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//=-- llvm/CodeGen/DwarfAccelTable.cpp - Dwarf Accelerator Tables -*- C++ -*-=//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains support for writing dwarf accelerator tables.
//
//===----------------------------------------------------------------------===//
#include "DwarfAccelTable.h"
#include "DIE.h"
#include "DwarfDebug.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
const char *DwarfAccelTable::Atom::AtomTypeString(enum AtomType AT) {
switch (AT) {
case eAtomTypeNULL: return "eAtomTypeNULL";
case eAtomTypeDIEOffset: return "eAtomTypeDIEOffset";
case eAtomTypeCUOffset: return "eAtomTypeCUOffset";
case eAtomTypeTag: return "eAtomTypeTag";
case eAtomTypeNameFlags: return "eAtomTypeNameFlags";
case eAtomTypeTypeFlags: return "eAtomTypeTypeFlags";
}
llvm_unreachable("invalid AtomType!");
}
// The length of the header data is always going to be 4 + 4 + 4*NumAtoms.
DwarfAccelTable::DwarfAccelTable(ArrayRef<DwarfAccelTable::Atom> atomList) :
Header(8 + (atomList.size() * 4)),
HeaderData(atomList),
Entries(Allocator) { }
DwarfAccelTable::~DwarfAccelTable() { }
void DwarfAccelTable::AddName(StringRef Name, DIE* die, char Flags) {
assert(Data.empty() && "Already finalized!");
// If the string is in the list already then add this die to the list
// otherwise add a new one.
DataArray &DIEs = Entries[Name];
DIEs.push_back(new (Allocator) HashDataContents(die, Flags));
}
void DwarfAccelTable::ComputeBucketCount(void) {
// First get the number of unique hashes.
std::vector<uint32_t> uniques(Data.size());
for (size_t i = 0, e = Data.size(); i < e; ++i)
uniques[i] = Data[i]->HashValue;
array_pod_sort(uniques.begin(), uniques.end());
std::vector<uint32_t>::iterator p =
std::unique(uniques.begin(), uniques.end());
uint32_t num = std::distance(uniques.begin(), p);
// Then compute the bucket size, minimum of 1 bucket.
if (num > 1024) Header.bucket_count = num/4;
if (num > 16) Header.bucket_count = num/2;
else Header.bucket_count = num > 0 ? num : 1;
Header.hashes_count = num;
}
// compareDIEs - comparison predicate that sorts DIEs by their offset.
static bool compareDIEs(const DwarfAccelTable::HashDataContents *A,
const DwarfAccelTable::HashDataContents *B) {
return A->Die->getOffset() < B->Die->getOffset();
}
void DwarfAccelTable::FinalizeTable(AsmPrinter *Asm, const char *Prefix) {
// Create the individual hash data outputs.
for (StringMap<DataArray>::iterator
EI = Entries.begin(), EE = Entries.end(); EI != EE; ++EI) {
// Unique the entries.
std::stable_sort(EI->second.begin(), EI->second.end(), compareDIEs);
EI->second.erase(std::unique(EI->second.begin(), EI->second.end()),
EI->second.end());
HashData *Entry = new (Allocator) HashData(EI->getKey(), EI->second);
Data.push_back(Entry);
}
// Figure out how many buckets we need, then compute the bucket
// contents and the final ordering. We'll emit the hashes and offsets
// by doing a walk during the emission phase. We add temporary
// symbols to the data so that we can reference them during the offset
// later, we'll emit them when we emit the data.
ComputeBucketCount();
// Compute bucket contents and final ordering.
Buckets.resize(Header.bucket_count);
for (size_t i = 0, e = Data.size(); i < e; ++i) {
uint32_t bucket = Data[i]->HashValue % Header.bucket_count;
Buckets[bucket].push_back(Data[i]);
Data[i]->Sym = Asm->GetTempSymbol(Prefix, i);
}
}
// Emits the header for the table via the AsmPrinter.
void DwarfAccelTable::EmitHeader(AsmPrinter *Asm) {
Asm->OutStreamer.AddComment("Header Magic");
Asm->EmitInt32(Header.magic);
Asm->OutStreamer.AddComment("Header Version");
Asm->EmitInt16(Header.version);
Asm->OutStreamer.AddComment("Header Hash Function");
Asm->EmitInt16(Header.hash_function);
Asm->OutStreamer.AddComment("Header Bucket Count");
Asm->EmitInt32(Header.bucket_count);
Asm->OutStreamer.AddComment("Header Hash Count");
Asm->EmitInt32(Header.hashes_count);
Asm->OutStreamer.AddComment("Header Data Length");
Asm->EmitInt32(Header.header_data_len);
Asm->OutStreamer.AddComment("HeaderData Die Offset Base");
Asm->EmitInt32(HeaderData.die_offset_base);
Asm->OutStreamer.AddComment("HeaderData Atom Count");
Asm->EmitInt32(HeaderData.Atoms.size());
for (size_t i = 0; i < HeaderData.Atoms.size(); i++) {
Atom A = HeaderData.Atoms[i];
Asm->OutStreamer.AddComment(Atom::AtomTypeString(A.type));
Asm->EmitInt16(A.type);
Asm->OutStreamer.AddComment(dwarf::FormEncodingString(A.form));
Asm->EmitInt16(A.form);
}
}
// Walk through and emit the buckets for the table. Each index is
// an offset into the list of hashes.
void DwarfAccelTable::EmitBuckets(AsmPrinter *Asm) {
unsigned index = 0;
for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
Asm->OutStreamer.AddComment("Bucket " + Twine(i));
if (Buckets[i].size() != 0)
Asm->EmitInt32(index);
else
Asm->EmitInt32(UINT32_MAX);
index += Buckets[i].size();
}
}
// Walk through the buckets and emit the individual hashes for each
// bucket.
void DwarfAccelTable::EmitHashes(AsmPrinter *Asm) {
for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
for (HashList::const_iterator HI = Buckets[i].begin(),
HE = Buckets[i].end(); HI != HE; ++HI) {
Asm->OutStreamer.AddComment("Hash in Bucket " + Twine(i));
Asm->EmitInt32((*HI)->HashValue);
}
}
}
// Walk through the buckets and emit the individual offsets for each
// element in each bucket. This is done via a symbol subtraction from the
// beginning of the section. The non-section symbol will be output later
// when we emit the actual data.
void DwarfAccelTable::EmitOffsets(AsmPrinter *Asm, MCSymbol *SecBegin) {
for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
for (HashList::const_iterator HI = Buckets[i].begin(),
HE = Buckets[i].end(); HI != HE; ++HI) {
Asm->OutStreamer.AddComment("Offset in Bucket " + Twine(i));
MCContext &Context = Asm->OutStreamer.getContext();
const MCExpr *Sub =
MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create((*HI)->Sym, Context),
MCSymbolRefExpr::Create(SecBegin, Context),
Context);
Asm->OutStreamer.EmitValue(Sub, sizeof(uint32_t));
}
}
}
// Walk through the buckets and emit the full data for each element in
// the bucket. For the string case emit the dies and the various offsets.
// Terminate each HashData bucket with 0.
void DwarfAccelTable::EmitData(AsmPrinter *Asm, DwarfUnits *D) {
uint64_t PrevHash = UINT64_MAX;
for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
for (HashList::const_iterator HI = Buckets[i].begin(),
HE = Buckets[i].end(); HI != HE; ++HI) {
// Remember to emit the label for our offset.
Asm->OutStreamer.EmitLabel((*HI)->Sym);
Asm->OutStreamer.AddComment((*HI)->Str);
Asm->EmitSectionOffset(D->getStringPoolEntry((*HI)->Str),
D->getStringPoolSym());
Asm->OutStreamer.AddComment("Num DIEs");
Asm->EmitInt32((*HI)->Data.size());
for (ArrayRef<HashDataContents*>::const_iterator
DI = (*HI)->Data.begin(), DE = (*HI)->Data.end();
DI != DE; ++DI) {
// Emit the DIE offset
Asm->EmitInt32((*DI)->Die->getOffset());
// If we have multiple Atoms emit that info too.
// FIXME: A bit of a hack, we either emit only one atom or all info.
if (HeaderData.Atoms.size() > 1) {
Asm->EmitInt16((*DI)->Die->getTag());
Asm->EmitInt8((*DI)->Flags);
}
}
// Emit a 0 to terminate the data unless we have a hash collision.
if (PrevHash != (*HI)->HashValue)
Asm->EmitInt32(0);
PrevHash = (*HI)->HashValue;
}
}
}
// Emit the entire data structure to the output file.
void DwarfAccelTable::Emit(AsmPrinter *Asm, MCSymbol *SecBegin,
DwarfUnits *D) {
// Emit the header.
EmitHeader(Asm);
// Emit the buckets.
EmitBuckets(Asm);
// Emit the hashes.
EmitHashes(Asm);
// Emit the offsets.
EmitOffsets(Asm, SecBegin);
// Emit the hash data.
EmitData(Asm, D);
}
#ifndef NDEBUG
void DwarfAccelTable::print(raw_ostream &O) {
Header.print(O);
HeaderData.print(O);
O << "Entries: \n";
for (StringMap<DataArray>::const_iterator
EI = Entries.begin(), EE = Entries.end(); EI != EE; ++EI) {
O << "Name: " << EI->getKeyData() << "\n";
for (DataArray::const_iterator DI = EI->second.begin(),
DE = EI->second.end();
DI != DE; ++DI)
(*DI)->print(O);
}
O << "Buckets and Hashes: \n";
for (size_t i = 0, e = Buckets.size(); i < e; ++i)
for (HashList::const_iterator HI = Buckets[i].begin(),
HE = Buckets[i].end(); HI != HE; ++HI)
(*HI)->print(O);
O << "Data: \n";
for (std::vector<HashData*>::const_iterator
DI = Data.begin(), DE = Data.end(); DI != DE; ++DI)
(*DI)->print(O);
}
#endif
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