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AArch64: use a different means to determine whether to byte swap relocations.

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This code depended on a bug in the FindAssociatedSection function that would
cause it to return the wrong result for certain absolute expressions. Instead,
use EvaluateAsRelocatable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233119 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Peter Collingbourne 2015-03-24 21:47:03 +00:00
parent f99b7d0538
commit 4b8dfba3a1
1 changed files with 18 additions and 3 deletions
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21
lib/Target/AArch64/MCTargetDesc/AArch64AsmBackend.cpp
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@ -18,6 +18,7 @@
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MachO.h"
using namespace llvm;
@ -493,14 +494,28 @@ void ELFAArch64AsmBackend::processFixupValue(
IsResolved = false;
}
// Returns whether this fixup is based on an address in the .eh_frame section,
// and therefore should be byte swapped.
// FIXME: Should be replaced with something more principled.
static bool isByteSwappedFixup(const MCExpr *E) {
MCValue Val;
if (!E->EvaluateAsRelocatable(Val, nullptr, nullptr))
return false;
if (!Val.getSymA() || Val.getSymA()->getSymbol().isUndefined())
return false;
const MCSectionELF *SecELF =
dyn_cast<MCSectionELF>(&Val.getSymA()->getSymbol().getSection());
return SecELF->getSectionName() == ".eh_frame";
}
void ELFAArch64AsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
unsigned DataSize, uint64_t Value,
bool IsPCRel) const {
// store fixups in .eh_frame section in big endian order
if (!IsLittleEndian && Fixup.getKind() == FK_Data_4) {
const MCSection *Sec = Fixup.getValue()->FindAssociatedSection();
const MCSectionELF *SecELF = dyn_cast_or_null<const MCSectionELF>(Sec);
if (SecELF && SecELF->getSectionName() == ".eh_frame")
if (isByteSwappedFixup(Fixup.getValue()))
Value = ByteSwap_32(unsigned(Value));
}
AArch64AsmBackend::applyFixup (Fixup, Data, DataSize, Value, IsPCRel);