llvm-project/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp

121 lines
4.0 KiB
C++

//===- llvm/CodeGen/DwarfFile.cpp - Dwarf Debug Framework -----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "DwarfFile.h"
#include "DwarfCompileUnit.h"
#include "DwarfDebug.h"
#include "DwarfUnit.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/DIE.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/MC/MCStreamer.h"
#include <algorithm>
#include <cstdint>
using namespace llvm;
DwarfFile::DwarfFile(AsmPrinter *AP, StringRef Pref, BumpPtrAllocator &DA)
: Asm(AP), Abbrevs(AbbrevAllocator), StrPool(DA, *Asm, Pref) {}
void DwarfFile::addUnit(std::unique_ptr<DwarfCompileUnit> U) {
CUs.push_back(std::move(U));
}
void DwarfFile::emitStringOffsetsTableHeader(MCSection *Section) {
if (StrPool.empty())
return;
Asm->OutStreamer->SwitchSection(Section);
unsigned EntrySize = 4;
// FIXME: DWARF64
// We are emitting the header for a contribution to the string offsets
// table. The header consists of an entry with the contribution's
// size (not including the size of the length field), the DWARF version and
// 2 bytes of padding.
Asm->emitInt32(StrPool.size() * EntrySize + 4);
Asm->emitInt16(Asm->getDwarfVersion());
Asm->emitInt16(0);
// Define the symbol that marks the start of the contribution. It is
// referenced by most unit headers via DW_AT_str_offsets_base.
// Split units do not use the attribute.
if (StringOffsetsStartSym)
Asm->OutStreamer->EmitLabel(StringOffsetsStartSym);
}
// Emit the various dwarf units to the unit section USection with
// the abbreviations going into ASection.
void DwarfFile::emitUnits(bool UseOffsets) {
for (const auto &TheU : CUs)
emitUnit(TheU.get(), UseOffsets);
}
void DwarfFile::emitUnit(DwarfUnit *TheU, bool UseOffsets) {
DIE &Die = TheU->getUnitDie();
MCSection *USection = TheU->getSection();
Asm->OutStreamer->SwitchSection(USection);
TheU->emitHeader(UseOffsets);
Asm->emitDwarfDIE(Die);
}
// Compute the size and offset for each DIE.
void DwarfFile::computeSizeAndOffsets() {
// Offset from the first CU in the debug info section is 0 initially.
unsigned SecOffset = 0;
// Iterate over each compile unit and set the size and offsets for each
// DIE within each compile unit. All offsets are CU relative.
for (const auto &TheU : CUs) {
TheU->setDebugSectionOffset(SecOffset);
SecOffset += computeSizeAndOffsetsForUnit(TheU.get());
}
}
unsigned DwarfFile::computeSizeAndOffsetsForUnit(DwarfUnit *TheU) {
// CU-relative offset is reset to 0 here.
unsigned Offset = sizeof(int32_t) + // Length of Unit Info
TheU->getHeaderSize(); // Unit-specific headers
// The return value here is CU-relative, after laying out
// all of the CU DIE.
return computeSizeAndOffset(TheU->getUnitDie(), Offset);
}
// Compute the size and offset of a DIE. The offset is relative to start of the
// CU. It returns the offset after laying out the DIE.
unsigned DwarfFile::computeSizeAndOffset(DIE &Die, unsigned Offset) {
return Die.computeOffsetsAndAbbrevs(Asm, Abbrevs, Offset);
}
void DwarfFile::emitAbbrevs(MCSection *Section) { Abbrevs.Emit(Asm, Section); }
// Emit strings into a string section.
void DwarfFile::emitStrings(MCSection *StrSection, MCSection *OffsetSection,
bool UseRelativeOffsets) {
StrPool.emit(*Asm, StrSection, OffsetSection, UseRelativeOffsets);
}
bool DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
auto &ScopeVars = ScopeVariables[LS];
const DILocalVariable *DV = Var->getVariable();
if (unsigned ArgNum = DV->getArg()) {
auto Cached = ScopeVars.Args.find(ArgNum);
if (Cached == ScopeVars.Args.end())
ScopeVars.Args[ArgNum] = Var;
else {
Cached->second->addMMIEntry(*Var);
return false;
}
} else {
ScopeVars.Locals.push_back(Var);
}
return true;
}