Add support for macho relocations. (#378)

This requires splitting X86PCRel4 into two separate relocations, to
distinguish the case where the instruction is a call, as Mach-O uses a
different relocation in that case.

This also makes it explicit that only x86-64 relocations are supported
currently.

cranelift/filetests/isa/x86/binary32.cton

@@ -352,7 +352,7 @@ ebb0:
     [-,%rsi]             v351 = bint.i32 v301   ; bin: 0f b6 f2
 
     ; asm: call foo
-    call fn0()                                  ; bin: stk_ovf e8 PCRel4(%foo-4) 00000000
+    call fn0()                                  ; bin: stk_ovf e8 CallPCRel4(%foo-4) 00000000
 
     ; asm: movl $0, %ecx
     [-,%rcx]            v400 = func_addr.i32 fn0        ; bin: b9 Abs4(%foo) 00000000

cranelift/filetests/isa/x86/binary64-pic.cton

@@ -30,7 +30,7 @@ ebb0:
     ; Colocated functions.
 
     ; asm: call foo
-    call fn1()                                  ; bin: stk_ovf e8 PCRel4(%bar-4) 00000000
+    call fn1()                                  ; bin: stk_ovf e8 CallPCRel4(%bar-4) 00000000
 
     ; asm: lea 0x0(%rip), %rax
     [-,%rax]            v0 = func_addr.i64 fn1        ; bin: 48 8d 05 PCRel4(%bar-4) 00000000
@@ -49,7 +49,7 @@ ebb0:
     ; Non-colocated functions.
 
     ; asm: call foo@PLT
-    call fn0()                                  ; bin: stk_ovf e8 PLTRel4(%foo-4) 00000000
+    call fn0()                                  ; bin: stk_ovf e8 CallPLTRel4(%foo-4) 00000000
 
     ; asm: mov 0x0(%rip), %rax
     [-,%rax]            v100 = func_addr.i64 fn0        ; bin: 48 8b 05 GOTPCRel4(%foo-4) 00000000

cranelift/filetests/isa/x86/binary64.cton

@@ -485,7 +485,7 @@ ebb0:
     ; Colocated functions.
 
     ; asm: call bar
-    call fn1()                                  ; bin: stk_ovf e8 PCRel4(%bar-4) 00000000
+    call fn1()                                  ; bin: stk_ovf e8 CallPCRel4(%bar-4) 00000000
 
     ; asm: lea 0x0(%rip), %rcx
     [-,%rcx]            v400 = func_addr.i64 fn1        ; bin: 48 8d 0d PCRel4(%bar-4) 00000000

lib/codegen/meta/isa/x86/recipes.py

@@ -1388,7 +1388,7 @@ call_id = TailRecipe(
         PUT_OP(bits, BASE_REX, sink);
         // The addend adjusts for the difference between the end of the
         // instruction and the beginning of the immediate field.
-        sink.reloc_external(Reloc::X86PCRel4,
+        sink.reloc_external(Reloc::X86CallPCRel4,
                             &func.dfg.ext_funcs[func_ref].name,
                             -4);
         sink.put4(0);
@@ -1399,7 +1399,7 @@ call_plt_id = TailRecipe(
         emit='''
         sink.trap(TrapCode::StackOverflow, func.srclocs[inst]);
         PUT_OP(bits, BASE_REX, sink);
-        sink.reloc_external(Reloc::X86PLTRel4,
+        sink.reloc_external(Reloc::X86CallPLTRel4,
                             &func.dfg.ext_funcs[func_ref].name,
                             -4);
         sink.put4(0);

lib/codegen/src/binemit/mod.rs

@@ -33,10 +33,12 @@ pub enum Reloc {
     Abs8,
     /// x86 PC-relative 4-byte
     X86PCRel4,
+    /// x86 call to PC-relative 4-byte
+    X86CallPCRel4,
+    /// x86 call to PLT-relative 4-byte
+    X86CallPLTRel4,
     /// x86 GOT PC-relative 4-byte
     X86GOTPCRel4,
-    /// x86 PLT-relative 4-byte
-    X86PLTRel4,
     /// Arm32 call target
     Arm32Call,
     /// Arm64 call target
@@ -53,8 +55,9 @@ impl fmt::Display for Reloc {
             Reloc::Abs4 => write!(f, "Abs4"),
             Reloc::Abs8 => write!(f, "Abs8"),
             Reloc::X86PCRel4 => write!(f, "PCRel4"),
+            Reloc::X86CallPCRel4 => write!(f, "CallPCRel4"),
+            Reloc::X86CallPLTRel4 => write!(f, "CallPLTRel4"),
             Reloc::X86GOTPCRel4 => write!(f, "GOTPCRel4"),
-            Reloc::X86PLTRel4 => write!(f, "PLTRel4"),
             Reloc::Arm32Call | Reloc::Arm64Call | Reloc::RiscvCall => write!(f, "Call"),
         }
     }

lib/faerie/src/backend.rs

@@ -11,7 +11,7 @@ use cretonne_module::{
 use faerie;
 use failure::Error;
 use std::fs::File;
-use target_lexicon::BinaryFormat;
+use target_lexicon::Triple;
 use traps::{FaerieTrapManifest, FaerieTrapSink};
 
 #[derive(Debug)]
@@ -29,7 +29,6 @@ pub enum FaerieTrapCollection {
 pub struct FaerieBuilder {
     isa: Box<TargetIsa>,
     name: String,
-    format: BinaryFormat,
     collect_traps: FaerieTrapCollection,
     libcall_names: Box<Fn(ir::LibCall) -> String>,
 }
@@ -51,7 +50,6 @@ impl FaerieBuilder {
     pub fn new(
         isa: Box<TargetIsa>,
         name: String,
-        format: BinaryFormat,
         collect_traps: FaerieTrapCollection,
         libcall_names: Box<Fn(ir::LibCall) -> String>,
     ) -> ModuleResult<Self> {
@@ -63,7 +61,6 @@ impl FaerieBuilder {
         Ok(Self {
             isa,
             name,
-            format,
             collect_traps,
             libcall_names,
         })
@@ -91,7 +88,6 @@ impl FaerieBuilder {
 pub struct FaerieBackend {
     isa: Box<TargetIsa>,
     artifact: faerie::Artifact,
-    format: BinaryFormat,
     trap_manifest: Option<FaerieTrapManifest>,
     libcall_names: Box<Fn(ir::LibCall) -> String>,
 }
@@ -120,7 +116,6 @@ impl Backend for FaerieBackend {
         Self {
             artifact: faerie::Artifact::new(builder.isa.triple().clone(), builder.name),
             isa: builder.isa,
-            format: builder.format,
             trap_manifest: match builder.collect_traps {
                 FaerieTrapCollection::Enabled => Some(FaerieTrapManifest::new()),
                 FaerieTrapCollection::Disabled => None,
@@ -158,7 +153,7 @@ impl Backend for FaerieBackend {
         // Non-lexical lifetimes would obviate the braces here.
         {
             let mut reloc_sink = FaerieRelocSink {
-                format: self.format,
+                triple: self.isa.triple().clone(),
                 artifact: &mut self.artifact,
                 name,
                 namespace,
@@ -348,7 +343,7 @@ fn translate_data_linkage(linkage: Linkage, writable: bool) -> faerie::Decl {
 }
 
 struct FaerieRelocSink<'a> {
-    format: BinaryFormat,
+    triple: Triple,
     artifact: &'a mut faerie::Artifact,
     name: &'a str,
     namespace: &'a ModuleNamespace<'a, FaerieBackend>,
@@ -384,9 +379,11 @@ impl<'a> RelocSink for FaerieRelocSink<'a> {
             }
             _ => panic!("invalid ExternalName {}", name),
         };
-        let addend_i32 = addend as i32;
+        let (raw_reloc, raw_addend) = container::raw_relocation(reloc, &self.triple);
-        debug_assert!(i64::from(addend_i32) == addend);
+        // TODO: Handle overflow.
-        let raw_reloc = container::raw_relocation(reloc, self.format);
+        let final_addend = addend + raw_addend;
+        let addend_i32 = final_addend as i32;
+        debug_assert!(i64::from(addend_i32) == final_addend);
         self.artifact
             .link_with(
                 faerie::Link {

lib/faerie/src/container.rs

@@ -1,7 +1,7 @@
 //! Utilities for working with Faerie container formats.
 
 use cretonne_codegen::binemit::Reloc;
-use target_lexicon::BinaryFormat;
+use target_lexicon::{Architecture, BinaryFormat, Triple};
 
 /// An object file format.
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
@@ -13,23 +13,53 @@ pub enum Format {
 }
 
 /// Translate from a Cretonne `Reloc` to a raw object-file-format-specific
-/// relocation code.
+/// relocation code and relocation-implied addend.
-pub fn raw_relocation(reloc: Reloc, format: BinaryFormat) -> u32 {
+pub fn raw_relocation(reloc: Reloc, triple: &Triple) -> (u32, i64) {
-    match format {
+    match triple.binary_format {
         BinaryFormat::Elf => {
             use goblin::elf;
-            match reloc {
+            (
-                Reloc::Abs4 => elf::reloc::R_X86_64_32,
+                match triple.architecture {
-                Reloc::Abs8 => elf::reloc::R_X86_64_64,
+                    Architecture::X86_64 => {
-                Reloc::X86PCRel4 => elf::reloc::R_X86_64_PC32,
+                        match reloc {
-                // TODO: Get Cretonne to tell us when we can use
+                            Reloc::Abs4 => elf::reloc::R_X86_64_32,
-                // R_X86_64_GOTPCRELX/R_X86_64_REX_GOTPCRELX.
+                            Reloc::Abs8 => elf::reloc::R_X86_64_64,
-                Reloc::X86GOTPCRel4 => elf::reloc::R_X86_64_GOTPCREL,
+                            Reloc::X86PCRel4 | Reloc::X86CallPCRel4 => elf::reloc::R_X86_64_PC32,
-                Reloc::X86PLTRel4 => elf::reloc::R_X86_64_PLT32,
+                            // TODO: Get Cretonne to tell us when we can use
-                _ => unimplemented!(),
+                            // R_X86_64_GOTPCRELX/R_X86_64_REX_GOTPCRELX.
+                            Reloc::X86CallPLTRel4 => elf::reloc::R_X86_64_PLT32,
+                            Reloc::X86GOTPCRel4 => elf::reloc::R_X86_64_GOTPCREL,
+                            _ => unimplemented!(),
+                        }
+                    }
+                    _ => unimplemented!("unsupported architecture: {}", triple),
+                },
+                // Most ELF relocations do not include an implicit addend.
+                0,
+            )
+        }
+        BinaryFormat::Macho => {
+            use goblin::mach;
+            match triple.architecture {
+                Architecture::X86_64 => {
+                    match reloc {
+                        Reloc::Abs8 => (u32::from(mach::relocation::R_ABS), 0),
+                        // Mach-O doesn't need us to distinguish between PC-relative calls
+                        // and PLT calls, but it does need us to distinguish between calls
+                        // and non-calls. And, it includes the 4-byte addend implicitly.
+                        Reloc::X86PCRel4 => (u32::from(mach::relocation::X86_64_RELOC_SIGNED), 4),
+                        Reloc::X86CallPCRel4 | Reloc::X86CallPLTRel4 => {
+                            (u32::from(mach::relocation::X86_64_RELOC_BRANCH), 4)
+                        }
+                        Reloc::X86GOTPCRel4 => {
+                            (u32::from(mach::relocation::X86_64_RELOC_GOT_LOAD), 4)
+                        }
+                        _ => unimplemented!("unsupported mach-o reloc: {}", reloc),
+                    }
+                }
+                _ => unimplemented!("unsupported architecture: {}", triple),
             }
         }
-        BinaryFormat::Macho => unimplemented!("macho relocations"),
         _ => unimplemented!("unsupported format"),
     }
 }

lib/simplejit/src/backend.rs

@@ -271,7 +271,7 @@ impl<'simple_jit_backend> Backend for SimpleJITBackend {
                         write_unaligned(at as *mut u64, what as u64)
                     };
                 }
-                Reloc::X86PCRel4 => {
+                Reloc::X86PCRel4 | Reloc::X86CallPCRel4 => {
                     // TODO: Handle overflow.
                     let pcrel = ((what as isize) - (at as isize)) as i32;
                     #[cfg_attr(feature = "cargo-clippy", allow(cast_ptr_alignment))]
@@ -279,7 +279,7 @@ impl<'simple_jit_backend> Backend for SimpleJITBackend {
                         write_unaligned(at as *mut i32, pcrel)
                     };
                 }
-                Reloc::X86GOTPCRel4 | Reloc::X86PLTRel4 => panic!("unexpected PIC relocation"),
+                Reloc::X86GOTPCRel4 | Reloc::X86CallPLTRel4 => panic!("unexpected PIC relocation"),
                 _ => unimplemented!(),
             }
         }
@@ -336,9 +336,10 @@ impl<'simple_jit_backend> Backend for SimpleJITBackend {
                                 write_unaligned(at as *mut u64, what as u64)
                             };
                         }
-                        Reloc::X86PCRel4 | Reloc::X86GOTPCRel4 | Reloc::X86PLTRel4 => {
+                        Reloc::X86PCRel4
-                            panic!("unexpected text relocation in data")
+                        | Reloc::X86CallPCRel4
-                        }
+                        | Reloc::X86GOTPCRel4
+                        | Reloc::X86CallPLTRel4 => panic!("unexpected text relocation in data"),
                         _ => unimplemented!(),
                     }
                 }