[llvm-mc] - Produce R_X86_64_PLT32 for "call/jmp foo".

For instructions like call foo and jmp foo patch changes
relocation produced from R_X86_64_PC32 to R_X86_64_PLT32.
Relocation can be used as a marker for 32-bit PC-relative branches.
Linker will reduce PLT32 relocation to PC32 if function is defined locally.

Differential revision: https://reviews.llvm.org/D43383

llvm-svn: 325569

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
index da4ca665d83..eea94b2eb1d 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
@@ -46,6 +46,7 @@ static unsigned getFixupKindLog2Size(unsigned Kind) {
   case X86::reloc_signed_4byte:
   case X86::reloc_signed_4byte_relax:
   case X86::reloc_global_offset_table:
+  case X86::reloc_branch_4byte_pcrel:
   case FK_SecRel_4:
   case FK_Data_4:
     return 2;
@@ -86,6 +87,7 @@ public:
         {"reloc_signed_4byte_relax", 0, 32, 0},
         {"reloc_global_offset_table", 0, 32, 0},
         {"reloc_global_offset_table8", 0, 64, 0},
+        {"reloc_branch_4byte_pcrel", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
     };
 
     if (Kind < FirstTargetFixupKind)
@@ -93,6 +95,7 @@ public:
 
     assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
            "Invalid kind!");
+    assert(Infos[Kind - FirstTargetFixupKind].Name && "Empty fixup name!");
     return Infos[Kind - FirstTargetFixupKind];
   }