[ELF] - R_386_COPY relocation inplemented (x86)

[grimar]

Summary

Little patch that implemens R_386_COPY relocation.
Similiar to one for x64 http://reviews.llvm.org/D14090 which did most of job needed.

[ruiu]

LGTM

ELF/Target.cpp

 class X86TargetInfo final : public TargetInfo {
 public:
   X86TargetInfo();
   void writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const override;
   void writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
                          uint64_t PltEntryAddr) const override;
   void writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
                      uint64_t PltEntryAddr, int32_t Index) const override;
+  bool relocNeedsCopy(uint32_t Type, const SymbolBody &S) const override;
   bool relocNeedsGot(uint32_t Type, const SymbolBody &S) const override;
   bool relocPointsToGot(uint32_t Type) const override;
   bool relocNeedsPlt(uint32_t Type, const SymbolBody &S) const override;
   void relocateOne(uint8_t *Loc, uint8_t *BufEnd, uint32_t Type, uint64_t P,
                    uint64_t SA) const override;
 };
 
 class X86_64TargetInfo final : public TargetInfo {

 void TargetInfo::relocateTlsOptimize(uint8_t *Loc, uint8_t *BufEnd, uint64_t P,
                                      uint64_t SA) const {}
 
 void TargetInfo::writeGotHeaderEntries(uint8_t *Buf) const {}
 
 void TargetInfo::writeGotPltHeaderEntries(uint8_t *Buf) const {}
 
 X86TargetInfo::X86TargetInfo() {
+  CopyReloc = R_386_COPY;
   PCRelReloc = R_386_PC32;
   GotReloc = R_386_GLOB_DAT;
   GotRefReloc = R_386_GOT32;
   PltReloc = R_386_JUMP_SLOT;
 }
 
 void X86TargetInfo::writeGotPltEntry(uint8_t *Buf, uint64_t Plt) const {}
 void X86TargetInfo::writePltZeroEntry(uint8_t *Buf, uint64_t GotEntryAddr,
                                       uint64_t PltEntryAddr) const {}
 
 void X86TargetInfo::writePltEntry(uint8_t *Buf, uint64_t GotEntryAddr,
                                   uint64_t PltEntryAddr, int32_t Index) const {
   // jmpl *val; nop; nop
   const uint8_t Inst[] = {0xff, 0x25, 0, 0, 0, 0, 0x90, 0x90};
   memcpy(Buf, Inst, sizeof(Inst));
   assert(isUInt<32>(GotEntryAddr));
   write32le(Buf + 2, GotEntryAddr);
 }
 
+bool X86TargetInfo::relocNeedsCopy(uint32_t Type, const SymbolBody &S) const {
+  if (Type == R_386_32 || Type == R_386_16 || Type == R_386_8)
+    if (auto *SS = dyn_cast<SharedSymbol<ELF32LE>>(&S))
+      return SS->Sym.getType() == STT_OBJECT;
+  return false;
+}
+
 bool X86TargetInfo::relocNeedsGot(uint32_t Type, const SymbolBody &S) const {
   return Type == R_386_GOT32 || relocNeedsPlt(Type, S);
 }
 
 bool X86TargetInfo::relocPointsToGot(uint32_t Type) const {
   return Type == R_386_GOTPC;
 }
 

test/ELF/relocation-copy-i686.s

+// REQUIRES: x86
+// RUN: llvm-mc -filetype=obj -triple=i686-pc-linux %s -o %t.o
+// RUN: llvm-mc -filetype=obj -triple=i686-pc-linux %p/Inputs/relocation-copy.s -o %t2.o
+// RUN: ld.lld -shared %t2.o -o %t.so
+// RUN: ld.lld -e main %t.o %t.so -o %t3
+// RUN: llvm-readobj -s -r --expand-relocs %t3 | FileCheck %s
+// RUN: llvm-objdump -d %t3 | FileCheck -check-prefix=CODE %s
+
+.text
+.globl main
+.align 16, 0x90
+.type main,@function
+main:
+movl $5, x
+movl $7, y
+movl $9, z
+
+// CHECK:      Name: .bss
+// CHECK-NEXT:  Type: SHT_NOBITS
+// CHECK-NEXT:  Flags [
+// CHECK-NEXT:   SHF_ALLOC
+// CHECK-NEXT:   SHF_WRITE
+// CHECK-NEXT:  ]
+// CHECK-NEXT:  Address: 0x12050
+// CHECK-NEXT:  Offset: 0x2050
+// CHECK-NEXT:  Size: 24
+// CHECK-NEXT:  Link: 0
+// CHECK-NEXT:  Info: 0
+// CHECK-NEXT:  AddressAlignment: 16
+// CHECK-NEXT:  EntrySize: 0
+
+// CHECK:      Relocations [
+// CHECK-NEXT:   Section ({{.*}}) .rel.dyn {
+// CHECK-NEXT:     Relocation {
+// CHECK-NEXT:       Offset:
+// CHECK-NEXT:       Type: R_386_COPY
+// CHECK-NEXT:       Symbol: x
+// CHECK-NEXT:       Addend: 0x0
+// CHECK-NEXT:     }
+// CHECK-NEXT:     Relocation {
+// CHECK-NEXT:       Offset:
+// CHECK-NEXT:       Type: R_386_COPY
+// CHECK-NEXT:       Symbol: y
+// CHECK-NEXT:       Addend: 0x0
+// CHECK-NEXT:     }
+// CHECK-NEXT:     Relocation {
+// CHECK-NEXT:       Offset:
+// CHECK-NEXT:       Type: R_386_COPY
+// CHECK-NEXT:       Symbol: z
+// CHECK-NEXT:       Addend: 0x0
+// CHECK-NEXT:     }
+// CHECK-NEXT:   }
+// CHECK-NEXT: ]
+
+// 73808 = 0x12050
+// 16 is alignment here
+// 73824 = 0x12050 + 16
+// 73828 = 0x12050 + 16 + 4
+// CODE: Disassembly of section .text:
+// CODE-NEXT: main:
+// CODE-NEXT: 11000: c7 05 50 20 01 00 05 00 00 00 movl $5, 73808
+// CODE-NEXT: 1100a: c7 05 60 20 01 00 07 00 00 00 movl $7, 73824
+// CODE-NEXT: 11014: c7 05 64 20 01 00 09 00 00 00 movl $9, 73828