llvm-project/llvm/lib/MC/MCObjectStreamer.cpp

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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/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/MCSymbol.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
MCObjectStreamer::MCObjectStreamer(StreamerKind Kind, MCContext &Context,
MCAsmBackend &TAB, raw_ostream &OS,
MCCodeEmitter *Emitter_)
: MCStreamer(Kind, Context),
Assembler(new MCAssembler(Context, TAB, *Emitter_,
*TAB.createObjectWriter(OS), OS)),
CurSectionData(0) {}
MCObjectStreamer::MCObjectStreamer(StreamerKind Kind, MCContext &Context,
MCAsmBackend &TAB, raw_ostream &OS,
MCCodeEmitter *Emitter_,
MCAssembler *_Assembler)
: MCStreamer(Kind, Context), Assembler(_Assembler), CurSectionData(0) {}
MCObjectStreamer::~MCObjectStreamer() {
delete &Assembler->getBackend();
delete &Assembler->getEmitter();
delete &Assembler->getWriter();
delete Assembler;
}
void MCObjectStreamer::reset() {
if (Assembler)
Assembler->reset();
CurSectionData = 0;
MCStreamer::reset();
}
MCFragment *MCObjectStreamer::getCurrentFragment() const {
assert(getCurrentSectionData() && "No current section!");
if (!getCurrentSectionData()->empty())
return &getCurrentSectionData()->getFragmentList().back();
return 0;
}
MCDataFragment *MCObjectStreamer::getOrCreateDataFragment() const {
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() && F->hasInstructions()))
F = new MCDataFragment(getCurrentSectionData());
return F;
}
const MCExpr *MCObjectStreamer::AddValueSymbols(const MCExpr *Value) {
switch (Value->getKind()) {
case MCExpr::Target:
cast<MCTargetExpr>(Value)->AddValueSymbols(Assembler);
break;
case MCExpr::Constant:
break;
case MCExpr::Binary: {
const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
AddValueSymbols(BE->getLHS());
AddValueSymbols(BE->getRHS());
break;
}
case MCExpr::SymbolRef:
Assembler->getOrCreateSymbolData(cast<MCSymbolRefExpr>(Value)->getSymbol());
break;
case MCExpr::Unary:
AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
break;
}
return Value;
}
void MCObjectStreamer::EmitValueImpl(const MCExpr *Value, unsigned Size,
unsigned AddrSpace) {
assert(AddrSpace == 0 && "Address space must be 0!");
MCDataFragment *DF = getOrCreateDataFragment();
// Avoid fixups when possible.
int64_t AbsValue;
if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue, getAssembler())) {
EmitIntValue(AbsValue, Size, AddrSpace);
return;
}
DF->getFixups().push_back(
MCFixup::Create(DF->getContents().size(), Value,
MCFixup::getKindForSize(Size, false)));
DF->getContents().resize(DF->getContents().size() + Size, 0);
}
void MCObjectStreamer::EmitCFIStartProcImpl(MCDwarfFrameInfo &Frame) {
RecordProcStart(Frame);
}
void MCObjectStreamer::EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
RecordProcEnd(Frame);
}
void MCObjectStreamer::EmitLabel(MCSymbol *Symbol) {
MCStreamer::EmitLabel(Symbol);
MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
// FIXME: This is wasteful, we don't necessarily need to create a data
// fragment. Instead, we should mark the symbol as pointing into the data
// fragment if it exists, otherwise we should just queue the label and set its
// fragment pointer when we emit the next fragment.
MCDataFragment *F = getOrCreateDataFragment();
assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
SD.setFragment(F);
SD.setOffset(F->getContents().size());
}
This patch is needed to make c++ exceptions work for mips16. Mips16 is really a processor decoding mode (ala thumb 1) and in the same program, mips16 and mips32 functions can exist and can call each other. If a jal type instruction encounters an address with the lower bit set, then the processor switches to mips16 mode (if it is not already in it). If the lower bit is not set, then it switches to mips32 mode. The linker knows which functions are mips16 and which are mips32. When relocation is performed on code labels, this lower order bit is set if the code label is a mips16 code label. In general this works just fine, however when creating exception handling tables and dwarf, there are cases where you don't want this lower order bit added in. This has been traditionally distinguished in gas assembly source by using a different syntax for the label. lab1: ; this will cause the lower order bit to be added lab2=. ; this will not cause the lower order bit to be added In some cases, it does not matter because in dwarf and debug tables the difference of two labels is used and in that case the lower order bits subtract each other out. To fix this, I have added to mcstreamer the notion of a debuglabel. The default is for label and debug label to be the same. So calling EmitLabel and EmitDebugLabel produce the same result. For various reasons, there is only one set of labels that needs to be modified for the mips exceptions to work. These are the "$eh_func_beginXXX" labels. Mips overrides the debug label suffix from ":" to "=." . This initial patch fixes exceptions. More changes most likely will be needed to DwarfCFException to make all of this work for actual debugging. These changes will be to emit debug labels in some places where a simple label is emitted now. Some historical discussion on this from gcc can be found at: http://gcc.gnu.org/ml/gcc-patches/2008-08/msg00623.html http://gcc.gnu.org/ml/gcc-patches/2008-11/msg01273.html llvm-svn: 170279
2012-12-16 12:00:45 +08:00
void MCObjectStreamer::EmitDebugLabel(MCSymbol *Symbol) {
EmitLabel(Symbol);
}
void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
int64_t IntValue;
if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
EmitULEB128IntValue(IntValue);
return;
}
Value = ForceExpAbs(Value);
new MCLEBFragment(*Value, false, getCurrentSectionData());
}
void MCObjectStreamer::EmitSLEB128Value(const MCExpr *Value) {
int64_t IntValue;
if (Value->EvaluateAsAbsolute(IntValue, getAssembler())) {
EmitSLEB128IntValue(IntValue);
return;
}
Value = ForceExpAbs(Value);
new MCLEBFragment(*Value, true, getCurrentSectionData());
}
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void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
const MCSymbol *Symbol) {
report_fatal_error("This file format doesn't support weak aliases.");
}
void MCObjectStreamer::ChangeSection(const MCSection *Section) {
assert(Section && "Cannot switch to a null section!");
CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
}
void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
getAssembler().getOrCreateSymbolData(*Symbol);
Symbol->setVariableValue(AddValueSymbols(Value));
}
void MCObjectStreamer::EmitInstruction(const MCInst &Inst) {
// Scan for values.
for (unsigned i = Inst.getNumOperands(); i--; )
if (Inst.getOperand(i).isExpr())
AddValueSymbols(Inst.getOperand(i).getExpr());
MCSectionData *SD = getCurrentSectionData();
SD->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.
MCLineEntry::Make(this, getCurrentSection());
// If this instruction doesn't need relaxation, just emit it as data.
MCAssembler &Assembler = getAssembler();
if (!Assembler.getBackend().mayNeedRelaxation(Inst)) {
EmitInstToData(Inst);
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() && SD->isBundleLocked())) {
MCInst Relaxed;
getAssembler().getBackend().relaxInstruction(Inst, Relaxed);
while (getAssembler().getBackend().mayNeedRelaxation(Relaxed))
getAssembler().getBackend().relaxInstruction(Relaxed, Relaxed);
EmitInstToData(Relaxed);
return;
}
// Otherwise emit to a separate fragment.
EmitInstToFragment(Inst);
}
void MCObjectStreamer::EmitInstToFragment(const MCInst &Inst) {
// Always create a new, separate fragment here, because its size can change
// during relaxation.
MCRelaxableFragment *IF =
new MCRelaxableFragment(Inst, getCurrentSectionData());
SmallString<128> Code;
raw_svector_ostream VecOS(Code);
getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, IF->getFixups());
VecOS.flush();
IF->getContents().append(Code.begin(), Code.end());
}
static const char *BundlingNotImplementedMsg =
"Aligned bundling is not implemented for this object format";
void MCObjectStreamer::EmitBundleAlignMode(unsigned AlignPow2) {
llvm_unreachable(BundlingNotImplementedMsg);
}
void MCObjectStreamer::EmitBundleLock(bool AlignToEnd) {
llvm_unreachable(BundlingNotImplementedMsg);
}
void MCObjectStreamer::EmitBundleUnlock() {
llvm_unreachable(BundlingNotImplementedMsg);
}
void MCObjectStreamer::EmitDwarfAdvanceLineAddr(int64_t LineDelta,
const MCSymbol *LastLabel,
const MCSymbol *Label,
unsigned PointerSize) {
if (!LastLabel) {
EmitDwarfSetLineAddr(LineDelta, Label, PointerSize);
return;
}
const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
int64_t Res;
if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
MCDwarfLineAddr::Emit(this, LineDelta, Res);
return;
}
AddrDelta = ForceExpAbs(AddrDelta);
new MCDwarfLineAddrFragment(LineDelta, *AddrDelta, getCurrentSectionData());
}
void MCObjectStreamer::EmitDwarfAdvanceFrameAddr(const MCSymbol *LastLabel,
const MCSymbol *Label) {
const MCExpr *AddrDelta = BuildSymbolDiff(getContext(), Label, LastLabel);
int64_t Res;
if (AddrDelta->EvaluateAsAbsolute(Res, getAssembler())) {
MCDwarfFrameEmitter::EmitAdvanceLoc(*this, Res);
return;
}
AddrDelta = ForceExpAbs(AddrDelta);
new MCDwarfCallFrameFragment(*AddrDelta, getCurrentSectionData());
}
void MCObjectStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
assert(AddrSpace == 0 && "Address space must be 0!");
getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
}
void MCObjectStreamer::EmitValueToAlignment(unsigned ByteAlignment,
int64_t Value,
unsigned ValueSize,
unsigned MaxBytesToEmit) {
if (MaxBytesToEmit == 0)
MaxBytesToEmit = ByteAlignment;
new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
getCurrentSectionData());
// Update the maximum alignment on the current section if necessary.
if (ByteAlignment > getCurrentSectionData()->getAlignment())
getCurrentSectionData()->setAlignment(ByteAlignment);
}
void MCObjectStreamer::EmitCodeAlignment(unsigned ByteAlignment,
unsigned MaxBytesToEmit) {
EmitValueToAlignment(ByteAlignment, 0, 1, MaxBytesToEmit);
cast<MCAlignFragment>(getCurrentFragment())->setEmitNops(true);
}
bool MCObjectStreamer::EmitValueToOffset(const MCExpr *Offset,
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unsigned char Value) {
int64_t Res;
if (Offset->EvaluateAsAbsolute(Res, getAssembler())) {
new MCOrgFragment(*Offset, Value, getCurrentSectionData());
return false;
}
MCSymbol *CurrentPos = getContext().CreateTempSymbol();
EmitLabel(CurrentPos);
MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
const MCExpr *Ref =
MCSymbolRefExpr::Create(CurrentPos, Variant, getContext());
const MCExpr *Delta =
MCBinaryExpr::Create(MCBinaryExpr::Sub, Offset, Ref, getContext());
if (!Delta->EvaluateAsAbsolute(Res, getAssembler()))
return true;
EmitFill(Res, Value);
return false;
}
// Associate GPRel32 fixup with data and resize data area
void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
MCDataFragment *DF = getOrCreateDataFragment();
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();
DF->getFixups().push_back(MCFixup::Create(DF->getContents().size(),
Value, FK_GPRel_4));
DF->getContents().resize(DF->getContents().size() + 8, 0);
}
void MCObjectStreamer::EmitFill(uint64_t NumBytes, uint8_t FillValue,
unsigned AddrSpace) {
assert(AddrSpace == 0 && "Address space must be 0!");
// FIXME: A MCFillFragment would be more memory efficient but MCExpr has
// problems evaluating expressions across multiple fragments.
getOrCreateDataFragment()->getContents().append(NumBytes, FillValue);
}
void MCObjectStreamer::FinishImpl() {
// Dump out the dwarf file & directory tables and line tables.
const MCSymbol *LineSectionSymbol = NULL;
if (getContext().hasDwarfFiles())
LineSectionSymbol = MCDwarfFileTable::Emit(this);
// If we are generating dwarf for assembly source files dump out the sections.
if (getContext().getGenDwarfForAssembly())
MCGenDwarfInfo::Emit(this, LineSectionSymbol);
getAssembler().Finish();
}