| //===- 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) { |
| // 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); |
| |
| SwitchSection(getContext().getObjectFileInfo()->getDataSection()); |
| EmitCodeAlignment(4); |
| |
| SwitchSection(getContext().getObjectFileInfo()->getBSSSection()); |
| EmitCodeAlignment(4); |
| |
| 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) { |
| llvm_unreachable("not implemented"); |
| } |
| |
| 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().getObjectFileInfo()->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(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(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().getObjectFileInfo()->getTargetTriple(); |
| if (T.isKnownWindowsMSVCEnvironment()) { |
| 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.isKnownWindowsMSVCEnvironment() && 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::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::FinishImpl() { |
| MCObjectStreamer::FinishImpl(); |
| } |
| |
| void MCWinCOFFStreamer::Error(const Twine &Msg) const { |
| getContext().reportError(SMLoc(), Msg); |
| } |