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Centralize the handling of the thumb bit.

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This patch centralizes the handling of the thumb bit around
MCStreamer::isThumbFunc and makes isThumbFunc handle aliases.

This fixes a corner case, but the main advantage is having just one
way to check if a MCSymbol is thumb or not. This should still be
refactored to be ARM only, but at least now it is just one predicate
that has to be refactored instead of 3 (isThumbFunc,
ELF_Other_ThumbFunc, and SF_ThumbFunc).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207522 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2014-04-29 12:46:50 +00:00
parent 65baf804ba
commit 1c5f439f41
9 changed files with 59 additions and 29 deletions
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6
include/llvm/MC/MCAssembler.h
View File

@ -902,7 +902,7 @@ private:
// here. Maybe when the relocation stuff moves to target specific,
// this can go with it? The streamer would need some target specific
// refactoring too.
SmallPtrSet<const MCSymbol*, 64> ThumbFuncs;
mutable SmallPtrSet<const MCSymbol*, 64> ThumbFuncs;
/// \brief The bundle alignment size currently set in the assembler.
///
@ -995,9 +995,7 @@ public:
const MCAsmLayout &Layout) const;
/// Check whether a given symbol has been flagged with .thumb_func.
bool isThumbFunc(const MCSymbol *Func) const {
return ThumbFuncs.count(Func);
}
bool isThumbFunc(const MCSymbol *Func) const;
/// Flag a function symbol as the target of a .thumb_func directive.
void setIsThumbFunc(const MCSymbol *Func) { ThumbFuncs.insert(Func); }

8
include/llvm/MC/MCELFSymbolFlags.h
View File

@ -24,9 +24,7 @@ namespace llvm {
ELF_STT_Shift = 0, // Shift value for STT_* flags.
ELF_STB_Shift = 4, // Shift value for STB_* flags.
ELF_STV_Shift = 8, // Shift value for STV_* flags.
ELF_STO_Shift = 10, // Shift value for STO_* flags.
ELF_Other_Shift = 16 // Shift value for llvm local flags,
// not part of the final object file
ELF_STO_Shift = 10 // Shift value for STO_* flags.
};
enum ELFSymbolFlags {
@ -49,9 +47,7 @@ namespace llvm {
ELF_STV_Default = (ELF::STV_DEFAULT << ELF_STV_Shift),
ELF_STV_Internal = (ELF::STV_INTERNAL << ELF_STV_Shift),
ELF_STV_Hidden = (ELF::STV_HIDDEN << ELF_STV_Shift),
ELF_STV_Protected = (ELF::STV_PROTECTED << ELF_STV_Shift),
ELF_Other_ThumbFunc = (1 << ELF_Other_Shift)
ELF_STV_Protected = (ELF::STV_PROTECTED << ELF_STV_Shift)
};
} // end namespace llvm

17
lib/MC/ELFObjectWriter.cpp
View File

@ -215,7 +215,8 @@ class ELFObjectWriter : public MCObjectWriter {
const MCAsmLayout &Layout,
SectionIndexMapTy &SectionIndexMap);
bool shouldRelocateWithSymbol(const MCSymbolRefExpr *RefA,
bool shouldRelocateWithSymbol(const MCAssembler &Asm,
const MCSymbolRefExpr *RefA,
const MCSymbolData *SD, uint64_t C,
unsigned Type) const;
@ -486,6 +487,7 @@ void ELFObjectWriter::WriteHeader(const MCAssembler &Asm,
uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &OrigData,
const MCAsmLayout &Layout) {
const MCSymbol &OrigSymbol = OrigData.getSymbol();
MCSymbolData *Data = &OrigData;
if (Data->isCommon() && Data->isExternal())
return Data->getCommonAlignment();
@ -512,8 +514,8 @@ uint64_t ELFObjectWriter::SymbolValue(MCSymbolData &OrigData,
}
}
if ((Data && Data->getFlags() & ELF_Other_ThumbFunc) ||
OrigData.getFlags() & ELF_Other_ThumbFunc)
const MCAssembler &Asm = Layout.getAssembler();
if (Asm.isThumbFunc(&OrigSymbol))
Res |= 1;
if (!Symbol || !Symbol->isInSection())
@ -641,8 +643,6 @@ void ELFObjectWriter::WriteSymbol(SymbolTableWriter &Writer, ELFSymbolData &MSD,
BaseSD = &Layout.getAssembler().getSymbolData(*Base);
Type = mergeTypeForSet(Type, MCELF::GetType(*BaseSD));
}
if (OrigData.getFlags() & ELF_Other_ThumbFunc)
Type = ELF::STT_FUNC;
uint8_t Info = (Binding << ELF_STB_Shift) | (Type << ELF_STT_Shift);
// Other and Visibility share the same byte with Visibility using the lower
@ -737,7 +737,8 @@ void ELFObjectWriter::WriteSymbolTable(MCDataFragment *SymtabF,
// It is always valid to create a relocation with a symbol. It is preferable
// to use a relocation with a section if that is possible. Using the section
// allows us to omit some local symbols from the symbol table.
bool ELFObjectWriter::shouldRelocateWithSymbol(const MCSymbolRefExpr *RefA,
bool ELFObjectWriter::shouldRelocateWithSymbol(const MCAssembler &Asm,
const MCSymbolRefExpr *RefA,
const MCSymbolData *SD,
uint64_t C,
unsigned Type) const {
@ -825,7 +826,7 @@ bool ELFObjectWriter::shouldRelocateWithSymbol(const MCSymbolRefExpr *RefA,
// bit. With a symbol that is done by just having the symbol have that bit
// set, so we would lose the bit if we relocated with the section.
// FIXME: We could use the section but add the bit to the relocation value.
if (SD->getFlags() & ELF_Other_ThumbFunc)
if (Asm.isThumbFunc(&Sym))
return true;
if (TargetObjectWriter->needsRelocateWithSymbol(Type))
@ -887,7 +888,7 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
const MCSymbolData *SymAD = SymA ? &Asm.getSymbolData(*SymA) : nullptr;
unsigned Type = GetRelocType(Target, Fixup, IsPCRel);
bool RelocateWithSymbol = shouldRelocateWithSymbol(RefA, SymAD, C, Type);
bool RelocateWithSymbol = shouldRelocateWithSymbol(Asm, RefA, SymAD, C, Type);
if (!RelocateWithSymbol && SymA && !SymA->isUndefined())
C += Layout.getSymbolOffset(SymAD);

25
lib/MC/MCAssembler.cpp
View File

@ -323,6 +323,31 @@ void MCAssembler::reset() {
getLOHContainer().reset();
}
bool MCAssembler::isThumbFunc(const MCSymbol *Symbol) const {
if (ThumbFuncs.count(Symbol))
return true;
if (!Symbol->isVariable())
return false;
// FIXME: It looks like gas support some cases of the form "foo + 2". It
// is not clear if that is a bug or a feature.
const MCExpr *Expr = Symbol->getVariableValue();
const MCSymbolRefExpr *Ref = dyn_cast<MCSymbolRefExpr>(Expr);
if (!Ref)
return false;
if (Ref->getKind() != MCSymbolRefExpr::VK_None)
return false;
const MCSymbol &Sym = Ref->getSymbol();
if (!isThumbFunc(&Sym))
return false;
ThumbFuncs.insert(Symbol); // Cache it.
return true;
}
bool MCAssembler::isSymbolLinkerVisible(const MCSymbol &Symbol) const {
// Non-temporary labels should always be visible to the linker.
if (!Symbol.isTemporary())

4
lib/MC/MCMachOStreamer.cpp
View File

@ -237,10 +237,6 @@ void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
// Remember that the function is a thumb function. Fixup and relocation
// values will need adjusted.
getAssembler().setIsThumbFunc(Symbol);
// Mark the thumb bit on the symbol.
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
SD.setFlags(SD.getFlags() | SF_ThumbFunc);
}
bool MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,

3
lib/MC/MachObjectWriter.cpp
View File

@ -351,6 +351,9 @@ void MachObjectWriter::WriteNlist(MachSymbolData &MSD,
}
}
if (Layout.getAssembler().isThumbFunc(&Symbol))
Flags |= SF_ThumbFunc;
// struct nlist (12 bytes)
Write32(MSD.StringIndex);

6
lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
View File

@ -609,12 +609,8 @@ private:
}
void EmitThumbFunc(MCSymbol *Func) override {
// FIXME: Anything needed here to flag the function as thumb?
getAssembler().setIsThumbFunc(Func);
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Func);
SD.setFlags(SD.getFlags() | ELF_Other_ThumbFunc);
EmitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
}
// Helper functions for ARM exception handling directives

4
lib/Target/ARM/MCTargetDesc/ARMMachObjectWriter.cpp
View File

@ -206,11 +206,11 @@ RecordARMScatteredHalfRelocation(MachObjectWriter *Writer,
// The thumb bit shouldn't be set in the 'other-half' bit of the
// relocation, but it will be set in FixedValue if the base symbol
// is a thumb function. Clear it out here.
if (A_SD->getFlags() & SF_ThumbFunc)
if (Asm.isThumbFunc(A))
FixedValue &= 0xfffffffe;
break;
case ARM::fixup_t2_movt_hi16:
if (A_SD->getFlags() & SF_ThumbFunc)
if (Asm.isThumbFunc(A))
FixedValue &= 0xfffffffe;
MovtBit = 1;
// Fallthrough

15
test/MC/ARM/thumb_set.s
View File

@ -14,6 +14,9 @@ arm_func:
.thumb_set alias_arm_func, arm_func
alias_arm_func2 = alias_arm_func
alias_arm_func3 = alias_arm_func2
@ ASM: .thumb_set alias_arm_func, arm_func
.thumb
@ -64,6 +67,18 @@ beta:
@ CHECK: Type: Function
@ CHECK: }
@ CHECK: Symbol {
@ CHECK: Name: alias_arm_func2
@ CHECK: Value: 0x1
@ CHECK: Type: Function
@ CHECK: }
@ CHECK: Symbol {
@ CHECK: Name: alias_arm_func3
@ CHECK: Value: 0x1
@ CHECK: Type: Function
@ CHECK: }
@ CHECK: Symbol {
@ CHECK: Name: alias_defined_data
@ CHECK: Value: 0x5