forked from OSchip/llvm-project
391 lines
14 KiB
C++
391 lines
14 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) {}
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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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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::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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MCStreamer::reset();
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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() const {
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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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const MCExpr *MCObjectStreamer::AddValueSymbols(const MCExpr *Value) {
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switch (Value->getKind()) {
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case MCExpr::Target:
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cast<MCTargetExpr>(Value)->AddValueSymbols(Assembler);
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break;
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case MCExpr::Constant:
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break;
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case MCExpr::Binary: {
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const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
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AddValueSymbols(BE->getLHS());
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AddValueSymbols(BE->getRHS());
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break;
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}
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case MCExpr::SymbolRef:
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Assembler->getOrCreateSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
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break;
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case MCExpr::Unary:
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AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
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break;
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}
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return Value;
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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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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 (AddValueSymbols(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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RecordProcStart(Frame);
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}
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void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
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RecordProcEnd(Frame);
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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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// FIXME: This is wasteful, we don't necessarily need to create a data
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// fragment. Instead, we should mark the symbol as pointing into the data
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// fragment if it exists, otherwise we should just queue the label and set its
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// fragment pointer when we emit the next fragment.
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MCDataFragment *F = getOrCreateDataFragment();
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assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
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SD.setFragment(F);
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SD.setOffset(F->getContents().size());
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}
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void MCObjectStreamer::EmitDebugLabel(MCSymbol *Symbol) {
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EmitLabel(Symbol);
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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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Value = ForceExpAbs(Value);
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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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Value = ForceExpAbs(Value);
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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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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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AddValueSymbols(Value);
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MCStreamer::EmitAssignment(Symbol, Value);
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}
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void MCObjectStreamer::EmitInstruction(const MCInst &Inst, const MCSubtargetInfo &STI) {
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// Scan for values.
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for (unsigned i = Inst.getNumOperands(); i--; )
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if (Inst.getOperand(i).isExpr())
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AddValueSymbols(Inst.getOperand(i).getExpr());
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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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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(LineDelta, Label, PointerSize);
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return;
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}
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const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), 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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AddrDelta = ForceExpAbs(AddrDelta);
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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(getContext(), 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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AddrDelta = ForceExpAbs(AddrDelta);
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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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getAssembler().Finish();
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}
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