contrib/llvm/lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp

   1 //===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the Dwarf emissions parts of AsmPrinter.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "ByteStreamer.h"
  15 #include "DwarfDebug.h"
  16 #include "DwarfExpression.h"
  17 #include "llvm/ADT/Twine.h"
  18 #include "llvm/BinaryFormat/Dwarf.h"
  19 #include "llvm/CodeGen/AsmPrinter.h"
  20 #include "llvm/CodeGen/DIE.h"
  21 #include "llvm/CodeGen/MachineFunction.h"
  22 #include "llvm/CodeGen/MachineModuleInfo.h"
  23 #include "llvm/IR/DataLayout.h"
  24 #include "llvm/MC/MCAsmInfo.h"
  25 #include "llvm/MC/MCRegisterInfo.h"
  26 #include "llvm/MC/MCSection.h"
  27 #include "llvm/MC/MCStreamer.h"
  28 #include "llvm/MC/MCSymbol.h"
  29 #include "llvm/MC/MachineLocation.h"
  30 #include "llvm/Support/ErrorHandling.h"
  31 #include "llvm/Target/TargetLoweringObjectFile.h"
  32 #include "llvm/Target/TargetMachine.h"
  33 #include "llvm/Target/TargetSubtargetInfo.h"
  34 using namespace llvm;
  35
  36 #define DEBUG_TYPE "asm-printer"
  37
  38 //===----------------------------------------------------------------------===//
  39 // Dwarf Emission Helper Routines
  40 //===----------------------------------------------------------------------===//
  41
  42 /// EmitSLEB128 - emit the specified signed leb128 value.
  43 void AsmPrinter::EmitSLEB128(int64_t Value, const char *Desc) const {
  44   if (isVerbose() && Desc)
  45     OutStreamer->AddComment(Desc);
  46
  47   OutStreamer->EmitSLEB128IntValue(Value);
  48 }
  49
  50 /// EmitULEB128 - emit the specified unsigned leb128 value.
  51 void AsmPrinter::EmitULEB128(uint64_t Value, const char *Desc,
  52                              unsigned PadTo) const {
  53   if (isVerbose() && Desc)
  54     OutStreamer->AddComment(Desc);
  55
  56   OutStreamer->EmitULEB128IntValue(Value, PadTo);
  57 }
  58
  59 static const char *DecodeDWARFEncoding(unsigned Encoding) {
  60   switch (Encoding) {
  61   case dwarf::DW_EH_PE_absptr:
  62     return "absptr";
  63   case dwarf::DW_EH_PE_omit:
  64     return "omit";
  65   case dwarf::DW_EH_PE_pcrel:
  66     return "pcrel";
  67   case dwarf::DW_EH_PE_udata4:
  68     return "udata4";
  69   case dwarf::DW_EH_PE_udata8:
  70     return "udata8";
  71   case dwarf::DW_EH_PE_sdata4:
  72     return "sdata4";
  73   case dwarf::DW_EH_PE_sdata8:
  74     return "sdata8";
  75   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
  76     return "pcrel udata4";
  77   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
  78     return "pcrel sdata4";
  79   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
  80     return "pcrel udata8";
  81   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
  82     return "pcrel sdata8";
  83   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4
  84       :
  85     return "indirect pcrel udata4";
  86   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
  87       :
  88     return "indirect pcrel sdata4";
  89   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
  90       :
  91     return "indirect pcrel udata8";
  92   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
  93       :
  94     return "indirect pcrel sdata8";
  95   }
  96
  97   return "<unknown encoding>";
  98 }
  99
 100 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
 101 /// encoding.  If verbose assembly output is enabled, we output comments
 102 /// describing the encoding.  Desc is an optional string saying what the
 103 /// encoding is specifying (e.g. "LSDA").
 104 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
 105   if (isVerbose()) {
 106     if (Desc)
 107       OutStreamer->AddComment(Twine(Desc) + " Encoding = " +
 108                               Twine(DecodeDWARFEncoding(Val)));
 109     else
 110       OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
 111   }
 112
 113   OutStreamer->EmitIntValue(Val, 1);
 114 }
 115
 116 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
 117 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
 118   if (Encoding == dwarf::DW_EH_PE_omit)
 119     return 0;
 120
 121   switch (Encoding & 0x07) {
 122   default:
 123     llvm_unreachable("Invalid encoded value.");
 124   case dwarf::DW_EH_PE_absptr:
 125     return MF->getDataLayout().getPointerSize();
 126   case dwarf::DW_EH_PE_udata2:
 127     return 2;
 128   case dwarf::DW_EH_PE_udata4:
 129     return 4;
 130   case dwarf::DW_EH_PE_udata8:
 131     return 8;
 132   }
 133 }
 134
 135 void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
 136                                     unsigned Encoding) const {
 137   if (GV) {
 138     const TargetLoweringObjectFile &TLOF = getObjFileLowering();
 139
 140     const MCExpr *Exp =
 141         TLOF.getTTypeGlobalReference(GV, Encoding, TM, MMI, *OutStreamer);
 142     OutStreamer->EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
 143   } else
 144     OutStreamer->EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
 145 }
 146
 147 void AsmPrinter::emitDwarfSymbolReference(const MCSymbol *Label,
 148                                           bool ForceOffset) const {
 149   if (!ForceOffset) {
 150     // On COFF targets, we have to emit the special .secrel32 directive.
 151     if (MAI->needsDwarfSectionOffsetDirective()) {
 152       OutStreamer->EmitCOFFSecRel32(Label, /*Offset=*/0);
 153       return;
 154     }
 155
 156     // If the format uses relocations with dwarf, refer to the symbol directly.
 157     if (MAI->doesDwarfUseRelocationsAcrossSections()) {
 158       OutStreamer->EmitSymbolValue(Label, 4);
 159       return;
 160     }
 161   }
 162
 163   // Otherwise, emit it as a label difference from the start of the section.
 164   EmitLabelDifference(Label, Label->getSection().getBeginSymbol(), 4);
 165 }
 166
 167 void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntryRef S) const {
 168   if (MAI->doesDwarfUseRelocationsAcrossSections()) {
 169     emitDwarfSymbolReference(S.getSymbol());
 170     return;
 171   }
 172
 173   // Just emit the offset directly; no need for symbol math.
 174   EmitInt32(S.getOffset());
 175 }
 176
 177 //===----------------------------------------------------------------------===//
 178 // Dwarf Lowering Routines
 179 //===----------------------------------------------------------------------===//
 180
 181 void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
 182   switch (Inst.getOperation()) {
 183   default:
 184     llvm_unreachable("Unexpected instruction");
 185   case MCCFIInstruction::OpDefCfaOffset:
 186     OutStreamer->EmitCFIDefCfaOffset(Inst.getOffset());
 187     break;
 188   case MCCFIInstruction::OpAdjustCfaOffset:
 189     OutStreamer->EmitCFIAdjustCfaOffset(Inst.getOffset());
 190     break;
 191   case MCCFIInstruction::OpDefCfa:
 192     OutStreamer->EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
 193     break;
 194   case MCCFIInstruction::OpDefCfaRegister:
 195     OutStreamer->EmitCFIDefCfaRegister(Inst.getRegister());
 196     break;
 197   case MCCFIInstruction::OpOffset:
 198     OutStreamer->EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
 199     break;
 200   case MCCFIInstruction::OpRegister:
 201     OutStreamer->EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
 202     break;
 203   case MCCFIInstruction::OpWindowSave:
 204     OutStreamer->EmitCFIWindowSave();
 205     break;
 206   case MCCFIInstruction::OpSameValue:
 207     OutStreamer->EmitCFISameValue(Inst.getRegister());
 208     break;
 209   case MCCFIInstruction::OpGnuArgsSize:
 210     OutStreamer->EmitCFIGnuArgsSize(Inst.getOffset());
 211     break;
 212   case MCCFIInstruction::OpEscape:
 213     OutStreamer->EmitCFIEscape(Inst.getValues());
 214     break;
 215   }
 216 }
 217
 218 void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
 219   // Emit the code (index) for the abbreviation.
 220   if (isVerbose())
 221     OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
 222                             Twine::utohexstr(Die.getOffset()) + ":0x" +
 223                             Twine::utohexstr(Die.getSize()) + " " +
 224                             dwarf::TagString(Die.getTag()));
 225   EmitULEB128(Die.getAbbrevNumber());
 226
 227   // Emit the DIE attribute values.
 228   for (const auto &V : Die.values()) {
 229     dwarf::Attribute Attr = V.getAttribute();
 230     assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");
 231
 232     if (isVerbose()) {
 233       OutStreamer->AddComment(dwarf::AttributeString(Attr));
 234       if (Attr == dwarf::DW_AT_accessibility)
 235         OutStreamer->AddComment(
 236             dwarf::AccessibilityString(V.getDIEInteger().getValue()));
 237     }
 238
 239     // Emit an attribute using the defined form.
 240     V.EmitValue(this);
 241   }
 242
 243   // Emit the DIE children if any.
 244   if (Die.hasChildren()) {
 245     for (auto &Child : Die.children())
 246       emitDwarfDIE(Child);
 247
 248     OutStreamer->AddComment("End Of Children Mark");
 249     EmitInt8(0);
 250   }
 251 }
 252
 253 void AsmPrinter::emitDwarfAbbrev(const DIEAbbrev &Abbrev) const {
 254   // Emit the abbreviations code (base 1 index.)
 255   EmitULEB128(Abbrev.getNumber(), "Abbreviation Code");
 256
 257   // Emit the abbreviations data.
 258   Abbrev.Emit(this);
 259 }