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[MC] [X86] Teach leaq _GLOBAL_OFFSET_TABLE(%rip), %r15 to use R_X86_64_GOTPC32 instead of R_X86_64_PC32 

Summary:
This is similar to D46319 (ARM). x86-64 psABI p40 gives an example:

  leaq _GLOBAL_OFFSET_TABLE(%rip), %r15 # GOTPC32 reloc

GNU as creates R_X86_64_GOTPC32. However, MC currently emits R_X86_64_PC32.

Reviewers: javed.absar, echristo

Subscribers: kristof.beyls, llvm-commits, peter.smith, grimar

Differential Revision: https://reviews.llvm.org/D47507

llvm-svn: 334515
This commit is contained in:
Fangrui Song 2018-06-12 16:20:44 +00:00
parent 5d49f66570
commit f72cdb50be
2 changed files with 24 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
llvm/lib/Target/X86/MCTargetDesc/X86MCCodeEmitter.cpp
View File

@ -350,8 +350,14 @@ EmitImmediate(const MCOperand &DispOp, SMLoc Loc, unsigned Size,
FixupKind == MCFixupKind(X86::reloc_riprel_4byte_movq_load) ||
FixupKind == MCFixupKind(X86::reloc_riprel_4byte_relax) ||
FixupKind == MCFixupKind(X86::reloc_riprel_4byte_relax_rex) ||
FixupKind == MCFixupKind(X86::reloc_branch_4byte_pcrel))
FixupKind == MCFixupKind(X86::reloc_branch_4byte_pcrel)) {
ImmOffset -= 4;
// If this is a pc-relative load off _GLOBAL_OFFSET_TABLE_:
// leaq _GLOBAL_OFFSET_TABLE_(%rip), %r15
// this needs to be a GOTPC32 relocation.
if (StartsWithGlobalOffsetTable(Expr) != GOT_None)
FixupKind = MCFixupKind(X86::reloc_global_offset_table);
}
if (FixupKind == FK_PCRel_2)
ImmOffset -= 2;
if (FixupKind == FK_PCRel_1)

30
llvm/test/MC/ELF/relocation.s
View File

@ -39,6 +39,8 @@ bar:
leaq -1+foo(%rip), %r11
leaq _GLOBAL_OFFSET_TABLE_(%rax), %r15
leaq _GLOBAL_OFFSET_TABLE_(%rip), %r15
movl $_GLOBAL_OFFSET_TABLE_, %eax
movabs $_GLOBAL_OFFSET_TABLE_, %rax
@ -94,18 +96,20 @@ weak_sym:
// CHECK-NEXT: 0x8F R_X86_64_PC8 foo 0x8F
// CHECK-NEXT: 0x91 R_X86_64_PLT32 zed 0xFFFFFFFFFFFFFFFC
// CHECK-NEXT: 0x98 R_X86_64_PC32 foo 0xFFFFFFFFFFFFFFFB
// CHECK-NEXT: 0x9D R_X86_64_GOTPC32 _GLOBAL_OFFSET_TABLE_ 0x1
// CHECK-NEXT: 0xA3 R_X86_64_GOTPC64 _GLOBAL_OFFSET_TABLE_ 0x2
// CHECK-NEXT: 0xAB R_X86_64_SIZE64 blah 0x0
// CHECK-NEXT: 0xB3 R_X86_64_SIZE64 blah 0x20
// CHECK-NEXT: 0xBB R_X86_64_SIZE64 blah 0xFFFFFFFFFFFFFFE0
// CHECK-NEXT: 0xC6 R_X86_64_SIZE32 blah 0x0
// CHECK-NEXT: 0xCD R_X86_64_SIZE32 blah 0x20
// CHECK-NEXT: 0xD4 R_X86_64_SIZE32 blah 0xFFFFFFFFFFFFFFE0
// CHECK-NEXT: 0xD8 R_X86_64_GOTPCREL foo 0x0
// CHECK-NEXT: 0xDC R_X86_64_PLT32 foo 0x0
// CHECK-NEXT: 0xF0 R_X86_64_32 .text 0xF0
// CHECK-NEXT: 0xF5 R_X86_64_PC16 pr23771 0xFFFFFFFFFFFFFFFE
// CHECK-NEXT: 0xF7 R_X86_64_PC32 pr23272 0x0
// CHECK-NEXT: 0x9F R_X86_64_GOTPC32 _GLOBAL_OFFSET_TABLE_ 0x3
// CHECK-NEXT: 0xA6 R_X86_64_GOTPC32 _GLOBAL_OFFSET_TABLE_ 0xFFFFFFFFFFFFFFFC
// CHECK-NEXT: 0xAB R_X86_64_GOTPC32 _GLOBAL_OFFSET_TABLE_ 0x1
// CHECK-NEXT: 0xB1 R_X86_64_GOTPC64 _GLOBAL_OFFSET_TABLE_ 0x2
// CHECK-NEXT: 0xB9 R_X86_64_SIZE64 blah 0x0
// CHECK-NEXT: 0xC1 R_X86_64_SIZE64 blah 0x20
// CHECK-NEXT: 0xC9 R_X86_64_SIZE64 blah 0xFFFFFFFFFFFFFFE0
// CHECK-NEXT: 0xD4 R_X86_64_SIZE32 blah 0x0
// CHECK-NEXT: 0xDB R_X86_64_SIZE32 blah 0x20
// CHECK-NEXT: 0xE2 R_X86_64_SIZE32 blah 0xFFFFFFFFFFFFFFE0
// CHECK-NEXT: 0xE6 R_X86_64_GOTPCREL foo 0x0
// CHECK-NEXT: 0xEA R_X86_64_PLT32 foo 0x0
// CHECK-NEXT: 0xFE R_X86_64_32 .text 0xFE
// CHECK-NEXT: 0x103 R_X86_64_PC16 pr23771 0xFFFFFFFFFFFFFFFE
// CHECK-NEXT: 0x105 R_X86_64_PC32 pr23272 0x0
// CHECK-NEXT: ]
// CHECK-NEXT: }