Add r224985 back with fixes.
The fixes are to note that AArch64 has additional restrictions on when local
relocations can be used. In particular, ld64 requires that relocations to
cstring/cfstrings use linker visible symbols.
Original message:
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.
llvm-svn: 226503
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMachObjectWriter.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMachObjectWriter.cpp
index df2f14a..f7259b9 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMachObjectWriter.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMachObjectWriter.cpp
@@ -41,7 +41,7 @@
: MCMachObjectTargetWriter(Is64Bit, CPUType, CPUSubtype,
/*UseAggressiveSymbolFolding=*/Is64Bit) {}
- void RecordRelocation(MachObjectWriter *Writer, const MCAssembler &Asm,
+ void RecordRelocation(MachObjectWriter *Writer, MCAssembler &Asm,
const MCAsmLayout &Layout, const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target,
uint64_t &FixedValue) override {
@@ -282,7 +282,7 @@
MachO::any_relocation_info MRE;
makeScatteredRelocationInfo(MRE, other_half, MachO::GENERIC_RELOC_PAIR,
Log2Size, IsPCRel, Value2);
- Writer->addRelocation(Fragment->getParent(), MRE);
+ Writer->addRelocation(nullptr, Fragment->getParent(), MRE);
} else {
// If the offset is more than 24-bits, it won't fit in a scattered
// relocation offset field, so we fall back to using a non-scattered
@@ -296,7 +296,7 @@
}
MachO::any_relocation_info MRE;
makeScatteredRelocationInfo(MRE, FixupOffset, Type, Log2Size, IsPCRel, Value);
- Writer->addRelocation(Fragment->getParent(), MRE);
+ Writer->addRelocation(nullptr, Fragment->getParent(), MRE);
return true;
}
@@ -331,9 +331,9 @@
// See <reloc.h>.
const uint32_t FixupOffset = getFixupOffset(Layout, Fragment, Fixup);
unsigned Index = 0;
- unsigned IsExtern = 0;
unsigned Type = RelocType;
+ const MCSymbolData *RelSymbol = nullptr;
if (Target.isAbsolute()) { // constant
// SymbolNum of 0 indicates the absolute section.
//
@@ -355,8 +355,7 @@
// Check whether we need an external or internal relocation.
if (Writer->doesSymbolRequireExternRelocation(SD)) {
- 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
// undefined. This occurs with weak definitions, for example.
@@ -375,9 +374,8 @@
// struct relocation_info (8 bytes)
MachO::any_relocation_info MRE;
- makeRelocationInfo(MRE, FixupOffset, Index, IsPCRel, Log2Size, IsExtern,
- Type);
- Writer->addRelocation(Fragment->getParent(), MRE);
+ makeRelocationInfo(MRE, FixupOffset, Index, IsPCRel, Log2Size, false, Type);
+ Writer->addRelocation(RelSymbol, Fragment->getParent(), MRE);
}
MCObjectWriter *llvm::createPPCMachObjectWriter(raw_ostream &OS, bool Is64Bit,