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[PowerPC] Fix @got references to local symbols 

A @got reference must always result in a relocation, so that
the linker has a chance to set up the GOT entry, even if the
symbol happens to be local.

Add a PPCELFObjectWriter::ExplicitRelSym routine that enforces
a relocation to be emitted for GOT references.

llvm-svn: 185353
This commit is contained in:
Ulrich Weigand 2013-07-01 18:19:56 +00:00
parent 28d8ba5f79
commit 3a75861b06
2 changed files with 80 additions and 0 deletions
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34
llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
View File

@ -30,6 +30,11 @@ namespace {
virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
bool IsPCRel, bool IsRelocWithSymbol,
int64_t Addend) const;
virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
const MCValue &Target,
const MCFragment &F,
const MCFixup &Fixup,
bool IsPCRel) const;
virtual const MCSymbol *undefinedExplicitRelSym(const MCValue &Target,
const MCFixup &Fixup,
bool IsPCRel) const;
@ -328,6 +333,35 @@ unsigned PPCELFObjectWriter::GetRelocType(const MCValue &Target,
return getRelocTypeInner(Target, Fixup, IsPCRel);
}
const MCSymbol *PPCELFObjectWriter::ExplicitRelSym(const MCAssembler &Asm,
const MCValue &Target,
const MCFragment &F,
const MCFixup &Fixup,
bool IsPCRel) const {
assert(Target.getSymA() && "SymA cannot be 0");
MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
bool EmitThisSym;
switch (Modifier) {
// GOT references always need a relocation, even if the
// target symbol is local.
case MCSymbolRefExpr::VK_GOT:
case MCSymbolRefExpr::VK_PPC_GOT_LO:
case MCSymbolRefExpr::VK_PPC_GOT_HI:
case MCSymbolRefExpr::VK_PPC_GOT_HA:
EmitThisSym = true;
break;
default:
EmitThisSym = false;
break;
}
if (EmitThisSym)
return &Target.getSymA()->getSymbol().AliasedSymbol();
return NULL;
}
const MCSymbol *PPCELFObjectWriter::undefinedExplicitRelSym(const MCValue &Target,
const MCFixup &Fixup,
bool IsPCRel) const {

46
llvm/test/MC/PowerPC/ppc64-fixup-explicit.s Normal file
View File

@ -0,0 +1,46 @@
# RUN: llvm-mc -triple powerpc64-unknown-unknown --show-encoding %s | FileCheck %s
# RUN: llvm-mc -triple powerpc64-unknown-unknown -filetype=obj %s | \
# RUN: llvm-readobj -r | FileCheck %s -check-prefix=REL
# GOT references must result in explicit relocations
# even if the target symbol is local.
target:
# CHECK: addi 4, 3, target@GOT # encoding: [0x38,0x83,A,A]
# CHECK-NEXT: # fixup A - offset: 2, value: target@GOT, kind: fixup_ppc_half16
# CHECK-REL: 0x{{[0-9A-F]*[26AE]}} R_PPC64_GOT16 target 0x0
addi 4, 3, target@got
# CHECK: ld 1, target@GOT(2) # encoding: [0xe8,0x22,A,0bAAAAAA00]
# CHECK-NEXT: # fixup A - offset: 2, value: target@GOT, kind: fixup_ppc_half16ds
# CHECK-REL: 0x{{[0-9A-F]*[26AE]}} R_PPC64_GOT16_DS target 0x0
ld 1, target@got(2)
# CHECK: addis 3, 2, target@got@ha # encoding: [0x3c,0x62,A,A]
# CHECK-NEXT: # fixup A - offset: 2, value: target@got@ha, kind: fixup_ppc_half16
# CHECK-REL: 0x{{[0-9A-F]*[26AE]}} R_PPC64_GOT16_HA target 0x0
addis 3, 2, target@got@ha
# CHECK: addi 4, 3, target@got@l # encoding: [0x38,0x83,A,A]
# CHECK-NEXT: # fixup A - offset: 2, value: target@got@l, kind: fixup_ppc_half16
# CHECK-REL: 0x{{[0-9A-F]*[26AE]}} R_PPC64_GOT16_LO target 0x0
addi 4, 3, target@got@l
# CHECK: addis 3, 2, target@got@h # encoding: [0x3c,0x62,A,A]
# CHECK-NEXT: # fixup A - offset: 2, value: target@got@h, kind: fixup_ppc_half16
# CHECK-REL: 0x{{[0-9A-F]*[26AE]}} R_PPC64_GOT16_HI target 0x0
addis 3, 2, target@got@h
# CHECK: lwz 1, target@got@l(3) # encoding: [0x80,0x23,A,A]
# CHECK-NEXT: # fixup A - offset: 2, value: target@got@l, kind: fixup_ppc_half16
# CHECK-REL: 0x{{[0-9A-F]*[26AE]}} R_PPC64_GOT16_LO target 0x0
lwz 1, target@got@l(3)
# CHECK: ld 1, target@got@l(3) # encoding: [0xe8,0x23,A,0bAAAAAA00]
# CHECK-NEXT: # fixup A - offset: 2, value: target@got@l, kind: fixup_ppc_half16ds
# CHECK-REL: 0x{{[0-9A-F]*[26AE]}} R_PPC64_GOT16_LO_DS target 0x0
ld 1, target@got@l(3)