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- //===- llvm/MC/MCWinCOFFStreamer.cpp --------------------------------------===//
- //
- // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
- // See https://llvm.org/LICENSE.txt for license information.
- // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
- //
- //===----------------------------------------------------------------------===//
- //
- // This file contains an implementation of a Windows COFF object file streamer.
- //
- //===----------------------------------------------------------------------===//
- #include "llvm/ADT/SmallString.h"
- #include "llvm/ADT/SmallVector.h"
- #include "llvm/ADT/Triple.h"
- #include "llvm/ADT/Twine.h"
- #include "llvm/BinaryFormat/COFF.h"
- #include "llvm/MC/MCAsmBackend.h"
- #include "llvm/MC/MCAssembler.h"
- #include "llvm/MC/MCCodeEmitter.h"
- #include "llvm/MC/MCContext.h"
- #include "llvm/MC/MCExpr.h"
- #include "llvm/MC/MCFixup.h"
- #include "llvm/MC/MCFragment.h"
- #include "llvm/MC/MCObjectFileInfo.h"
- #include "llvm/MC/MCObjectStreamer.h"
- #include "llvm/MC/MCObjectWriter.h"
- #include "llvm/MC/MCSection.h"
- #include "llvm/MC/MCSymbolCOFF.h"
- #include "llvm/MC/MCWinCOFFStreamer.h"
- #include "llvm/Support/Casting.h"
- #include "llvm/Support/ErrorHandling.h"
- #include "llvm/Support/MathExtras.h"
- #include "llvm/Support/SMLoc.h"
- #include "llvm/Support/raw_ostream.h"
- #include <algorithm>
- #include <cassert>
- #include <cstdint>
- using namespace llvm;
- #define DEBUG_TYPE "WinCOFFStreamer"
- MCWinCOFFStreamer::MCWinCOFFStreamer(MCContext &Context,
- std::unique_ptr<MCAsmBackend> MAB,
- std::unique_ptr<MCCodeEmitter> CE,
- std::unique_ptr<MCObjectWriter> OW)
- : MCObjectStreamer(Context, std::move(MAB), std::move(OW), std::move(CE)),
- CurSymbol(nullptr) {}
- void MCWinCOFFStreamer::emitInstToData(const MCInst &Inst,
- const MCSubtargetInfo &STI) {
- MCDataFragment *DF = getOrCreateDataFragment();
- SmallVector<MCFixup, 4> Fixups;
- SmallString<256> Code;
- raw_svector_ostream VecOS(Code);
- getAssembler().getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
- // Add the fixups and data.
- for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
- Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
- DF->getFixups().push_back(Fixups[i]);
- }
- DF->setHasInstructions(STI);
- DF->getContents().append(Code.begin(), Code.end());
- }
- void MCWinCOFFStreamer::initSections(bool NoExecStack,
- const MCSubtargetInfo &STI) {
- // FIXME: this is identical to the ELF one.
- // This emulates the same behavior of GNU as. This makes it easier
- // to compare the output as the major sections are in the same order.
- SwitchSection(getContext().getObjectFileInfo()->getTextSection());
- emitCodeAlignment(4, &STI);
- SwitchSection(getContext().getObjectFileInfo()->getDataSection());
- emitCodeAlignment(4, &STI);
- SwitchSection(getContext().getObjectFileInfo()->getBSSSection());
- emitCodeAlignment(4, &STI);
- SwitchSection(getContext().getObjectFileInfo()->getTextSection());
- }
- void MCWinCOFFStreamer::emitLabel(MCSymbol *S, SMLoc Loc) {
- auto *Symbol = cast<MCSymbolCOFF>(S);
- MCObjectStreamer::emitLabel(Symbol, Loc);
- }
- void MCWinCOFFStreamer::emitAssemblerFlag(MCAssemblerFlag Flag) {
- // Let the target do whatever target specific stuff it needs to do.
- getAssembler().getBackend().handleAssemblerFlag(Flag);
- switch (Flag) {
- // None of these require COFF specific handling.
- case MCAF_SyntaxUnified:
- case MCAF_Code16:
- case MCAF_Code32:
- case MCAF_Code64:
- break;
- case MCAF_SubsectionsViaSymbols:
- llvm_unreachable("COFF doesn't support .subsections_via_symbols");
- }
- }
- void MCWinCOFFStreamer::emitThumbFunc(MCSymbol *Func) {
- llvm_unreachable("not implemented");
- }
- bool MCWinCOFFStreamer::emitSymbolAttribute(MCSymbol *S,
- MCSymbolAttr Attribute) {
- auto *Symbol = cast<MCSymbolCOFF>(S);
- getAssembler().registerSymbol(*Symbol);
- switch (Attribute) {
- default: return false;
- case MCSA_WeakReference:
- case MCSA_Weak:
- Symbol->setIsWeakExternal();
- Symbol->setExternal(true);
- break;
- case MCSA_Global:
- Symbol->setExternal(true);
- break;
- case MCSA_AltEntry:
- llvm_unreachable("COFF doesn't support the .alt_entry attribute");
- }
- return true;
- }
- void MCWinCOFFStreamer::emitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
- llvm_unreachable("not implemented");
- }
- void MCWinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *S) {
- auto *Symbol = cast<MCSymbolCOFF>(S);
- if (CurSymbol)
- Error("starting a new symbol definition without completing the "
- "previous one");
- CurSymbol = Symbol;
- }
- void MCWinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
- if (!CurSymbol) {
- Error("storage class specified outside of symbol definition");
- return;
- }
- if (StorageClass & ~COFF::SSC_Invalid) {
- Error("storage class value '" + Twine(StorageClass) +
- "' out of range");
- return;
- }
- getAssembler().registerSymbol(*CurSymbol);
- cast<MCSymbolCOFF>(CurSymbol)->setClass((uint16_t)StorageClass);
- }
- void MCWinCOFFStreamer::EmitCOFFSymbolType(int Type) {
- if (!CurSymbol) {
- Error("symbol type specified outside of a symbol definition");
- return;
- }
- if (Type & ~0xffff) {
- Error("type value '" + Twine(Type) + "' out of range");
- return;
- }
- getAssembler().registerSymbol(*CurSymbol);
- cast<MCSymbolCOFF>(CurSymbol)->setType((uint16_t)Type);
- }
- void MCWinCOFFStreamer::EndCOFFSymbolDef() {
- if (!CurSymbol)
- Error("ending symbol definition without starting one");
- CurSymbol = nullptr;
- }
- void MCWinCOFFStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) {
- // SafeSEH is a feature specific to 32-bit x86. It does not exist (and is
- // unnecessary) on all platforms which use table-based exception dispatch.
- if (getContext().getTargetTriple().getArch() != Triple::x86)
- return;
- const MCSymbolCOFF *CSymbol = cast<MCSymbolCOFF>(Symbol);
- if (CSymbol->isSafeSEH())
- return;
- MCSection *SXData = getContext().getObjectFileInfo()->getSXDataSection();
- getAssembler().registerSection(*SXData);
- if (SXData->getAlignment() < 4)
- SXData->setAlignment(Align(4));
- new MCSymbolIdFragment(Symbol, SXData);
- getAssembler().registerSymbol(*Symbol);
- CSymbol->setIsSafeSEH();
- // The Microsoft linker requires that the symbol type of a handler be
- // function. Go ahead and oblige it here.
- CSymbol->setType(COFF::IMAGE_SYM_DTYPE_FUNCTION
- << COFF::SCT_COMPLEX_TYPE_SHIFT);
- }
- void MCWinCOFFStreamer::EmitCOFFSymbolIndex(MCSymbol const *Symbol) {
- MCSection *Sec = getCurrentSectionOnly();
- getAssembler().registerSection(*Sec);
- if (Sec->getAlignment() < 4)
- Sec->setAlignment(Align(4));
- new MCSymbolIdFragment(Symbol, getCurrentSectionOnly());
- getAssembler().registerSymbol(*Symbol);
- }
- void MCWinCOFFStreamer::EmitCOFFSectionIndex(const MCSymbol *Symbol) {
- visitUsedSymbol(*Symbol);
- MCDataFragment *DF = getOrCreateDataFragment();
- const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext());
- MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, FK_SecRel_2);
- DF->getFixups().push_back(Fixup);
- DF->getContents().resize(DF->getContents().size() + 2, 0);
- }
- void MCWinCOFFStreamer::EmitCOFFSecRel32(const MCSymbol *Symbol,
- uint64_t Offset) {
- visitUsedSymbol(*Symbol);
- MCDataFragment *DF = getOrCreateDataFragment();
- // Create Symbol A for the relocation relative reference.
- const MCExpr *MCE = MCSymbolRefExpr::create(Symbol, getContext());
- // Add the constant offset, if given.
- if (Offset)
- MCE = MCBinaryExpr::createAdd(
- MCE, MCConstantExpr::create(Offset, getContext()), getContext());
- // Build the secrel32 relocation.
- MCFixup Fixup = MCFixup::create(DF->getContents().size(), MCE, FK_SecRel_4);
- // Record the relocation.
- DF->getFixups().push_back(Fixup);
- // Emit 4 bytes (zeros) to the object file.
- DF->getContents().resize(DF->getContents().size() + 4, 0);
- }
- void MCWinCOFFStreamer::EmitCOFFImgRel32(const MCSymbol *Symbol,
- int64_t Offset) {
- visitUsedSymbol(*Symbol);
- MCDataFragment *DF = getOrCreateDataFragment();
- // Create Symbol A for the relocation relative reference.
- const MCExpr *MCE = MCSymbolRefExpr::create(
- Symbol, MCSymbolRefExpr::VK_COFF_IMGREL32, getContext());
- // Add the constant offset, if given.
- if (Offset)
- MCE = MCBinaryExpr::createAdd(
- MCE, MCConstantExpr::create(Offset, getContext()), getContext());
- // Build the imgrel relocation.
- MCFixup Fixup = MCFixup::create(DF->getContents().size(), MCE, FK_Data_4);
- // Record the relocation.
- DF->getFixups().push_back(Fixup);
- // Emit 4 bytes (zeros) to the object file.
- DF->getContents().resize(DF->getContents().size() + 4, 0);
- }
- void MCWinCOFFStreamer::emitCommonSymbol(MCSymbol *S, uint64_t Size,
- unsigned ByteAlignment) {
- auto *Symbol = cast<MCSymbolCOFF>(S);
- const Triple &T = getContext().getTargetTriple();
- if (T.isWindowsMSVCEnvironment()) {
- if (ByteAlignment > 32)
- report_fatal_error("alignment is limited to 32-bytes");
- // Round size up to alignment so that we will honor the alignment request.
- Size = std::max(Size, static_cast<uint64_t>(ByteAlignment));
- }
- getAssembler().registerSymbol(*Symbol);
- Symbol->setExternal(true);
- Symbol->setCommon(Size, ByteAlignment);
- if (!T.isWindowsMSVCEnvironment() && ByteAlignment > 1) {
- SmallString<128> Directive;
- raw_svector_ostream OS(Directive);
- const MCObjectFileInfo *MFI = getContext().getObjectFileInfo();
- OS << " -aligncomm:\"" << Symbol->getName() << "\","
- << Log2_32_Ceil(ByteAlignment);
- PushSection();
- SwitchSection(MFI->getDrectveSection());
- emitBytes(Directive);
- PopSection();
- }
- }
- void MCWinCOFFStreamer::emitLocalCommonSymbol(MCSymbol *S, uint64_t Size,
- unsigned ByteAlignment) {
- auto *Symbol = cast<MCSymbolCOFF>(S);
- MCSection *Section = getContext().getObjectFileInfo()->getBSSSection();
- PushSection();
- SwitchSection(Section);
- emitValueToAlignment(ByteAlignment, 0, 1, 0);
- emitLabel(Symbol);
- Symbol->setExternal(false);
- emitZeros(Size);
- PopSection();
- }
- void MCWinCOFFStreamer::emitWeakReference(MCSymbol *AliasS,
- const MCSymbol *Symbol) {
- auto *Alias = cast<MCSymbolCOFF>(AliasS);
- emitSymbolAttribute(Alias, MCSA_Weak);
- getAssembler().registerSymbol(*Symbol);
- Alias->setVariableValue(MCSymbolRefExpr::create(
- Symbol, MCSymbolRefExpr::VK_WEAKREF, getContext()));
- }
- void MCWinCOFFStreamer::emitZerofill(MCSection *Section, MCSymbol *Symbol,
- uint64_t Size, unsigned ByteAlignment,
- SMLoc Loc) {
- llvm_unreachable("not implemented");
- }
- void MCWinCOFFStreamer::emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
- uint64_t Size, unsigned ByteAlignment) {
- llvm_unreachable("not implemented");
- }
- // TODO: Implement this if you want to emit .comment section in COFF obj files.
- void MCWinCOFFStreamer::emitIdent(StringRef IdentString) {
- llvm_unreachable("not implemented");
- }
- void MCWinCOFFStreamer::EmitWinEHHandlerData(SMLoc Loc) {
- llvm_unreachable("not implemented");
- }
- void MCWinCOFFStreamer::emitCGProfileEntry(const MCSymbolRefExpr *From,
- const MCSymbolRefExpr *To,
- uint64_t Count) {
- // Ignore temporary symbols for now.
- if (!From->getSymbol().isTemporary() && !To->getSymbol().isTemporary())
- getAssembler().CGProfile.push_back({From, To, Count});
- }
- void MCWinCOFFStreamer::finalizeCGProfileEntry(const MCSymbolRefExpr *&SRE) {
- const MCSymbol *S = &SRE->getSymbol();
- bool Created;
- getAssembler().registerSymbol(*S, &Created);
- if (Created)
- cast<MCSymbolCOFF>(S)->setExternal(true);
- }
- void MCWinCOFFStreamer::finalizeCGProfile() {
- for (MCAssembler::CGProfileEntry &E : getAssembler().CGProfile) {
- finalizeCGProfileEntry(E.From);
- finalizeCGProfileEntry(E.To);
- }
- }
- void MCWinCOFFStreamer::finishImpl() {
- finalizeCGProfile();
- MCObjectStreamer::finishImpl();
- }
- void MCWinCOFFStreamer::Error(const Twine &Msg) const {
- getContext().reportError(SMLoc(), Msg);
- }
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