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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.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "asm-printer"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/MC/MachineLocation.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/DataLayout.h"
#include "llvm/Target/TargetFrameLowering.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// Dwarf Emission Helper Routines
//===----------------------------------------------------------------------===//
/// EmitSLEB128 - emit the specified signed leb128 value.
void AsmPrinter::EmitSLEB128(int Value, const char *Desc) const {
if (isVerbose() && Desc)
OutStreamer.AddComment(Desc);
OutStreamer.EmitSLEB128IntValue(Value);
}
/// EmitULEB128 - emit the specified signed leb128 value.
void AsmPrinter::EmitULEB128(unsigned Value, const char *Desc,
unsigned PadTo) const {
if (isVerbose() && Desc)
OutStreamer.AddComment(Desc);
OutStreamer.EmitULEB128IntValue(Value, 0/*addrspace*/, PadTo);
}
/// EmitCFAByte - Emit a .byte 42 directive for a DW_CFA_xxx value.
void AsmPrinter::EmitCFAByte(unsigned Val) const {
if (isVerbose()) {
if (Val >= dwarf::DW_CFA_offset && Val < dwarf::DW_CFA_offset+64)
OutStreamer.AddComment("DW_CFA_offset + Reg (" +
Twine(Val-dwarf::DW_CFA_offset) + ")");
else
OutStreamer.AddComment(dwarf::CallFrameString(Val));
}
OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
}
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_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";
}
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 != 0)
OutStreamer.AddComment(Twine(Desc)+" Encoding = " +
Twine(DecodeDWARFEncoding(Val)));
else
OutStreamer.AddComment(Twine("Encoding = ") +
DecodeDWARFEncoding(Val));
}
OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
}
/// 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 TM.getDataLayout()->getPointerSize(0);
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::EmitReference(const MCSymbol *Sym, unsigned Encoding) const {
const TargetLoweringObjectFile &TLOF = getObjFileLowering();
const MCExpr *Exp =
TLOF.getExprForDwarfReference(Sym, Encoding, OutStreamer);
OutStreamer.EmitAbsValue(Exp, GetSizeOfEncodedValue(Encoding));
}
void AsmPrinter::EmitReference(const GlobalValue *GV, unsigned Encoding)const{
const TargetLoweringObjectFile &TLOF = getObjFileLowering();
const MCExpr *Exp =
TLOF.getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, OutStreamer);
OutStreamer.EmitValue(Exp, GetSizeOfEncodedValue(Encoding), /*addrspace*/0);
}
/// 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->getDwarfSectionOffsetDirective()) {
OutStreamer.EmitCOFFSecRel32(Label);
return;
}
// Get the section that we're referring to, based on SectionLabel.
const MCSection &Section = SectionLabel->getSection();
// 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");
// 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, 0/*AddrSpace*/);
return;
}
// Otherwise, emit it as a label difference from the start of the section.
EmitLabelDifference(Label, SectionLabel, 4);
}
//===----------------------------------------------------------------------===//
// Dwarf Lowering Routines
//===----------------------------------------------------------------------===//
/// EmitCFIFrameMove - Emit a frame instruction.
void AsmPrinter::EmitCFIFrameMove(const MachineMove &Move) const {
const TargetRegisterInfo *RI = TM.getRegisterInfo();
const MachineLocation &Dst = Move.getDestination();
const MachineLocation &Src = Move.getSource();
// If advancing cfa.
if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
if (Src.getReg() == MachineLocation::VirtualFP) {
OutStreamer.EmitCFIDefCfaOffset(-Src.getOffset());
} else {
// Reg + Offset
OutStreamer.EmitCFIDefCfa(RI->getDwarfRegNum(Src.getReg(), true),
Src.getOffset());
}
} else if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
assert(Dst.isReg() && "Machine move not supported yet.");
OutStreamer.EmitCFIDefCfaRegister(RI->getDwarfRegNum(Dst.getReg(), true));
} else {
assert(!Dst.isReg() && "Machine move not supported yet.");
OutStreamer.EmitCFIOffset(RI->getDwarfRegNum(Src.getReg(), true),
Dst.getOffset());
}
}
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