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//===-- 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 "DwarfDebug.h"
#include "DwarfUnit.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Support/LEB128.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
namespace llvm {
DwarfFile::DwarfFile(AsmPrinter *AP, DwarfDebug &DD, StringRef Pref,
BumpPtrAllocator &DA)
: Asm(AP), DD(DD), StrPool(DA, *Asm, Pref) {}
DwarfFile::~DwarfFile() {}
// Define a unique number for the abbreviation.
//
void DwarfFile::assignAbbrevNumber(DIEAbbrev &Abbrev) {
// Check the set for priors.
DIEAbbrev *InSet = AbbreviationsSet.GetOrInsertNode(&Abbrev);
// If it's newly added.
if (InSet == &Abbrev) {
// Add to abbreviation list.
Abbreviations.push_back(&Abbrev);
// Assign the vector position + 1 as its number.
Abbrev.setNumber(Abbreviations.size());
} else {
// Assign existing abbreviation number.
Abbrev.setNumber(InSet->getNumber());
}
}
void DwarfFile::addUnit(std::unique_ptr<DwarfUnit> U) {
CUs.push_back(std::move(U));
}
// Emit the various dwarf units to the unit section USection with
// the abbreviations going into ASection.
void DwarfFile::emitUnits(const MCSymbol *ASectionSym) {
for (const auto &TheU : CUs) {
DIE &Die = TheU->getUnitDie();
const MCSection *USection = TheU->getSection();
Asm->OutStreamer.SwitchSection(USection);
TheU->emitHeader(ASectionSym);
DD.emitDIE(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->setDebugInfoOffset(SecOffset);
// CU-relative offset is reset to 0 here.
unsigned Offset = sizeof(int32_t) + // Length of Unit Info
TheU->getHeaderSize(); // Unit-specific headers
// EndOffset here is CU-relative, after laying out
// all of the CU DIE.
unsigned EndOffset = computeSizeAndOffset(TheU->getUnitDie(), Offset);
SecOffset += EndOffset;
}
}
// 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) {
// Record the abbreviation.
assignAbbrevNumber(Die.getAbbrev());
// Get the abbreviation for this DIE.
const DIEAbbrev &Abbrev = Die.getAbbrev();
// Set DIE offset
Die.setOffset(Offset);
// Start the size with the size of abbreviation code.
Offset += getULEB128Size(Die.getAbbrevNumber());
const SmallVectorImpl<DIEValue *> &Values = Die.getValues();
const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
// Size the DIE attribute values.
for (unsigned i = 0, N = Values.size(); i < N; ++i)
// Size attribute value.
Offset += Values[i]->SizeOf(Asm, AbbrevData[i].getForm());
// Get the children.
const auto &Children = Die.getChildren();
// Size the DIE children if any.
if (!Children.empty()) {
assert(Abbrev.hasChildren() && "Children flag not set");
for (auto &Child : Children)
Offset = computeSizeAndOffset(*Child, Offset);
// End of children marker.
Offset += sizeof(int8_t);
}
Die.setSize(Offset - Die.getOffset());
return Offset;
}
void DwarfFile::emitAbbrevs(const MCSection *Section) {
// Check to see if it is worth the effort.
if (!Abbreviations.empty()) {
// Start the debug abbrev section.
Asm->OutStreamer.SwitchSection(Section);
// For each abbrevation.
for (const DIEAbbrev *Abbrev : Abbreviations) {
// Emit the abbrevations code (base 1 index.)
Asm->EmitULEB128(Abbrev->getNumber(), "Abbreviation Code");
// Emit the abbreviations data.
Abbrev->Emit(Asm);
}
// Mark end of abbreviations.
Asm->EmitULEB128(0, "EOM(3)");
}
}
// Emit strings into a string section.
void DwarfFile::emitStrings(const MCSection *StrSection,
const MCSection *OffsetSection) {
StrPool.emit(*Asm, StrSection, OffsetSection);
}
bool DwarfFile::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
SmallVectorImpl<DbgVariable *> &Vars = ScopeVariables[LS];
DIVariable DV = Var->getVariable();
// Variables with positive arg numbers are parameters.
if (unsigned ArgNum = DV.getArgNumber()) {
// Keep all parameters in order at the start of the variable list to ensure
// function types are correct (no out-of-order parameters)
//
// This could be improved by only doing it for optimized builds (unoptimized
// builds have the right order to begin with), searching from the back (this
// would catch the unoptimized case quickly), or doing a binary search
// rather than linear search.
auto I = Vars.begin();
while (I != Vars.end()) {
unsigned CurNum = (*I)->getVariable().getArgNumber();
// A local (non-parameter) variable has been found, insert immediately
// before it.
if (CurNum == 0)
break;
// A later indexed parameter has been found, insert immediately before it.
if (CurNum > ArgNum)
break;
if (CurNum == ArgNum) {
(*I)->addMMIEntry(*Var);
return false;
}
++I;
}
Vars.insert(I, Var);
return true;
}
Vars.push_back(Var);
return true;
}
}
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