lib/CodeGen/AsmPrinter/AsmPrinterDwarf.cpp

   1 //===-- AsmPrinterDwarf.cpp - AsmPrinter Dwarf Support --------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file implements the Dwarf emissions parts of AsmPrinter.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "ByteStreamer.h"
  14 #include "llvm/ADT/Twine.h"
  15 #include "llvm/BinaryFormat/Dwarf.h"
  16 #include "llvm/CodeGen/AsmPrinter.h"
  17 #include "llvm/CodeGen/DIE.h"
  18 #include "llvm/CodeGen/MachineFunction.h"
  19 #include "llvm/IR/DataLayout.h"
  20 #include "llvm/MC/MCAsmInfo.h"
  21 #include "llvm/MC/MCRegisterInfo.h"
  22 #include "llvm/MC/MCSection.h"
  23 #include "llvm/MC/MCStreamer.h"
  24 #include "llvm/MC/MCSymbol.h"
  25 #include "llvm/MC/MachineLocation.h"
  26 #include "llvm/Support/ErrorHandling.h"
  27 #include "llvm/Target/TargetLoweringObjectFile.h"
  28 #include "llvm/Target/TargetMachine.h"
  29 using namespace llvm;
  30
  31 #define DEBUG_TYPE "asm-printer"
  32
  33 //===----------------------------------------------------------------------===//
  34 // Dwarf Emission Helper Routines
  35 //===----------------------------------------------------------------------===//
  36
  37 /// EmitSLEB128 - emit the specified signed leb128 value.
  38 void AsmPrinter::EmitSLEB128(int64_t Value, const char *Desc) const {
  39   if (isVerbose() && Desc)
  40     OutStreamer->AddComment(Desc);
  41
  42   OutStreamer->EmitSLEB128IntValue(Value);
  43 }
  44
  45 void AsmPrinter::EmitULEB128(uint64_t Value, const char *Desc) const {
  46   if (isVerbose() && Desc)
  47     OutStreamer->AddComment(Desc);
  48
  49   OutStreamer->EmitULEB128IntValue(Value);
  50 }
  51
  52 /// Emit something like ".uleb128 Hi-Lo".
  53 void AsmPrinter::EmitLabelDifferenceAsULEB128(const MCSymbol *Hi,
  54                                               const MCSymbol *Lo) const {
  55   OutStreamer->emitAbsoluteSymbolDiffAsULEB128(Hi, Lo);
  56 }
  57
  58 static const char *DecodeDWARFEncoding(unsigned Encoding) {
  59   switch (Encoding) {
  60   case dwarf::DW_EH_PE_absptr:
  61     return "absptr";
  62   case dwarf::DW_EH_PE_omit:
  63     return "omit";
  64   case dwarf::DW_EH_PE_pcrel:
  65     return "pcrel";
  66   case dwarf::DW_EH_PE_uleb128:
  67     return "uleb128";
  68   case dwarf::DW_EH_PE_sleb128:
  69     return "sleb128";
  70   case dwarf::DW_EH_PE_udata4:
  71     return "udata4";
  72   case dwarf::DW_EH_PE_udata8:
  73     return "udata8";
  74   case dwarf::DW_EH_PE_sdata4:
  75     return "sdata4";
  76   case dwarf::DW_EH_PE_sdata8:
  77     return "sdata8";
  78   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
  79     return "pcrel udata4";
  80   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
  81     return "pcrel sdata4";
  82   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
  83     return "pcrel udata8";
  84   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
  85     return "pcrel sdata8";
  86   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4
  87       :
  88     return "indirect pcrel udata4";
  89   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
  90       :
  91     return "indirect pcrel sdata4";
  92   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
  93       :
  94     return "indirect pcrel udata8";
  95   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
  96       :
  97     return "indirect pcrel sdata8";
  98   }
  99
 100   return "<unknown encoding>";
 101 }
 102
 103 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
 104 /// encoding.  If verbose assembly output is enabled, we output comments
 105 /// describing the encoding.  Desc is an optional string saying what the
 106 /// encoding is specifying (e.g. "LSDA").
 107 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
 108   if (isVerbose()) {
 109     if (Desc)
 110       OutStreamer->AddComment(Twine(Desc) + " Encoding = " +
 111                               Twine(DecodeDWARFEncoding(Val)));
 112     else
 113       OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
 114   }
 115
 116   OutStreamer->EmitIntValue(Val, 1);
 117 }
 118
 119 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
 120 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
 121   if (Encoding == dwarf::DW_EH_PE_omit)
 122     return 0;
 123
 124   switch (Encoding & 0x07) {
 125   default:
 126     llvm_unreachable("Invalid encoded value.");
 127   case dwarf::DW_EH_PE_absptr:
 128     return MF->getDataLayout().getPointerSize();
 129   case dwarf::DW_EH_PE_udata2:
 130     return 2;
 131   case dwarf::DW_EH_PE_udata4:
 132     return 4;
 133   case dwarf::DW_EH_PE_udata8:
 134     return 8;
 135   }
 136 }
 137
 138 void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
 139                                     unsigned Encoding) const {
 140   if (GV) {
 141     const TargetLoweringObjectFile &TLOF = getObjFileLowering();
 142
 143     const MCExpr *Exp =
 144         TLOF.getTTypeGlobalReference(GV, Encoding, TM, MMI, *OutStreamer);
 145     OutStreamer->EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
 146   } else
 147     OutStreamer->EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
 148 }
 149
 150 void AsmPrinter::emitDwarfSymbolReference(const MCSymbol *Label,
 151                                           bool ForceOffset) const {
 152   if (!ForceOffset) {
 153     // On COFF targets, we have to emit the special .secrel32 directive.
 154     if (MAI->needsDwarfSectionOffsetDirective()) {
 155       OutStreamer->EmitCOFFSecRel32(Label, /*Offset=*/0);
 156       return;
 157     }
 158
 159     // If the format uses relocations with dwarf, refer to the symbol directly.
 160     if (MAI->doesDwarfUseRelocationsAcrossSections()) {
 161       OutStreamer->EmitSymbolValue(Label, 4);
 162       return;
 163     }
 164   }
 165
 166   // Otherwise, emit it as a label difference from the start of the section.
 167   EmitLabelDifference(Label, Label->getSection().getBeginSymbol(), 4);
 168 }
 169
 170 void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntry S) const {
 171   if (MAI->doesDwarfUseRelocationsAcrossSections()) {
 172     assert(S.Symbol && "No symbol available");
 173     emitDwarfSymbolReference(S.Symbol);
 174     return;
 175   }
 176
 177   // Just emit the offset directly; no need for symbol math.
 178   emitInt32(S.Offset);
 179 }
 180
 181 void AsmPrinter::EmitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const {
 182   EmitLabelPlusOffset(Label, Offset, MAI->getCodePointerSize());
 183 }
 184
 185 //===----------------------------------------------------------------------===//
 186 // Dwarf Lowering Routines
 187 //===----------------------------------------------------------------------===//
 188
 189 void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
 190   switch (Inst.getOperation()) {
 191   default:
 192     llvm_unreachable("Unexpected instruction");
 193   case MCCFIInstruction::OpDefCfaOffset:
 194     OutStreamer->EmitCFIDefCfaOffset(Inst.getOffset());
 195     break;
 196   case MCCFIInstruction::OpAdjustCfaOffset:
 197     OutStreamer->EmitCFIAdjustCfaOffset(Inst.getOffset());
 198     break;
 199   case MCCFIInstruction::OpDefCfa:
 200     OutStreamer->EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
 201     break;
 202   case MCCFIInstruction::OpDefCfaRegister:
 203     OutStreamer->EmitCFIDefCfaRegister(Inst.getRegister());
 204     break;
 205   case MCCFIInstruction::OpOffset:
 206     OutStreamer->EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
 207     break;
 208   case MCCFIInstruction::OpRegister:
 209     OutStreamer->EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
 210     break;
 211   case MCCFIInstruction::OpWindowSave:
 212     OutStreamer->EmitCFIWindowSave();
 213     break;
 214   case MCCFIInstruction::OpNegateRAState:
 215     OutStreamer->EmitCFINegateRAState();
 216     break;
 217   case MCCFIInstruction::OpSameValue:
 218     OutStreamer->EmitCFISameValue(Inst.getRegister());
 219     break;
 220   case MCCFIInstruction::OpGnuArgsSize:
 221     OutStreamer->EmitCFIGnuArgsSize(Inst.getOffset());
 222     break;
 223   case MCCFIInstruction::OpEscape:
 224     OutStreamer->EmitCFIEscape(Inst.getValues());
 225     break;
 226   case MCCFIInstruction::OpRestore:
 227     OutStreamer->EmitCFIRestore(Inst.getRegister());
 228     break;
 229   }
 230 }
 231
 232 void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
 233   // Emit the code (index) for the abbreviation.
 234   if (isVerbose())
 235     OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
 236                             Twine::utohexstr(Die.getOffset()) + ":0x" +
 237                             Twine::utohexstr(Die.getSize()) + " " +
 238                             dwarf::TagString(Die.getTag()));
 239   EmitULEB128(Die.getAbbrevNumber());
 240
 241   // Emit the DIE attribute values.
 242   for (const auto &V : Die.values()) {
 243     dwarf::Attribute Attr = V.getAttribute();
 244     assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");
 245
 246     if (isVerbose()) {
 247       OutStreamer->AddComment(dwarf::AttributeString(Attr));
 248       if (Attr == dwarf::DW_AT_accessibility)
 249         OutStreamer->AddComment(
 250             dwarf::AccessibilityString(V.getDIEInteger().getValue()));
 251     }
 252
 253     // Emit an attribute using the defined form.
 254     V.EmitValue(this);
 255   }
 256
 257   // Emit the DIE children if any.
 258   if (Die.hasChildren()) {
 259     for (auto &Child : Die.children())
 260       emitDwarfDIE(Child);
 261
 262     OutStreamer->AddComment("End Of Children Mark");
 263     emitInt8(0);
 264   }
 265 }
 266
 267 void AsmPrinter::emitDwarfAbbrev(const DIEAbbrev &Abbrev) const {
 268   // Emit the abbreviations code (base 1 index.)
 269   EmitULEB128(Abbrev.getNumber(), "Abbreviation Code");
 270
 271   // Emit the abbreviations data.
 272   Abbrev.Emit(this);
 273 }