140 lines · cpp
1//===- llvm/CodeGen/DwarfFile.cpp - Dwarf Debug Framework -----------------===//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#include "DwarfFile.h"10#include "DwarfCompileUnit.h"11#include "DwarfDebug.h"12#include "DwarfUnit.h"13#include "llvm/CodeGen/AsmPrinter.h"14#include "llvm/IR/DebugInfoMetadata.h"15#include "llvm/MC/MCStreamer.h"16#include <cstdint>17 18using namespace llvm;19 20DwarfFile::DwarfFile(AsmPrinter *AP, StringRef Pref, BumpPtrAllocator &DA)21 : Asm(AP), Abbrevs(AbbrevAllocator), StrPool(DA, *Asm, Pref) {}22 23void DwarfFile::addUnit(std::unique_ptr<DwarfCompileUnit> U) {24 CUs.push_back(std::move(U));25}26 27// Emit the various dwarf units to the unit section USection with28// the abbreviations going into ASection.29void DwarfFile::emitUnits(bool UseOffsets) {30 for (const auto &TheU : CUs)31 emitUnit(TheU.get(), UseOffsets);32}33 34void DwarfFile::emitUnit(DwarfUnit *TheU, bool UseOffsets) {35 if (TheU->getCUNode()->isDebugDirectivesOnly())36 return;37 38 MCSection *S = TheU->getSection();39 40 if (!S)41 return;42 43 // Skip CUs that ended up not being needed (split CUs that were abandoned44 // because they added no information beyond the non-split CU)45 if (TheU->getUnitDie().values().empty())46 return;47 48 Asm->OutStreamer->switchSection(S);49 TheU->emitHeader(UseOffsets);50 Asm->emitDwarfDIE(TheU->getUnitDie());51 52 if (MCSymbol *EndLabel = TheU->getEndLabel())53 Asm->OutStreamer->emitLabel(EndLabel);54}55 56// Compute the size and offset for each DIE.57void DwarfFile::computeSizeAndOffsets() {58 // Offset from the first CU in the debug info section is 0 initially.59 uint64_t SecOffset = 0;60 61 // Iterate over each compile unit and set the size and offsets for each62 // DIE within each compile unit. All offsets are CU relative.63 for (const auto &TheU : CUs) {64 if (TheU->getCUNode()->isDebugDirectivesOnly())65 continue;66 67 // Skip CUs that ended up not being needed (split CUs that were abandoned68 // because they added no information beyond the non-split CU)69 if (TheU->getUnitDie().values().empty())70 return;71 72 TheU->setDebugSectionOffset(SecOffset);73 SecOffset += computeSizeAndOffsetsForUnit(TheU.get());74 }75 if (SecOffset > UINT32_MAX && !Asm->isDwarf64())76 report_fatal_error("The generated debug information is too large "77 "for the 32-bit DWARF format.");78}79 80unsigned DwarfFile::computeSizeAndOffsetsForUnit(DwarfUnit *TheU) {81 // CU-relative offset is reset to 0 here.82 unsigned Offset = Asm->getUnitLengthFieldByteSize() + // Length of Unit Info83 TheU->getHeaderSize(); // Unit-specific headers84 85 // The return value here is CU-relative, after laying out86 // all of the CU DIE.87 return computeSizeAndOffset(TheU->getUnitDie(), Offset);88}89 90// Compute the size and offset of a DIE. The offset is relative to start of the91// CU. It returns the offset after laying out the DIE.92unsigned DwarfFile::computeSizeAndOffset(DIE &Die, unsigned Offset) {93 return Die.computeOffsetsAndAbbrevs(Asm->getDwarfFormParams(), Abbrevs,94 Offset);95}96 97void DwarfFile::emitAbbrevs(MCSection *Section) { Abbrevs.Emit(Asm, Section); }98 99// Emit strings into a string section.100void DwarfFile::emitStrings(MCSection *StrSection, MCSection *OffsetSection,101 bool UseRelativeOffsets) {102 StrPool.emit(*Asm, StrSection, OffsetSection, UseRelativeOffsets);103}104 105void DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {106 auto &ScopeVars = ScopeVariables[LS];107 const DILocalVariable *DV = Var->getVariable();108 if (unsigned ArgNum = DV->getArg()) {109 auto Ret = ScopeVars.Args.insert({ArgNum, Var});110 assert(Ret.second);111 (void)Ret;112 } else {113 ScopeVars.Locals.push_back(Var);114 }115}116 117void DwarfFile::addScopeLabel(LexicalScope *LS, DbgLabel *Label) {118 SmallVectorImpl<DbgLabel *> &Labels = ScopeLabels[LS];119 Labels.push_back(Label);120}121 122std::pair<uint32_t, RangeSpanList *>123DwarfFile::addRange(const DwarfCompileUnit &CU, SmallVector<RangeSpan, 2> R) {124 bool CanReuseLastRange = false;125 126 if (!CURangeLists.empty()) {127 auto Last = CURangeLists.back();128 if (Last.CU == &CU && Last.Ranges == R) {129 CanReuseLastRange = true;130 }131 }132 133 if (!CanReuseLastRange) {134 CURangeLists.push_back(RangeSpanList{Asm->createTempSymbol("debug_ranges"),135 &CU, std::move(R)});136 }137 138 return std::make_pair(CURangeLists.size() - 1, &CURangeLists.back());139}140