.extends_baldrdash() {
         match r.get_class() {
             RegClass::I64 => {
                 let enc = r.get_hw_encoding();
@@ -808,8 +821,21 @@ fn is_caller_save_reg(call_conv: isa::CallConv, r: RealReg) -> bool {
             r.get_hw_encoding() <= 17
         }
         RegClass::V128 => {
-            // v0 - v7 inclusive and v16 - v31 inclusive are caller-saves.
-            r.get_hw_encoding() <= 7 || (r.get_hw_encoding() >= 16 && r.get_hw_encoding() <= 31)
+            // v0 - v7 inclusive and v16 - v31 inclusive are caller-saves. The
+            // upper 64 bits of v8 - v15 inclusive are also caller-saves.
+            // However, because we cannot currently represent partial registers
+            // to regalloc.rs, we indicate here that every vector register is
+            // caller-save. Because this function is used at *callsites*,
+            // approximating in this direction (save more than necessary) is
+            // conservative and thus safe.
+            //
+            // Note that we set the 'not included in clobber set' flag in the
+            // regalloc.rs API when a call instruction's callee has the same ABI
+            // as the caller (the current function body); this is safe (anything
+            // clobbered by callee can be clobbered by caller as well) and
+            // avoids unnecessary saves of v8-v15 in the prologue even though we
+            // include them as defs here.
+            true
         }
         _ => panic!("Unexpected RegClass"),
     }
diff --git a/cranelift/codegen/src/isa/aarch64/inst/args.rs b/cranelift/codegen/src/isa/aarch64/inst/args.rs
index 2ac9d064a1..f85c1028ff 100644
--- a/cranelift/codegen/src/isa/aarch64/inst/args.rs
+++ b/cranelift/codegen/src/isa/aarch64/inst/args.rs
@@ -8,7 +8,7 @@ use crate::ir::Type;
 use crate::isa::aarch64::inst::*;
 use crate::machinst::{ty_bits, MachLabel};
 
-use regalloc::{RealRegUniverse, Reg, Writable};
+use regalloc::{PrettyPrint, RealRegUniverse, Reg, Writable};
 
 use core::convert::Into;
 use std::string::String;
@@ -348,19 +348,19 @@ impl BranchTarget {
     }
 }
 
-impl ShowWithRRU for ShiftOpAndAmt {
+impl PrettyPrint for ShiftOpAndAmt {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("{:?} {}", self.op(), self.amt().value())
     }
 }
 
-impl ShowWithRRU for ExtendOp {
+impl PrettyPrint for ExtendOp {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("{:?}", self)
     }
 }
 
-impl ShowWithRRU for MemLabel {
+impl PrettyPrint for MemLabel {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         match self {
             &MemLabel::PCRel(off) => format!("pc+{}", off),
@@ -379,7 +379,7 @@ fn shift_for_type(ty: Type) -> usize {
     }
 }
 
-impl ShowWithRRU for AMode {
+impl PrettyPrint for AMode {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         match self {
             &AMode::Unscaled(reg, simm9) => {
@@ -458,7 +458,7 @@ impl ShowWithRRU for AMode {
     }
 }
 
-impl ShowWithRRU for PairAMode {
+impl PrettyPrint for PairAMode {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         match self {
             &PairAMode::SignedOffset(reg, simm7) => {
@@ -482,7 +482,7 @@ impl ShowWithRRU for PairAMode {
     }
 }
 
-impl ShowWithRRU for Cond {
+impl PrettyPrint for Cond {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         let mut s = format!("{:?}", self);
         s.make_ascii_lowercase();
@@ -490,7 +490,7 @@ impl ShowWithRRU for Cond {
     }
 }
 
-impl ShowWithRRU for BranchTarget {
+impl PrettyPrint for BranchTarget {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         match self {
             &BranchTarget::Label(label) => format!("label{:?}", label.get()),
diff --git a/cranelift/codegen/src/isa/aarch64/inst/emit_tests.rs b/cranelift/codegen/src/isa/aarch64/inst/emit_tests.rs
index 6d68e2b65e..1a29ba9659 100644
--- a/cranelift/codegen/src/isa/aarch64/inst/emit_tests.rs
+++ b/cranelift/codegen/src/isa/aarch64/inst/emit_tests.rs
@@ -1,6 +1,7 @@
 use crate::ir::types::*;
 use crate::isa::aarch64::inst::*;
 use crate::isa::test_utils;
+use crate::isa::CallConv;
 use crate::settings;
 
 use alloc::boxed::Box;
@@ -3789,6 +3790,8 @@ fn test_aarch64_binemit() {
                 defs: Vec::new(),
                 loc: SourceLoc::default(),
                 opcode: Opcode::Call,
+                caller_callconv: CallConv::SystemV,
+                callee_callconv: CallConv::SystemV,
             }),
         },
         "00000094",
@@ -3803,6 +3806,8 @@ fn test_aarch64_binemit() {
                 defs: Vec::new(),
                 loc: SourceLoc::default(),
                 opcode: Opcode::CallIndirect,
+                caller_callconv: CallConv::SystemV,
+                callee_callconv: CallConv::SystemV,
             }),
         },
         "40013FD6",
diff --git a/cranelift/codegen/src/isa/aarch64/inst/imms.rs b/cranelift/codegen/src/isa/aarch64/inst/imms.rs
index f1a98ab66c..d8dd45afca 100644
--- a/cranelift/codegen/src/isa/aarch64/inst/imms.rs
+++ b/cranelift/codegen/src/isa/aarch64/inst/imms.rs
@@ -5,9 +5,8 @@
 use crate::ir::types::*;
 use crate::ir::Type;
 use crate::isa::aarch64::inst::OperandSize;
-use crate::machinst::*;
 
-use regalloc::RealRegUniverse;
+use regalloc::{PrettyPrint, RealRegUniverse};
 
 use core::convert::TryFrom;
 use std::string::String;
@@ -668,7 +667,7 @@ impl MoveWideConst {
     }
 }
 
-impl ShowWithRRU for NZCV {
+impl PrettyPrint for NZCV {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         let fmt = |c: char, v| if v { c.to_ascii_uppercase() } else { c };
         format!(
@@ -681,13 +680,13 @@ impl ShowWithRRU for NZCV {
     }
 }
 
-impl ShowWithRRU for UImm5 {
+impl PrettyPrint for UImm5 {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("#{}", self.value)
     }
 }
 
-impl ShowWithRRU for Imm12 {
+impl PrettyPrint for Imm12 {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         let shift = if self.shift12 { 12 } else { 0 };
         let value = u32::from(self.bits) << shift;
@@ -695,49 +694,49 @@ impl ShowWithRRU for Imm12 {
     }
 }
 
-impl ShowWithRRU for SImm7Scaled {
+impl PrettyPrint for SImm7Scaled {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("#{}", self.value)
     }
 }
 
-impl ShowWithRRU for FPULeftShiftImm {
+impl PrettyPrint for FPULeftShiftImm {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("#{}", self.amount)
     }
 }
 
-impl ShowWithRRU for FPURightShiftImm {
+impl PrettyPrint for FPURightShiftImm {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("#{}", self.amount)
     }
 }
 
-impl ShowWithRRU for SImm9 {
+impl PrettyPrint for SImm9 {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("#{}", self.value)
     }
 }
 
-impl ShowWithRRU for UImm12Scaled {
+impl PrettyPrint for UImm12Scaled {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("#{}", self.value)
     }
 }
 
-impl ShowWithRRU for ImmLogic {
+impl PrettyPrint for ImmLogic {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("#{}", self.value())
     }
 }
 
-impl ShowWithRRU for ImmShift {
+impl PrettyPrint for ImmShift {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("#{}", self.imm)
     }
 }
 
-impl ShowWithRRU for MoveWideConst {
+impl PrettyPrint for MoveWideConst {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         if self.shift == 0 {
             format!("#{}", self.bits)
diff --git a/cranelift/codegen/src/isa/aarch64/inst/mod.rs b/cranelift/codegen/src/isa/aarch64/inst/mod.rs
index bb71058c5f..544d04c23c 100644
--- a/cranelift/codegen/src/isa/aarch64/inst/mod.rs
+++ b/cranelift/codegen/src/isa/aarch64/inst/mod.rs
@@ -9,10 +9,11 @@ use crate::ir::types::{
     I32, I32X4, I64, I64X2, I8, I8X16, IFLAGS, R32, R64,
 };
 use crate::ir::{ExternalName, Opcode, SourceLoc, TrapCode, Type};
+use crate::isa::CallConv;
 use crate::machinst::*;
 use crate::{settings, CodegenError, CodegenResult};
 
-use regalloc::{RealRegUniverse, Reg, RegClass, SpillSlot, VirtualReg, Writable};
+use regalloc::{PrettyPrint, RealRegUniverse, Reg, RegClass, SpillSlot, VirtualReg, Writable};
 use regalloc::{RegUsageCollector, RegUsageMapper};
 
 use alloc::boxed::Box;
@@ -392,6 +393,8 @@ pub struct CallInfo {
     pub defs: Vec<Writable<Reg>>,
     pub loc: SourceLoc,
     pub opcode: Opcode,
+    pub caller_callconv: CallConv,
+    pub callee_callconv: CallConv,
 }
 
 /// Additional information for CallInd instructions, left out of line to lower the size of the Inst
@@ -403,6 +406,8 @@ pub struct CallIndInfo {
     pub defs: Vec<Writable<Reg>>,
     pub loc: SourceLoc,
     pub opcode: Opcode,
+    pub caller_callconv: CallConv,
+    pub callee_callconv: CallConv,
 }
 
 /// Additional information for JTSequence instructions, left out of line to lower the size of the Inst
@@ -2491,6 +2496,24 @@ impl MachInst for Inst {
         }
     }
 
+    fn is_included_in_clobbers(&self) -> bool {
+        // We exclude call instructions from the clobber-set when they are calls
+        // from caller to callee with the same ABI. Such calls cannot possibly
+        // force any new registers to be saved in the prologue, because anything
+        // that the callee clobbers, the caller is also allowed to clobber. This
+        // both saves work and enables us to more precisely follow the
+        // half-caller-save, half-callee-save SysV ABI for some vector
+        // registers.
+        //
+        // See the note in [crate::isa::aarch64::abi::is_caller_save_reg] for
+        // more information on this ABI-implementation hack.
+        match self {
+            &Inst::Call { ref info } => info.caller_callconv != info.callee_callconv,
+            &Inst::CallInd { ref info } => info.caller_callconv != info.callee_callconv,
+            _ => true,
+        }
+    }
+
     fn is_term<'a>(&'a self) -> MachTerminator<'a> {
         match self {
             &Inst::Ret | &Inst::EpiloguePlaceholder => MachTerminator::Ret,
@@ -2623,7 +2646,7 @@ fn mem_finalize_for_show(
     (mem_str, mem)
 }
 
-impl ShowWithRRU for Inst {
+impl PrettyPrint for Inst {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         self.pretty_print(mb_rru, &mut EmitState::default())
     }
@@ -2883,13 +2906,13 @@ impl Inst {
             &Inst::StoreP64 { rt, rt2, ref mem } => {
                 let rt = rt.show_rru(mb_rru);
                 let rt2 = rt2.show_rru(mb_rru);
-                let mem = mem.show_rru_sized(mb_rru, /* size = */ 8);
+                let mem = mem.show_rru(mb_rru);
                 format!("stp {}, {}, {}", rt, rt2, mem)
             }
             &Inst::LoadP64 { rt, rt2, ref mem } => {
                 let rt = rt.to_reg().show_rru(mb_rru);
                 let rt2 = rt2.to_reg().show_rru(mb_rru);
-                let mem = mem.show_rru_sized(mb_rru, /* size = */ 8);
+                let mem = mem.show_rru(mb_rru);
                 format!("ldp {}, {}, {}", rt, rt2, mem)
             }
             &Inst::Mov64 { rd, rm } => {
diff --git a/cranelift/codegen/src/isa/aarch64/inst/regs.rs b/cranelift/codegen/src/isa/aarch64/inst/regs.rs
index cbf1440927..0b4babe04a 100644
--- a/cranelift/codegen/src/isa/aarch64/inst/regs.rs
+++ b/cranelift/codegen/src/isa/aarch64/inst/regs.rs
@@ -3,10 +3,11 @@
 use crate::isa::aarch64::inst::OperandSize;
 use crate::isa::aarch64::inst::ScalarSize;
 use crate::isa::aarch64::inst::VectorSize;
-use crate::machinst::*;
 use crate::settings;
 
-use regalloc::{RealRegUniverse, Reg, RegClass, RegClassInfo, Writable, NUM_REG_CLASSES};
+use regalloc::{
+    PrettyPrint, RealRegUniverse, Reg, RegClass, RegClassInfo, Writable, NUM_REG_CLASSES,
+};
 
 use std::string::{String, ToString};
 
diff --git a/cranelift/codegen/src/isa/aarch64/lower_inst.rs b/cranelift/codegen/src/isa/aarch64/lower_inst.rs
index 5e2fed9064..fc28cb3581 100644
--- a/cranelift/codegen/src/isa/aarch64/lower_inst.rs
+++ b/cranelift/codegen/src/isa/aarch64/lower_inst.rs
@@ -1857,6 +1857,7 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
 
         Opcode::Call | Opcode::CallIndirect => {
             let loc = ctx.srcloc(insn);
+            let caller_conv = ctx.abi().call_conv();
             let (mut abi, inputs) = match op {
                 Opcode::Call => {
                     let (extname, dist) = ctx.call_target(insn).unwrap();
@@ -1865,7 +1866,7 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
                     assert!(inputs.len() == sig.params.len());
                     assert!(outputs.len() == sig.returns.len());
                     (
-                        AArch64ABICaller::from_func(sig, &extname, dist, loc)?,
+                        AArch64ABICaller::from_func(sig, &extname, dist, loc, caller_conv)?,
                         &inputs[..],
                     )
                 }
@@ -1874,7 +1875,10 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
                     let sig = ctx.call_sig(insn).unwrap();
                     assert!(inputs.len() - 1 == sig.params.len());
                     assert!(outputs.len() == sig.returns.len());
-                    (AArch64ABICaller::from_ptr(sig, ptr, loc, op)?, &inputs[1..])
+                    (
+                        AArch64ABICaller::from_ptr(sig, ptr, loc, op, caller_conv)?,
+                        &inputs[1..],
+                    )
                 }
                 _ => unreachable!(),
             };
diff --git a/cranelift/codegen/src/isa/aarch64/mod.rs b/cranelift/codegen/src/isa/aarch64/mod.rs
index bd34a58cf5..9cbbd633f5 100644
--- a/cranelift/codegen/src/isa/aarch64/mod.rs
+++ b/cranelift/codegen/src/isa/aarch64/mod.rs
@@ -3,15 +3,13 @@
 use crate::ir::condcodes::IntCC;
 use crate::ir::Function;
 use crate::isa::Builder as IsaBuilder;
-use crate::machinst::{
-    compile, MachBackend, MachCompileResult, ShowWithRRU, TargetIsaAdapter, VCode,
-};
+use crate::machinst::{compile, MachBackend, MachCompileResult, TargetIsaAdapter, VCode};
 use crate::result::CodegenResult;
 use crate::settings;
 
 use alloc::boxed::Box;
 
-use regalloc::RealRegUniverse;
+use regalloc::{PrettyPrint, RealRegUniverse};
 use target_lexicon::{Aarch64Architecture, Architecture, Triple};
 
 // New backend:
diff --git a/cranelift/codegen/src/isa/arm32/abi.rs b/cranelift/codegen/src/isa/arm32/abi.rs
index 54f0d3e6a8..8cd2df1396 100644
--- a/cranelift/codegen/src/isa/arm32/abi.rs
+++ b/cranelift/codegen/src/isa/arm32/abi.rs
@@ -361,6 +361,8 @@ impl ABIMachineSpec for Arm32MachineDeps {
         loc: SourceLoc,
         opcode: ir::Opcode,
         tmp: Writable<Reg>,
+        _callee_conv: isa::CallConv,
+        _caller_conv: isa::CallConv,
     ) -> SmallVec<[(InstIsSafepoint, Inst); 2]> {
         let mut insts = SmallVec::new();
         match &dest {
@@ -431,11 +433,11 @@ impl ABIMachineSpec for Arm32MachineDeps {
         s.nominal_sp_to_fp
     }
 
-    fn get_caller_saves(_call_conv: isa::CallConv) -> Vec<Writable<Reg>> {
+    fn get_regs_clobbered_by_call(_: isa::CallConv) -> Vec<Writable<Reg>> {
         let mut caller_saved = Vec::new();
         for i in 0..15 {
             let r = writable_rreg(i);
-            if is_caller_save(r.to_reg().to_real_reg()) {
+            if is_reg_clobbered_by_call(r.to_reg().to_real_reg()) {
                 caller_saved.push(r);
             }
         }
@@ -461,7 +463,7 @@ fn get_callee_saves(regs: &Set<Writable<RealReg>>) -> Vec<Writable<RealReg>> {
     ret
 }
 
-fn is_caller_save(r: RealReg) -> bool {
+fn is_reg_clobbered_by_call(r: RealReg) -> bool {
     let enc = r.get_hw_encoding();
     enc <= 3
 }
diff --git a/cranelift/codegen/src/isa/arm32/inst/args.rs b/cranelift/codegen/src/isa/arm32/inst/args.rs
index 252581a2a1..2c1b8e97d6 100644
--- a/cranelift/codegen/src/isa/arm32/inst/args.rs
+++ b/cranelift/codegen/src/isa/arm32/inst/args.rs
@@ -2,7 +2,7 @@
 
 use crate::isa::arm32::inst::*;
 
-use regalloc::{RealRegUniverse, Reg};
+use regalloc::{PrettyPrint, RealRegUniverse, Reg};
 
 use std::string::String;
 
@@ -265,7 +265,7 @@ impl BranchTarget {
     }
 }
 
-impl ShowWithRRU for ShiftOpAndAmt {
+impl PrettyPrint for ShiftOpAndAmt {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         let op = match self.op() {
             ShiftOp::LSL => "lsl",
@@ -277,19 +277,19 @@ impl ShowWithRRU for ShiftOpAndAmt {
     }
 }
 
-impl ShowWithRRU for UImm8 {
+impl PrettyPrint for UImm8 {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("#{}", self.value)
     }
 }
 
-impl ShowWithRRU for UImm12 {
+impl PrettyPrint for UImm12 {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         format!("#{}", self.value)
     }
 }
 
-impl ShowWithRRU for AMode {
+impl PrettyPrint for AMode {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         match self {
             &AMode::RegReg(rn, rm, imm2) => {
@@ -317,7 +317,7 @@ impl ShowWithRRU for AMode {
     }
 }
 
-impl ShowWithRRU for Cond {
+impl PrettyPrint for Cond {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         let mut s = format!("{:?}", self);
         s.make_ascii_lowercase();
@@ -325,7 +325,7 @@ impl ShowWithRRU for Cond {
     }
 }
 
-impl ShowWithRRU for BranchTarget {
+impl PrettyPrint for BranchTarget {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         match self {
             &BranchTarget::Label(label) => format!("label{:?}", label.get()),
diff --git a/cranelift/codegen/src/isa/arm32/inst/mod.rs b/cranelift/codegen/src/isa/arm32/inst/mod.rs
index dfd4906f05..78aa0d784f 100644
--- a/cranelift/codegen/src/isa/arm32/inst/mod.rs
+++ b/cranelift/codegen/src/isa/arm32/inst/mod.rs
@@ -8,7 +8,7 @@ use crate::ir::{ExternalName, Opcode, SourceLoc, TrapCode, Type};
 use crate::machinst::*;
 use crate::{settings, CodegenError, CodegenResult};
 
-use regalloc::{RealRegUniverse, Reg, RegClass, SpillSlot, VirtualReg, Writable};
+use regalloc::{PrettyPrint, RealRegUniverse, Reg, RegClass, SpillSlot, VirtualReg, Writable};
 use regalloc::{RegUsageCollector, RegUsageMapper};
 
 use alloc::boxed::Box;
@@ -897,7 +897,7 @@ fn mem_finalize_for_show(
     (mem_str, mem)
 }
 
-impl ShowWithRRU for Inst {
+impl PrettyPrint for Inst {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         self.pretty_print(mb_rru, &mut EmitState::default())
     }
diff --git a/cranelift/codegen/src/isa/arm32/lower_inst.rs b/cranelift/codegen/src/isa/arm32/lower_inst.rs
index 7a584fe103..1cff717da3 100644
--- a/cranelift/codegen/src/isa/arm32/lower_inst.rs
+++ b/cranelift/codegen/src/isa/arm32/lower_inst.rs
@@ -513,6 +513,7 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
         }
         Opcode::Call | Opcode::CallIndirect => {
             let loc = ctx.srcloc(insn);
+            let caller_conv = ctx.abi().call_conv();
             let (mut abi, inputs) = match op {
                 Opcode::Call => {
                     let (extname, dist) = ctx.call_target(insn).unwrap();
@@ -521,7 +522,7 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
                     assert_eq!(inputs.len(), sig.params.len());
                     assert_eq!(outputs.len(), sig.returns.len());
                     (
-                        Arm32ABICaller::from_func(sig, &extname, dist, loc)?,
+                        Arm32ABICaller::from_func(sig, &extname, dist, loc, caller_conv)?,
                         &inputs[..],
                     )
                 }
@@ -530,7 +531,10 @@ pub(crate) fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
                     let sig = ctx.call_sig(insn).unwrap();
                     assert_eq!(inputs.len() - 1, sig.params.len());
                     assert_eq!(outputs.len(), sig.returns.len());
-                    (Arm32ABICaller::from_ptr(sig, ptr, loc, op)?, &inputs[1..])
+                    (
+                        Arm32ABICaller::from_ptr(sig, ptr, loc, op, caller_conv)?,
+                        &inputs[1..],
+                    )
                 }
                 _ => unreachable!(),
             };
diff --git a/cranelift/codegen/src/isa/arm32/mod.rs b/cranelift/codegen/src/isa/arm32/mod.rs
index c61d3f27ad..2a278a233d 100644
--- a/cranelift/codegen/src/isa/arm32/mod.rs
+++ b/cranelift/codegen/src/isa/arm32/mod.rs
@@ -3,14 +3,12 @@
 use crate::ir::condcodes::IntCC;
 use crate::ir::Function;
 use crate::isa::Builder as IsaBuilder;
-use crate::machinst::{
-    compile, MachBackend, MachCompileResult, ShowWithRRU, TargetIsaAdapter, VCode,
-};
+use crate::machinst::{compile, MachBackend, MachCompileResult, TargetIsaAdapter, VCode};
 use crate::result::CodegenResult;
 use crate::settings;
 
 use alloc::boxed::Box;
-use regalloc::RealRegUniverse;
+use regalloc::{PrettyPrint, RealRegUniverse};
 use target_lexicon::{Architecture, ArmArchitecture, Triple};
 
 // New backend:
diff --git a/cranelift/codegen/src/isa/x64/abi.rs b/cranelift/codegen/src/isa/x64/abi.rs
index 2c1404937c..a253a92bae 100644
--- a/cranelift/codegen/src/isa/x64/abi.rs
+++ b/cranelift/codegen/src/isa/x64/abi.rs
@@ -493,6 +493,8 @@ impl ABIMachineSpec for X64ABIMachineSpec {
         loc: SourceLoc,
         opcode: ir::Opcode,
         tmp: Writable<Reg>,
+        _callee_conv: isa::CallConv,
+        _caller_conv: isa::CallConv,
     ) -> SmallVec<[(InstIsSafepoint, Self::I); 2]> {
         let mut insts = SmallVec::new();
         match dest {
@@ -545,7 +547,7 @@ impl ABIMachineSpec for X64ABIMachineSpec {
         s.nominal_sp_to_fp
     }
 
-    fn get_caller_saves(call_conv: isa::CallConv) -> Vec<Writable<Reg>> {
+    fn get_regs_clobbered_by_call(call_conv_of_callee: isa::CallConv) -> Vec<Writable<Reg>> {
         let mut caller_saved = vec![
             // Systemv calling convention:
             // - GPR: all except RBX, RBP, R12 to R15 (which are callee-saved).
@@ -577,7 +579,7 @@ impl ABIMachineSpec for X64ABIMachineSpec {
             Writable::from_reg(regs::xmm15()),
         ];
 
-        if call_conv.extends_baldrdash() {
+        if call_conv_of_callee.extends_baldrdash() {
             caller_saved.push(Writable::from_reg(regs::r12()));
             caller_saved.push(Writable::from_reg(regs::r13()));
             // Not r14; implicitly preserved in the entry.
diff --git a/cranelift/codegen/src/isa/x64/inst/args.rs b/cranelift/codegen/src/isa/x64/inst/args.rs
index 29cf01c71a..3eeec52bf0 100644
--- a/cranelift/codegen/src/isa/x64/inst/args.rs
+++ b/cranelift/codegen/src/isa/x64/inst/args.rs
@@ -5,7 +5,10 @@ use super::EmitState;
 use crate::ir::condcodes::{FloatCC, IntCC};
 use crate::machinst::*;
 use core::fmt::Debug;
-use regalloc::{RealRegUniverse, Reg, RegClass, RegUsageCollector, RegUsageMapper, Writable};
+use regalloc::{
+    PrettyPrint, PrettyPrintSized, RealRegUniverse, Reg, RegClass, RegUsageCollector,
+    RegUsageMapper, Writable,
+};
 use std::fmt;
 use std::string::{String, ToString};
 
@@ -68,7 +71,7 @@ impl Amode {
     }
 }
 
-impl ShowWithRRU for Amode {
+impl PrettyPrint for Amode {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         match self {
             Amode::ImmReg { simm32, base } => {
@@ -156,7 +159,7 @@ impl Into<SyntheticAmode> for Amode {
     }
 }
 
-impl ShowWithRRU for SyntheticAmode {
+impl PrettyPrint for SyntheticAmode {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         match self {
             SyntheticAmode::Real(addr) => addr.show_rru(mb_rru),
@@ -214,11 +217,13 @@ impl RegMemImm {
     }
 }
 
-impl ShowWithRRU for RegMemImm {
+impl PrettyPrint for RegMemImm {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         self.show_rru_sized(mb_rru, 8)
     }
+}
 
+impl PrettyPrintSized for RegMemImm {
     fn show_rru_sized(&self, mb_rru: Option<&RealRegUniverse>, size: u8) -> String {
         match self {
             Self::Reg { reg } => show_ireg_sized(*reg, mb_rru, size),
@@ -271,11 +276,13 @@ impl From<Writable<Reg>> for RegMem {
     }
 }
 
-impl ShowWithRRU for RegMem {
+impl PrettyPrint for RegMem {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         self.show_rru_sized(mb_rru, 8)
     }
+}
 
+impl PrettyPrintSized for RegMem {
     fn show_rru_sized(&self, mb_rru: Option<&RealRegUniverse>, size: u8) -> String {
         match self {
             RegMem::Reg { reg } => show_ireg_sized(*reg, mb_rru, size),
@@ -1098,7 +1105,7 @@ pub enum BranchTarget {
     ResolvedOffset(isize),
 }
 
-impl ShowWithRRU for BranchTarget {
+impl PrettyPrint for BranchTarget {
     fn show_rru(&self, _mb_rru: Option<&RealRegUniverse>) -> String {
         match self {
             BranchTarget::Label(l) => format!("{:?}", l),
diff --git a/cranelift/codegen/src/isa/x64/inst/mod.rs b/cranelift/codegen/src/isa/x64/inst/mod.rs
index 4818022398..b370c97f44 100644
--- a/cranelift/codegen/src/isa/x64/inst/mod.rs
+++ b/cranelift/codegen/src/isa/x64/inst/mod.rs
@@ -8,8 +8,8 @@ use crate::{settings, settings::Flags, CodegenError, CodegenResult};
 use alloc::boxed::Box;
 use alloc::vec::Vec;
 use regalloc::{
-    RealRegUniverse, Reg, RegClass, RegUsageCollector, RegUsageMapper, SpillSlot, VirtualReg,
-    Writable,
+    PrettyPrint, PrettyPrintSized, RealRegUniverse, Reg, RegClass, RegUsageCollector,
+    RegUsageMapper, SpillSlot, VirtualReg, Writable,
 };
 use smallvec::SmallVec;
 use std::fmt;
@@ -1165,7 +1165,7 @@ impl Inst {
 //=============================================================================
 // Instructions: printing
 
-impl ShowWithRRU for Inst {
+impl PrettyPrint for Inst {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         fn ljustify(s: String) -> String {
             let w = 7;
diff --git a/cranelift/codegen/src/isa/x64/inst/regs.rs b/cranelift/codegen/src/isa/x64/inst/regs.rs
index 5cc9a83295..04bc1f09bf 100644
--- a/cranelift/codegen/src/isa/x64/inst/regs.rs
+++ b/cranelift/codegen/src/isa/x64/inst/regs.rs
@@ -10,9 +10,11 @@
 //! Also, they will have to be ABI dependent.  Need to find a way to avoid constructing a universe
 //! for each function we compile.
 
-use crate::{machinst::pretty_print::ShowWithRRU, settings};
+use crate::settings;
 use alloc::vec::Vec;
-use regalloc::{RealReg, RealRegUniverse, Reg, RegClass, RegClassInfo, NUM_REG_CLASSES};
+use regalloc::{
+    PrettyPrint, RealReg, RealRegUniverse, Reg, RegClass, RegClassInfo, NUM_REG_CLASSES,
+};
 use std::string::String;
 
 // Hardware encodings for a few registers.
diff --git a/cranelift/codegen/src/isa/x64/lower.rs b/cranelift/codegen/src/isa/x64/lower.rs
index 6eac09618a..4fd1da9f3b 100644
--- a/cranelift/codegen/src/isa/x64/lower.rs
+++ b/cranelift/codegen/src/isa/x64/lower.rs
@@ -384,9 +384,10 @@ fn emit_vm_call<C: LowerCtx<I = Inst>>(
     // TODO avoid recreating signatures for every single Libcall function.
     let call_conv = CallConv::for_libcall(flags, CallConv::triple_default(triple));
     let sig = make_libcall_sig(ctx, insn, call_conv, types::I64);
+    let caller_conv = ctx.abi().call_conv();
 
     let loc = ctx.srcloc(insn);
-    let mut abi = X64ABICaller::from_func(&sig, &extname, dist, loc)?;
+    let mut abi = X64ABICaller::from_func(&sig, &extname, dist, loc, caller_conv)?;
 
     abi.emit_stack_pre_adjust(ctx);
 
@@ -1558,6 +1559,7 @@ fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
 
         Opcode::Call | Opcode::CallIndirect => {
             let loc = ctx.srcloc(insn);
+            let caller_conv = ctx.abi().call_conv();
             let (mut abi, inputs) = match op {
                 Opcode::Call => {
                     let (extname, dist) = ctx.call_target(insn).unwrap();
@@ -1565,7 +1567,7 @@ fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
                     assert_eq!(inputs.len(), sig.params.len());
                     assert_eq!(outputs.len(), sig.returns.len());
                     (
-                        X64ABICaller::from_func(sig, &extname, dist, loc)?,
+                        X64ABICaller::from_func(sig, &extname, dist, loc, caller_conv)?,
                         &inputs[..],
                     )
                 }
@@ -1575,7 +1577,10 @@ fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
                     let sig = ctx.call_sig(insn).unwrap();
                     assert_eq!(inputs.len() - 1, sig.params.len());
                     assert_eq!(outputs.len(), sig.returns.len());
-                    (X64ABICaller::from_ptr(sig, ptr, loc, op)?, &inputs[1..])
+                    (
+                        X64ABICaller::from_ptr(sig, ptr, loc, op, caller_conv)?,
+                        &inputs[1..],
+                    )
                 }
 
                 _ => unreachable!(),
diff --git a/cranelift/codegen/src/isa/x64/mod.rs b/cranelift/codegen/src/isa/x64/mod.rs
index 5dfc078a75..211bc50081 100644
--- a/cranelift/codegen/src/isa/x64/mod.rs
+++ b/cranelift/codegen/src/isa/x64/mod.rs
@@ -4,13 +4,11 @@ use super::TargetIsa;
 use crate::ir::{condcodes::IntCC, Function};
 use crate::isa::x64::{inst::regs::create_reg_universe_systemv, settings as x64_settings};
 use crate::isa::Builder as IsaBuilder;
-use crate::machinst::{
-    compile, pretty_print::ShowWithRRU, MachBackend, MachCompileResult, TargetIsaAdapter, VCode,
-};
+use crate::machinst::{compile, MachBackend, MachCompileResult, TargetIsaAdapter, VCode};
 use crate::result::CodegenResult;
 use crate::settings::{self as shared_settings, Flags};
 use alloc::boxed::Box;
-use regalloc::RealRegUniverse;
+use regalloc::{PrettyPrint, RealRegUniverse};
 use target_lexicon::Triple;
 
 mod abi;
diff --git a/cranelift/codegen/src/machinst/abi.rs b/cranelift/codegen/src/machinst/abi.rs
index c00b58b955..8308cfd49d 100644
--- a/cranelift/codegen/src/machinst/abi.rs
+++ b/cranelift/codegen/src/machinst/abi.rs
@@ -2,6 +2,7 @@
 
 use crate::binemit::StackMap;
 use crate::ir::StackSlot;
+use crate::isa::CallConv;
 use crate::machinst::*;
 use crate::settings;
 
@@ -25,6 +26,9 @@ pub trait ABICallee {
     /// Get the settings controlling this function's compilation.
     fn flags(&self) -> &settings::Flags;
 
+    /// Get the calling convention implemented by this ABI object.
+    fn call_conv(&self) -> CallConv;
+
     /// Get the liveins of the function.
     fn liveins(&self) -> Set<RealReg>;
 
diff --git a/cranelift/codegen/src/machinst/abi_impl.rs b/cranelift/codegen/src/machinst/abi_impl.rs
index ed7a8f1448..2f218fd3a8 100644
--- a/cranelift/codegen/src/machinst/abi_impl.rs
+++ b/cranelift/codegen/src/machinst/abi_impl.rs
@@ -347,6 +347,8 @@ pub trait ABIMachineSpec {
         loc: SourceLoc,
         opcode: ir::Opcode,
         tmp: Writable<Reg>,
+        callee_conv: isa::CallConv,
+        callee_conv: isa::CallConv,
     ) -> SmallVec<[(InstIsSafepoint, Self::I); 2]>;
 
     /// Get the number of spillslots required for the given register-class and
@@ -359,8 +361,9 @@ pub trait ABIMachineSpec {
     /// Get the "nominal SP to FP" offset from an instruction-emission state.
     fn get_nominal_sp_to_fp(s: &<Self::I as MachInstEmit>::State) -> i64;
 
-    /// Get all caller-save registers.
-    fn get_caller_saves(call_conv: isa::CallConv) -> Vec<Writable<Reg>>;
+    /// Get all caller-save registers, that is, registers that we expect
+    /// not to be saved across a call to a callee with the given ABI.
+    fn get_regs_clobbered_by_call(call_conv_of_callee: isa::CallConv) -> Vec<Writable<Reg>>;
 }
 
 /// ABI information shared between body (callee) and caller.
@@ -682,6 +685,10 @@ impl<M: ABIMachineSpec> ABICallee for ABICalleeImpl<M> {
         &self.flags
     }
 
+    fn call_conv(&self) -> isa::CallConv {
+        self.sig.call_conv
+    }
+
     fn liveins(&self) -> Set<RealReg> {
         let mut set: Set<RealReg> = Set::empty();
         for &arg in &self.sig.args {
@@ -1040,7 +1047,7 @@ fn abisig_to_uses_and_defs<M: ABIMachineSpec>(sig: &ABISig) -> (Vec<Reg>, Vec<Wr
     }
 
     // Compute defs: all retval regs, and all caller-save (clobbered) regs.
-    let mut defs = M::get_caller_saves(sig.call_conv);
+    let mut defs = M::get_regs_clobbered_by_call(sig.call_conv);
     for ret in &sig.rets {
         match ret {
             &ABIArg::Reg(reg, ..) => defs.push(Writable::from_reg(reg.to_reg())),
@@ -1063,8 +1070,10 @@ pub struct ABICallerImpl<M: ABIMachineSpec> {
     dest: CallDest,
     /// Location of callsite.
     loc: ir::SourceLoc,
-    /// Actuall call opcode; used to distinguish various types of calls.
+    /// Actual call opcode; used to distinguish various types of calls.
     opcode: ir::Opcode,
+    /// Caller's calling convention.
+    caller_conv: isa::CallConv,
 
     _mach: PhantomData<M>,
 }
@@ -1085,6 +1094,7 @@ impl<M: ABIMachineSpec> ABICallerImpl<M> {
         extname: &ir::ExternalName,
         dist: RelocDistance,
         loc: ir::SourceLoc,
+        caller_conv: isa::CallConv,
     ) -> CodegenResult<ABICallerImpl<M>> {
         let sig = ABISig::from_func_sig::<M>(sig)?;
         let (uses, defs) = abisig_to_uses_and_defs::<M>(&sig);
@@ -1095,6 +1105,7 @@ impl<M: ABIMachineSpec> ABICallerImpl<M> {
             dest: CallDest::ExtName(extname.clone(), dist),
             loc,
             opcode: ir::Opcode::Call,
+            caller_conv,
             _mach: PhantomData,
         })
     }
@@ -1106,6 +1117,7 @@ impl<M: ABIMachineSpec> ABICallerImpl<M> {
         ptr: Reg,
         loc: ir::SourceLoc,
         opcode: ir::Opcode,
+        caller_conv: isa::CallConv,
     ) -> CodegenResult<ABICallerImpl<M>> {
         let sig = ABISig::from_func_sig::<M>(sig)?;
         let (uses, defs) = abisig_to_uses_and_defs::<M>(&sig);
@@ -1116,6 +1128,7 @@ impl<M: ABIMachineSpec> ABICallerImpl<M> {
             dest: CallDest::Reg(ptr),
             loc,
             opcode,
+            caller_conv,
             _mach: PhantomData,
         })
     }
@@ -1255,8 +1268,17 @@ impl<M: ABIMachineSpec> ABICaller for ABICallerImpl<M> {
             self.emit_copy_reg_to_arg(ctx, i, rd.to_reg());
         }
         let tmp = ctx.alloc_tmp(word_rc, word_type);
-        for (is_safepoint, inst) in
-            M::gen_call(&self.dest, uses, defs, self.loc, self.opcode, tmp).into_iter()
+        for (is_safepoint, inst) in M::gen_call(
+            &self.dest,
+            uses,
+            defs,
+            self.loc,
+            self.opcode,
+            tmp,
+            self.sig.call_conv,
+            self.caller_conv,
+        )
+        .into_iter()
         {
             match is_safepoint {
                 InstIsSafepoint::Yes => ctx.emit_safepoint(inst),
diff --git a/cranelift/codegen/src/machinst/compile.rs b/cranelift/codegen/src/machinst/compile.rs
index 67db2dbafa..1264340a30 100644
--- a/cranelift/codegen/src/machinst/compile.rs
+++ b/cranelift/codegen/src/machinst/compile.rs
@@ -6,7 +6,7 @@ use crate::settings;
 use crate::timing;
 
 use log::debug;
-use regalloc::{allocate_registers_with_opts, Algorithm, Options};
+use regalloc::{allocate_registers_with_opts, Algorithm, Options, PrettyPrint};
 
 /// Compile the given function down to VCode with allocated registers, ready
 /// for binary emission.
@@ -16,7 +16,7 @@ pub fn compile<B: LowerBackend + MachBackend>(
     abi: Box<dyn ABICallee<I = B::MInst>>,
 ) -> CodegenResult<VCode<B::MInst>>
 where
-    B::MInst: ShowWithRRU,
+    B::MInst: PrettyPrint,
 {
     // Compute lowered block order.
     let block_order = BlockLoweringOrder::new(f);
diff --git a/cranelift/codegen/src/machinst/mod.rs b/cranelift/codegen/src/machinst/mod.rs
index 72f351aa88..3a470d852c 100644
--- a/cranelift/codegen/src/machinst/mod.rs
+++ b/cranelift/codegen/src/machinst/mod.rs
@@ -125,8 +125,6 @@ pub mod abi;
 pub use abi::*;
 pub mod abi_impl;
 pub use abi_impl::*;
-pub mod pretty_print;
-pub use pretty_print::*;
 pub mod buffer;
 pub use buffer::*;
 pub mod adapter;
@@ -156,6 +154,11 @@ pub trait MachInst: Clone + Debug {
     /// Returns true if the instruction is an epilogue placeholder.
     fn is_epilogue_placeholder(&self) -> bool;
 
+    /// Should this instruction be included in the clobber-set?
+    fn is_included_in_clobbers(&self) -> bool {
+        true
+    }
+
     /// Generate a move.
     fn gen_move(to_reg: Writable<Reg>, from_reg: Reg, ty: Type) -> Self;
 
diff --git a/cranelift/codegen/src/machinst/pretty_print.rs b/cranelift/codegen/src/machinst/pretty_print.rs
deleted file mode 100644
index 40e7c1b842..0000000000
--- a/cranelift/codegen/src/machinst/pretty_print.rs
+++ /dev/null
@@ -1,66 +0,0 @@
-//! Pretty-printing for machine code (virtual-registerized or final).
-
-use regalloc::{RealRegUniverse, Reg, Writable};
-
-use std::fmt::Debug;
-use std::hash::Hash;
-use std::string::{String, ToString};
-
-// FIXME: Should this go into regalloc.rs instead?
-
-/// A trait for printing instruction bits and pieces, with the the ability to
-/// take a contextualising RealRegUniverse that is used to give proper names to
-/// registers.
-pub trait ShowWithRRU {
-    /// Return a string that shows the implementing object in context of the
-    /// given `RealRegUniverse`, if provided.
-    fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String;
-
-    /// The same as |show_rru|, but with an optional hint giving a size in
-    /// bytes.  Its interpretation is object-dependent, and it is intended to
-    /// pass around enough information to facilitate printing sub-parts of
-    /// real registers correctly.  Objects may ignore size hints that are
-    /// irrelevant to them.
-    fn show_rru_sized(&self, mb_rru: Option<&RealRegUniverse>, _size: u8) -> String {
-        // Default implementation is to ignore the hint.
-        self.show_rru(mb_rru)
-    }
-}
-
-impl ShowWithRRU for Reg {
-    fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
-        if self.is_real() {
-            if let Some(rru) = mb_rru {
-                let reg_ix = self.get_index();
-                if reg_ix < rru.regs.len() {
-                    return rru.regs[reg_ix].1.to_string();
-                } else {
-                    // We have a real reg which isn't listed in the universe.
-                    // Per the regalloc.rs interface requirements, this is
-                    // Totally Not Allowed.  Print it generically anyway, so
-                    // we have something to debug.
-                    return format!("!!{:?}!!", self);
-                }
-            }
-        }
-        // The reg is virtual, or we have no universe.  Be generic.
-        format!("%{:?}", self)
-    }
-
-    fn show_rru_sized(&self, _mb_rru: Option<&RealRegUniverse>, _size: u8) -> String {
-        // For the specific case of Reg, we demand not to have a size hint,
-        // since interpretation of the size is target specific, but this code
-        // is used by all targets.
-        panic!("Reg::show_rru_sized: impossible to implement");
-    }
-}
-
-impl<R: ShowWithRRU + Copy + Ord + Hash + Eq + Debug> ShowWithRRU for Writable<R> {
-    fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
-        self.to_reg().show_rru(mb_rru)
-    }
-
-    fn show_rru_sized(&self, mb_rru: Option<&RealRegUniverse>, size: u8) -> String {
-        self.to_reg().show_rru_sized(mb_rru, size)
-    }
-}
diff --git a/cranelift/codegen/src/machinst/vcode.rs b/cranelift/codegen/src/machinst/vcode.rs
index 6733e89da4..26176a7411 100644
--- a/cranelift/codegen/src/machinst/vcode.rs
+++ b/cranelift/codegen/src/machinst/vcode.rs
@@ -25,8 +25,8 @@ use crate::timing;
 use regalloc::Function as RegallocFunction;
 use regalloc::Set as RegallocSet;
 use regalloc::{
-    BlockIx, InstIx, Range, RegAllocResult, RegClass, RegUsageCollector, RegUsageMapper, SpillSlot,
-    StackmapRequestInfo,
+    BlockIx, InstIx, PrettyPrint, Range, RegAllocResult, RegClass, RegUsageCollector,
+    RegUsageMapper, SpillSlot, StackmapRequestInfo,
 };
 
 use alloc::boxed::Box;
@@ -543,6 +543,10 @@ impl<I: VCodeInst> RegallocFunction for VCode<I> {
         }
     }
 
+    fn is_included_in_clobbers(&self, insn: &I) -> bool {
+        insn.is_included_in_clobbers()
+    }
+
     fn get_regs(insn: &I, collector: &mut RegUsageCollector) {
         insn.get_regs(collector)
     }
@@ -624,7 +628,7 @@ impl<I: VCodeInst> fmt::Debug for VCode<I> {
 }
 
 /// Pretty-printing with `RealRegUniverse` context.
-impl<I: VCodeInst> ShowWithRRU for VCode<I> {
+impl<I: VCodeInst> PrettyPrint for VCode<I> {
     fn show_rru(&self, mb_rru: Option<&RealRegUniverse>) -> String {
         use std::fmt::Write;
 
diff --git a/cranelift/filetests/filetests/isa/aarch64/call.clif b/cranelift/filetests/filetests/isa/aarch64/call.clif
index f08b7c23fc..96ec0ff04b 100644
--- a/cranelift/filetests/filetests/isa/aarch64/call.clif
+++ b/cranelift/filetests/filetests/isa/aarch64/call.clif
@@ -151,34 +151,27 @@ block0:
 
 ; check:  stp fp, lr, [sp, #-16]!
 ; nextln:  mov fp, sp
-; nextln:  sub sp, sp, #48
-; nextln:  str q8, [sp]
-; nextln:  str q9, [sp, #16]
-; nextln:  str q10, [sp, #32]
-; nextln:  virtual_sp_offset_adjust 48
+; nextln:  sub sp, sp, #32
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v8.16b, v0.16b
+; nextln:  str s0, [sp]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v9.16b, v0.16b
+; nextln:  str d0, [sp, #8]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v10.16b, v0.16b
+; nextln:  str d0, [sp, #16]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v0.16b, v8.16b
+; nextln:  ldr s0, [sp]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v0.16b, v9.16b
+; nextln:  ldr d0, [sp, #8]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v0.16b, v10.16b
+; nextln:  ldr d0, [sp, #16]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  ldr q8, [sp]
-; nextln:  ldr q9, [sp, #16]
-; nextln:  ldr q10, [sp, #32]
 ; nextln:  mov sp, fp
 ; nextln:  ldp fp, lr, [sp], #16
 ; nextln:  ret
@@ -202,33 +195,26 @@ block0:
 ; check:  stp fp, lr, [sp, #-16]!
 ; nextln:  mov fp, sp
 ; nextln:  sub sp, sp, #48
-; nextln:  str q8, [sp]
-; nextln:  str q9, [sp, #16]
-; nextln:  str q10, [sp, #32]
-; nextln:  virtual_sp_offset_adjust 48
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v8.16b, v0.16b
+; nextln:  str q0, [sp]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v9.16b, v0.16b
+; nextln:  str q0, [sp, #16]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v10.16b, v0.16b
+; nextln:  str q0, [sp, #32]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v0.16b, v8.16b
+; nextln:  ldr q0, [sp]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v0.16b, v9.16b
+; nextln:  ldr q0, [sp, #16]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v0.16b, v10.16b
+; nextln:  ldr q0, [sp, #32]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  ldr q8, [sp]
-; nextln:  ldr q9, [sp, #16]
-; nextln:  ldr q10, [sp, #32]
 ; nextln:  mov sp, fp
 ; nextln:  ldp fp, lr, [sp], #16
 ; nextln:  ret
@@ -255,34 +241,27 @@ block0:
 
 ; check:  stp fp, lr, [sp, #-16]!
 ; nextln:  mov fp, sp
-; nextln:  sub sp, sp, #48
-; nextln:  str q8, [sp]
-; nextln:  str q9, [sp, #16]
-; nextln:  str q10, [sp, #32]
-; nextln:  virtual_sp_offset_adjust 48
+; nextln:  sub sp, sp, #32
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v8.16b, v0.16b
+; nextln:  str s0, [sp]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v9.16b, v0.16b
+; nextln:  str d0, [sp, #8]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v10.16b, v0.16b
+; nextln:  str q0, [sp, #16]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v0.16b, v8.16b
+; nextln:  ldr s0, [sp]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v0.16b, v9.16b
+; nextln:  ldr d0, [sp, #8]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  mov v0.16b, v10.16b
+; nextln:  ldr q0, [sp, #16]
 ; nextln:  ldr x0, 8 ; b 12 ; data
 ; nextln:  blr x0
-; nextln:  ldr q8, [sp]
-; nextln:  ldr q9, [sp, #16]
-; nextln:  ldr q10, [sp, #32]
 ; nextln:  mov sp, fp
 ; nextln:  ldp fp, lr, [sp], #16
 ; nextln:  ret
diff --git a/cranelift/filetests/filetests/isa/aarch64/prologue.clif b/cranelift/filetests/filetests/isa/aarch64/prologue.clif
new file mode 100644
index 0000000000..c172f9bee3
--- /dev/null
+++ b/cranelift/filetests/filetests/isa/aarch64/prologue.clif
@@ -0,0 +1,99 @@
+test compile
+target aarch64
+
+function %f(f64) -> f64 {
+block0(v0: f64):
+    v1 = fadd.f64 v0, v0
+    v2 = fadd.f64 v0, v0
+    v3 = fadd.f64 v0, v0
+    v4 = fadd.f64 v0, v0
+    v5 = fadd.f64 v0, v0
+    v6 = fadd.f64 v0, v0
+    v7 = fadd.f64 v0, v0
+    v8 = fadd.f64 v0, v0
+    v9 = fadd.f64 v0, v0
+    v10 = fadd.f64 v0, v0
+    v11 = fadd.f64 v0, v0
+    v12 = fadd.f64 v0, v0
+    v13 = fadd.f64 v0, v0
+    v14 = fadd.f64 v0, v0
+    v15 = fadd.f64 v0, v0
+    v16 = fadd.f64 v0, v0
+    v17 = fadd.f64 v0, v0
+    v18 = fadd.f64 v0, v0
+    v19 = fadd.f64 v0, v0
+    v20 = fadd.f64 v0, v0
+    v21 = fadd.f64 v0, v0
+    v22 = fadd.f64 v0, v0
+    v23 = fadd.f64 v0, v0
+    v24 = fadd.f64 v0, v0
+    v25 = fadd.f64 v0, v0
+    v26 = fadd.f64 v0, v0
+    v27 = fadd.f64 v0, v0
+    v28 = fadd.f64 v0, v0
+    v29 = fadd.f64 v0, v0
+    v30 = fadd.f64 v0, v0
+    v31 = fadd.f64 v0, v0
+
+    v32 = fadd.f64 v0, v1
+    v33 = fadd.f64 v2, v3
+    v34 = fadd.f64 v4, v5
+    v35 = fadd.f64 v6, v7
+    v36 = fadd.f64 v8, v9
+    v37 = fadd.f64 v10, v11
+    v38 = fadd.f64 v12, v13
+    v39 = fadd.f64 v14, v15
+    v40 = fadd.f64 v16, v17
+    v41 = fadd.f64 v18, v19
+    v42 = fadd.f64 v20, v21
+    v43 = fadd.f64 v22, v23
+    v44 = fadd.f64 v24, v25
+    v45 = fadd.f64 v26, v27
+    v46 = fadd.f64 v28, v29
+    v47 = fadd.f64 v30, v31
+
+    v48 = fadd.f64 v32, v33
+    v49 = fadd.f64 v34, v35
+    v50 = fadd.f64 v36, v37
+    v51 = fadd.f64 v38, v39
+    v52 = fadd.f64 v40, v41
+    v53 = fadd.f64 v42, v43
+    v54 = fadd.f64 v44, v45
+    v55 = fadd.f64 v46, v47
+
+    v56 = fadd.f64 v48, v49
+    v57 = fadd.f64 v50, v51
+    v58 = fadd.f64 v52, v53
+    v59 = fadd.f64 v54, v55
+
+    v60 = fadd.f64 v56, v57
+    v61 = fadd.f64 v58, v59
+
+    v62 = fadd.f64 v60, v61
+
+    return v62
+}
+
+; check: stp fp, lr, [sp, #-16]!
+; nextln: mov fp, sp
+; nextln: sub sp, sp, #128
+; nextln: str q8, [sp]
+; nextln: str q9, [sp, #16]
+; nextln: str q10, [sp, #32]
+; nextln: str q11, [sp, #48]
+; nextln: str q12, [sp, #64]
+; nextln: str q13, [sp, #80]
+; nextln: str q14, [sp, #96]
+; nextln: str q15, [sp, #112]
+
+; check: ldr q8, [sp]
+; nextln: ldr q9, [sp, #16]
+; nextln: ldr q10, [sp, #32]
+; nextln: ldr q11, [sp, #48]
+; nextln: ldr q12, [sp, #64]
+; nextln: ldr q13, [sp, #80]
+; nextln: ldr q14, [sp, #96]
+; nextln: ldr q15, [sp, #112]
+; nextln: mov sp, fp
+; nextln: ldp fp, lr, [sp], #16
+; nextln: ret