mirror of
https://github.com/c64scene-ar/llvm-6502.git
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6c56decee0
This makes emitAbsoluteSymbolDiff always succeed and moves logic from the asm printer to it. The object one now also works on ELF. If two symbols are in the same fragment, we will never move them apart. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239552 91177308-0d34-0410-b5e6-96231b3b80d8
452 lines
16 KiB
C++
452 lines
16 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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#include "llvm/Support/TargetRegistry.h"
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using namespace llvm;
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MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB,
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raw_pwrite_stream &OS,
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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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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, uint64_t FOffset) {
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if (PendingLabels.size()) {
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if (!F) {
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F = new MCDataFragment();
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MCSection *CurSection = getCurrentSectionOnly();
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CurSection->getFragmentList().insert(CurInsertionPoint, F);
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F->setParent(CurSection);
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}
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for (MCSymbol *Sym : PendingLabels) {
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Sym->setFragment(F);
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Sym->setOffset(FOffset);
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}
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PendingLabels.clear();
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}
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}
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void MCObjectStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi,
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const MCSymbol *Lo,
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unsigned Size) {
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// If not assigned to the same (valid) fragment, fallback.
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if (!Hi->getFragment() || Hi->getFragment() != Lo->getFragment()) {
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MCStreamer::emitAbsoluteSymbolDiff(Hi, Lo, Size);
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return;
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}
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assert(Hi->getOffset() >= Lo->getOffset() &&
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"Expected Hi to be greater than Lo");
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EmitIntValue(Hi->getOffset() - Lo->getOffset(), Size);
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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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CurInsertionPoint = MCSection::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(getCurrentSectionOnly() && "No current section!");
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if (CurInsertionPoint != getCurrentSectionOnly()->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() && !Assembler->getRelaxAll() &&
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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->registerSymbol(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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getAssembler().registerSymbol(*Symbol);
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assert(!Symbol->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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auto *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
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if (F && !(getAssembler().isBundlingEnabled() &&
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getAssembler().getRelaxAll())) {
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Symbol->setFragment(F);
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Symbol->setOffset(F->getContents().size());
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} else {
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PendingLabels.push_back(Symbol);
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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(MCSection *Section,
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const MCExpr *Subsection) {
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changeSectionImpl(Section, Subsection);
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}
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bool MCObjectStreamer::changeSectionImpl(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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bool Created = getAssembler().registerSection(*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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Section->getSubsectionInsertionPoint(unsigned(IntSubsection));
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return Created;
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}
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void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
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getAssembler().registerSymbol(*Symbol);
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MCStreamer::EmitAssignment(Symbol, Value);
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}
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bool MCObjectStreamer::mayHaveInstructions(MCSection &Sec) const {
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return Sec.hasInstructions();
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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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MCSection *Sec = getCurrentSectionOnly();
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Sec->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() && Sec->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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if (getAssembler().getRelaxAll() && getAssembler().isBundlingEnabled())
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llvm_unreachable("All instructions should have already been relaxed");
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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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MCSection *CurSec = getCurrentSection().first;
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if (ByteAlignment > CurSec->getAlignment())
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CurSec->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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const MCSection *Sec = getCurrentSection().first;
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assert(Sec && "need a section");
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unsigned ItemSize = Sec->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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