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llvm-project/llvm/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp

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//===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements the Dwarf emissions parts of AsmPrinter.
//
//===----------------------------------------------------------------------===//
#include "ByteStreamer.h"
#include "llvm/ADT/Twine.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/DIE.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCDwarf.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MachineLocation.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include <cstdint>
using namespace llvm;
#define DEBUG_TYPE "asm-printer"
//===----------------------------------------------------------------------===//
// Dwarf Emission Helper Routines
//===----------------------------------------------------------------------===//
/// EmitSLEB128 - emit the specified signed leb128 value.
void AsmPrinter::emitSLEB128(int64_t Value, const char *Desc) const {
if (isVerbose() && Desc)
OutStreamer->AddComment(Desc);
OutStreamer->emitSLEB128IntValue(Value);
}
void AsmPrinter::emitULEB128(uint64_t Value, const char *Desc,
unsigned PadTo) const {
if (isVerbose() && Desc)
OutStreamer->AddComment(Desc);
OutStreamer->emitULEB128IntValue(Value, PadTo);
}
/// Emit something like ".uleb128 Hi-Lo".
void AsmPrinter::emitLabelDifferenceAsULEB128(const MCSymbol *Hi,
const MCSymbol *Lo) const {
OutStreamer->emitAbsoluteSymbolDiffAsULEB128(Hi, Lo);
}
static const char *DecodeDWARFEncoding(unsigned Encoding) {
switch (Encoding) {
case dwarf::DW_EH_PE_absptr:
return "absptr";
case dwarf::DW_EH_PE_omit:
return "omit";
case dwarf::DW_EH_PE_pcrel:
return "pcrel";
case dwarf::DW_EH_PE_uleb128:
return "uleb128";
case dwarf::DW_EH_PE_sleb128:
return "sleb128";
case dwarf::DW_EH_PE_udata4:
return "udata4";
case dwarf::DW_EH_PE_udata8:
return "udata8";
case dwarf::DW_EH_PE_sdata4:
return "sdata4";
case dwarf::DW_EH_PE_sdata8:
return "sdata8";
case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
return "pcrel udata4";
case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
return "pcrel sdata4";
case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
return "pcrel udata8";
case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
return "pcrel sdata8";
case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4
:
return "indirect pcrel udata4";
case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
:
return "indirect pcrel sdata4";
case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
:
return "indirect pcrel udata8";
case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
:
return "indirect pcrel sdata8";
case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_datarel |
dwarf::DW_EH_PE_sdata4:
return "indirect datarel sdata4";
case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_datarel |
dwarf::DW_EH_PE_sdata8:
return "indirect datarel sdata8";
}
return "<unknown encoding>";
}
/// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
/// encoding. If verbose assembly output is enabled, we output comments
/// describing the encoding. Desc is an optional string saying what the
/// encoding is specifying (e.g. "LSDA").
void AsmPrinter::emitEncodingByte(unsigned Val, const char *Desc) const {
if (isVerbose()) {
if (Desc)
OutStreamer->AddComment(Twine(Desc) + " Encoding = " +
Twine(DecodeDWARFEncoding(Val)));
else
OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
}
OutStreamer->emitIntValue(Val, 1);
}
/// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
if (Encoding == dwarf::DW_EH_PE_omit)
return 0;
switch (Encoding & 0x07) {
default:
llvm_unreachable("Invalid encoded value.");
case dwarf::DW_EH_PE_absptr:
return MF->getDataLayout().getPointerSize();
case dwarf::DW_EH_PE_udata2:
return 2;
case dwarf::DW_EH_PE_udata4:
return 4;
case dwarf::DW_EH_PE_udata8:
return 8;
}
}
void AsmPrinter::emitTTypeReference(const GlobalValue *GV, unsigned Encoding) {
if (GV) {
const TargetLoweringObjectFile &TLOF = getObjFileLowering();
const MCExpr *Exp =
TLOF.getTTypeGlobalReference(GV, Encoding, TM, MMI, *OutStreamer);
OutStreamer->emitValue(Exp, GetSizeOfEncodedValue(Encoding));
} else
OutStreamer->emitIntValue(0, GetSizeOfEncodedValue(Encoding));
}
void AsmPrinter::emitDwarfSymbolReference(const MCSymbol *Label,
bool ForceOffset) const {
if (!ForceOffset) {
// On COFF targets, we have to emit the special .secrel32 directive.
if (MAI->needsDwarfSectionOffsetDirective()) {
assert(!isDwarf64() &&
"emitting DWARF64 is not implemented for COFF targets");
OutStreamer->EmitCOFFSecRel32(Label, /*Offset=*/0);
return;
}
// If the format uses relocations with dwarf, refer to the symbol directly.
if (MAI->doesDwarfUseRelocationsAcrossSections()) {
OutStreamer->emitSymbolValue(Label, getDwarfOffsetByteSize());
return;
}
}
// Otherwise, emit it as a label difference from the start of the section.
emitLabelDifference(Label, Label->getSection().getBeginSymbol(),
getDwarfOffsetByteSize());
}
void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntry S) const {
if (MAI->doesDwarfUseRelocationsAcrossSections()) {
assert(S.Symbol && "No symbol available");
emitDwarfSymbolReference(S.Symbol);
return;
}
// Just emit the offset directly; no need for symbol math.
OutStreamer->emitIntValue(S.Offset, getDwarfOffsetByteSize());
}
void AsmPrinter::emitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const {
emitLabelPlusOffset(Label, Offset, getDwarfOffsetByteSize());
}
void AsmPrinter::emitDwarfLengthOrOffset(uint64_t Value) const {
assert(isDwarf64() || Value <= UINT32_MAX);
OutStreamer->emitIntValue(Value, getDwarfOffsetByteSize());
}
void AsmPrinter::emitDwarfUnitLength(uint64_t Length,
const Twine &Comment) const {
OutStreamer->emitDwarfUnitLength(Length, Comment);
}
MCSymbol *AsmPrinter::emitDwarfUnitLength(const Twine &Prefix,
const Twine &Comment) const {
return OutStreamer->emitDwarfUnitLength(Prefix, Comment);
}
void AsmPrinter::emitCallSiteOffset(const MCSymbol *Hi, const MCSymbol *Lo,
unsigned Encoding) const {
// The least significant 3 bits specify the width of the encoding
if ((Encoding & 0x7) == dwarf::DW_EH_PE_uleb128)
emitLabelDifferenceAsULEB128(Hi, Lo);
else
emitLabelDifference(Hi, Lo, GetSizeOfEncodedValue(Encoding));
}
void AsmPrinter::emitCallSiteValue(uint64_t Value, unsigned Encoding) const {
// The least significant 3 bits specify the width of the encoding
if ((Encoding & 0x7) == dwarf::DW_EH_PE_uleb128)
emitULEB128(Value);
else
OutStreamer->emitIntValue(Value, GetSizeOfEncodedValue(Encoding));
}
//===----------------------------------------------------------------------===//
// Dwarf Lowering Routines
//===----------------------------------------------------------------------===//
void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
switch (Inst.getOperation()) {
default:
llvm_unreachable("Unexpected instruction");
case MCCFIInstruction::OpDefCfaOffset:
OutStreamer->emitCFIDefCfaOffset(Inst.getOffset());
break;
case MCCFIInstruction::OpAdjustCfaOffset:
OutStreamer->emitCFIAdjustCfaOffset(Inst.getOffset());
break;
case MCCFIInstruction::OpDefCfa:
OutStreamer->emitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
break;
case MCCFIInstruction::OpDefCfaRegister:
OutStreamer->emitCFIDefCfaRegister(Inst.getRegister());
break;
case MCCFIInstruction::OpLLVMDefAspaceCfa:
OutStreamer->emitCFILLVMDefAspaceCfa(Inst.getRegister(), Inst.getOffset(),
Inst.getAddressSpace());
break;
case MCCFIInstruction::OpOffset:
OutStreamer->emitCFIOffset(Inst.getRegister(), Inst.getOffset());
break;
case MCCFIInstruction::OpRegister:
OutStreamer->emitCFIRegister(Inst.getRegister(), Inst.getRegister2());
break;
case MCCFIInstruction::OpWindowSave:
OutStreamer->emitCFIWindowSave();
break;
case MCCFIInstruction::OpNegateRAState:
OutStreamer->emitCFINegateRAState();
break;
case MCCFIInstruction::OpSameValue:
OutStreamer->emitCFISameValue(Inst.getRegister());
break;
case MCCFIInstruction::OpGnuArgsSize:
OutStreamer->emitCFIGnuArgsSize(Inst.getOffset());
break;
case MCCFIInstruction::OpEscape:
OutStreamer->AddComment(Inst.getComment());
OutStreamer->emitCFIEscape(Inst.getValues());
break;
case MCCFIInstruction::OpRestore:
OutStreamer->emitCFIRestore(Inst.getRegister());
break;
case MCCFIInstruction::OpUndefined:
OutStreamer->emitCFIUndefined(Inst.getRegister());
break;
}
}
void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
// Emit the code (index) for the abbreviation.
if (isVerbose())
OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
Twine::utohexstr(Die.getOffset()) + ":0x" +
Twine::utohexstr(Die.getSize()) + " " +
dwarf::TagString(Die.getTag()));
emitULEB128(Die.getAbbrevNumber());
// Emit the DIE attribute values.
for (const auto &V : Die.values()) {
dwarf::Attribute Attr = V.getAttribute();
assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");
if (isVerbose()) {
OutStreamer->AddComment(dwarf::AttributeString(Attr));
if (Attr == dwarf::DW_AT_accessibility)
OutStreamer->AddComment(
dwarf::AccessibilityString(V.getDIEInteger().getValue()));
}
// Emit an attribute using the defined form.
V.emitValue(this);
}
// Emit the DIE children if any.
if (Die.hasChildren()) {
for (auto &Child : Die.children())
emitDwarfDIE(Child);
OutStreamer->AddComment("End Of Children Mark");
emitInt8(0);
}
}
void AsmPrinter::emitDwarfAbbrev(const DIEAbbrev &Abbrev) const {
// Emit the abbreviations code (base 1 index.)
emitULEB128(Abbrev.getNumber(), "Abbreviation Code");
// Emit the abbreviations data.
Abbrev.Emit(this);
}
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