mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-07-24 08:29:39 +00:00
cdb105b62f
Summary: Currently when emitting a label, a new data fragment is created for it if the current fragment isn't a data fragment. This change instead enqueues the label and attaches it to the next fragment (e.g. created for the next instruction) if possible. When bundle alignment is not enabled, this has no functionality change (it just results in fewer extra fragments being created). For bundle alignment, previously labels would point to the beginning of the bundle padding instead of the beginning of the emitted instruction. This was not only less efficient (e.g. jumping to the nops instead of past them) but also led to miscalculation of the address of the GOT (since MC uses a label difference rather than emitting a "." symbol). Fixes https://code.google.com/p/nativeclient/issues/detail?id=3982 Test Plan: regression test attached Reviewers: jvoung, eliben Subscribers: jfb, llvm-commits Differential Revision: http://reviews.llvm.org/D5915 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220439 91177308-0d34-0410-b5e6-96231b3b80d8
423 lines
15 KiB
C++
423 lines
15 KiB
C++
//===- lib/MC/MCObjectStreamer.cpp - Object File MCStreamer Interface -----===//
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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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#include "llvm/MC/MCObjectStreamer.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCAsmInfo.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/MCDwarf.h"
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#include "llvm/MC/MCExpr.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/MCSymbol.h"
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#include "llvm/Support/ErrorHandling.h"
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using namespace llvm;
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MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB,
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raw_ostream &OS, MCCodeEmitter *Emitter_)
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: MCStreamer(Context),
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Assembler(new MCAssembler(Context, TAB, *Emitter_,
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*TAB.createObjectWriter(OS), OS)),
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CurSectionData(nullptr), EmitEHFrame(true), EmitDebugFrame(false) {}
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MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB,
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raw_ostream &OS, MCCodeEmitter *Emitter_,
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MCAssembler *_Assembler)
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: MCStreamer(Context), Assembler(_Assembler), CurSectionData(nullptr),
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EmitEHFrame(true), EmitDebugFrame(false) {}
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MCObjectStreamer::~MCObjectStreamer() {
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delete &Assembler->getBackend();
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delete &Assembler->getEmitter();
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delete &Assembler->getWriter();
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delete Assembler;
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}
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void MCObjectStreamer::flushPendingLabels(MCFragment *F) {
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if (PendingLabels.size()) {
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if (!F) {
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F = new MCDataFragment();
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CurSectionData->getFragmentList().insert(CurInsertionPoint, F);
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F->setParent(CurSectionData);
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}
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for (MCSymbolData *SD : PendingLabels) {
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SD->setFragment(F);
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SD->setOffset(0);
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}
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PendingLabels.clear();
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}
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}
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void MCObjectStreamer::reset() {
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if (Assembler)
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Assembler->reset();
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CurSectionData = nullptr;
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CurInsertionPoint = MCSectionData::iterator();
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EmitEHFrame = true;
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EmitDebugFrame = false;
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PendingLabels.clear();
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MCStreamer::reset();
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}
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void MCObjectStreamer::EmitFrames(MCAsmBackend *MAB) {
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if (!getNumFrameInfos())
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return;
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if (EmitEHFrame)
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MCDwarfFrameEmitter::Emit(*this, MAB, true);
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if (EmitDebugFrame)
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MCDwarfFrameEmitter::Emit(*this, MAB, false);
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}
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MCFragment *MCObjectStreamer::getCurrentFragment() const {
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assert(getCurrentSectionData() && "No current section!");
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if (CurInsertionPoint != getCurrentSectionData()->getFragmentList().begin())
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return std::prev(CurInsertionPoint);
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return nullptr;
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}
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MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() {
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MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
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// When bundling is enabled, we don't want to add data to a fragment that
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// already has instructions (see MCELFStreamer::EmitInstToData for details)
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if (!F || (Assembler->isBundlingEnabled() && F->hasInstructions())) {
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F = new MCDataFragment();
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insert(F);
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}
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return F;
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}
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void MCObjectStreamer::visitUsedSymbol(const MCSymbol &Sym) {
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Assembler->getOrCreateSymbolData(Sym);
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}
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void MCObjectStreamer::EmitCFISections(bool EH, bool Debug) {
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MCStreamer::EmitCFISections(EH, Debug);
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EmitEHFrame = EH;
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EmitDebugFrame = Debug;
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}
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void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
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const SMLoc &Loc) {
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MCStreamer::EmitValueImpl(Value, Size, Loc);
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MCDataFragment *DF = getOrCreateDataFragment();
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MCLineEntry::Make(this, getCurrentSection().first);
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// Avoid fixups when possible.
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int64_t AbsValue;
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if (Value->EvaluateAsAbsolute(AbsValue, getAssembler())) {
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EmitIntValue(AbsValue, Size);
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return;
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}
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DF->getFixups().push_back(
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MCFixup::Create(DF->getContents().size(), Value,
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MCFixup::getKindForSize(Size, false), Loc));
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DF->getContents().resize(DF->getContents().size() + Size, 0);
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}
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void MCObjectStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
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// We need to create a local symbol to avoid relocations.
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Frame.Begin = getContext().CreateTempSymbol();
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EmitLabel(Frame.Begin);
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}
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void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
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Frame.End = getContext().CreateTempSymbol();
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EmitLabel(Frame.End);
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}
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void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
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MCStreamer::EmitLabel(Symbol);
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MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
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assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
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// If there is a current fragment, mark the symbol as pointing into it.
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// Otherwise queue the label and set its fragment pointer when we emit the
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// next fragment.
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if (dyn_cast_or_null<MCDataFragment>(getCurrentFragment())) {
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SD.setFragment(F);
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SD.setOffset(F->getContents().size());
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} else {
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PendingLabels.push_back(&SD);
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}
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}
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void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
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int64_t IntValue;
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if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
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EmitULEB128IntValue(IntValue);
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return;
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}
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insert(new MCLEBFragment(*Value, false));
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}
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void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
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int64_t IntValue;
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if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
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EmitSLEB128IntValue(IntValue);
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return;
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}
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insert(new MCLEBFragment(*Value, true));
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}
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void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
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const MCSymbol *Symbol) {
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report_fatal_error("This file format doesn't support weak aliases.");
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}
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void MCObjectStreamer::ChangeSection(const MCSection *Section,
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const MCExpr *Subsection) {
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assert(Section && "Cannot switch to a null section!");
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flushPendingLabels(nullptr);
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CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
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int64_t IntSubsection = 0;
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if (Subsection &&
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!Subsection->EvaluateAsAbsolute(IntSubsection, getAssembler()))
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report_fatal_error("Cannot evaluate subsection number");
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if (IntSubsection < 0 || IntSubsection > 8192)
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report_fatal_error("Subsection number out of range");
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CurInsertionPoint =
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CurSectionData->getSubsectionInsertionPoint(unsigned(IntSubsection));
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}
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void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
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getAssembler().getOrCreateSymbolData(*Symbol);
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MCStreamer::EmitAssignment(Symbol, Value);
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}
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void MCObjectStreamer::EmitInstruction(const MCInst &Inst,
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const MCSubtargetInfo &STI) {
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MCStreamer::EmitInstruction(Inst, STI);
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MCSectionData *SD = getCurrentSectionData();
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SD->setHasInstructions(true);
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// Now that a machine instruction has been assembled into this section, make
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// a line entry for any .loc directive that has been seen.
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MCLineEntry::Make(this, getCurrentSection().first);
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// If this instruction doesn't need relaxation, just emit it as data.
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MCAssembler &Assembler = getAssembler();
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if (!Assembler.getBackend().mayNeedRelaxation(Inst)) {
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EmitInstToData(Inst, STI);
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return;
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}
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// Otherwise, relax and emit it as data if either:
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// - The RelaxAll flag was passed
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// - Bundling is enabled and this instruction is inside a bundle-locked
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// group. We want to emit all such instructions into the same data
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// fragment.
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if (Assembler.getRelaxAll() ||
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(Assembler.isBundlingEnabled() && SD->isBundleLocked())) {
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MCInst Relaxed;
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getAssembler().getBackend().relaxInstruction(Inst, Relaxed);
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while (getAssembler().getBackend().mayNeedRelaxation(Relaxed))
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getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed);
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EmitInstToData(Relaxed, STI);
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return;
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}
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// Otherwise emit to a separate fragment.
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EmitInstToFragment(Inst, STI);
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}
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void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst,
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const MCSubtargetInfo &STI) {
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// Always create a new, separate fragment here, because its size can change
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// during relaxation.
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MCRelaxableFragment *IF = new MCRelaxableFragment(Inst, STI);
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insert(IF);
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SmallString<128> Code;
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raw_svector_ostream VecOS(Code);
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getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups(),
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STI);
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VecOS.flush();
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IF->getContents().append(Code.begin(), Code.end());
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}
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#ifndef NDEBUG
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static const char *const BundlingNotImplementedMsg =
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"Aligned bundling is not implemented for this object format";
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#endif
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void MCObjectStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
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llvm_unreachable(BundlingNotImplementedMsg);
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}
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void MCObjectStreamer::EmitBundleLock(bool AlignToEnd) {
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llvm_unreachable(BundlingNotImplementedMsg);
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}
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void MCObjectStreamer::EmitBundleUnlock() {
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llvm_unreachable(BundlingNotImplementedMsg);
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}
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void MCObjectStreamer::EmitDwarfLocDirective(unsigned FileNo, unsigned Line,
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unsigned Column, unsigned Flags,
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unsigned Isa,
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unsigned Discriminator,
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StringRef FileName) {
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// In case we see two .loc directives in a row, make sure the
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// first one gets a line entry.
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MCLineEntry::Make(this, getCurrentSection().first);
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this->MCStreamer::EmitDwarfLocDirective(FileNo, Line, Column, Flags,
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Isa, Discriminator, FileName);
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}
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static const MCExpr *buildSymbolDiff(MCObjectStreamer &OS, const MCSymbol *A,
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const MCSymbol *B) {
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MCContext &Context = OS.getContext();
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MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
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const MCExpr *ARef = MCSymbolRefExpr::Create(A, Variant, Context);
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const MCExpr *BRef = MCSymbolRefExpr::Create(B, Variant, Context);
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const MCExpr *AddrDelta =
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MCBinaryExpr::Create(MCBinaryExpr::Sub, ARef, BRef, Context);
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return AddrDelta;
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}
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static void emitDwarfSetLineAddr(MCObjectStreamer &OS, int64_t LineDelta,
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const MCSymbol *Label, int PointerSize) {
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// emit the sequence to set the address
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OS.EmitIntValue(dwarf::DW_LNS_extended_op, 1);
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OS.EmitULEB128IntValue(PointerSize + 1);
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OS.EmitIntValue(dwarf::DW_LNE_set_address, 1);
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OS.EmitSymbolValue(Label, PointerSize);
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// emit the sequence for the LineDelta (from 1) and a zero address delta.
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MCDwarfLineAddr::Emit(&OS, LineDelta, 0);
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}
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void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
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const MCSymbol *LastLabel,
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const MCSymbol *Label,
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unsigned PointerSize) {
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if (!LastLabel) {
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emitDwarfSetLineAddr(*this, LineDelta, Label, PointerSize);
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return;
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}
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const MCExpr *AddrDelta = buildSymbolDiff(*this, Label, LastLabel);
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int64_t Res;
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if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
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MCDwarfLineAddr::Emit(this, LineDelta, Res);
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return;
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}
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insert(new MCDwarfLineAddrFragment(LineDelta, *AddrDelta));
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}
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void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
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const MCSymbol *Label) {
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const MCExpr *AddrDelta = buildSymbolDiff(*this, Label, LastLabel);
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int64_t Res;
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if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
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MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
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return;
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}
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insert(new MCDwarfCallFrameFragment(*AddrDelta));
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}
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void MCObjectStreamer::EmitBytes(StringRef Data) {
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MCLineEntry::Make(this, getCurrentSection().first);
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getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
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}
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void MCObjectStreamer::EmitValueToAlignment(unsigned ByteAlignment,
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int64_t Value,
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unsigned ValueSize,
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unsigned MaxBytesToEmit) {
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if (MaxBytesToEmit == 0)
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MaxBytesToEmit = ByteAlignment;
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insert(new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit));
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// Update the maximum alignment on the current section if necessary.
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if (ByteAlignment > getCurrentSectionData()->getAlignment())
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getCurrentSectionData()->setAlignment(ByteAlignment);
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}
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void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment,
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unsigned MaxBytesToEmit) {
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EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit);
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cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true);
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}
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bool MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
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unsigned char Value) {
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int64_t Res;
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if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
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insert(new MCOrgFragment(*Offset, Value));
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return false;
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}
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MCSymbol *CurrentPos = getContext().CreateTempSymbol();
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EmitLabel(CurrentPos);
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MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
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const MCExpr *Ref =
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MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
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const MCExpr *Delta =
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MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
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if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
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return true;
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EmitFill(Res, Value);
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return false;
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}
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// Associate GPRel32 fixup with data and resize data area
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void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
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MCDataFragment *DF = getOrCreateDataFragment();
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DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
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Value, FK_GPRel_4));
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DF->getContents().resize(DF->getContents().size() + 4, 0);
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}
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// Associate GPRel32 fixup with data and resize data area
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void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) {
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MCDataFragment *DF = getOrCreateDataFragment();
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DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
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Value, FK_GPRel_4));
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DF->getContents().resize(DF->getContents().size() + 8, 0);
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}
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void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue) {
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// FIXME: A MCFillFragment would be more memory efficient but MCExpr has
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// problems evaluating expressions across multiple fragments.
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getOrCreateDataFragment()->getContents().append(NumBytes, FillValue);
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}
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void MCObjectStreamer::EmitZeros(uint64_t NumBytes) {
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unsigned ItemSize = getCurrentSection().first->isVirtualSection() ? 0 : 1;
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insert(new MCFillFragment(0, ItemSize, NumBytes));
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}
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void MCObjectStreamer::FinishImpl() {
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// If we are generating dwarf for assembly source files dump out the sections.
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if (getContext().getGenDwarfForAssembly())
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MCGenDwarfInfo::Emit(this);
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// Dump out the dwarf file & directory tables and line tables.
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MCDwarfLineTable::Emit(this);
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flushPendingLabels(nullptr);
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getAssembler().Finish();
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}
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