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/MCDwarf.h"
  22 #include "llvm/MC/MCRegisterInfo.h"
  23 #include "llvm/MC/MCSection.h"
  24 #include "llvm/MC/MCStreamer.h"
  25 #include "llvm/MC/MCSymbol.h"
  26 #include "llvm/MC/MachineLocation.h"
  27 #include "llvm/Support/ErrorHandling.h"
  28 #include "llvm/Target/TargetLoweringObjectFile.h"
  29 #include "llvm/Target/TargetMachine.h"
  30 using namespace llvm;
  31
  32 #define DEBUG_TYPE "asm-printer"
  33
  34 //===----------------------------------------------------------------------===//
  35 // Dwarf Emission Helper Routines
  36 //===----------------------------------------------------------------------===//
  37
  38 /// EmitSLEB128 - emit the specified signed leb128 value.
  39 void AsmPrinter::EmitSLEB128(int64_t Value, const char *Desc) const {
  40   if (isVerbose() && Desc)
  41     OutStreamer->AddComment(Desc);
  42
  43   OutStreamer->EmitSLEB128IntValue(Value);
  44 }
  45
  46 void AsmPrinter::EmitULEB128(uint64_t Value, const char *Desc, unsigned PadTo) const {
  47   if (isVerbose() && Desc)
  48     OutStreamer->AddComment(Desc);
  49
  50   OutStreamer->EmitULEB128IntValue(Value, PadTo);
  51 }
  52
  53 /// Emit something like ".uleb128 Hi-Lo".
  54 void AsmPrinter::EmitLabelDifferenceAsULEB128(const MCSymbol *Hi,
  55                                               const MCSymbol *Lo) const {
  56   OutStreamer->emitAbsoluteSymbolDiffAsULEB128(Hi, Lo);
  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_uleb128:
  68     return "uleb128";
  69   case dwarf::DW_EH_PE_sleb128:
  70     return "sleb128";
  71   case dwarf::DW_EH_PE_udata4:
  72     return "udata4";
  73   case dwarf::DW_EH_PE_udata8:
  74     return "udata8";
  75   case dwarf::DW_EH_PE_sdata4:
  76     return "sdata4";
  77   case dwarf::DW_EH_PE_sdata8:
  78     return "sdata8";
  79   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:
  80     return "pcrel udata4";
  81   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:
  82     return "pcrel sdata4";
  83   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:
  84     return "pcrel udata8";
  85   case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:
  86     return "pcrel sdata8";
  87   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4
  88       :
  89     return "indirect pcrel udata4";
  90   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
  91       :
  92     return "indirect pcrel sdata4";
  93   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8
  94       :
  95     return "indirect pcrel udata8";
  96   case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8
  97       :
  98     return "indirect pcrel sdata8";
  99   }
 100
 101   return "<unknown encoding>";
 102 }
 103
 104 /// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an
 105 /// encoding.  If verbose assembly output is enabled, we output comments
 106 /// describing the encoding.  Desc is an optional string saying what the
 107 /// encoding is specifying (e.g. "LSDA").
 108 void AsmPrinter::EmitEncodingByte(unsigned Val, const char *Desc) const {
 109   if (isVerbose()) {
 110     if (Desc)
 111       OutStreamer->AddComment(Twine(Desc) + " Encoding = " +
 112                               Twine(DecodeDWARFEncoding(Val)));
 113     else
 114       OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));
 115   }
 116
 117   OutStreamer->EmitIntValue(Val, 1);
 118 }
 119
 120 /// GetSizeOfEncodedValue - Return the size of the encoding in bytes.
 121 unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {
 122   if (Encoding == dwarf::DW_EH_PE_omit)
 123     return 0;
 124
 125   switch (Encoding & 0x07) {
 126   default:
 127     llvm_unreachable("Invalid encoded value.");
 128   case dwarf::DW_EH_PE_absptr:
 129     return MF->getDataLayout().getPointerSize();
 130   case dwarf::DW_EH_PE_udata2:
 131     return 2;
 132   case dwarf::DW_EH_PE_udata4:
 133     return 4;
 134   case dwarf::DW_EH_PE_udata8:
 135     return 8;
 136   }
 137 }
 138
 139 void AsmPrinter::EmitTTypeReference(const GlobalValue *GV,
 140                                     unsigned Encoding) const {
 141   if (GV) {
 142     const TargetLoweringObjectFile &TLOF = getObjFileLowering();
 143
 144     const MCExpr *Exp =
 145         TLOF.getTTypeGlobalReference(GV, Encoding, TM, MMI, *OutStreamer);
 146     OutStreamer->EmitValue(Exp, GetSizeOfEncodedValue(Encoding));
 147   } else
 148     OutStreamer->EmitIntValue(0, GetSizeOfEncodedValue(Encoding));
 149 }
 150
 151 void AsmPrinter::emitDwarfSymbolReference(const MCSymbol *Label,
 152                                           bool ForceOffset) const {
 153   if (!ForceOffset) {
 154     // On COFF targets, we have to emit the special .secrel32 directive.
 155     if (MAI->needsDwarfSectionOffsetDirective()) {
 156       OutStreamer->EmitCOFFSecRel32(Label, /*Offset=*/0);
 157       return;
 158     }
 159
 160     // If the format uses relocations with dwarf, refer to the symbol directly.
 161     if (MAI->doesDwarfUseRelocationsAcrossSections()) {
 162       OutStreamer->EmitSymbolValue(Label, 4);
 163       return;
 164     }
 165   }
 166
 167   // Otherwise, emit it as a label difference from the start of the section.
 168   EmitLabelDifference(Label, Label->getSection().getBeginSymbol(), 4);
 169 }
 170
 171 void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntry S) const {
 172   if (MAI->doesDwarfUseRelocationsAcrossSections()) {
 173     assert(S.Symbol && "No symbol available");
 174     emitDwarfSymbolReference(S.Symbol);
 175     return;
 176   }
 177
 178   // Just emit the offset directly; no need for symbol math.
 179   emitInt32(S.Offset);
 180 }
 181
 182 void AsmPrinter::EmitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const {
 183   EmitLabelPlusOffset(Label, Offset, MAI->getCodePointerSize());
 184 }
 185
 186 void AsmPrinter::EmitCallSiteOffset(const MCSymbol *Hi,
 187                                     const MCSymbol *Lo,
 188                                     unsigned Encoding) const {
 189   // The least significant 3 bits specify the width of the encoding
 190   if ((Encoding & 0x7) == dwarf::DW_EH_PE_uleb128)
 191     EmitLabelDifferenceAsULEB128(Hi, Lo);
 192   else
 193     EmitLabelDifference(Hi, Lo, GetSizeOfEncodedValue(Encoding));
 194 }
 195
 196 void AsmPrinter::EmitCallSiteValue(uint64_t Value,
 197                                    unsigned Encoding) const {
 198   // The least significant 3 bits specify the width of the encoding
 199   if ((Encoding & 0x7) == dwarf::DW_EH_PE_uleb128)
 200     EmitULEB128(Value);
 201   else
 202     OutStreamer->EmitIntValue(Value, GetSizeOfEncodedValue(Encoding));
 203 }
 204
 205 //===----------------------------------------------------------------------===//
 206 // Dwarf Lowering Routines
 207 //===----------------------------------------------------------------------===//
 208
 209 void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {
 210   switch (Inst.getOperation()) {
 211   default:
 212     llvm_unreachable("Unexpected instruction");
 213   case MCCFIInstruction::OpDefCfaOffset:
 214     OutStreamer->EmitCFIDefCfaOffset(Inst.getOffset());
 215     break;
 216   case MCCFIInstruction::OpAdjustCfaOffset:
 217     OutStreamer->EmitCFIAdjustCfaOffset(Inst.getOffset());
 218     break;
 219   case MCCFIInstruction::OpDefCfa:
 220     OutStreamer->EmitCFIDefCfa(Inst.getRegister(), Inst.getOffset());
 221     break;
 222   case MCCFIInstruction::OpDefCfaRegister:
 223     OutStreamer->EmitCFIDefCfaRegister(Inst.getRegister());
 224     break;
 225   case MCCFIInstruction::OpOffset:
 226     OutStreamer->EmitCFIOffset(Inst.getRegister(), Inst.getOffset());
 227     break;
 228   case MCCFIInstruction::OpRegister:
 229     OutStreamer->EmitCFIRegister(Inst.getRegister(), Inst.getRegister2());
 230     break;
 231   case MCCFIInstruction::OpWindowSave:
 232     OutStreamer->EmitCFIWindowSave();
 233     break;
 234   case MCCFIInstruction::OpNegateRAState:
 235     OutStreamer->EmitCFINegateRAState();
 236     break;
 237   case MCCFIInstruction::OpSameValue:
 238     OutStreamer->EmitCFISameValue(Inst.getRegister());
 239     break;
 240   case MCCFIInstruction::OpGnuArgsSize:
 241     OutStreamer->EmitCFIGnuArgsSize(Inst.getOffset());
 242     break;
 243   case MCCFIInstruction::OpEscape:
 244     OutStreamer->EmitCFIEscape(Inst.getValues());
 245     break;
 246   case MCCFIInstruction::OpRestore:
 247     OutStreamer->EmitCFIRestore(Inst.getRegister());
 248     break;
 249   }
 250 }
 251
 252 void AsmPrinter::emitDwarfDIE(const DIE &Die) const {
 253   // Emit the code (index) for the abbreviation.
 254   if (isVerbose())
 255     OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +
 256                             Twine::utohexstr(Die.getOffset()) + ":0x" +
 257                             Twine::utohexstr(Die.getSize()) + " " +
 258                             dwarf::TagString(Die.getTag()));
 259   EmitULEB128(Die.getAbbrevNumber());
 260
 261   // Emit the DIE attribute values.
 262   for (const auto &V : Die.values()) {
 263     dwarf::Attribute Attr = V.getAttribute();
 264     assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");
 265
 266     if (isVerbose()) {
 267       OutStreamer->AddComment(dwarf::AttributeString(Attr));
 268       if (Attr == dwarf::DW_AT_accessibility)
 269         OutStreamer->AddComment(
 270             dwarf::AccessibilityString(V.getDIEInteger().getValue()));
 271     }
 272
 273     // Emit an attribute using the defined form.
 274     V.EmitValue(this);
 275   }
 276
 277   // Emit the DIE children if any.
 278   if (Die.hasChildren()) {
 279     for (auto &Child : Die.children())
 280       emitDwarfDIE(Child);
 281
 282     OutStreamer->AddComment("End Of Children Mark");
 283     emitInt8(0);
 284   }
 285 }
 286
 287 void AsmPrinter::emitDwarfAbbrev(const DIEAbbrev &Abbrev) const {
 288   // Emit the abbreviations code (base 1 index.)
 289   EmitULEB128(Abbrev.getNumber(), "Abbreviation Code");
 290
 291   // Emit the abbreviations data.
 292   Abbrev.Emit(this);
 293 }