[ELFv2] Implement R_X86_64_32 relocation

[davide]

Summary

More to come.

[• rafael]

Please check the symbol value of bar to see that it matches.

Please factor the base + offset expression. Every relocation is likely to
use it.

Lgtm with that.

lld/trunk/ELF/Writer.cpp

for (const Elf_Shdr *RelSec : C->RelocSections) {
         if (isa<Undefined<ELFT>>(Body) && Body->isWeak())
           continue;
         if (!isa<DefinedRegular<ELFT>>(Body))
           error(Twine("Can't relocate symbol ") + Body->getName());
         uintX_t Offset = RI.r_offset;
         uint32_t Type = RI.getType(EObj->isMips64EL());
         uintX_t P = this->getVA() + C->getOutputSectionOff();
         uintX_t SymVA = getSymVA<ELFT>(cast<DefinedRegular<ELFT>>(Body));
+        uint8_t *Location = Base + Offset;
         switch (Type) {
         case llvm::ELF::R_X86_64_PC32:
-          support::endian::write32le(Base + Offset,
+          support::endian::write32le(Location,
                                      SymVA + (RI.r_addend - (P + Offset)));
           break;
+        case llvm::ELF::R_X86_64_32:
+          support::endian::write32le(Location, SymVA + RI.r_addend);
+          break;
         default:
           llvm::errs() << Twine("unrecognized reloc ") + Twine(Type) << '\n';
           break;
         }
       }
     }
   }
 }

lld/trunk/test/elf2/relocation.s

 // RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t
 // RUN: lld -flavor gnu2 %t -o %t2
-// RUN: llvm-objdump -d %t2 | FileCheck %s
+// RUN: llvm-objdump -t -d %t2 | FileCheck %s
 // REQUIRES: x86
 
 
 .section       .text,"ax",@progbits,unique,1
 .global _start
 _start:
   call lulz
 
 .section       .text,"ax",@progbits,unique,2
 .zero 4
 .global lulz
 lulz:
 
+.global bar
+.text
+bar:
+  movl $bar, %edx // R_X86_64_32
+
+// R_X86_64_32
+// CHECK: bar:
+// CHECK:    1000: ba 00 10 00 00 movl $4096, %edx
+
 // CHECK: e8 04 00 00 00  callq   4
+
+// Also check that symbols match.
+// CHECK: 0000000000001000         .text           00000000 bar