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[Object][Archive] Improve performance.
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Improve performance of iterating over children and accessing the member file
buffer by caching the file size and moving code out to the header.

This also makes getBuffer return a StringRef instead of a MemoryBuffer. Both
fixing a memory leak and removing a malloc.

This takes getBuffer from ~10% of the time in lld to unmeasurable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174272 91177308-0d34-0410-b5e6-96231b3b80d8
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@Bigcheese
Bigcheese committed Feb 3, 2013
1 parent d9d2f18 commit 0f76e64
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Showing 3 changed files with 106 additions and 104 deletions.
98 changes: 93 additions & 5 deletions include/llvm/Object/Archive.h
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Original file line number Diff line number Diff line change
Expand Up @@ -14,22 +14,78 @@
#ifndef LLVM_OBJECT_ARCHIVE_H
#define LLVM_OBJECT_ARCHIVE_H

#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Object/Binary.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MemoryBuffer.h"

namespace llvm {
namespace object {
struct ArchiveMemberHeader {
char Name[16];
char LastModified[12];
char UID[6];
char GID[6];
char AccessMode[8];
char Size[10]; ///< Size of data, not including header or padding.
char Terminator[2];

///! Get the name without looking up long names.
llvm::StringRef getName() const {
char EndCond;
if (Name[0] == '/' || Name[0] == '#')
EndCond = ' ';
else
EndCond = '/';
llvm::StringRef::size_type end =
llvm::StringRef(Name, sizeof(Name)).find(EndCond);
if (end == llvm::StringRef::npos)
end = sizeof(Name);
assert(end <= sizeof(Name) && end > 0);
// Don't include the EndCond if there is one.
return llvm::StringRef(Name, end);
}

uint64_t getSize() const {
uint64_t ret;
if (llvm::StringRef(Size, sizeof(Size)).rtrim(" ").getAsInteger(10, ret))
llvm_unreachable("Size is not an integer.");
return ret;
}
};

static const ArchiveMemberHeader *ToHeader(const char *base) {
return reinterpret_cast<const ArchiveMemberHeader *>(base);
}

class Archive : public Binary {
virtual void anchor();
public:
class Child {
const Archive *Parent;
/// \brief Includes header but not padding byte.
StringRef Data;
/// \brief Offset from Data to the start of the file.
uint16_t StartOfFile;

public:
Child(const Archive *p, StringRef d) : Parent(p), Data(d) {}
Child(const Archive *p, StringRef d) : Parent(p), Data(d) {
if (!p || d.empty())
return;
// Setup StartOfFile and PaddingBytes.
StartOfFile = sizeof(ArchiveMemberHeader);
// Don't include attached name.
StringRef Name = ToHeader(Data.data())->getName();
if (Name.startswith("#1/")) {
uint64_t NameSize;
if (Name.substr(3).rtrim(" ").getAsInteger(10, NameSize))
llvm_unreachable("Long name length is not an integer");
StartOfFile += NameSize;
}
}

bool operator ==(const Child &other) const {
return (Parent == other.Parent) && (Data.begin() == other.Data.begin());
Expand All @@ -39,16 +95,48 @@ class Archive : public Binary {
return Data.begin() < other.Data.begin();
}

Child getNext() const;
Child getNext() const {
size_t SpaceToSkip = Data.size();
// If it's odd, add 1 to make it even.
if (SpaceToSkip & 1)
++SpaceToSkip;

const char *NextLoc = Data.data() + SpaceToSkip;

// Check to see if this is past the end of the archive.
if (NextLoc >= Parent->Data->getBufferEnd())
return Child(Parent, StringRef(0, 0));

size_t NextSize =
sizeof(ArchiveMemberHeader) + ToHeader(NextLoc)->getSize();

return Child(Parent, StringRef(NextLoc, NextSize));
}

error_code getName(StringRef &Result) const;
int getLastModified() const;
int getUID() const;
int getGID() const;
int getAccessMode() const;
///! Return the size of the archive member without the header or padding.
uint64_t getSize() const;
/// \return the size of the archive member without the header or padding.
uint64_t getSize() const { return Data.size() - StartOfFile; }

StringRef getBuffer() const {
return StringRef(Data.data() + StartOfFile, getSize());
}

error_code getMemoryBuffer(OwningPtr<MemoryBuffer> &Result,
bool FullPath = false) const {
StringRef Name;
if (error_code ec = getName(Name))
return ec;
SmallString<128> Path;
Result.reset(MemoryBuffer::getMemBuffer(
getBuffer(), FullPath ? (Twine(Parent->getFileName()) + "(" + Name +
")").toStringRef(Path) : Name, false));
return error_code::success();
}

MemoryBuffer *getBuffer() const;
error_code getAsBinary(OwningPtr<Binary> &Result) const;
};

Expand Down
108 changes: 10 additions & 98 deletions lib/Object/Archive.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -14,53 +14,13 @@
#include "llvm/Object/Archive.h"
#include "llvm/ADT/APInt.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MemoryBuffer.h"

using namespace llvm;
using namespace object;

static const char *Magic = "!<arch>\n";

namespace {
struct ArchiveMemberHeader {
char Name[16];
char LastModified[12];
char UID[6];
char GID[6];
char AccessMode[8];
char Size[10]; ///< Size of data, not including header or padding.
char Terminator[2];

///! Get the name without looking up long names.
StringRef getName() const {
char EndCond;
if (Name[0] == '/' || Name[0] == '#')
EndCond = ' ';
else
EndCond = '/';
StringRef::size_type end = StringRef(Name, sizeof(Name)).find(EndCond);
if (end == StringRef::npos)
end = sizeof(Name);
assert(end <= sizeof(Name) && end > 0);
// Don't include the EndCond if there is one.
return StringRef(Name, end);
}

uint64_t getSize() const {
uint64_t ret;
if (StringRef(Size, sizeof(Size)).rtrim(" ").getAsInteger(10, ret))
llvm_unreachable("Size is not an integer.");
return ret;
}
};
}

static const ArchiveMemberHeader *ToHeader(const char *base) {
return reinterpret_cast<const ArchiveMemberHeader *>(base);
}


static bool isInternalMember(const ArchiveMemberHeader &amh) {
static const char *const internals[] = {
"/",
Expand All @@ -78,25 +38,6 @@ static bool isInternalMember(const ArchiveMemberHeader &amh) {

void Archive::anchor() { }

Archive::Child Archive::Child::getNext() const {
size_t SpaceToSkip = sizeof(ArchiveMemberHeader) +
ToHeader(Data.data())->getSize();
// If it's odd, add 1 to make it even.
if (SpaceToSkip & 1)
++SpaceToSkip;

const char *NextLoc = Data.data() + SpaceToSkip;

// Check to see if this is past the end of the archive.
if (NextLoc >= Parent->Data->getBufferEnd())
return Child(Parent, StringRef(0, 0));

size_t NextSize = sizeof(ArchiveMemberHeader) +
ToHeader(NextLoc)->getSize();

return Child(Parent, StringRef(NextLoc, NextSize));
}

error_code Archive::Child::getName(StringRef &Result) const {
StringRef name = ToHeader(Data.data())->getName();
// Check if it's a special name.
Expand Down Expand Up @@ -149,39 +90,12 @@ error_code Archive::Child::getName(StringRef &Result) const {
return object_error::success;
}

uint64_t Archive::Child::getSize() const {
uint64_t size = ToHeader(Data.data())->getSize();
// Don't include attached name.
StringRef name = ToHeader(Data.data())->getName();
if (name.startswith("#1/")) {
uint64_t name_size;
if (name.substr(3).rtrim(" ").getAsInteger(10, name_size))
llvm_unreachable("Long name length is not an integer");
size -= name_size;
}
return size;
}

MemoryBuffer *Archive::Child::getBuffer() const {
StringRef name = ToHeader(Data.data())->getName();
int size = sizeof(ArchiveMemberHeader);
if (name.startswith("#1/")) {
uint64_t name_size;
if (name.substr(3).rtrim(" ").getAsInteger(10, name_size))
llvm_unreachable("Long name length is not an integer");
size += name_size;
}
if (getName(name))
return 0;
return MemoryBuffer::getMemBuffer(Data.substr(size, getSize()),
name,
false);
}

error_code Archive::Child::getAsBinary(OwningPtr<Binary> &Result) const {
OwningPtr<Binary> ret;
if (error_code ec =
createBinary(getBuffer(), ret))
OwningPtr<MemoryBuffer> Buff;
if (error_code ec = getMemoryBuffer(Buff))
return ec;
if (error_code ec = createBinary(Buff.take(), ret))
return ec;
Result.swap(ret);
return object_error::success;
Expand Down Expand Up @@ -270,13 +184,12 @@ Archive::child_iterator Archive::end_children() const {
}

error_code Archive::Symbol::getName(StringRef &Result) const {
Result =
StringRef(Parent->SymbolTable->getBuffer()->getBufferStart() + StringIndex);
Result = StringRef(Parent->SymbolTable->getBuffer().begin() + StringIndex);
return object_error::success;
}

error_code Archive::Symbol::getMember(child_iterator &Result) const {
const char *Buf = Parent->SymbolTable->getBuffer()->getBufferStart();
const char *Buf = Parent->SymbolTable->getBuffer().begin();
const char *Offsets = Buf + 4;
uint32_t Offset = 0;
if (Parent->kind() == K_GNU) {
Expand Down Expand Up @@ -326,13 +239,13 @@ Archive::Symbol Archive::Symbol::getNext() const {
Symbol t(*this);
// Go to one past next null.
t.StringIndex =
Parent->SymbolTable->getBuffer()->getBuffer().find('\0', t.StringIndex) + 1;
Parent->SymbolTable->getBuffer().find('\0', t.StringIndex) + 1;
++t.SymbolIndex;
return t;
}

Archive::symbol_iterator Archive::begin_symbols() const {
const char *buf = SymbolTable->getBuffer()->getBufferStart();
const char *buf = SymbolTable->getBuffer().begin();
if (kind() == K_GNU) {
uint32_t symbol_count = 0;
symbol_count = *reinterpret_cast<const support::ubig32_t*>(buf);
Expand All @@ -347,13 +260,12 @@ Archive::symbol_iterator Archive::begin_symbols() const {
symbol_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
buf += 4 + (symbol_count * 2); // Skip indices.
}
uint32_t string_start_offset =
buf - SymbolTable->getBuffer()->getBufferStart();
uint32_t string_start_offset = buf - SymbolTable->getBuffer().begin();
return symbol_iterator(Symbol(this, 0, string_start_offset));
}

Archive::symbol_iterator Archive::end_symbols() const {
const char *buf = SymbolTable->getBuffer()->getBufferStart();
const char *buf = SymbolTable->getBuffer().begin();
uint32_t symbol_count = 0;
if (kind() == K_GNU) {
symbol_count = *reinterpret_cast<const support::ubig32_t*>(buf);
Expand Down
4 changes: 3 additions & 1 deletion tools/llvm-nm/llvm-nm.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -384,7 +384,9 @@ static void DumpSymbolNamesFromFile(std::string &Filename) {
OwningPtr<Binary> child;
if (i->getAsBinary(child)) {
// Try opening it as a bitcode file.
OwningPtr<MemoryBuffer> buff(i->getBuffer());
OwningPtr<MemoryBuffer> buff;
if (error(i->getMemoryBuffer(buff)))
return;
Module *Result = 0;
if (buff)
Result = ParseBitcodeFile(buff.get(), Context, &ErrorMessage);
Expand Down

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