//===- 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/MC/MCWinCOFFStreamer.h"

#include "llvm/ADT/SmallString.h"

#include "llvm/ADT/SmallVector.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/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 "llvm/TargetParser/Triple.h"

#include <algorithm>

#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;

  getAssembler().getEmitter().encodeInstruction(Inst, Code, 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(Align(4), &STI);

  switchSection(getContext().getObjectFileInfo()->getDataSection());

  emitCodeAlignment(Align(4), &STI);

  switchSection(getContext().getObjectFileInfo()->getBSSSection());

  emitCodeAlignment(Align(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->setWeakExternalCharacteristics(COFF::IMAGE_WEAK_EXTERN_SEARCH_ALIAS);

    Symbol->setExternal(true);

    break;

  case MCSA_WeakAntiDep:

    Symbol->setWeakExternalCharacteristics(COFF::IMAGE_WEAK_EXTERN_ANTI_DEPENDENCY);

    Symbol->setExternal(true);

    Symbol->setIsWeakExternal(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);

  SXData->ensureMinAlignment(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);

  Sec->ensureMinAlignment(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,

                                         Align 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, ByteAlignment.value());

  }

  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.value());

    pushSection();

    switchSection(MFI->getDrectveSection());

    emitBytes(Directive);

    popSection();

  }

}

void MCWinCOFFStreamer::emitLocalCommonSymbol(MCSymbol *S, uint64_t Size,

                                              Align 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, Align ByteAlignment,

                                     SMLoc Loc) {

  llvm_unreachable("not implemented");

}

void MCWinCOFFStreamer::emitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,

                                       uint64_t Size, Align 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();

  if (getAssembler().registerSymbol(*S))

    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);

}