311 lines · 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-exception6//7//===----------------------------------------------------------------------===//8//9// This file implements the Dwarf emissions parts of AsmPrinter.10//11//===----------------------------------------------------------------------===//12 13#include "llvm/ADT/Twine.h"14#include "llvm/BinaryFormat/Dwarf.h"15#include "llvm/CodeGen/AsmPrinter.h"16#include "llvm/CodeGen/DIE.h"17#include "llvm/CodeGen/MachineFunction.h"18#include "llvm/MC/MCAsmInfo.h"19#include "llvm/MC/MCDwarf.h"20#include "llvm/MC/MCSection.h"21#include "llvm/MC/MCStreamer.h"22#include "llvm/MC/MCSymbol.h"23#include "llvm/Support/ErrorHandling.h"24#include "llvm/Target/TargetLoweringObjectFile.h"25#include <cstdint>26using namespace llvm;27 28#define DEBUG_TYPE "asm-printer"29 30//===----------------------------------------------------------------------===//31// Dwarf Emission Helper Routines32//===----------------------------------------------------------------------===//33 34static const char *DecodeDWARFEncoding(unsigned Encoding) {35 switch (Encoding) {36 case dwarf::DW_EH_PE_absptr:37 return "absptr";38 case dwarf::DW_EH_PE_omit:39 return "omit";40 case dwarf::DW_EH_PE_pcrel:41 return "pcrel";42 case dwarf::DW_EH_PE_uleb128:43 return "uleb128";44 case dwarf::DW_EH_PE_sleb128:45 return "sleb128";46 case dwarf::DW_EH_PE_udata4:47 return "udata4";48 case dwarf::DW_EH_PE_udata8:49 return "udata8";50 case dwarf::DW_EH_PE_sdata4:51 return "sdata4";52 case dwarf::DW_EH_PE_sdata8:53 return "sdata8";54 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata4:55 return "pcrel udata4";56 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4:57 return "pcrel sdata4";58 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8:59 return "pcrel udata8";60 case dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8:61 return "pcrel sdata8";62 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata463 :64 return "indirect pcrel udata4";65 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata466 :67 return "indirect pcrel sdata4";68 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata869 :70 return "indirect pcrel udata8";71 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata872 :73 return "indirect pcrel sdata8";74 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_datarel |75 dwarf::DW_EH_PE_sdata4:76 return "indirect datarel sdata4";77 case dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_datarel |78 dwarf::DW_EH_PE_sdata8:79 return "indirect datarel sdata8";80 }81 82 return "<unknown encoding>";83}84 85/// EmitEncodingByte - Emit a .byte 42 directive that corresponds to an86/// encoding. If verbose assembly output is enabled, we output comments87/// describing the encoding. Desc is an optional string saying what the88/// encoding is specifying (e.g. "LSDA").89void AsmPrinter::emitEncodingByte(unsigned Val, const char *Desc) const {90 if (isVerbose()) {91 if (Desc)92 OutStreamer->AddComment(Twine(Desc) + " Encoding = " +93 Twine(DecodeDWARFEncoding(Val)));94 else95 OutStreamer->AddComment(Twine("Encoding = ") + DecodeDWARFEncoding(Val));96 }97 98 OutStreamer->emitIntValue(Val, 1);99}100 101/// GetSizeOfEncodedValue - Return the size of the encoding in bytes.102unsigned AsmPrinter::GetSizeOfEncodedValue(unsigned Encoding) const {103 if (Encoding == dwarf::DW_EH_PE_omit)104 return 0;105 106 switch (Encoding & 0x07) {107 default:108 llvm_unreachable("Invalid encoded value.");109 case dwarf::DW_EH_PE_absptr:110 return MAI->getCodePointerSize();111 case dwarf::DW_EH_PE_udata2:112 return 2;113 case dwarf::DW_EH_PE_udata4:114 return 4;115 case dwarf::DW_EH_PE_udata8:116 return 8;117 }118}119 120void AsmPrinter::emitTTypeReference(const GlobalValue *GV, unsigned Encoding) {121 if (GV) {122 const TargetLoweringObjectFile &TLOF = getObjFileLowering();123 124 const MCExpr *Exp =125 TLOF.getTTypeGlobalReference(GV, Encoding, TM, MMI, *OutStreamer);126 OutStreamer->emitValue(Exp, GetSizeOfEncodedValue(Encoding));127 } else128 OutStreamer->emitIntValue(0, GetSizeOfEncodedValue(Encoding));129}130 131void AsmPrinter::emitDwarfSymbolReference(const MCSymbol *Label,132 bool ForceOffset) const {133 if (!ForceOffset) {134 // On COFF targets, we have to emit the special .secrel32 directive.135 if (MAI->needsDwarfSectionOffsetDirective()) {136 assert(!isDwarf64() &&137 "emitting DWARF64 is not implemented for COFF targets");138 OutStreamer->emitCOFFSecRel32(Label, /*Offset=*/0);139 return;140 }141 142 // If the format uses relocations with dwarf, refer to the symbol directly.143 if (doesDwarfUseRelocationsAcrossSections()) {144 OutStreamer->emitSymbolValue(Label, getDwarfOffsetByteSize());145 return;146 }147 }148 149 // Otherwise, emit it as a label difference from the start of the section.150 emitLabelDifference(Label, Label->getSection().getBeginSymbol(),151 getDwarfOffsetByteSize());152}153 154void AsmPrinter::emitDwarfStringOffset(DwarfStringPoolEntry S) const {155 if (doesDwarfUseRelocationsAcrossSections()) {156 assert(S.Symbol && "No symbol available");157 emitDwarfSymbolReference(S.Symbol);158 return;159 }160 161 // Just emit the offset directly; no need for symbol math.162 OutStreamer->emitIntValue(S.Offset, getDwarfOffsetByteSize());163}164 165void AsmPrinter::emitDwarfOffset(const MCSymbol *Label, uint64_t Offset) const {166 emitLabelPlusOffset(Label, Offset, getDwarfOffsetByteSize());167}168 169void AsmPrinter::emitDwarfLengthOrOffset(uint64_t Value) const {170 assert(isDwarf64() || Value <= UINT32_MAX);171 OutStreamer->emitIntValue(Value, getDwarfOffsetByteSize());172}173 174void AsmPrinter::emitDwarfUnitLength(uint64_t Length,175 const Twine &Comment) const {176 OutStreamer->emitDwarfUnitLength(Length, Comment);177}178 179MCSymbol *AsmPrinter::emitDwarfUnitLength(const Twine &Prefix,180 const Twine &Comment) const {181 return OutStreamer->emitDwarfUnitLength(Prefix, Comment);182}183 184void AsmPrinter::emitCallSiteOffset(const MCSymbol *Hi, const MCSymbol *Lo,185 unsigned Encoding) const {186 // The least significant 3 bits specify the width of the encoding187 if ((Encoding & 0x7) == dwarf::DW_EH_PE_uleb128)188 emitLabelDifferenceAsULEB128(Hi, Lo);189 else190 emitLabelDifference(Hi, Lo, GetSizeOfEncodedValue(Encoding));191}192 193void AsmPrinter::emitCallSiteValue(uint64_t Value, unsigned Encoding) const {194 // The least significant 3 bits specify the width of the encoding195 if ((Encoding & 0x7) == dwarf::DW_EH_PE_uleb128)196 emitULEB128(Value);197 else198 OutStreamer->emitIntValue(Value, GetSizeOfEncodedValue(Encoding));199}200 201//===----------------------------------------------------------------------===//202// Dwarf Lowering Routines203//===----------------------------------------------------------------------===//204 205void AsmPrinter::emitCFIInstruction(const MCCFIInstruction &Inst) const {206 SMLoc Loc = Inst.getLoc();207 switch (Inst.getOperation()) {208 default:209 llvm_unreachable("Unexpected instruction");210 case MCCFIInstruction::OpDefCfaOffset:211 OutStreamer->emitCFIDefCfaOffset(Inst.getOffset(), Loc);212 break;213 case MCCFIInstruction::OpAdjustCfaOffset:214 OutStreamer->emitCFIAdjustCfaOffset(Inst.getOffset(), Loc);215 break;216 case MCCFIInstruction::OpDefCfa:217 OutStreamer->emitCFIDefCfa(Inst.getRegister(), Inst.getOffset(), Loc);218 break;219 case MCCFIInstruction::OpDefCfaRegister:220 OutStreamer->emitCFIDefCfaRegister(Inst.getRegister(), Loc);221 break;222 case MCCFIInstruction::OpLLVMDefAspaceCfa:223 OutStreamer->emitCFILLVMDefAspaceCfa(Inst.getRegister(), Inst.getOffset(),224 Inst.getAddressSpace(), Loc);225 break;226 case MCCFIInstruction::OpOffset:227 OutStreamer->emitCFIOffset(Inst.getRegister(), Inst.getOffset(), Loc);228 break;229 case MCCFIInstruction::OpRegister:230 OutStreamer->emitCFIRegister(Inst.getRegister(), Inst.getRegister2(), Loc);231 break;232 case MCCFIInstruction::OpWindowSave:233 OutStreamer->emitCFIWindowSave(Loc);234 break;235 case MCCFIInstruction::OpNegateRAState:236 OutStreamer->emitCFINegateRAState(Loc);237 break;238 case MCCFIInstruction::OpNegateRAStateWithPC:239 OutStreamer->emitCFINegateRAStateWithPC(Loc);240 break;241 case MCCFIInstruction::OpSameValue:242 OutStreamer->emitCFISameValue(Inst.getRegister(), Loc);243 break;244 case MCCFIInstruction::OpGnuArgsSize:245 OutStreamer->emitCFIGnuArgsSize(Inst.getOffset(), Loc);246 break;247 case MCCFIInstruction::OpEscape:248 OutStreamer->AddComment(Inst.getComment());249 OutStreamer->emitCFIEscape(Inst.getValues(), Loc);250 break;251 case MCCFIInstruction::OpRestore:252 OutStreamer->emitCFIRestore(Inst.getRegister(), Loc);253 break;254 case MCCFIInstruction::OpUndefined:255 OutStreamer->emitCFIUndefined(Inst.getRegister(), Loc);256 break;257 case MCCFIInstruction::OpRememberState:258 OutStreamer->emitCFIRememberState(Loc);259 break;260 case MCCFIInstruction::OpRestoreState:261 OutStreamer->emitCFIRestoreState(Loc);262 break;263 case MCCFIInstruction::OpValOffset:264 OutStreamer->emitCFIValOffset(Inst.getRegister(), Inst.getOffset(), Loc);265 break;266 }267}268 269void AsmPrinter::emitDwarfDIE(const DIE &Die) const {270 // Emit the code (index) for the abbreviation.271 if (isVerbose())272 OutStreamer->AddComment("Abbrev [" + Twine(Die.getAbbrevNumber()) + "] 0x" +273 Twine::utohexstr(Die.getOffset()) + ":0x" +274 Twine::utohexstr(Die.getSize()) + " " +275 dwarf::TagString(Die.getTag()));276 emitULEB128(Die.getAbbrevNumber());277 278 // Emit the DIE attribute values.279 for (const auto &V : Die.values()) {280 dwarf::Attribute Attr = V.getAttribute();281 assert(V.getForm() && "Too many attributes for DIE (check abbreviation)");282 283 if (isVerbose()) {284 OutStreamer->AddComment(dwarf::AttributeString(Attr));285 if (Attr == dwarf::DW_AT_accessibility)286 OutStreamer->AddComment(287 dwarf::AccessibilityString(V.getDIEInteger().getValue()));288 }289 290 // Emit an attribute using the defined form.291 V.emitValue(this);292 }293 294 // Emit the DIE children if any.295 if (Die.hasChildren()) {296 for (const auto &Child : Die.children())297 emitDwarfDIE(Child);298 299 OutStreamer->AddComment("End Of Children Mark");300 emitInt8(0);301 }302}303 304void AsmPrinter::emitDwarfAbbrev(const DIEAbbrev &Abbrev) const {305 // Emit the abbreviations code (base 1 index.)306 emitULEB128(Abbrev.getNumber(), "Abbreviation Code");307 308 // Emit the abbreviations data.309 Abbrev.Emit(this);310}311