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Implement support for .local and its "interesting" interactions with .comm. 

llvm-svn: 114382
This commit is contained in:
Rafael Espindola 2010-09-21 00:24:38 +00:00
parent 958da040e4
commit f0591c1642
4 changed files with 99 additions and 11 deletions
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15
llvm/lib/MC/ELFObjectWriter.cpp
View File

@ -386,6 +386,8 @@ void ELFObjectWriterImpl::WriteSymbol(MCDataFragment *F, ELFSymbolData &MSD,
if (Data.isCommon() && Data.isExternal())
Value = Data.getCommonAlignment();
assert(!(Data.isCommon() && !Data.isExternal()));
if (!Data.isCommon() && !(Data.getFlags() & ELF_STB_Weak))
if (MCFragment *FF = Data.getFragment())
Value = Layout.getSymbolAddress(&Data) -
@ -502,7 +504,10 @@ void ELFObjectWriterImpl::RecordRelocation(const MCAssembler &Asm,
if (Base) {
if (F && (!Symbol->isInSection() || SD.isCommon()) && !SD.isExternal()) {
Index = F->getParent()->getOrdinal() + LocalSymbolData.size() + 1;
Value += Layout.getSymbolAddress(&SD);
MCSectionData *FSD = F->getParent();
// Offset of the symbol in the section
Value += Layout.getSymbolAddress(&SD) - Layout.getSectionAddress(FSD);
} else
Index = getSymbolIndexInSymbolTable(Asm, Symbol);
if (Base != &SD)
@ -672,7 +677,10 @@ void ELFObjectWriterImpl::ComputeSymbolTable(MCAssembler &Asm) {
MSD.SymbolData = it;
MSD.StringIndex = Entry;
if (Symbol.isUndefined()) {
if (it->isCommon()) {
MSD.SectionIndex = ELF::SHN_COMMON;
ExternalSymbolData.push_back(MSD);
} else if (Symbol.isUndefined()) {
MSD.SectionIndex = ELF::SHN_UNDEF;
// XXX: for some reason we dont Emit* this
it->setFlags(it->getFlags() | ELF_STB_Global);
@ -680,9 +688,6 @@ void ELFObjectWriterImpl::ComputeSymbolTable(MCAssembler &Asm) {
} else if (Symbol.isAbsolute()) {
MSD.SectionIndex = ELF::SHN_ABS;
ExternalSymbolData.push_back(MSD);
} else if (it->isCommon()) {
MSD.SectionIndex = ELF::SHN_COMMON;
ExternalSymbolData.push_back(MSD);
} else {
MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
assert(MSD.SectionIndex && "Invalid section index!");

29
llvm/lib/MC/MCELFStreamer.cpp
View File

@ -13,6 +13,7 @@
#include "llvm/MC/MCStreamer.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCCodeEmitter.h"
@ -109,6 +110,8 @@ public:
virtual void EmitInstruction(const MCInst &Inst);
virtual void Finish();
private:
SmallPtrSet<MCSymbol *, 16> BindingExplicitlySet;
/// @}
void SetSection(StringRef Section, unsigned Type, unsigned Flags,
SectionKind Kind) {
@ -187,6 +190,13 @@ static void SetBinding(MCSymbolData &SD, unsigned Binding) {
SD.setFlags(OtherFlags | (Binding << ELF_STB_Shift));
}
static unsigned GetBinding(const MCSymbolData &SD) {
uint32_t Binding = (SD.getFlags() & (0xf << ELF_STB_Shift)) >> ELF_STB_Shift;
assert(Binding == ELF::STB_LOCAL || Binding == ELF::STB_GLOBAL ||
Binding == ELF::STB_WEAK);
return Binding;
}
static void SetType(MCSymbolData &SD, unsigned Type) {
assert(Type == ELF::STT_NOTYPE || Type == ELF::STT_OBJECT ||
Type == ELF::STT_FUNC || Type == ELF::STT_SECTION ||
@ -246,15 +256,19 @@ void MCELFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
case MCSA_Global:
SetBinding(SD, ELF::STB_GLOBAL);
SD.setExternal(true);
BindingExplicitlySet.insert(Symbol);
break;
case MCSA_WeakReference:
case MCSA_Weak:
SetBinding(SD, ELF::STB_WEAK);
BindingExplicitlySet.insert(Symbol);
break;
case MCSA_Local:
SetBinding(SD, ELF::STB_LOCAL);
SD.setExternal(false);
BindingExplicitlySet.insert(Symbol);
break;
case MCSA_ELF_TypeFunction:
@ -295,7 +309,12 @@ void MCELFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
if ((SD.getFlags() & (0xf << ELF_STB_Shift)) == ELF_STB_Local) {
if (!BindingExplicitlySet.count(Symbol)) {
SetBinding(SD, ELF::STB_GLOBAL);
SD.setExternal(true);
}
if (GetBinding(SD) == ELF_STB_Local) {
const MCSection *Section = getAssembler().getContext().getELFSection(".bss",
MCSectionELF::SHT_NOBITS,
MCSectionELF::SHF_WRITE |
@ -306,13 +325,11 @@ void MCELFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
SD.setFragment(F);
Symbol->setSection(*Section);
SD.setSize(MCConstantExpr::Create(Size, getContext()));
} else {
SD.setCommon(Size, ByteAlignment);
}
SetBinding(SD, ELF::STB_GLOBAL);
SD.setExternal(true);
SD.setCommon(Size, ByteAlignment);
SD.setSize(MCConstantExpr::Create(Size, getContext()));
}
void MCELFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {

3
llvm/lib/MC/MCParser/AsmParser.cpp
View File

@ -961,6 +961,9 @@ bool AsmParser::ParseStatement() {
if (IDVal == ".globl" || IDVal == ".global")
return ParseDirectiveSymbolAttribute(MCSA_Global);
// ELF only? Should it be here?
if (IDVal == ".local")
return ParseDirectiveSymbolAttribute(MCSA_Local);
if (IDVal == ".hidden")
return ParseDirectiveSymbolAttribute(MCSA_Hidden);
if (IDVal == ".indirect_symbol")

63
llvm/test/MC/ELF/common.s Normal file
View File

@ -0,0 +1,63 @@
// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | elf-dump --dump-section-data | FileCheck %s
.text
// Test that this produces a regular local symbol.
.type common1,@object
.local common1
.comm common1,1,1
// CHECK: ('st_name', 1) # 'common1'
// CHECK-NEXT: ('st_bind', 0)
// CHECK-NEXT: ('st_type', 1)
// CHECK-NEXT: ('st_other', 0)
// CHECK-NEXT: ('st_shndx',
// CHECK-NEXT: ('st_value', 0)
// CHECK-NEXT: ('st_size', 1)
// Same as common1, but with directives in a different order.
.local common2
.type common2,@object
.comm common2,1,1
// CHECK: ('st_name', 9) # 'common2'
// CHECK-NEXT: ('st_bind', 0)
// CHECK-NEXT: ('st_type', 1)
// CHECK-NEXT: ('st_other', 0)
// CHECK-NEXT: ('st_shndx',
// CHECK-NEXT: ('st_value', 1)
// CHECK-NEXT: ('st_size', 1)
// Test that without an explicit .local we produce a global.
.type common3,@object
.comm common3,4,4
// CHECK: ('st_name', 17) # 'common3'
// CHECK-NEXT: ('st_bind', 1)
// CHECK-NEXT: ('st_type', 1)
// CHECK-NEXT: ('st_other', 0)
// CHECK-NEXT: ('st_shndx', 65522)
// CHECK-NEXT: ('st_value', 4)
// CHECK-NEXT: ('st_size', 4)
// Test that without an explicit .local we produce a global, even if the first
// occurrence is not in a directive.
.globl foo
.type foo,@function
foo:
movsbl common4+3(%rip), %eax
.type common4,@object
.comm common4,40,16
// CHECK: ('st_name', 29) # 'common4'
// CHECK-NEXT: ('st_bind', 1)
// CHECK-NEXT: ('st_type', 1)
// CHECK-NEXT: ('st_other', 0)
// CHECK-NEXT: ('st_shndx', 65522)
// CHECK-NEXT: ('st_value', 16)
// CHECK-NEXT: ('st_size', 40)