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Misc improvements to StringTableBuilder. 

This patch adds write methods to StringTableBuilder so that it is
easier to change the underlying implementation.

Using the write methods, avoid creating a temporary buffer when using
mmaped output.

It also uses a more compact key in the DenseMap. Overall this produces
a slightly faster lld:

firefox
  master 6.853419709
  patch  6.841968912 1.00167361138x faster
chromium
  master 4.297280174
  patch  4.298712163 1.00033323147x slower
chromium fast
  master 1.802335952
  patch  1.806872459 1.00251701521x slower
the gold plugin
  master 0.3247149
  patch  0.321971644 1.00852017888x faster
clang
  master 0.551279945
  patch  0.543733194 1.01387951128x faster
llvm-as
  master 0.032743458
  patch  0.032143478 1.01866568391x faster
the gold plugin fsds
  master 0.350814247
  patch  0.348571741 1.00643341309x faster
clang fsds
  master 0.6281672
  patch  0.621130222 1.01132931187x faster
llvm-as fsds
  master 0.030168899
  patch  0.029797155 1.01247582194x faster
scylla
  master 3.104222518
  patch  3.059590248 1.01458766252x faster

llvm-svn: 283266
This commit is contained in:
Rafael Espindola 2016-10-04 22:43:25 +00:00
parent 9a78ebd6d8
commit 39751afc4e
7 changed files with 135 additions and 102 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
llvm/include/llvm/MC/StringTableBuilder.h
View File

@ -15,6 +15,24 @@
#include <cassert>
namespace llvm {
class raw_ostream;
class CachedHashString {
const char *P;
uint32_t Size;
uint32_t Hash;
public:
CachedHashString(StringRef S)
: CachedHashString(S, DenseMapInfo<StringRef>::getHashValue(S)) {}
CachedHashString(StringRef S, uint32_t Hash)
: P(S.data()), Size(S.size()), Hash(Hash) {
assert(S.size() <= std::numeric_limits<uint32_t>::max());
}
StringRef val() const { return StringRef(P, Size); }
uint32_t hash() const { return Hash; }
};
/// \brief Utility for building string tables with deduplicated suffixes.
class StringTableBuilder {
@ -22,16 +40,18 @@ public:
enum Kind { ELF, WinCOFF, MachO, RAW };
private:
SmallString<256> StringTable;
DenseMap<CachedHash<StringRef>, size_t> StringIndexMap;
DenseMap<CachedHashString, size_t> StringIndexMap;
size_t Size = 0;
Kind K;
unsigned Alignment;
bool Finalized = false;
void finalizeStringTable(bool Optimize);
void initSize();
public:
StringTableBuilder(Kind K, unsigned Alignment = 1);
~StringTableBuilder();
/// \brief Add a string to the builder. Returns the position of S in the
/// table. The position will be changed if finalize is used.
@ -46,28 +66,18 @@ public:
/// returned by add will still be valid.
void finalizeInOrder();
/// \brief Retrieve the string table data. Can only be used after the table
/// is finalized.
StringRef data() const {
assert(isFinalized());
return StringTable;
}
/// \brief Get the offest of a string in the string table. Can only be used
/// after the table is finalized.
size_t getOffset(StringRef S) const;
const DenseMap<CachedHash<StringRef>, size_t> &getMap() const {
return StringIndexMap;
}
size_t getSize() const { return Size; }
void clear();
void write(raw_ostream &OS) const;
void write(uint8_t *Buf) const;
private:
bool isFinalized() const {
return !StringTable.empty();
}
bool isFinalized() const { return Finalized; }
};
} // end llvm namespace

2
llvm/lib/MC/ELFObjectWriter.cpp
View File

@ -1127,7 +1127,7 @@ void ELFObjectWriter::writeRelocations(const MCAssembler &Asm,
const MCSectionELF *ELFObjectWriter::createStringTable(MCContext &Ctx) {
const MCSectionELF *StrtabSection = SectionTable[StringTableIndex - 1];
getStream() << StrTabBuilder.data();
StrTabBuilder.write(getStream());
return StrtabSection;
}

4
llvm/lib/MC/MachObjectWriter.cpp
View File

@ -882,7 +882,7 @@ void MachObjectWriter::writeObject(MCAssembler &Asm,
sizeof(MachO::nlist_64) :
sizeof(MachO::nlist));
writeSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols,
StringTableOffset, StringTable.data().size());
StringTableOffset, StringTable.getSize());
writeDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols,
FirstExternalSymbol, NumExternalSymbols,
@ -977,7 +977,7 @@ void MachObjectWriter::writeObject(MCAssembler &Asm,
writeNlist(Entry, Layout);
// Write the string table.
getStream() << StringTable.data();
StringTable.write(getStream());
}
}

162
llvm/lib/MC/StringTableBuilder.cpp
View File

@ -11,13 +11,37 @@
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/COFF.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/raw_ostream.h"
#include <vector>
using namespace llvm;
StringTableBuilder::StringTableBuilder(Kind K, unsigned Alignment)
: K(K), Alignment(Alignment) {
namespace llvm {
template <> struct DenseMapInfo<CachedHashString> {
static CachedHashString getEmptyKey() {
StringRef S = DenseMapInfo<StringRef>::getEmptyKey();
return {S, 0};
}
static CachedHashString getTombstoneKey() {
StringRef S = DenseMapInfo<StringRef>::getTombstoneKey();
return {S, 0};
}
static unsigned getHashValue(CachedHashString Val) {
assert(!isEqual(Val, getEmptyKey()) && "Cannot hash the empty key!");
assert(!isEqual(Val, getTombstoneKey()) &&
"Cannot hash the tombstone key!");
return Val.hash();
}
static bool isEqual(CachedHashString A, CachedHashString B) {
return DenseMapInfo<StringRef>::isEqual(A.val(), B.val());
}
};
}
StringTableBuilder::~StringTableBuilder() {}
void StringTableBuilder::initSize() {
// Account for leading bytes in table so that offsets returned from add are
// correct.
switch (K) {
@ -26,19 +50,45 @@ StringTableBuilder::StringTableBuilder(Kind K, unsigned Alignment)
break;
case MachO:
case ELF:
// Start the table with a NUL byte.
Size = 1;
break;
case WinCOFF:
// Make room to write the table size later.
Size = 4;
break;
}
}
typedef std::pair<CachedHash<StringRef>, size_t> StringPair;
StringTableBuilder::StringTableBuilder(Kind K, unsigned Alignment)
: K(K), Alignment(Alignment) {
initSize();
}
void StringTableBuilder::write(raw_ostream &OS) const {
assert(isFinalized());
SmallString<0> Data;
Data.resize(getSize());
write((uint8_t *)&Data[0]);
OS << Data;
}
typedef std::pair<CachedHashString, size_t> StringPair;
void StringTableBuilder::write(uint8_t *Buf) const {
assert(isFinalized());
for (const StringPair &P : StringIndexMap) {
StringRef Data = P.first.val();
memcpy(Buf + P.second, Data.data(), Data.size());
}
if (K != WinCOFF)
return;
support::endian::write32le(Buf, Size);
}
// Returns the character at Pos from end of a string.
static int charTailAt(StringPair *P, size_t Pos) {
StringRef S = P->first.Val;
StringRef S = P->first.val();
if (Pos >= S.size())
return -1;
return (unsigned char)S[S.size() - Pos - 1];
@ -86,90 +136,49 @@ void StringTableBuilder::finalizeInOrder() {
}
void StringTableBuilder::finalizeStringTable(bool Optimize) {
std::vector<StringPair *> Strings;
Strings.reserve(StringIndexMap.size());
for (StringPair &P : StringIndexMap)
Strings.push_back(&P);
Finalized = true;
if (!Strings.empty()) {
// If we're optimizing, sort by name. If not, sort by previously assigned
// offset.
if (Optimize) {
if (Optimize) {
std::vector<StringPair *> Strings;
Strings.reserve(StringIndexMap.size());
for (StringPair &P : StringIndexMap)
Strings.push_back(&P);
if (!Strings.empty()) {
// If we're optimizing, sort by name. If not, sort by previously assigned
// offset.
multikey_qsort(&Strings[0], &Strings[0] + Strings.size(), 0);
} else {
std::sort(Strings.begin(), Strings.end(),
[](const StringPair *LHS, const StringPair *RHS) {
return LHS->second < RHS->second;
});
}
}
switch (K) {
case RAW:
break;
case ELF:
case MachO:
// Start the table with a NUL byte.
StringTable += '\x00';
break;
case WinCOFF:
// Make room to write the table size later.
StringTable.append(4, '\x00');
break;
}
initSize();
StringRef Previous;
for (StringPair *P : Strings) {
StringRef S = P->first.Val;
if (K == WinCOFF)
assert(S.size() > COFF::NameSize && "Short string in COFF string table!");
if (Optimize && Previous.endswith(S)) {
size_t Pos = StringTable.size() - S.size() - (K != RAW);
if (!(Pos & (Alignment - 1))) {
P->second = Pos;
continue;
StringRef Previous;
for (StringPair *P : Strings) {
StringRef S = P->first.val();
if (Previous.endswith(S)) {
size_t Pos = Size - S.size() - (K != RAW);
if (!(Pos & (Alignment - 1))) {
P->second = Pos;
continue;
}
}
}
if (Optimize) {
size_t Start = alignTo(StringTable.size(), Alignment);
P->second = Start;
StringTable.append(Start - StringTable.size(), '\0');
} else {
assert(P->second == StringTable.size() &&
"different strtab offset after finalization");
}
Size = alignTo(Size, Alignment);
P->second = Size;
StringTable += S;
if (K != RAW)
StringTable += '\x00';
Previous = S;
Size += S.size();
if (K != RAW)
++Size;
Previous = S;
}
}
switch (K) {
case RAW:
case ELF:
break;
case MachO:
// Pad to multiple of 4.
while (StringTable.size() % 4)
StringTable += '\x00';
break;
case WinCOFF:
// Write the table size in the first word.
assert(StringTable.size() <= std::numeric_limits<uint32_t>::max());
uint32_t Size = static_cast<uint32_t>(StringTable.size());
support::endian::write<uint32_t, support::little, support::unaligned>(
StringTable.data(), Size);
break;
}
Size = StringTable.size();
if (K == MachO)
Size = alignTo(Size, 4); // Pad to multiple of 4.
}
void StringTableBuilder::clear() {
StringTable.clear();
Finalized = false;
StringIndexMap.clear();
}
@ -181,6 +190,9 @@ size_t StringTableBuilder::getOffset(StringRef S) const {
}
size_t StringTableBuilder::add(StringRef S) {
if (K == WinCOFF)
assert(S.size() > COFF::NameSize && "Short string in COFF string table!");
assert(!isFinalized());
size_t Start = alignTo(Size, Alignment);
auto P = StringIndexMap.insert(std::make_pair(S, Start));

2
llvm/lib/MC/WinCOFFObjectWriter.cpp
View File

@ -1082,7 +1082,7 @@ void WinCOFFObjectWriter::writeObject(MCAssembler &Asm,
if (Symbol->getIndex() != -1)
WriteSymbol(*Symbol);
getStream().write(Strings.data().data(), Strings.data().size());
Strings.write(getStream());
}
MCWinCOFFObjectTargetWriter::MCWinCOFFObjectTargetWriter(unsigned Machine_)

5
llvm/tools/yaml2obj/yaml2elf.cpp
View File

@ -305,9 +305,8 @@ void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
zero(SHeader);
SHeader.sh_name = DotShStrtab.getOffset(Name);
SHeader.sh_type = ELF::SHT_STRTAB;
CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign)
<< STB.data();
SHeader.sh_size = STB.data().size();
STB.write(CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign));
SHeader.sh_size = STB.getSize();
SHeader.sh_addralign = 1;
}

20
llvm/unittests/MC/StringTableBuilderTest.cpp
View File

@ -32,7 +32,11 @@ TEST(StringTableBuilderTest, BasicELF) {
Expected += "foo";
Expected += '\x00';
EXPECT_EQ(Expected, B.data());
SmallString<64> Data;
raw_svector_ostream OS(Data);
B.write(OS);
EXPECT_EQ(Expected, Data);
EXPECT_EQ(1U, B.getOffset("foobar"));
EXPECT_EQ(4U, B.getOffset("bar"));
EXPECT_EQ(8U, B.getOffset("foo"));
@ -50,7 +54,7 @@ TEST(StringTableBuilderTest, BasicWinCOFF) {
// size_field + "pygmy hippopotamus\0" + "river horse\0"
uint32_t ExpectedSize = 4 + 19 + 12;
EXPECT_EQ(ExpectedSize, B.data().size());
EXPECT_EQ(ExpectedSize, B.getSize());
std::string Expected;
@ -62,7 +66,11 @@ TEST(StringTableBuilderTest, BasicWinCOFF) {
Expected += "river horse";
Expected += '\x00';
EXPECT_EQ(Expected, B.data());
SmallString<64> Data;
raw_svector_ostream OS(Data);
B.write(OS);
EXPECT_EQ(Expected, Data);
EXPECT_EQ(4U, B.getOffset("pygmy hippopotamus"));
EXPECT_EQ(10U, B.getOffset("hippopotamus"));
EXPECT_EQ(23U, B.getOffset("river horse"));
@ -85,7 +93,11 @@ TEST(StringTableBuilderTest, ELFInOrder) {
Expected += "foobar";
Expected += '\x00';
EXPECT_EQ(Expected, B.data());
SmallString<64> Data;
raw_svector_ostream OS(Data);
B.write(OS);
EXPECT_EQ(Expected, Data);
EXPECT_EQ(1U, B.getOffset("foo"));
EXPECT_EQ(5U, B.getOffset("bar"));
EXPECT_EQ(9U, B.getOffset("foobar"));