327 lines
11 KiB
C++
327 lines
11 KiB
C++
//===- llvm/MC/MCWinCOFFStreamer.cpp --------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains an implementation of a Windows COFF object file streamer.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/BinaryFormat/COFF.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCAssembler.h"
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#include "llvm/MC/MCCodeEmitter.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCFixup.h"
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#include "llvm/MC/MCFragment.h"
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#include "llvm/MC/MCObjectFileInfo.h"
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#include "llvm/MC/MCObjectStreamer.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/MCSymbolCOFF.h"
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#include "llvm/MC/MCWinCOFFStreamer.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/SMLoc.h"
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#include "llvm/Support/raw_ostream.h"
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#include <algorithm>
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#include <cassert>
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#include <cstdint>
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using namespace llvm;
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#define DEBUG_TYPE "WinCOFFStreamer"
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MCWinCOFFStreamer::MCWinCOFFStreamer(MCContext &Context,
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std::unique_ptr<MCAsmBackend> MAB,
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std::unique_ptr<MCCodeEmitter> CE,
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std::unique_ptr<MCObjectWriter> OW)
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: MCObjectStreamer(Context, std::move(MAB), std::move(OW), std::move(CE)),
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CurSymbol(nullptr) {}
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void MCWinCOFFStreamer::EmitInstToData(const MCInst &Inst,
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const MCSubtargetInfo &STI) {
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MCDataFragment *DF = getOrCreateDataFragment();
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SmallVector<MCFixup, 4> Fixups;
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SmallString<256> Code;
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raw_svector_ostream VecOS(Code);
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getAssembler().getEmitter().encodeInstruction(Inst, VecOS, Fixups, STI);
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// Add the fixups and data.
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for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
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Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
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DF->getFixups().push_back(Fixups[i]);
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}
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DF->setHasInstructions(STI);
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DF->getContents().append(Code.begin(), Code.end());
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}
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void MCWinCOFFStreamer::InitSections(bool NoExecStack) {
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// FIXME: this is identical to the ELF one.
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// This emulates the same behavior of GNU as. This makes it easier
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// to compare the output as the major sections are in the same order.
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SwitchSection(getContext().getObjectFileInfo()->getTextSection());
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EmitCodeAlignment(4);
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SwitchSection(getContext().getObjectFileInfo()->getDataSection());
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EmitCodeAlignment(4);
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SwitchSection(getContext().getObjectFileInfo()->getBSSSection());
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EmitCodeAlignment(4);
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SwitchSection(getContext().getObjectFileInfo()->getTextSection());
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}
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void MCWinCOFFStreamer::EmitLabel(MCSymbol *S, SMLoc Loc) {
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auto *Symbol = cast<MCSymbolCOFF>(S);
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MCObjectStreamer::EmitLabel(Symbol, Loc);
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}
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void MCWinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
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llvm_unreachable("not implemented");
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}
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void MCWinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {
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llvm_unreachable("not implemented");
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}
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bool MCWinCOFFStreamer::EmitSymbolAttribute(MCSymbol *S,
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MCSymbolAttr Attribute) {
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auto *Symbol = cast<MCSymbolCOFF>(S);
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getAssembler().registerSymbol(*Symbol);
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switch (Attribute) {
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default: return false;
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case MCSA_WeakReference:
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case MCSA_Weak:
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Symbol->setIsWeakExternal();
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Symbol->setExternal(true);
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break;
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case MCSA_Global:
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Symbol->setExternal(true);
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break;
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case MCSA_AltEntry:
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llvm_unreachable("COFF doesn't support the .alt_entry attribute");
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}
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return true;
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}
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void MCWinCOFFStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
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llvm_unreachable("not implemented");
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}
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void MCWinCOFFStreamer::BeginCOFFSymbolDef(MCSymbol const *S) {
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auto *Symbol = cast<MCSymbolCOFF>(S);
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if (CurSymbol)
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Error("starting a new symbol definition without completing the "
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"previous one");
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CurSymbol = Symbol;
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}
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void MCWinCOFFStreamer::EmitCOFFSymbolStorageClass(int StorageClass) {
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if (!CurSymbol) {
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Error("storage class specified outside of symbol definition");
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return;
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}
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if (StorageClass & ~COFF::SSC_Invalid) {
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Error("storage class value '" + Twine(StorageClass) +
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"' out of range");
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return;
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}
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getAssembler().registerSymbol(*CurSymbol);
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cast<MCSymbolCOFF>(CurSymbol)->setClass((uint16_t)StorageClass);
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}
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void MCWinCOFFStreamer::EmitCOFFSymbolType(int Type) {
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if (!CurSymbol) {
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Error("symbol type specified outside of a symbol definition");
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return;
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}
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if (Type & ~0xffff) {
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Error("type value '" + Twine(Type) + "' out of range");
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return;
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}
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getAssembler().registerSymbol(*CurSymbol);
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cast<MCSymbolCOFF>(CurSymbol)->setType((uint16_t)Type);
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}
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void MCWinCOFFStreamer::EndCOFFSymbolDef() {
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if (!CurSymbol)
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Error("ending symbol definition without starting one");
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CurSymbol = nullptr;
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}
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void MCWinCOFFStreamer::EmitCOFFSafeSEH(MCSymbol const *Symbol) {
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// SafeSEH is a feature specific to 32-bit x86. It does not exist (and is
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// unnecessary) on all platforms which use table-based exception dispatch.
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if (getContext().getObjectFileInfo()->getTargetTriple().getArch() !=
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Triple::x86)
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return;
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const MCSymbolCOFF *CSymbol = cast<MCSymbolCOFF>(Symbol);
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if (CSymbol->isSafeSEH())
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return;
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MCSection *SXData = getContext().getObjectFileInfo()->getSXDataSection();
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getAssembler().registerSection(*SXData);
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if (SXData->getAlignment() < 4)
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SXData->setAlignment(4);
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new MCSymbolIdFragment(Symbol, SXData);
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getAssembler().registerSymbol(*Symbol);
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CSymbol->setIsSafeSEH();
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// The Microsoft linker requires that the symbol type of a handler be
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// function. Go ahead and oblige it here.
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CSymbol->setType(COFF::IMAGE_SYM_DTYPE_FUNCTION
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<< COFF::SCT_COMPLEX_TYPE_SHIFT);
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}
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void MCWinCOFFStreamer::EmitCOFFSymbolIndex(MCSymbol const *Symbol) {
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MCSection *Sec = getCurrentSectionOnly();
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getAssembler().registerSection(*Sec);
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if (Sec->getAlignment() < 4)
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Sec->setAlignment(4);
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new MCSymbolIdFragment(Symbol, getCurrentSectionOnly());
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getAssembler().registerSymbol(*Symbol);
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}
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void MCWinCOFFStreamer::EmitCOFFSectionIndex(const MCSymbol *Symbol) {
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visitUsedSymbol(*Symbol);
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MCDataFragment *DF = getOrCreateDataFragment();
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const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext());
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MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, FK_SecRel_2);
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DF->getFixups().push_back(Fixup);
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DF->getContents().resize(DF->getContents().size() + 2, 0);
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}
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void MCWinCOFFStreamer::EmitCOFFSecRel32(const MCSymbol *Symbol,
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uint64_t Offset) {
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visitUsedSymbol(*Symbol);
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MCDataFragment *DF = getOrCreateDataFragment();
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// Create Symbol A for the relocation relative reference.
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const MCExpr *MCE = MCSymbolRefExpr::create(Symbol, getContext());
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// Add the constant offset, if given.
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if (Offset)
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MCE = MCBinaryExpr::createAdd(
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MCE, MCConstantExpr::create(Offset, getContext()), getContext());
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// Build the secrel32 relocation.
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MCFixup Fixup = MCFixup::create(DF->getContents().size(), MCE, FK_SecRel_4);
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// Record the relocation.
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DF->getFixups().push_back(Fixup);
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// Emit 4 bytes (zeros) to the object file.
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DF->getContents().resize(DF->getContents().size() + 4, 0);
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}
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void MCWinCOFFStreamer::EmitCOFFImgRel32(const MCSymbol *Symbol,
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int64_t Offset) {
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visitUsedSymbol(*Symbol);
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MCDataFragment *DF = getOrCreateDataFragment();
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// Create Symbol A for the relocation relative reference.
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const MCExpr *MCE = MCSymbolRefExpr::create(
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Symbol, MCSymbolRefExpr::VK_COFF_IMGREL32, getContext());
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// Add the constant offset, if given.
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if (Offset)
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MCE = MCBinaryExpr::createAdd(
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MCE, MCConstantExpr::create(Offset, getContext()), getContext());
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// Build the imgrel relocation.
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MCFixup Fixup = MCFixup::create(DF->getContents().size(), MCE, FK_Data_4);
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// Record the relocation.
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DF->getFixups().push_back(Fixup);
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// Emit 4 bytes (zeros) to the object file.
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DF->getContents().resize(DF->getContents().size() + 4, 0);
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}
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void MCWinCOFFStreamer::EmitCommonSymbol(MCSymbol *S, uint64_t Size,
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unsigned ByteAlignment) {
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auto *Symbol = cast<MCSymbolCOFF>(S);
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const Triple &T = getContext().getObjectFileInfo()->getTargetTriple();
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if (T.isKnownWindowsMSVCEnvironment()) {
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if (ByteAlignment > 32)
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report_fatal_error("alignment is limited to 32-bytes");
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// Round size up to alignment so that we will honor the alignment request.
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Size = std::max(Size, static_cast<uint64_t>(ByteAlignment));
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}
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getAssembler().registerSymbol(*Symbol);
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Symbol->setExternal(true);
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Symbol->setCommon(Size, ByteAlignment);
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if (!T.isKnownWindowsMSVCEnvironment() && ByteAlignment > 1) {
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SmallString<128> Directive;
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raw_svector_ostream OS(Directive);
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const MCObjectFileInfo *MFI = getContext().getObjectFileInfo();
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OS << " -aligncomm:\"" << Symbol->getName() << "\","
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<< Log2_32_Ceil(ByteAlignment);
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PushSection();
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SwitchSection(MFI->getDrectveSection());
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EmitBytes(Directive);
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PopSection();
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}
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}
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void MCWinCOFFStreamer::EmitLocalCommonSymbol(MCSymbol *S, uint64_t Size,
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unsigned ByteAlignment) {
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auto *Symbol = cast<MCSymbolCOFF>(S);
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MCSection *Section = getContext().getObjectFileInfo()->getBSSSection();
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PushSection();
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SwitchSection(Section);
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EmitValueToAlignment(ByteAlignment, 0, 1, 0);
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EmitLabel(Symbol);
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Symbol->setExternal(false);
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EmitZeros(Size);
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PopSection();
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}
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void MCWinCOFFStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
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uint64_t Size, unsigned ByteAlignment,
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SMLoc Loc) {
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llvm_unreachable("not implemented");
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}
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void MCWinCOFFStreamer::EmitTBSSSymbol(MCSection *Section, MCSymbol *Symbol,
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uint64_t Size, unsigned ByteAlignment) {
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llvm_unreachable("not implemented");
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}
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// TODO: Implement this if you want to emit .comment section in COFF obj files.
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void MCWinCOFFStreamer::EmitIdent(StringRef IdentString) {
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llvm_unreachable("not implemented");
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}
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void MCWinCOFFStreamer::EmitWinEHHandlerData(SMLoc Loc) {
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llvm_unreachable("not implemented");
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}
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void MCWinCOFFStreamer::FinishImpl() {
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MCObjectStreamer::FinishImpl();
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}
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void MCWinCOFFStreamer::Error(const Twine &Msg) const {
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getContext().reportError(SMLoc(), Msg);
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}
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