6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-11-01 15:17:25 +00:00
Code Issues Projects Releases Wiki Activity

Remove doesSectionRequireSymbols.

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

37
lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp
View File

@@ -54,10 +54,10 @@ public:
: MCMachObjectTargetWriter(Is64Bit, CPUType, CPUSubtype,
/*UseAggressiveSymbolFolding=*/true) {}
void RecordRelocation(MachObjectWriter *Writer,
const MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment *Fragment, const MCFixup &Fixup,
MCValue Target, uint64_t &FixedValue) override;
void RecordRelocation(MachObjectWriter *Writer, MCAssembler &Asm,
const MCAsmLayout &Layout, const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target,
uint64_t &FixedValue) override;
};
}
@@ -232,7 +232,7 @@ RecordARMScatteredHalfRelocation(MachObjectWriter *Writer,
(IsPCRel << 30) |
MachO::R_SCATTERED);
MRE.r_word1 = Value2;
Writer->addRelocation(Fragment->getParent(), MRE);
Writer->addRelocation(nullptr, Fragment->getParent(), MRE);
}
MachO::any_relocation_info MRE;
@@ -243,7 +243,7 @@ RecordARMScatteredHalfRelocation(MachObjectWriter *Writer,
(IsPCRel << 30) |
MachO::R_SCATTERED);
MRE.r_word1 = Value;
Writer->addRelocation(Fragment->getParent(), MRE);
Writer->addRelocation(nullptr, Fragment->getParent(), MRE);
}
void ARMMachObjectWriter::RecordARMScatteredRelocation(MachObjectWriter *Writer,
@@ -297,7 +297,7 @@ void ARMMachObjectWriter::RecordARMScatteredRelocation(MachObjectWriter *Writer,
(IsPCRel << 30) |
MachO::R_SCATTERED);
MRE.r_word1 = Value2;
Writer->addRelocation(Fragment->getParent(), MRE);
Writer->addRelocation(nullptr, Fragment->getParent(), MRE);
}
MachO::any_relocation_info MRE;
@@ -307,7 +307,7 @@ void ARMMachObjectWriter::RecordARMScatteredRelocation(MachObjectWriter *Writer,
(IsPCRel << 30) |
MachO::R_SCATTERED);
MRE.r_word1 = Value;
Writer->addRelocation(Fragment->getParent(), MRE);
Writer->addRelocation(nullptr, Fragment->getParent(), MRE);
}
bool ARMMachObjectWriter::requiresExternRelocation(MachObjectWriter *Writer,
@@ -351,11 +351,10 @@ bool ARMMachObjectWriter::requiresExternRelocation(MachObjectWriter *Writer,
}
void ARMMachObjectWriter::RecordRelocation(MachObjectWriter *Writer,
const MCAssembler &Asm,
MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup,
MCValue Target,
const MCFixup &Fixup, MCValue Target,
uint64_t &FixedValue) {
unsigned IsPCRel = Writer->isFixupKindPCRel(Asm, Fixup.getKind());
unsigned Log2Size;
@@ -401,8 +400,8 @@ void ARMMachObjectWriter::RecordRelocation(MachObjectWriter *Writer,
// See <reloc.h>.
uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
unsigned Index = 0;
unsigned IsExtern = 0;
unsigned Type = 0;
const MCSymbolData *RelSymbol = nullptr;
if (Target.isAbsolute()) { // constant
// FIXME!
@@ -422,8 +421,7 @@ void ARMMachObjectWriter::RecordRelocation(MachObjectWriter *Writer,
// Check whether we need an external or internal relocation.
if (requiresExternRelocation(Writer, Asm, *Fragment, RelocType, SD,
FixedValue)) {
IsExtern = 1;
Index = SD->getIndex();
RelSymbol = SD;
// For external relocations, make sure to offset the fixup value to
// compensate for the addend of the symbol address, if it was
@@ -447,11 +445,8 @@ void ARMMachObjectWriter::RecordRelocation(MachObjectWriter *Writer,
// struct relocation_info (8 bytes)
MachO::any_relocation_info MRE;
MRE.r_word0 = FixupOffset;
MRE.r_word1 = ((Index << 0) |
(IsPCRel << 24) |
(Log2Size << 25) |
(IsExtern << 27) |
(Type << 28));
MRE.r_word1 =
(Index << 0) | (IsPCRel << 24) | (Log2Size << 25) | (Type << 28);
// Even when it's not a scattered relocation, movw/movt always uses
// a PAIR relocation.
@@ -476,10 +471,10 @@ void ARMMachObjectWriter::RecordRelocation(MachObjectWriter *Writer,
(Log2Size << 25) |
(MachO::ARM_RELOC_PAIR << 28));
Writer->addRelocation(Fragment->getParent(), MREPair);
Writer->addRelocation(nullptr, Fragment->getParent(), MREPair);
}
Writer->addRelocation(Fragment->getParent(), MRE);
Writer->addRelocation(RelSymbol, Fragment->getParent(), MRE);
}
MCObjectWriter *llvm::createARMMachObjectWriter(raw_ostream &OS,