[lld-macho][re-land] Support X86_64_RELOC_UNSIGNED

This reverts commit db8559eee4a07c44babcc4618eef3d185cf79cc6.

Author: int3

lld/MachO/Arch/X86_64.cpp

@@ -47,6 +47,8 @@ uint64_t X86_64::getImplicitAddend(const uint8_t *loc, uint8_t type) const {
   case X86_64_RELOC_SIGNED_4:
   case X86_64_RELOC_GOT_LOAD:
     return read32le(loc);
+  case X86_64_RELOC_UNSIGNED:
+    return read64le(loc);
   default:
     error("TODO: Unhandled relocation type " + std::to_string(type));
     return 0;
@@ -65,6 +67,9 @@ void X86_64::relocateOne(uint8_t *loc, uint8_t type, uint64_t val) const {
     // since the RIP has advanced by 4 at this point.
     write32le(loc, val - 4);
     break;
+  case X86_64_RELOC_UNSIGNED:
+    write64le(loc, val);
+    break;
   default:
     llvm_unreachable(
         "getImplicitAddend should have flagged all unhandled relocation types");

lld/MachO/InputFiles.cpp

@@ -173,11 +173,10 @@ void InputFile::parseRelocations(const section_64 &sec,
       fatal("TODO: Scattered relocations not supported");
 
     auto rel = reinterpret_cast<const relocation_info &>(anyRel);
-    if (!rel.r_pcrel)
-      fatal("TODO: Only pcrel relocations are supported");
 
     Reloc r;
     r.type = rel.r_type;
+    r.pcrel = rel.r_pcrel;
     uint32_t secRelOffset = rel.r_address;
     uint64_t rawAddend =
         target->getImplicitAddend(buf + sec.offset + secRelOffset, r.type);
@@ -186,6 +185,9 @@ void InputFile::parseRelocations(const section_64 &sec,
       r.target = symbols[rel.r_symbolnum];
       r.addend = rawAddend;
     } else {
+      if (!rel.r_pcrel)
+        fatal("TODO: Only pcrel section relocations are supported");
+
       if (rel.r_symbolnum == 0 || rel.r_symbolnum > subsections.size())
         fatal("invalid section index in relocation for offset " +
               std::to_string(r.offset) + " in section " + sec.sectname +

lld/MachO/InputSection.cpp

@@ -43,7 +43,7 @@ void InputSection::writeTo(uint8_t *buf) {
     }
 
     uint64_t val = va + r.addend;
-    if (1) // TODO: handle non-pcrel relocations
+    if (r.pcrel)
       val -= getVA() + r.offset;
     target->relocateOne(buf + r.offset, r.type, val);
   }

lld/MachO/InputSection.h

@@ -24,12 +24,13 @@ class Symbol;
 
 struct Reloc {
   uint8_t type;
-  // Adding this offset to the address of the target symbol or subsection gives
-  // the destination that this relocation refers to.
-  uint32_t addend;
+  bool pcrel;
   // The offset from the start of the subsection that this relocation belongs
   // to.
   uint32_t offset;
+  // Adding this offset to the address of the target symbol or subsection gives
+  // the destination that this relocation refers to.
+  uint64_t addend;
   llvm::PointerUnion<Symbol *, InputSection *> target;
 };
 

lld/MachO/Target.h

@@ -29,6 +29,7 @@ enum {
 class TargetInfo {
 public:
   virtual ~TargetInfo() = default;
+
   virtual uint64_t getImplicitAddend(const uint8_t *loc,
                                      uint8_t type) const = 0;
   virtual void relocateOne(uint8_t *loc, uint8_t type, uint64_t val) const = 0;

lld/test/MachO/x86-64-reloc-unsigned.s

@@ -0,0 +1,24 @@
+# REQUIRES: x86
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %s -o %t.o
+# RUN: lld -flavor darwinnew -o %t %t.o
+# RUN: llvm-objdump --full-contents %t | FileCheck %s
+# CHECK: Contents of section foo:
+# CHECK:  2000 08200000 00000000
+# CHECK: Contents of section bar:
+# CHECK:  2008 11311111 01000000
+
+.globl _main, _foo, _bar
+
+.section __DATA,foo
+_foo:
+.quad _bar
+
+.section __DATA,bar
+_bar:
+## The unsigned relocation should support 64-bit addends
+.quad _foo + 0x111111111
+
+.text
+_main:
+  mov $0, %rax
+  ret