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//===- lib/MC/MCObjectStreamer.cpp - Object File MCStreamer Interface -----===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCCodeView.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SourceMgr.h"
using namespace llvm;
MCObjectStreamer::MCObjectStreamer(MCContext &Context,
std::unique_ptr<MCAsmBackend> TAB,
std::unique_ptr<MCObjectWriter> OW,
std::unique_ptr<MCCodeEmitter> Emitter)
: MCStreamer(Context),
Assembler(std::make_unique<MCAssembler>(
Context, std::move(TAB), std::move(Emitter), std::move(OW))),
EmitEHFrame(true), EmitDebugFrame(false) {
if (Assembler->getBackendPtr())
setAllowAutoPadding(Assembler->getBackend().allowAutoPadding());
}
MCObjectStreamer::~MCObjectStreamer() = default;
// AssemblerPtr is used for evaluation of expressions and causes
// difference between asm and object outputs. Return nullptr to in
// inline asm mode to limit divergence to assembly inputs.
MCAssembler *MCObjectStreamer::getAssemblerPtr() {
if (getUseAssemblerInfoForParsing())
return Assembler.get();
return nullptr;
}
void MCObjectStreamer::addPendingLabel(MCSymbol* S) {
MCSection *CurSection = getCurrentSectionOnly();
if (CurSection) {
// Register labels that have not yet been assigned to a Section.
if (!PendingLabels.empty()) {
for (MCSymbol* Sym : PendingLabels)
CurSection->addPendingLabel(Sym);
PendingLabels.clear();
}
// Add this label to the current Section / Subsection.
CurSection->addPendingLabel(S, CurSubsectionIdx);
// Add this Section to the list of PendingLabelSections.
PendingLabelSections.insert(CurSection);
} else
// There is no Section / Subsection for this label yet.
PendingLabels.push_back(S);
}
void MCObjectStreamer::flushPendingLabels(MCFragment *F, uint64_t FOffset) {
assert(F);
MCSection *CurSection = getCurrentSectionOnly();
if (!CurSection) {
assert(PendingLabels.empty());
return;
}
// Register labels that have not yet been assigned to a Section.
if (!PendingLabels.empty()) {
for (MCSymbol* Sym : PendingLabels)
CurSection->addPendingLabel(Sym, CurSubsectionIdx);
PendingLabels.clear();
}
// Associate the labels with F.
CurSection->flushPendingLabels(F, FOffset, CurSubsectionIdx);
}
void MCObjectStreamer::flushPendingLabels() {
// Register labels that have not yet been assigned to a Section.
if (!PendingLabels.empty()) {
MCSection *CurSection = getCurrentSectionOnly();
assert(CurSection);
for (MCSymbol* Sym : PendingLabels)
CurSection->addPendingLabel(Sym, CurSubsectionIdx);
PendingLabels.clear();
}
// Assign an empty data fragment to all remaining pending labels.
for (MCSection* Section : PendingLabelSections)
Section->flushPendingLabels();
}
// When fixup's offset is a forward declared label, e.g.:
//
// .reloc 1f, R_MIPS_JALR, foo
// 1: nop
//
// postpone adding it to Fixups vector until the label is defined and its offset
// is known.
void MCObjectStreamer::resolvePendingFixups() {
for (PendingMCFixup &PendingFixup : PendingFixups) {
if (!PendingFixup.Sym || PendingFixup.Sym->isUndefined ()) {
getContext().reportError(PendingFixup.Fixup.getLoc(),
"unresolved relocation offset");
continue;
}
flushPendingLabels(PendingFixup.DF, PendingFixup.DF->getContents().size());
PendingFixup.Fixup.setOffset(PendingFixup.Sym->getOffset() +
PendingFixup.Fixup.getOffset());
// If the location symbol to relocate is in MCEncodedFragmentWithFixups,
// put the Fixup into location symbol's fragment. Otherwise
// put into PendingFixup.DF
MCFragment *SymFragment = PendingFixup.Sym->getFragment();
switch (SymFragment->getKind()) {
case MCFragment::FT_Relaxable:
case MCFragment::FT_Dwarf:
case MCFragment::FT_PseudoProbe:
cast<MCEncodedFragmentWithFixups<8, 1>>(SymFragment)
->getFixups()
.push_back(PendingFixup.Fixup);
break;
case MCFragment::FT_Data:
case MCFragment::FT_CVDefRange:
cast<MCEncodedFragmentWithFixups<32, 4>>(SymFragment)
->getFixups()
.push_back(PendingFixup.Fixup);
break;
default:
PendingFixup.DF->getFixups().push_back(PendingFixup.Fixup);
break;
}
}
PendingFixups.clear();
}
// As a compile-time optimization, avoid allocating and evaluating an MCExpr
// tree for (Hi - Lo) when Hi and Lo are offsets into the same fragment.
static std::optional<uint64_t> absoluteSymbolDiff(const MCSymbol *Hi,
const MCSymbol *Lo) {
assert(Hi && Lo);
if (!Hi->getFragment() || Hi->getFragment() != Lo->getFragment() ||
Hi->isVariable() || Lo->isVariable())
return std::nullopt;
return Hi->getOffset() - Lo->getOffset();
}
void MCObjectStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi,
const MCSymbol *Lo,
unsigned Size) {
if (!getAssembler().getContext().getTargetTriple().isRISCV())
if (std::optional<uint64_t> Diff = absoluteSymbolDiff(Hi, Lo))
return emitIntValue(*Diff, Size);
MCStreamer::emitAbsoluteSymbolDiff(Hi, Lo, Size);
}
void MCObjectStreamer::emitAbsoluteSymbolDiffAsULEB128(const MCSymbol *Hi,
const MCSymbol *Lo) {
if (!getAssembler().getContext().getTargetTriple().isRISCV())
if (std::optional<uint64_t> Diff = absoluteSymbolDiff(Hi, Lo)) {
emitULEB128IntValue(*Diff);
return;
}
MCStreamer::emitAbsoluteSymbolDiffAsULEB128(Hi, Lo);
}
void MCObjectStreamer::reset() {
if (Assembler)
Assembler->reset();
CurInsertionPoint = MCSection::iterator();
EmitEHFrame = true;
EmitDebugFrame = false;
PendingLabels.clear();
PendingLabelSections.clear();
MCStreamer::reset();
}
void MCObjectStreamer::emitFrames(MCAsmBackend *MAB) {
if (!getNumFrameInfos())
return;
if (EmitEHFrame)
MCDwarfFrameEmitter::Emit(*this, MAB, true);
if (EmitDebugFrame)
MCDwarfFrameEmitter::Emit(*this, MAB, false);
}
MCFragment *MCObjectStreamer::getCurrentFragment() const {
assert(getCurrentSectionOnly() && "No current section!");
if (CurInsertionPoint != getCurrentSectionOnly()->getFragmentList().begin())
return &*std::prev(CurInsertionPoint);
return nullptr;
}
static bool canReuseDataFragment(const MCDataFragment &F,
const MCAssembler &Assembler,
const MCSubtargetInfo *STI) {
if (!F.hasInstructions())
return true;
// Do not add data after a linker-relaxable instruction. The difference
// between a new label and a label at or before the linker-relaxable
// instruction cannot be resolved at assemble-time.
if (F.isLinkerRelaxable())
return false;
// When bundling is enabled, we don't want to add data to a fragment that
// already has instructions (see MCELFStreamer::emitInstToData for details)
if (Assembler.isBundlingEnabled())
return Assembler.getRelaxAll();
// If the subtarget is changed mid fragment we start a new fragment to record
// the new STI.
return !STI || F.getSubtargetInfo() == STI;
}
MCDataFragment *
MCObjectStreamer::getOrCreateDataFragment(const MCSubtargetInfo *STI) {
MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
if (!F || !canReuseDataFragment(*F, *Assembler, STI)) {
F = new MCDataFragment();
insert(F);
}
return F;
}
void MCObjectStreamer::visitUsedSymbol(const MCSymbol &Sym) {
Assembler->registerSymbol(Sym);
}
void MCObjectStreamer::emitCFISections(bool EH, bool Debug) {
MCStreamer::emitCFISections(EH, Debug);
EmitEHFrame = EH;
EmitDebugFrame = Debug;
}
void MCObjectStreamer::emitValueImpl(const MCExpr *Value, unsigned Size,
SMLoc Loc) {
MCStreamer::emitValueImpl(Value, Size, Loc);
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
MCDwarfLineEntry::make(this, getCurrentSectionOnly());
// Avoid fixups when possible.
int64_t AbsValue;
if (Value->evaluateAsAbsolute(AbsValue, getAssemblerPtr())) {
if (!isUIntN(8 * Size, AbsValue) && !isIntN(8 * Size, AbsValue)) {
getContext().reportError(
Loc, "value evaluated as " + Twine(AbsValue) + " is out of range.");
return;
}
emitIntValue(AbsValue, Size);
return;
}
DF->getFixups().push_back(
MCFixup::create(DF->getContents().size(), Value,
MCFixup::getKindForSize(Size, false), Loc));
DF->getContents().resize(DF->getContents().size() + Size, 0);
}
MCSymbol *MCObjectStreamer::emitCFILabel() {
MCSymbol *Label = getContext().createTempSymbol("cfi");
emitLabel(Label);
return Label;
}
void MCObjectStreamer::emitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
// We need to create a local symbol to avoid relocations.
Frame.Begin = getContext().createTempSymbol();
emitLabel(Frame.Begin);
}
void MCObjectStreamer::emitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
Frame.End = getContext().createTempSymbol();
emitLabel(Frame.End);
}
void MCObjectStreamer::emitLabel(MCSymbol *Symbol, SMLoc Loc) {
MCStreamer::emitLabel(Symbol, Loc);
getAssembler().registerSymbol(*Symbol);
// If there is a current fragment, mark the symbol as pointing into it.
// Otherwise queue the label and set its fragment pointer when we emit the
// next fragment.
auto *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
if (F && !(getAssembler().isBundlingEnabled() &&
getAssembler().getRelaxAll())) {
Symbol->setFragment(F);
Symbol->setOffset(F->getContents().size());
} else {
// Assign all pending labels to offset 0 within the dummy "pending"
// fragment. (They will all be reassigned to a real fragment in
// flushPendingLabels())
Symbol->setOffset(0);
addPendingLabel(Symbol);
}
emitPendingAssignments(Symbol);
}
void MCObjectStreamer::emitPendingAssignments(MCSymbol *Symbol) {
auto Assignments = pendingAssignments.find(Symbol);
if (Assignments != pendingAssignments.end()) {
for (const PendingAssignment &A : Assignments->second)
emitAssignment(A.Symbol, A.Value);
pendingAssignments.erase(Assignments);
}
}
// Emit a label at a previously emitted fragment/offset position. This must be
// within the currently-active section.
void MCObjectStreamer::emitLabelAtPos(MCSymbol *Symbol, SMLoc Loc,
MCFragment *F, uint64_t Offset) {
assert(F->getParent() == getCurrentSectionOnly());
MCStreamer::emitLabel(Symbol, Loc);
getAssembler().registerSymbol(*Symbol);
auto *DF = dyn_cast_or_null<MCDataFragment>(F);
Symbol->setOffset(Offset);
if (DF) {
Symbol->setFragment(F);
} else {
assert(isa<MCDummyFragment>(F) &&
"F must either be an MCDataFragment or the pending MCDummyFragment");
assert(Offset == 0);
addPendingLabel(Symbol);
}
}
void MCObjectStreamer::emitULEB128Value(const MCExpr *Value) {
int64_t IntValue;
if (Value->evaluateAsAbsolute(IntValue, getAssemblerPtr())) {
emitULEB128IntValue(IntValue);
return;
}
insert(new MCLEBFragment(*Value, false));
}
void MCObjectStreamer::emitSLEB128Value(const MCExpr *Value) {
int64_t IntValue;
if (Value->evaluateAsAbsolute(IntValue, getAssemblerPtr())) {
emitSLEB128IntValue(IntValue);
return;
}
insert(new MCLEBFragment(*Value, true));
}
void MCObjectStreamer::emitWeakReference(MCSymbol *Alias,
const MCSymbol *Symbol) {
report_fatal_error("This file format doesn't support weak aliases.");
}
void MCObjectStreamer::changeSection(MCSection *Section,
const MCExpr *Subsection) {
changeSectionImpl(Section, Subsection);
}
bool MCObjectStreamer::changeSectionImpl(MCSection *Section,
const MCExpr *Subsection) {
assert(Section && "Cannot switch to a null section!");
getContext().clearDwarfLocSeen();
bool Created = getAssembler().registerSection(*Section);
int64_t IntSubsection = 0;
if (Subsection &&
!Subsection->evaluateAsAbsolute(IntSubsection, getAssemblerPtr())) {
getContext().reportError(Subsection->getLoc(),
"cannot evaluate subsection number");
}
if (!isUInt<31>(IntSubsection)) {
getContext().reportError(Subsection->getLoc(),
"subsection number " + Twine(IntSubsection) +
" is not within [0,2147483647]");
}
CurSubsectionIdx = unsigned(IntSubsection);
CurInsertionPoint =
Section->getSubsectionInsertionPoint(CurSubsectionIdx);
return Created;
}
void MCObjectStreamer::emitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
getAssembler().registerSymbol(*Symbol);
MCStreamer::emitAssignment(Symbol, Value);
emitPendingAssignments(Symbol);
}
void MCObjectStreamer::emitConditionalAssignment(MCSymbol *Symbol,
const MCExpr *Value) {
const MCSymbol *Target = &cast<MCSymbolRefExpr>(*Value).getSymbol();
// If the symbol already exists, emit the assignment. Otherwise, emit it
// later only if the symbol is also emitted.
if (Target->isRegistered())
emitAssignment(Symbol, Value);
else
pendingAssignments[Target].push_back({Symbol, Value});
}
bool MCObjectStreamer::mayHaveInstructions(MCSection &Sec) const {
return Sec.hasInstructions();
}
void MCObjectStreamer::emitInstruction(const MCInst &Inst,
const MCSubtargetInfo &STI) {
const MCSection &Sec = *getCurrentSectionOnly();
if (Sec.isVirtualSection()) {
getContext().reportError(Inst.getLoc(), Twine(Sec.getVirtualSectionKind()) +
" section '" + Sec.getName() +
"' cannot have instructions");
return;
}
getAssembler().getBackend().emitInstructionBegin(*this, Inst, STI);
emitInstructionImpl(Inst, STI);
getAssembler().getBackend().emitInstructionEnd(*this, Inst);
}
void MCObjectStreamer::emitInstructionImpl(const MCInst &Inst,
const MCSubtargetInfo &STI) {
MCStreamer::emitInstruction(Inst, STI);
MCSection *Sec = getCurrentSectionOnly();
Sec->setHasInstructions(true);
// Now that a machine instruction has been assembled into this section, make
// a line entry for any .loc directive that has been seen.
MCDwarfLineEntry::make(this, getCurrentSectionOnly());
// If this instruction doesn't need relaxation, just emit it as data.
MCAssembler &Assembler = getAssembler();
MCAsmBackend &Backend = Assembler.getBackend();
if (!(Backend.mayNeedRelaxation(Inst, STI) ||
Backend.allowEnhancedRelaxation())) {
emitInstToData(Inst, STI);
return;
}
// Otherwise, relax and emit it as data if either:
// - The RelaxAll flag was passed
// - Bundling is enabled and this instruction is inside a bundle-locked
// group. We want to emit all such instructions into the same data
// fragment.
if (Assembler.getRelaxAll() ||
(Assembler.isBundlingEnabled() && Sec->isBundleLocked())) {
MCInst Relaxed = Inst;
while (Backend.mayNeedRelaxation(Relaxed, STI))
Backend.relaxInstruction(Relaxed, STI);
emitInstToData(Relaxed, STI);
return;
}
// Otherwise emit to a separate fragment.
emitInstToFragment(Inst, STI);
}
void MCObjectStreamer::emitInstToFragment(const MCInst &Inst,
const MCSubtargetInfo &STI) {
if (getAssembler().getRelaxAll() && getAssembler().isBundlingEnabled())
llvm_unreachable("All instructions should have already been relaxed");
// Always create a new, separate fragment here, because its size can change
// during relaxation.
MCRelaxableFragment *IF = new MCRelaxableFragment(Inst, STI);
insert(IF);
SmallString<128> Code;
getAssembler().getEmitter().encodeInstruction(Inst, Code, IF->getFixups(),
STI);
IF->getContents().append(Code.begin(), Code.end());
}
#ifndef NDEBUG
static const char *const BundlingNotImplementedMsg =
"Aligned bundling is not implemented for this object format";
#endif
void MCObjectStreamer::emitBundleAlignMode(Align Alignment) {
llvm_unreachable(BundlingNotImplementedMsg);
}
void MCObjectStreamer::emitBundleLock(bool AlignToEnd) {
llvm_unreachable(BundlingNotImplementedMsg);
}
void MCObjectStreamer::emitBundleUnlock() {
llvm_unreachable(BundlingNotImplementedMsg);
}
void MCObjectStreamer::emitDwarfLocDirective(unsigned FileNo, unsigned Line,
unsigned Column, unsigned Flags,
unsigned Isa,
unsigned Discriminator,
StringRef FileName) {
// In case we see two .loc directives in a row, make sure the
// first one gets a line entry.
MCDwarfLineEntry::make(this, getCurrentSectionOnly());
this->MCStreamer::emitDwarfLocDirective(FileNo, Line, Column, Flags, Isa,
Discriminator, FileName);
}
static const MCExpr *buildSymbolDiff(MCObjectStreamer &OS, const MCSymbol *A,
const MCSymbol *B, SMLoc Loc) {
MCContext &Context = OS.getContext();
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
const MCExpr *ARef = MCSymbolRefExpr::create(A, Variant, Context);
const MCExpr *BRef = MCSymbolRefExpr::create(B, Variant, Context);
const MCExpr *AddrDelta =
MCBinaryExpr::create(MCBinaryExpr::Sub, ARef, BRef, Context, Loc);
return AddrDelta;
}
static void emitDwarfSetLineAddr(MCObjectStreamer &OS,
MCDwarfLineTableParams Params,
int64_t LineDelta, const MCSymbol *Label,
int PointerSize) {
// emit the sequence to set the address
OS.emitIntValue(dwarf::DW_LNS_extended_op, 1);
OS.emitULEB128IntValue(PointerSize + 1);
OS.emitIntValue(dwarf::DW_LNE_set_address, 1);
OS.emitSymbolValue(Label, PointerSize);
// emit the sequence for the LineDelta (from 1) and a zero address delta.
MCDwarfLineAddr::Emit(&OS, Params, LineDelta, 0);
}
void MCObjectStreamer::emitDwarfAdvanceLineAddr(int64_t LineDelta,
const MCSymbol *LastLabel,
const MCSymbol *Label,
unsigned PointerSize) {
if (!LastLabel) {
emitDwarfSetLineAddr(*this, Assembler->getDWARFLinetableParams(), LineDelta,
Label, PointerSize);
return;
}
const MCExpr *AddrDelta = buildSymbolDiff(*this, Label, LastLabel, SMLoc());
insert(new MCDwarfLineAddrFragment(LineDelta, *AddrDelta));
}
void MCObjectStreamer::emitDwarfLineEndEntry(MCSection *Section,
MCSymbol *LastLabel) {
// Emit a DW_LNE_end_sequence for the end of the section.
// Use the section end label to compute the address delta and use INT64_MAX
// as the line delta which is the signal that this is actually a
// DW_LNE_end_sequence.
MCSymbol *SectionEnd = endSection(Section);
// Switch back the dwarf line section, in case endSection had to switch the
// section.
MCContext &Ctx = getContext();
switchSection(Ctx.getObjectFileInfo()->getDwarfLineSection());
const MCAsmInfo *AsmInfo = Ctx.getAsmInfo();
emitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd,
AsmInfo->getCodePointerSize());
}
void MCObjectStreamer::emitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
const MCSymbol *Label,
SMLoc Loc) {
const MCExpr *AddrDelta = buildSymbolDiff(*this, Label, LastLabel, Loc);
insert(new MCDwarfCallFrameFragment(*AddrDelta, nullptr));
}
void MCObjectStreamer::emitCVLocDirective(unsigned FunctionId, unsigned FileNo,
unsigned Line, unsigned Column,
bool PrologueEnd, bool IsStmt,
StringRef FileName, SMLoc Loc) {
// Validate the directive.
if (!checkCVLocSection(FunctionId, FileNo, Loc))
return;
// Emit a label at the current position and record it in the CodeViewContext.
MCSymbol *LineSym = getContext().createTempSymbol();
emitLabel(LineSym);
getContext().getCVContext().recordCVLoc(getContext(), LineSym, FunctionId,
FileNo, Line, Column, PrologueEnd,
IsStmt);
}
void MCObjectStreamer::emitCVLinetableDirective(unsigned FunctionId,
const MCSymbol *Begin,
const MCSymbol *End) {
getContext().getCVContext().emitLineTableForFunction(*this, FunctionId, Begin,
End);
this->MCStreamer::emitCVLinetableDirective(FunctionId, Begin, End);
}
void MCObjectStreamer::emitCVInlineLinetableDirective(
unsigned PrimaryFunctionId, unsigned SourceFileId, unsigned SourceLineNum,
const MCSymbol *FnStartSym, const MCSymbol *FnEndSym) {
getContext().getCVContext().emitInlineLineTableForFunction(
*this, PrimaryFunctionId, SourceFileId, SourceLineNum, FnStartSym,
FnEndSym);
this->MCStreamer::emitCVInlineLinetableDirective(
PrimaryFunctionId, SourceFileId, SourceLineNum, FnStartSym, FnEndSym);
}
void MCObjectStreamer::emitCVDefRangeDirective(
ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
StringRef FixedSizePortion) {
MCFragment *Frag =
getContext().getCVContext().emitDefRange(*this, Ranges, FixedSizePortion);
// Attach labels that were pending before we created the defrange fragment to
// the beginning of the new fragment.
flushPendingLabels(Frag, 0);
this->MCStreamer::emitCVDefRangeDirective(Ranges, FixedSizePortion);
}
void MCObjectStreamer::emitCVStringTableDirective() {
getContext().getCVContext().emitStringTable(*this);
}
void MCObjectStreamer::emitCVFileChecksumsDirective() {
getContext().getCVContext().emitFileChecksums(*this);
}
void MCObjectStreamer::emitCVFileChecksumOffsetDirective(unsigned FileNo) {
getContext().getCVContext().emitFileChecksumOffset(*this, FileNo);
}
void MCObjectStreamer::emitBytes(StringRef Data) {
MCDwarfLineEntry::make(this, getCurrentSectionOnly());
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
DF->getContents().append(Data.begin(), Data.end());
}
void MCObjectStreamer::emitValueToAlignment(Align Alignment, int64_t Value,
unsigned ValueSize,
unsigned MaxBytesToEmit) {
if (MaxBytesToEmit == 0)
MaxBytesToEmit = Alignment.value();
insert(new MCAlignFragment(Alignment, Value, ValueSize, MaxBytesToEmit));
// Update the maximum alignment on the current section if necessary.
MCSection *CurSec = getCurrentSectionOnly();
CurSec->ensureMinAlignment(Alignment);
}
void MCObjectStreamer::emitCodeAlignment(Align Alignment,
const MCSubtargetInfo *STI,
unsigned MaxBytesToEmit) {
emitValueToAlignment(Alignment, 0, 1, MaxBytesToEmit);
cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true, STI);
}
void MCObjectStreamer::emitValueToOffset(const MCExpr *Offset,
unsigned char Value,
SMLoc Loc) {
insert(new MCOrgFragment(*Offset, Value, Loc));
}
// Associate DTPRel32 fixup with data and resize data area
void MCObjectStreamer::emitDTPRel32Value(const MCExpr *Value) {
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
Value, FK_DTPRel_4));
DF->getContents().resize(DF->getContents().size() + 4, 0);
}
// Associate DTPRel64 fixup with data and resize data area
void MCObjectStreamer::emitDTPRel64Value(const MCExpr *Value) {
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
Value, FK_DTPRel_8));
DF->getContents().resize(DF->getContents().size() + 8, 0);
}
// Associate TPRel32 fixup with data and resize data area
void MCObjectStreamer::emitTPRel32Value(const MCExpr *Value) {
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
Value, FK_TPRel_4));
DF->getContents().resize(DF->getContents().size() + 4, 0);
}
// Associate TPRel64 fixup with data and resize data area
void MCObjectStreamer::emitTPRel64Value(const MCExpr *Value) {
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
Value, FK_TPRel_8));
DF->getContents().resize(DF->getContents().size() + 8, 0);
}
// Associate GPRel32 fixup with data and resize data area
void MCObjectStreamer::emitGPRel32Value(const MCExpr *Value) {
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
DF->getFixups().push_back(
MCFixup::create(DF->getContents().size(), Value, FK_GPRel_4));
DF->getContents().resize(DF->getContents().size() + 4, 0);
}
// Associate GPRel64 fixup with data and resize data area
void MCObjectStreamer::emitGPRel64Value(const MCExpr *Value) {
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
DF->getFixups().push_back(
MCFixup::create(DF->getContents().size(), Value, FK_GPRel_4));
DF->getContents().resize(DF->getContents().size() + 8, 0);
}
static std::optional<std::pair<bool, std::string>>
getOffsetAndDataFragment(const MCSymbol &Symbol, uint32_t &RelocOffset,
MCDataFragment *&DF) {
if (Symbol.isVariable()) {
const MCExpr *SymbolExpr = Symbol.getVariableValue();
MCValue OffsetVal;
if(!SymbolExpr->evaluateAsRelocatable(OffsetVal, nullptr, nullptr))
return std::make_pair(false,
std::string("symbol in .reloc offset is not "
"relocatable"));
if (OffsetVal.isAbsolute()) {
RelocOffset = OffsetVal.getConstant();
MCFragment *Fragment = Symbol.getFragment();
// FIXME Support symbols with no DF. For example:
// .reloc .data, ENUM_VALUE, <some expr>
if (!Fragment || Fragment->getKind() != MCFragment::FT_Data)
return std::make_pair(false,
std::string("symbol in offset has no data "
"fragment"));
DF = cast<MCDataFragment>(Fragment);
return std::nullopt;
}
if (OffsetVal.getSymB())
return std::make_pair(false,
std::string(".reloc symbol offset is not "
"representable"));
const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*OffsetVal.getSymA());
if (!SRE.getSymbol().isDefined())
return std::make_pair(false,
std::string("symbol used in the .reloc offset is "
"not defined"));
if (SRE.getSymbol().isVariable())
return std::make_pair(false,
std::string("symbol used in the .reloc offset is "
"variable"));
MCFragment *Fragment = SRE.getSymbol().getFragment();
// FIXME Support symbols with no DF. For example:
// .reloc .data, ENUM_VALUE, <some expr>
if (!Fragment || Fragment->getKind() != MCFragment::FT_Data)
return std::make_pair(false,
std::string("symbol in offset has no data "
"fragment"));
RelocOffset = SRE.getSymbol().getOffset() + OffsetVal.getConstant();
DF = cast<MCDataFragment>(Fragment);
} else {
RelocOffset = Symbol.getOffset();
MCFragment *Fragment = Symbol.getFragment();
// FIXME Support symbols with no DF. For example:
// .reloc .data, ENUM_VALUE, <some expr>
if (!Fragment || Fragment->getKind() != MCFragment::FT_Data)
return std::make_pair(false,
std::string("symbol in offset has no data "
"fragment"));
DF = cast<MCDataFragment>(Fragment);
}
return std::nullopt;
}
std::optional<std::pair<bool, std::string>>
MCObjectStreamer::emitRelocDirective(const MCExpr &Offset, StringRef Name,
const MCExpr *Expr, SMLoc Loc,
const MCSubtargetInfo &STI) {
std::optional<MCFixupKind> MaybeKind =
Assembler->getBackend().getFixupKind(Name);
if (!MaybeKind)
return std::make_pair(true, std::string("unknown relocation name"));
MCFixupKind Kind = *MaybeKind;
if (Expr)
visitUsedExpr(*Expr);
else
Expr =
MCSymbolRefExpr::create(getContext().createTempSymbol(), getContext());
MCDataFragment *DF = getOrCreateDataFragment(&STI);
flushPendingLabels(DF, DF->getContents().size());
MCValue OffsetVal;
if (!Offset.evaluateAsRelocatable(OffsetVal, nullptr, nullptr))
return std::make_pair(false,
std::string(".reloc offset is not relocatable"));
if (OffsetVal.isAbsolute()) {
if (OffsetVal.getConstant() < 0)
return std::make_pair(false, std::string(".reloc offset is negative"));
DF->getFixups().push_back(
MCFixup::create(OffsetVal.getConstant(), Expr, Kind, Loc));
return std::nullopt;
}
if (OffsetVal.getSymB())
return std::make_pair(false,
std::string(".reloc offset is not representable"));
const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*OffsetVal.getSymA());
const MCSymbol &Symbol = SRE.getSymbol();
if (Symbol.isDefined()) {
uint32_t SymbolOffset = 0;
std::optional<std::pair<bool, std::string>> Error =
getOffsetAndDataFragment(Symbol, SymbolOffset, DF);
if (Error != std::nullopt)
return Error;
DF->getFixups().push_back(
MCFixup::create(SymbolOffset + OffsetVal.getConstant(),
Expr, Kind, Loc));
return std::nullopt;
}
PendingFixups.emplace_back(
&SRE.getSymbol(), DF,
MCFixup::create(OffsetVal.getConstant(), Expr, Kind, Loc));
return std::nullopt;
}
void MCObjectStreamer::emitFill(const MCExpr &NumBytes, uint64_t FillValue,
SMLoc Loc) {
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
assert(getCurrentSectionOnly() && "need a section");
insert(new MCFillFragment(FillValue, 1, NumBytes, Loc));
}
void MCObjectStreamer::emitFill(const MCExpr &NumValues, int64_t Size,
int64_t Expr, SMLoc Loc) {
int64_t IntNumValues;
// Do additional checking now if we can resolve the value.
if (NumValues.evaluateAsAbsolute(IntNumValues, getAssemblerPtr())) {
if (IntNumValues < 0) {
getContext().getSourceManager()->PrintMessage(
Loc, SourceMgr::DK_Warning,
"'.fill' directive with negative repeat count has no effect");
return;
}
// Emit now if we can for better errors.
int64_t NonZeroSize = Size > 4 ? 4 : Size;
Expr &= ~0ULL >> (64 - NonZeroSize * 8);
for (uint64_t i = 0, e = IntNumValues; i != e; ++i) {
emitIntValue(Expr, NonZeroSize);
if (NonZeroSize < Size)
emitIntValue(0, Size - NonZeroSize);
}
return;
}
// Otherwise emit as fragment.
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
assert(getCurrentSectionOnly() && "need a section");
insert(new MCFillFragment(Expr, Size, NumValues, Loc));
}
void MCObjectStreamer::emitNops(int64_t NumBytes, int64_t ControlledNopLength,
SMLoc Loc, const MCSubtargetInfo &STI) {
// Emit an NOP fragment.
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
assert(getCurrentSectionOnly() && "need a section");
insert(new MCNopsFragment(NumBytes, ControlledNopLength, Loc, STI));
}
void MCObjectStreamer::emitFileDirective(StringRef Filename) {
getAssembler().addFileName(Filename);
}
void MCObjectStreamer::emitFileDirective(StringRef Filename,
StringRef CompilerVersion,
StringRef TimeStamp,
StringRef Description) {
getAssembler().addFileName(Filename);
getAssembler().setCompilerVersion(CompilerVersion.str());
// TODO: add TimeStamp and Description to .file symbol table entry
// with the integrated assembler.
}
void MCObjectStreamer::emitAddrsig() {
getAssembler().getWriter().emitAddrsigSection();
}
void MCObjectStreamer::emitAddrsigSym(const MCSymbol *Sym) {
getAssembler().getWriter().addAddrsigSymbol(Sym);
}
void MCObjectStreamer::finishImpl() {
getContext().RemapDebugPaths();
// If we are generating dwarf for assembly source files dump out the sections.
if (getContext().getGenDwarfForAssembly())
MCGenDwarfInfo::Emit(this);
// Dump out the dwarf file & directory tables and line tables.
MCDwarfLineTable::emit(this, getAssembler().getDWARFLinetableParams());
// Emit pseudo probes for the current module.
MCPseudoProbeTable::emit(this);
// Update any remaining pending labels with empty data fragments.
flushPendingLabels();
resolvePendingFixups();
getAssembler().Finish();
}