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llvm/lib/MC/WinCOFFStreamer.cpp
Benjamin Kramer 36a16015ac Don't drop alignment info on local common symbols. 
- On COFF the .lcomm directive has an alignment argument.
- On ELF we fall back to .local + .comm

Based on a patch by NAKAMURA Takumi.

Fixes PR9337, PR9483 and PR10128.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138976 91177308-0d34-0410-b5e6-96231b3b80d8
2011-09-01 23:04:27 +00:00

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//===-- llvm/MC/WinCOFFStreamer.cpp -----------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains an implementation of a Win32 COFF object file streamer.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "WinCOFFStreamer"
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCValue.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCWin64EH.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Support/COFF.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace {
class WinCOFFStreamer : public MCObjectStreamer {
public:
MCSymbol const *CurSymbol;
WinCOFFStreamer(MCContext &Context,
MCAsmBackend &MAB,
MCCodeEmitter &CE,
raw_ostream &OS);
void AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment, bool External);
// MCStreamer interface
virtual void InitSections();
virtual void EmitLabel(MCSymbol *Symbol);
virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
virtual void EmitThumbFunc(MCSymbol *Func);
virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
virtual void BeginCOFFSymbolDef(MCSymbol const *Symbol);
virtual void EmitCOFFSymbolStorageClass(int StorageClass);
virtual void EmitCOFFSymbolType(int Type);
virtual void EndCOFFSymbolDef();
virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value);
virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment);
virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment);
virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
unsigned Size,unsigned ByteAlignment);
virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment);
virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
unsigned ValueSize, unsigned MaxBytesToEmit);
virtual void EmitCodeAlignment(unsigned ByteAlignment,
unsigned MaxBytesToEmit);
virtual void EmitFileDirective(StringRef Filename);
virtual void EmitInstruction(const MCInst &Instruction);
virtual void EmitWin64EHHandlerData();
virtual void Finish();
private:
virtual void EmitInstToFragment(const MCInst &Inst) {
llvm_unreachable("Not used by WinCOFF.");
}
virtual void EmitInstToData(const MCInst &Inst) {
llvm_unreachable("Not used by WinCOFF.");
}
void SetSection(StringRef Section,
unsigned Characteristics,
SectionKind Kind) {
SwitchSection(getContext().getCOFFSection(Section, Characteristics, Kind));
}
void SetSectionText() {
SetSection(".text",
COFF::IMAGE_SCN_CNT_CODE
| COFF::IMAGE_SCN_MEM_EXECUTE
| COFF::IMAGE_SCN_MEM_READ,
SectionKind::getText());
EmitCodeAlignment(4, 0);
}
void SetSectionData() {
SetSection(".data",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA
| COFF::IMAGE_SCN_MEM_READ
| COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getDataRel());
EmitCodeAlignment(4, 0);
}
void SetSectionBSS() {
SetSection(".bss",
COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA
| COFF::IMAGE_SCN_MEM_READ
| COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getBSS());
EmitCodeAlignment(4, 0);
}
};
} // end anonymous namespace.
WinCOFFStreamer::WinCOFFStreamer(MCContext &Context,
MCAsmBackend &MAB,
MCCodeEmitter &CE,
raw_ostream &OS)
: MCObjectStreamer(Context, MAB, OS, &CE)
, CurSymbol(NULL) {
}
void WinCOFFStreamer::AddCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment, bool External) {
assert(!Symbol->isInSection() && "Symbol must not already have a section!");
std::string SectionName(".bss$linkonce");
SectionName.append(Symbol->getName().begin(), Symbol->getName().end());
MCSymbolData &SymbolData = getAssembler().getOrCreateSymbolData(*Symbol);
unsigned Characteristics =
COFF::IMAGE_SCN_LNK_COMDAT |
COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE;
int Selection = COFF::IMAGE_COMDAT_SELECT_LARGEST;
const MCSection *Section = MCStreamer::getContext().getCOFFSection(
SectionName, Characteristics, Selection, SectionKind::getBSS());
MCSectionData &SectionData = getAssembler().getOrCreateSectionData(*Section);
if (SectionData.getAlignment() < ByteAlignment)
SectionData.setAlignment(ByteAlignment);
SymbolData.setExternal(External);
Symbol->setSection(*Section);
if (ByteAlignment != 1)
new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectionData);
SymbolData.setFragment(new MCFillFragment(0, 0, Size, &SectionData));
}
// MCStreamer interface
void WinCOFFStreamer::InitSections() {
SetSectionText();
SetSectionData();
SetSectionBSS();
SetSectionText();
}
void WinCOFFStreamer::EmitLabel(MCSymbol *Symbol) {
assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
MCObjectStreamer::EmitLabel(Symbol);
}
void WinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
llvm_unreachable("not implemented");
}
void WinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
llvm_unreachable("not implemented");
}
void WinCOFFStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
assert((Symbol->isInSection()
? Symbol->getSection().getVariant() == MCSection::SV_COFF
: true) && "Got non COFF section in the COFF backend!");
// FIXME: This is all very ugly and depressing. What needs to happen here
// depends on quite a few things that are all part of relaxation, which we
// don't really even do.
if (Value->getKind() != MCExpr::SymbolRef) {
// TODO: This is exactly the same as MachOStreamer. Consider merging into
// MCObjectStreamer.
getAssembler().getOrCreateSymbolData(*Symbol);
AddValueSymbols(Value);
Symbol->setVariableValue(Value);
} else {
// FIXME: This is a horrible way to do this :(. This should really be
// handled after we are done with the MC* objects and immediately before
// writing out the object file when we know exactly what the symbol should
// look like in the coff symbol table. I'm not doing that now because the
// COFF object writer doesn't have a clearly defined separation between MC
// data structures, the object writers data structures, and the raw, POD,
// data structures that get written to disk.
// Copy over the aliased data.
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
const MCSymbolData &RealSD = getAssembler().getOrCreateSymbolData(
dyn_cast<const MCSymbolRefExpr>(Value)->getSymbol());
// FIXME: This is particularly nasty because it breaks as soon as any data
// members of MCSymbolData change.
SD.CommonAlign = RealSD.CommonAlign;
SD.CommonSize = RealSD.CommonSize;
SD.Flags = RealSD.Flags;
SD.Fragment = RealSD.Fragment;
SD.Index = RealSD.Index;
SD.IsExternal = RealSD.IsExternal;
SD.IsPrivateExtern = RealSD.IsPrivateExtern;
SD.Offset = RealSD.Offset;
SD.SymbolSize = RealSD.SymbolSize;
}
}
void WinCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
MCSymbolAttr Attribute) {
assert(Symbol && "Symbol must be non-null!");
assert((Symbol->isInSection()
? Symbol->getSection().getVariant() == MCSection::SV_COFF
: true) && "Got non COFF section in the COFF backend!");
switch (Attribute) {
case MCSA_WeakReference:
case MCSA_Weak: {
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
SD.modifyFlags(COFF::SF_WeakExternal, COFF::SF_WeakExternal);
SD.setExternal(true);
}
break;
case MCSA_Global:
getAssembler().getOrCreateSymbolData(*Symbol).setExternal(true);
break;
default:
llvm_unreachable("unsupported attribute");
break;
}
}
void WinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
llvm_unreachable("not implemented");
}
void WinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *Symbol) {
assert((Symbol->isInSection()
? Symbol->getSection().getVariant() == MCSection::SV_COFF
: true) && "Got non COFF section in the COFF backend!");
assert(CurSymbol == NULL && "EndCOFFSymbolDef must be called between calls "
"to BeginCOFFSymbolDef!");
CurSymbol = Symbol;
}
void WinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
assert((StorageClass & ~0xFF) == 0 && "StorageClass must only have data in "
"the first byte!");
getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
StorageClass << COFF::SF_ClassShift,
COFF::SF_ClassMask);
}
void WinCOFFStreamer::EmitCOFFSymbolType(int Type) {
assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
assert((Type & ~0xFFFF) == 0 && "Type must only have data in the first 2 "
"bytes");
getAssembler().getOrCreateSymbolData(*CurSymbol).modifyFlags(
Type << COFF::SF_TypeShift,
COFF::SF_TypeMask);
}
void WinCOFFStreamer::EndCOFFSymbolDef() {
assert(CurSymbol != NULL && "BeginCOFFSymbolDef must be called first!");
CurSymbol = NULL;
}
void WinCOFFStreamer::EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
llvm_unreachable("not implemented");
}
void WinCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {
assert((Symbol->isInSection()
? Symbol->getSection().getVariant() == MCSection::SV_COFF
: true) && "Got non COFF section in the COFF backend!");
AddCommonSymbol(Symbol, Size, ByteAlignment, true);
}
void WinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {
assert((Symbol->isInSection()
? Symbol->getSection().getVariant() == MCSection::SV_COFF
: true) && "Got non COFF section in the COFF backend!");
AddCommonSymbol(Symbol, Size, ByteAlignment, false);
}
void WinCOFFStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
unsigned Size,unsigned ByteAlignment) {
llvm_unreachable("not implemented");
}
void WinCOFFStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment) {
llvm_unreachable("not implemented");
}
void WinCOFFStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
// TODO: This is copied exactly from the MachOStreamer. Consider merging into
// MCObjectStreamer?
getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
}
void WinCOFFStreamer::EmitValueToAlignment(unsigned ByteAlignment,
int64_t Value,
unsigned ValueSize,
unsigned MaxBytesToEmit) {
// TODO: This is copied exactly from the MachOStreamer. Consider merging into
// MCObjectStreamer?
if (MaxBytesToEmit == 0)
MaxBytesToEmit = ByteAlignment;
new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
getCurrentSectionData());
// Update the maximum alignment on the current section if necessary.
if (ByteAlignment > getCurrentSectionData()->getAlignment())
getCurrentSectionData()->setAlignment(ByteAlignment);
}
void WinCOFFStreamer::EmitCodeAlignment(unsigned ByteAlignment,
unsigned MaxBytesToEmit) {
// TODO: This is copied exactly from the MachOStreamer. Consider merging into
// MCObjectStreamer?
if (MaxBytesToEmit == 0)
MaxBytesToEmit = ByteAlignment;
MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
getCurrentSectionData());
F->setEmitNops(true);
// Update the maximum alignment on the current section if necessary.
if (ByteAlignment > getCurrentSectionData()->getAlignment())
getCurrentSectionData()->setAlignment(ByteAlignment);
}
void WinCOFFStreamer::EmitFileDirective(StringRef Filename) {
// Ignore for now, linkers don't care, and proper debug
// info will be a much large effort.
}
void WinCOFFStreamer::EmitInstruction(const MCInst &Instruction) {
for (unsigned i = 0, e = Instruction.getNumOperands(); i != e; ++i)
if (Instruction.getOperand(i).isExpr())
AddValueSymbols(Instruction.getOperand(i).getExpr());
getCurrentSectionData()->setHasInstructions(true);
MCInstFragment *Fragment =
new MCInstFragment(Instruction, getCurrentSectionData());
raw_svector_ostream VecOS(Fragment->getCode());
getAssembler().getEmitter().EncodeInstruction(Instruction, VecOS,
Fragment->getFixups());
}
void WinCOFFStreamer::EmitWin64EHHandlerData() {
MCStreamer::EmitWin64EHHandlerData();
// We have to emit the unwind info now, because this directive
// actually switches to the .xdata section!
MCWin64EHUnwindEmitter::EmitUnwindInfo(*this, getCurrentW64UnwindInfo());
}
void WinCOFFStreamer::Finish() {
EmitW64Tables();
MCObjectStreamer::Finish();
}
namespace llvm
{
MCStreamer *createWinCOFFStreamer(MCContext &Context,
MCAsmBackend &MAB,
MCCodeEmitter &CE,
raw_ostream &OS,
bool RelaxAll) {
WinCOFFStreamer *S = new WinCOFFStreamer(Context, MAB, CE, OS);
S->getAssembler().setRelaxAll(RelaxAll);
return S;
}
}
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