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Remove doesSectionRequireSymbols.

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In an assembly expression like

bar:
.long L0 + 1

the intended semantics is that bar will contain a pointer one byte past L0.

In sections that are merged by content (strings, 4 byte constants, etc), a
single position in the section doesn't give the linker enough information.
For example, it would not be able to tell a relocation must point to the
end of a string, since that would look just like the start of the next.

The solution used in ELF to use relocation with symbols if there is a non-zero
addend.

In MachO before this patch we would just keep all symbols in some sections.

This would miss some cases (only cstrings on x86_64 were implemented) and was
inefficient since most relocations have an addend of 0 and can be represented
without the symbol.

This patch implements the non-zero addend logic for MachO too.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224985 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola
2014-12-30 13:13:27 +00:00
parent 96341cbb36
commit 65300b95e6
19 changed files with 293 additions and 241 deletions
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12
lib/MC/WinCOFFObjectWriter.cpp
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@@ -175,7 +175,7 @@ public:
const MCFragment &FB, bool InSet,
bool IsPCRel) const override;
void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
void RecordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment *Fragment, const MCFixup &Fixup,
MCValue Target, bool &IsPCRel,
uint64_t &FixedValue) override;
@@ -661,13 +661,9 @@ bool WinCOFFObjectWriter::IsSymbolRefDifferenceFullyResolvedImpl(
InSet, IsPCRel);
}
void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup,
MCValue Target,
bool &IsPCRel,
uint64_t &FixedValue) {
void WinCOFFObjectWriter::RecordRelocation(
MCAssembler &Asm, const MCAsmLayout &Layout, const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target, bool &IsPCRel, uint64_t &FixedValue) {
assert(Target.getSymA() && "Relocation must reference a symbol!");
const MCSymbol &Symbol = Target.getSymA()->getSymbol();