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llvm/lib/MC/MCObjectStreamer.cpp
David Majnemer 7ddc547ea9 [MC] Add support for encoding CodeView variable definition ranges 
CodeView, like most other debug formats, represents the live range of a
variable so that debuggers might print them out.

They use a variety of records to represent how a particular variable
might be available (in a register, in a frame pointer, etc.) along with
a set of ranges where this debug information is relevant.

However, the format only allows us to use ranges which are limited to a
maximum of 0xF000 in size.  This means that we need to split our debug
information into chunks of 0xF000.

Because the layout of code is not known until *very* late, we must use a
new fragment to record the information we need until we can know
*exactly* what the range is.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@259868 91177308-0d34-0410-b5e6-96231b3b80d8
2016-02-05 01:55:49 +00:00

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//===- lib/MC/MCObjectStreamer.cpp - Object File MCStreamer Interface -----===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCObjectStreamer.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/MC/MCAsmBackend.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCCodeEmitter.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/TargetRegistry.h"
using namespace llvm;
MCObjectStreamer::MCObjectStreamer(MCContext &Context, MCAsmBackend &TAB,
raw_pwrite_stream &OS,
MCCodeEmitter *Emitter_)
: MCStreamer(Context),
Assembler(new MCAssembler(Context, TAB, *Emitter_,
*TAB.createObjectWriter(OS))),
EmitEHFrame(true), EmitDebugFrame(false) {}
MCObjectStreamer::~MCObjectStreamer() {
delete &Assembler->getBackend();
delete &Assembler->getEmitter();
delete &Assembler->getWriter();
delete Assembler;
}
void MCObjectStreamer::flushPendingLabels(MCFragment *F, uint64_t FOffset) {
if (PendingLabels.empty())
return;
if (!F) {
F = new MCDataFragment();
MCSection *CurSection = getCurrentSectionOnly();
CurSection->getFragmentList().insert(CurInsertionPoint, F);
F->setParent(CurSection);
}
for (MCSymbol *Sym : PendingLabels) {
Sym->setFragment(F);
Sym->setOffset(FOffset);
}
PendingLabels.clear();
}
void MCObjectStreamer::emitAbsoluteSymbolDiff(const MCSymbol *Hi,
const MCSymbol *Lo,
unsigned Size) {
// If not assigned to the same (valid) fragment, fallback.
if (!Hi->getFragment() || Hi->getFragment() != Lo->getFragment() ||
Hi->isVariable() || Lo->isVariable()) {
MCStreamer::emitAbsoluteSymbolDiff(Hi, Lo, Size);
return;
}
EmitIntValue(Hi->getOffset() - Lo->getOffset(), Size);
}
void MCObjectStreamer::reset() {
if (Assembler)
Assembler->reset();
CurInsertionPoint = MCSection::iterator();
EmitEHFrame = true;
EmitDebugFrame = false;
PendingLabels.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;
}
MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() {
MCDataFragment *F = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
// When bundling is enabled, we don't want to add data to a fragment that
// already has instructions (see MCELFStreamer::EmitInstToData for details)
if (!F || (Assembler->isBundlingEnabled() && !Assembler->getRelaxAll() &&
F->hasInstructions())) {
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());
MCCVLineEntry::Make(this);
MCDwarfLineEntry::Make(this, getCurrentSection().first);
// Avoid fixups when possible.
int64_t AbsValue;
if (Value->evaluateAsAbsolute(AbsValue, getAssembler())) {
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);
}
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) {
MCStreamer::EmitLabel(Symbol);
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 {
PendingLabels.push_back(Symbol);
}
}
void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
int64_t IntValue;
if (Value->evaluateAsAbsolute(IntValue, getAssembler())) {
EmitULEB128IntValue(IntValue);
return;
}
insert(new MCLEBFragment(*Value, false));
}
void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
int64_t IntValue;
if (Value->evaluateAsAbsolute(IntValue, getAssembler())) {
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!");
flushPendingLabels(nullptr);
bool Created = getAssembler().registerSection(*Section);
int64_t IntSubsection = 0;
if (Subsection &&
!Subsection->evaluateAsAbsolute(IntSubsection, getAssembler()))
report_fatal_error("Cannot evaluate subsection number");
if (IntSubsection < 0 || IntSubsection > 8192)
report_fatal_error("Subsection number out of range");
CurInsertionPoint =
Section->getSubsectionInsertionPoint(unsigned(IntSubsection));
return Created;
}
void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
getAssembler().registerSymbol(*Symbol);
MCStreamer::EmitAssignment(Symbol, Value);
}
bool MCObjectStreamer::mayHaveInstructions(MCSection &Sec) const {
return Sec.hasInstructions();
}
void MCObjectStreamer::EmitInstruction(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.
MCCVLineEntry::Make(this);
MCDwarfLineEntry::Make(this, getCurrentSection().first);
// If this instruction doesn't need relaxation, just emit it as data.
MCAssembler &Assembler = getAssembler();
if (!Assembler.getBackend().mayNeedRelaxation(Inst)) {
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;
getAssembler().getBackend().relaxInstruction(Inst, Relaxed);
while (getAssembler().getBackend().mayNeedRelaxation(Relaxed))
getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed);
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;
raw_svector_ostream VecOS(Code);
getAssembler().getEmitter().encodeInstruction(Inst, VecOS, 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(unsigned AlignPow2) {
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, getCurrentSection().first);
this->MCStreamer::EmitDwarfLocDirective(FileNo, Line, Column, Flags,
Isa, Discriminator, FileName);
}
static const MCExpr *buildSymbolDiff(MCObjectStreamer &OS, const MCSymbol *A,
const MCSymbol *B) {
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);
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);
int64_t Res;
if (AddrDelta->evaluateAsAbsolute(Res, getAssembler())) {
MCDwarfLineAddr::Emit(this, Assembler->getDWARFLinetableParams(), LineDelta,
Res);
return;
}
insert(new MCDwarfLineAddrFragment(LineDelta, *AddrDelta));
}
void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
const MCSymbol *Label) {
const MCExpr *AddrDelta = buildSymbolDiff(*this, Label, LastLabel);
int64_t Res;
if (AddrDelta->evaluateAsAbsolute(Res, getAssembler())) {
MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
return;
}
insert(new MCDwarfCallFrameFragment(*AddrDelta));
}
void MCObjectStreamer::EmitCVLocDirective(unsigned FunctionId, unsigned FileNo,
unsigned Line, unsigned Column,
bool PrologueEnd, bool IsStmt,
StringRef FileName) {
// In case we see two .cv_loc directives in a row, make sure the
// first one gets a line entry.
MCCVLineEntry::Make(this);
this->MCStreamer::EmitCVLocDirective(FunctionId, FileNo, Line, Column,
PrologueEnd, IsStmt, FileName);
}
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,
ArrayRef<unsigned> SecondaryFunctionIds) {
getContext().getCVContext().emitInlineLineTableForFunction(
*this, PrimaryFunctionId, SourceFileId, SourceLineNum, FnStartSym,
FnEndSym, SecondaryFunctionIds);
this->MCStreamer::EmitCVInlineLinetableDirective(
PrimaryFunctionId, SourceFileId, SourceLineNum, FnStartSym, FnEndSym,
SecondaryFunctionIds);
}
void MCObjectStreamer::EmitCVDefRangeDirective(
ArrayRef<std::pair<const MCSymbol *, const MCSymbol *>> Ranges,
StringRef FixedSizePortion) {
getContext().getCVContext().emitDefRange(*this, Ranges, FixedSizePortion);
this->MCStreamer::EmitCVDefRangeDirective(Ranges, FixedSizePortion);
}
void MCObjectStreamer::EmitCVStringTableDirective() {
getContext().getCVContext().emitStringTable(*this);
}
void MCObjectStreamer::EmitCVFileChecksumsDirective() {
getContext().getCVContext().emitFileChecksums(*this);
}
void MCObjectStreamer::EmitBytes(StringRef Data) {
MCCVLineEntry::Make(this);
MCDwarfLineEntry::Make(this, getCurrentSection().first);
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
DF->getContents().append(Data.begin(), Data.end());
}
void MCObjectStreamer::EmitValueToAlignment(unsigned ByteAlignment,
int64_t Value,
unsigned ValueSize,
unsigned MaxBytesToEmit) {
if (MaxBytesToEmit == 0)
MaxBytesToEmit = ByteAlignment;
insert(new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit));
// Update the maximum alignment on the current section if necessary.
MCSection *CurSec = getCurrentSection().first;
if (ByteAlignment > CurSec->getAlignment())
CurSec->setAlignment(ByteAlignment);
}
void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment,
unsigned MaxBytesToEmit) {
EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit);
cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true);
}
void MCObjectStreamer::emitValueToOffset(const MCExpr *Offset,
unsigned char Value) {
insert(new MCOrgFragment(*Offset, Value));
}
// 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 GPRel32 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);
}
bool MCObjectStreamer::EmitRelocDirective(const MCExpr &Offset, StringRef Name,
const MCExpr *Expr, SMLoc Loc) {
int64_t OffsetValue;
if (!Offset.evaluateAsAbsolute(OffsetValue))
llvm_unreachable("Offset is not absolute");
if (OffsetValue < 0)
llvm_unreachable("Offset is negative");
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
Optional<MCFixupKind> MaybeKind = Assembler->getBackend().getFixupKind(Name);
if (!MaybeKind.hasValue())
return true;
MCFixupKind Kind = *MaybeKind;
if (Expr == nullptr)
Expr =
MCSymbolRefExpr::create(getContext().createTempSymbol(), getContext());
DF->getFixups().push_back(MCFixup::create(OffsetValue, Expr, Kind, Loc));
return false;
}
void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue) {
const MCSection *Sec = getCurrentSection().first;
(void)Sec;
assert(Sec && "need a section");
insert(new MCFillFragment(FillValue, NumBytes));
}
void MCObjectStreamer::FinishImpl() {
// 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());
flushPendingLabels(nullptr);
getAssembler().Finish();
}
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