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

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//===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Dwarf emissions parts of AsmPrinter.
//
//===----------------------------------------------------------------------===//
#include "ByteStreamer.h"
#include "DwarfDebug.h"
#include "DwarfExpression.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/MC/MCAsmInfo.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/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetSubtargetInfo.h"
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);
}
/// EmitULEB128 - emit the specified signed leb128 value.
void AsmPrinter::EmitULEB128(uint64_t Value, const char *Desc,
unsigned PadTo) const {
if (isVerbose() && Desc)
OutStreamer.AddComment(Desc);
OutStreamer.EmitULEB128IntValue(Value, PadTo);
}
/// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
void AsmPrinter::EmitCFAByte(unsigned Val) const {
if (isVerbose()) {
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if (Val >= dwarf::DW_CFA_offset && Val < dwarf::DW_CFA_offset + 64)
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OutStreamer.AddComment("DW_CFA_offset + Reg (" +
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Twine(Val - dwarf::DW_CFA_offset) + ")");
else
OutStreamer.AddComment(dwarf::CallFrameString(Val));
}
OutStreamer.EmitIntValue(Val, 1);
}
static const char *DecodeDWARFEncoding(unsigned Encoding) {
switch (Encoding) {
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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_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";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
:
return "indirect pcrel sdata4";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
:
return "indirect pcrel udata8";
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case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
:
return "indirect pcrel sdata8";
}
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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()) {
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if (Desc)
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OutStreamer.AddComment(Twine(Desc) + " Encoding = " +
Twine(DecodeDWARFEncoding(Val)));
else
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OutStreamer.AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
}
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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;
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switch (Encoding & 0x07) {
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default:
llvm_unreachable("Invalid encoded value.");
case dwarf::DW_EH_PE_absptr:
return TM.getDataLayout()->getPointerSize();
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case dwarf::DW_EH_PE_udata2:
return 2;
case dwarf::DW_EH_PE_udata4:
return 4;
case dwarf::DW_EH_PE_udata8:
return 8;
}
}
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void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
unsigned Encoding) const {
if (GV) {
const TargetLoweringObjectFile &TLOF = getObjFileLowering();
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const MCExpr *Exp =
TLOF.getTTypeGlobalReference(GV, Encoding, *Mang, TM, MMI, OutStreamer);
OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
} else
OutStreamer.EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
}
/// EmitSectionOffset - Emit the 4-byte offset of Label from the start of its
/// section. This can be done with a special directive if the target supports
/// it (e.g. cygwin) or by emitting it as an offset from a label at the start
/// of the section.
///
/// SectionLabel is a temporary label emitted at the start of the section that
/// Label lives in.
void AsmPrinter::EmitSectionOffset(const MCSymbol *Label,
const MCSymbol *SectionLabel) const {
// On COFF targets, we have to emit the special .secrel32 directive.
if (MAI->needsDwarfSectionOffsetDirective()) {
OutStreamer.EmitCOFFSecRel32(Label);
return;
}
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// Get the section that we're referring to, based on SectionLabel.
const MCSection &Section = SectionLabel->getSection();
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// If Label has already been emitted, verify that it is in the same section as
// section label for sanity.
assert((!Label->isInSection() || &Label->getSection() == &Section) &&
"Section offset using wrong section base for label");
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// If the section in question will end up with an address of 0 anyway, we can
// just emit an absolute reference to save a relocation.
if (Section.isBaseAddressKnownZero()) {
OutStreamer.EmitSymbolValue(Label, 4);
return;
}
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// Otherwise, emit it as a label difference from the start of the section.
EmitLabelDifference(Label, SectionLabel, 4);
}
/// EmitDwarfRegOp - Emit dwarf register operation.
void AsmPrinter::EmitDwarfRegOp(ByteStreamer &Streamer,
const MachineLocation &MLoc) const {
DebugLocDwarfExpression Expr(*TM.getSubtargetImpl()->getRegisterInfo(),
getDwarfDebug()->getDwarfVersion(), Streamer);
const MCRegisterInfo *MRI = MMI->getContext().getRegisterInfo();
int Reg = MRI->getDwarfRegNum(MLoc.getReg(), false);
if (Reg < 0) {
// We assume that pointers are always in an addressable register.
if (MLoc.isIndirect())
// FIXME: We have no reasonable way of handling errors in here. The
// caller might be in the middle of a dwarf expression. We should
// probably assert that Reg >= 0 once debug info generation is more
// mature.
return Expr.EmitOp(dwarf::DW_OP_nop,
"nop (could not find a dwarf register number)");
// Attempt to find a valid super- or sub-register.
if (!Expr.AddMachineRegPiece(MLoc.getReg()))
Expr.EmitOp(dwarf::DW_OP_nop,
"nop (could not find a dwarf register number)");
return;
}
if (MLoc.isIndirect())
Expr.AddRegIndirect(Reg, MLoc.getOffset());
else
Expr.AddReg(Reg);
}
//===----------------------------------------------------------------------===//
// 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::OpDefCfa:
OutStreamer.EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
break;
case MCCFIInstruction::OpDefCfaRegister:
OutStreamer.EmitCFIDefCfaRegister(Inst.getRegister());
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::OpSameValue:
OutStreamer.EmitCFISameValue(Inst.getRegister());
break;
}
}