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//===--- lib/CodeGen/DwarfPrinter.cpp - Dwarf Printer ---------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Emit general DWARF directives.
//
//===----------------------------------------------------------------------===//
#include "DwarfPrinter.h"
#include "llvm/Module.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/ADT/SmallString.h"
using namespace llvm;
DwarfPrinter::DwarfPrinter(AsmPrinter *A)
: Asm(A), MAI(A->MAI), TD(Asm->TM.getTargetData()),
RI(Asm->TM.getRegisterInfo()), M(NULL), MF(NULL), MMI(NULL),
SubprogramCount(0) {}
/// SizeOfEncodedValue - Return the size of the encoding in bytes.
unsigned DwarfPrinter::SizeOfEncodedValue(unsigned Encoding) const {
if (Encoding == dwarf::DW_EH_PE_omit)
return 0;
switch (Encoding & 0x07) {
case dwarf::DW_EH_PE_absptr:
return TD->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;
}
assert(0 && "Invalid encoded value.");
return 0;
}
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 DwarfPrinter::EmitEncodingByte(unsigned Val, const char *Desc) {
if (Asm->isVerbose()) {
if (Desc != 0)
Asm->OutStreamer.AddComment(Twine(Desc)+" Encoding = " +
Twine(DecodeDWARFEncoding(Val)));
else
Asm->OutStreamer.AddComment(Twine("Encoding = ") +
DecodeDWARFEncoding(Val));
}
Asm->OutStreamer.EmitIntValue(Val, 1, 0/*addrspace*/);
}
void DwarfPrinter::EmitReference(const MCSymbol *Sym, unsigned Encoding) const {
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
const MCExpr *Exp = TLOF.getExprForDwarfReference(Sym, Asm->Mang,
Asm->MMI, Encoding,
Asm->OutStreamer);
Asm->OutStreamer.EmitValue(Exp, SizeOfEncodedValue(Encoding), /*addrspace*/0);
}
void DwarfPrinter::EmitReference(const GlobalValue *GV, unsigned Encoding)const{
const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
const MCExpr *Exp =
TLOF.getExprForDwarfGlobalReference(GV, Asm->Mang, Asm->MMI, Encoding,
Asm->OutStreamer);
Asm->OutStreamer.EmitValue(Exp, SizeOfEncodedValue(Encoding), /*addrspace*/0);
}
void DwarfPrinter::EmitSectionOffset(const MCSymbol *Label,
const MCSymbol *Section,
bool IsSmall, bool isEH) {
bool isAbsolute;
if (isEH)
isAbsolute = MAI->isAbsoluteEHSectionOffsets();
else
isAbsolute = MAI->isAbsoluteDebugSectionOffsets();
if (!isAbsolute)
return Asm->EmitLabelDifference(Label, Section,
IsSmall ? 4 : TD->getPointerSize());
// On COFF targets, we have to emit the weird .secrel32 directive.
if (const char *SecOffDir = MAI->getDwarfSectionOffsetDirective()) {
// FIXME: MCize.
Asm->OutStreamer.EmitRawText(SecOffDir + Twine(Label->getName()));
} else {
unsigned Size = IsSmall ? 4 : TD->getPointerSize();
Asm->OutStreamer.EmitSymbolValue(Label, Size, 0/*AddrSpace*/);
}
}
/// EmitFrameMoves - Emit frame instructions to describe the layout of the
/// frame.
void DwarfPrinter::EmitFrameMoves(MCSymbol *BaseLabel,
const std::vector<MachineMove> &Moves,
bool isEH) {
int stackGrowth = TD->getPointerSize();
if (Asm->TM.getFrameInfo()->getStackGrowthDirection() !=
TargetFrameInfo::StackGrowsUp)
stackGrowth *= -1;
for (unsigned i = 0, N = Moves.size(); i < N; ++i) {
const MachineMove &Move = Moves[i];
MCSymbol *Label = Move.getLabel();
// Throw out move if the label is invalid.
if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.
const MachineLocation &Dst = Move.getDestination();
const MachineLocation &Src = Move.getSource();
// Advance row if new location.
if (BaseLabel && Label) {
MCSymbol *ThisSym = Label;
if (ThisSym != BaseLabel) {
Asm->EmitCFAByte(dwarf::DW_CFA_advance_loc4);
Asm->EmitLabelDifference(ThisSym, BaseLabel, 4);
BaseLabel = ThisSym;
}
}
// If advancing cfa.
if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
if (!Src.isReg()) {
if (Src.getReg() == MachineLocation::VirtualFP) {
Asm->EmitCFAByte(dwarf::DW_CFA_def_cfa_offset);
} else {
Asm->EmitCFAByte(dwarf::DW_CFA_def_cfa);
Asm->EmitULEB128(RI->getDwarfRegNum(Src.getReg(), isEH), "Register");
}
int Offset = -Src.getOffset();
Asm->EmitULEB128(Offset, "Offset");
} else {
llvm_unreachable("Machine move not supported yet.");
}
} else if (Src.isReg() &&
Src.getReg() == MachineLocation::VirtualFP) {
if (Dst.isReg()) {
Asm->EmitCFAByte(dwarf::DW_CFA_def_cfa_register);
Asm->EmitULEB128(RI->getDwarfRegNum(Dst.getReg(), isEH), "Register");
} else {
llvm_unreachable("Machine move not supported yet.");
}
} else {
unsigned Reg = RI->getDwarfRegNum(Src.getReg(), isEH);
int Offset = Dst.getOffset() / stackGrowth;
if (Offset < 0) {
Asm->EmitCFAByte(dwarf::DW_CFA_offset_extended_sf);
Asm->EmitULEB128(Reg, "Reg");
Asm->EmitSLEB128(Offset, "Offset");
} else if (Reg < 64) {
Asm->EmitCFAByte(dwarf::DW_CFA_offset + Reg);
Asm->EmitULEB128(Offset, "Offset");
} else {
Asm->EmitCFAByte(dwarf::DW_CFA_offset_extended);
Asm->EmitULEB128(Reg, "Reg");
Asm->EmitULEB128(Offset, "Offset");
}
}
}
}
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