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llvm-mirror/lib/CodeGen/AsmPrinter/DwarfFile.h
Peter Collingbourne 909a12080b DwarfDebug: emit type units immediately.
Rather than storing type units in a vector and emitting them at the end
of code generation, emit them immediately and destroy them, reclaiming the
memory we were using for their DIEs.

In one benchmark carried out against Chromium's 50 largest (by bitcode
file size) translation units, total peak memory consumption with type units
decreased by median 17%, or by 7% when compared against disabling type units.

Tested using check-{llvm,clang}, the GDB 7.5 test suite (with
'-fdebug-types-section') and by eyeballing llvm-dwarfdump output on those
Chromium translation units with split DWARF both disabled and enabled, and
verifying that the only changes were to addresses and abbreviation ordering.

Differential Revision: http://reviews.llvm.org/D17118

llvm-svn: 260578
2016-02-11 19:57:46 +00:00

130 lines
3.8 KiB
C++

//===-- llvm/CodeGen/DwarfFile.h - Dwarf Debug Framework -------*- C++ -*--===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_DWARFFILE_H
#define LLVM_LIB_CODEGEN_ASMPRINTER_DWARFFILE_H
#include "AddressPool.h"
#include "DwarfStringPool.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/IR/Metadata.h"
#include "llvm/Support/Allocator.h"
#include <memory>
#include <string>
#include <vector>
namespace llvm {
class AsmPrinter;
class DbgVariable;
class DwarfCompileUnit;
class DwarfUnit;
class DIEAbbrev;
class MCSymbol;
class DIE;
class LexicalScope;
class StringRef;
class DwarfDebug;
class MCSection;
class MDNode;
class DwarfFile {
// Target of Dwarf emission, used for sizing of abbreviations.
AsmPrinter *Asm;
BumpPtrAllocator AbbrevAllocator;
// Used to uniquely define abbreviations.
FoldingSet<DIEAbbrev> AbbreviationsSet;
// A list of all the unique abbreviations in use.
std::vector<DIEAbbrev *> Abbreviations;
// A pointer to all units in the section.
SmallVector<std::unique_ptr<DwarfCompileUnit>, 1> CUs;
DwarfStringPool StrPool;
// Collection of dbg variables of a scope.
DenseMap<LexicalScope *, SmallVector<DbgVariable *, 8>> ScopeVariables;
// Collection of abstract subprogram DIEs.
DenseMap<const MDNode *, DIE *> AbstractSPDies;
/// Maps MDNodes for type system with the corresponding DIEs. These DIEs can
/// be shared across CUs, that is why we keep the map here instead
/// of in DwarfCompileUnit.
DenseMap<const MDNode *, DIE *> DITypeNodeToDieMap;
public:
DwarfFile(AsmPrinter *AP, StringRef Pref, BumpPtrAllocator &DA);
~DwarfFile();
const SmallVectorImpl<std::unique_ptr<DwarfCompileUnit>> &getUnits() {
return CUs;
}
/// \brief Compute the size and offset of a DIE given an incoming Offset.
unsigned computeSizeAndOffset(DIE &Die, unsigned Offset);
/// \brief Compute the size and offset of all the DIEs.
void computeSizeAndOffsets();
/// \brief Compute the size and offset of all the DIEs in the given unit.
/// \returns The size of the root DIE.
unsigned computeSizeAndOffsetsForUnit(DwarfUnit *TheU);
/// Define a unique number for the abbreviation.
///
/// Compute the abbreviation for \c Die, look up its unique number, and
/// return a reference to it in the uniquing table.
DIEAbbrev &assignAbbrevNumber(DIE &Die);
/// \brief Add a unit to the list of CUs.
void addUnit(std::unique_ptr<DwarfCompileUnit> U);
/// \brief Emit all of the units to the section listed with the given
/// abbreviation section.
void emitUnits(bool UseOffsets);
/// \brief Emit the given unit to its section.
void emitUnit(DwarfUnit *U, bool UseOffsets);
/// \brief Emit a set of abbreviations to the specific section.
void emitAbbrevs(MCSection *);
/// \brief Emit all of the strings to the section given.
void emitStrings(MCSection *StrSection, MCSection *OffsetSection = nullptr);
/// \brief Returns the string pool.
DwarfStringPool &getStringPool() { return StrPool; }
/// \returns false if the variable was merged with a previous one.
bool addScopeVariable(LexicalScope *LS, DbgVariable *Var);
DenseMap<LexicalScope *, SmallVector<DbgVariable *, 8>> &getScopeVariables() {
return ScopeVariables;
}
DenseMap<const MDNode *, DIE *> &getAbstractSPDies() {
return AbstractSPDies;
}
void insertDIE(const MDNode *TypeMD, DIE *Die) {
DITypeNodeToDieMap.insert(std::make_pair(TypeMD, Die));
}
DIE *getDIE(const MDNode *TypeMD) {
return DITypeNodeToDieMap.lookup(TypeMD);
}
};
}
#endif