Add R_386_TLS_LE as a relocation having an implicit addend.

[ed]

Summary

TLS on i386 in non-PIE/PIC code seems broken right now, because we don't
properly add the addend encoded in the instruction to the resulting
offset when processing R_386_TLS_LE relocations.

Extend one of the existing tests for TLS on i686 to use an addend.

[ruiu]

LGTM

ELF/Target.cpp

default:
     return 0;
   case R_386_32:
   case R_386_GOT32:
   case R_386_GOT32X:
   case R_386_GOTOFF:
   case R_386_GOTPC:
   case R_386_PC32:
   case R_386_PLT32:
+  case R_386_TLS_LE:
     return read32le(Buf);
   }
 }
 
 void X86TargetInfo::relocateOne(uint8_t *Loc, uint32_t Type,
                                 uint64_t Val) const {
   checkInt<32>(Val, Type);
   write32le(Loc, Val);

test/ELF/tls-i686.s

  subl %edx, %eax
  movl $var1@tpoff, %edx
  movl %gs:0, %ecx
  subl %edx, %eax
 
  movl %gs:0, %ecx
  leal var@ntpoff(%ecx), %eax
  movl %gs:0, %ecx
- leal var1@ntpoff(%ecx), %eax
+ leal var1@ntpoff+123(%ecx), %eax
 
 // DIS:      Disassembly of section test:
 // DIS-NEXT: _start:
 // DIS-NEXT: 12000: ba 08 00 00 00       movl $8, %edx
 // DIS-NEXT: 12005: 65 8b 0d 00 00 00 00 movl %gs:0, %ecx
 // DIS-NEXT: 1200c: 29 d0                subl %edx, %eax
 // DIS-NEXT: 1200e: ba 04 00 00 00       movl $4, %edx
 // DIS-NEXT: 12013: 65 8b 0d 00 00 00 00 movl %gs:0, %ecx
 // DIS-NEXT: 1201a: 29 d0                subl %edx, %eax
 // DIS-NEXT: 1201c: 65 8b 0d 00 00 00 00 movl %gs:0, %ecx
 // DIS-NEXT: 12023: 8d 81 f8 ff ff ff    leal -8(%ecx), %eax
 // DIS-NEXT: 12029: 65 8b 0d 00 00 00 00 movl %gs:0, %ecx
-// DIS-NEXT: 12030: 8d 81 fc ff ff ff    leal -4(%ecx), %eax
+// DIS-NEXT: 12030: 8d 81 77 00 00 00    leal 119(%ecx), %eax
 
 // RELOC: Relocations [
 // RELOC-NEXT: ]
 
 // DISSHARED: Disassembly of section test:
 // DISSHARED-NEXT: _start:
 // DISSHARED-NEXT: 2000: ba 00 00 00 00 movl   $0, %edx
 // DISSHARED-NEXT: 2005: 65 8b 0d 00 00 00 00  movl %gs:0, %ecx
 // DISSHARED-NEXT: 200c: 29 d0 subl            %edx, %eax
 // DISSHARED-NEXT: 200e: ba 00 00 00 00        movl $0, %edx
 // DISSHARED-NEXT: 2013: 65 8b 0d 00 00 00 00  movl %gs:0, %ecx
 // DISSHARED-NEXT: 201a: 29 d0 subl            %edx, %eax
 // DISSHARED-NEXT: 201c: 65 8b 0d 00 00 00 00  movl %gs:0, %ecx
 // DISSHARED-NEXT: 2023: 8d 81 00 00 00 00     leal (%ecx), %eax
 // DISSHARED-NEXT: 2029: 65 8b 0d 00 00 00 00  movl %gs:0, %ecx
-// DISSHARED-NEXT: 2030: 8d 81 00 00 00 00     leal (%ecx), %eax
+// DISSHARED-NEXT: 2030: 8d 81 7b 00 00 00     leal 123(%ecx), %eax
 
 // RELOCSHARED:      Relocations [
 // RELOCSHARED-NEXT: Section (4) .rel.dyn {
 // RELOCSHARED-NEXT:   0x2001 R_386_TLS_TPOFF32 var 0x0
 // RELOCSHARED-NEXT:   0x2025 R_386_TLS_TPOFF var 0x0
 // RELOCSHARED-NEXT:   0x200F R_386_TLS_TPOFF32 var1 0x0
 // RELOCSHARED-NEXT:   0x2032 R_386_TLS_TPOFF var1 0x0
 // RELOCSHARED-NEXT:  }
 // RELOCSHARED-NEXT: ]