llvm-6502/lib/Object/Archive.cpp
Michael J. Spencer 0f76e648d8 [Object][Archive] Improve performance.
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
2013-02-03 10:48:50 +00:00

302 lines
9.5 KiB
C++

//===- Archive.cpp - ar File Format implementation --------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the ArchiveObjectFile class.
//
//===----------------------------------------------------------------------===//
#include "llvm/Object/Archive.h"
#include "llvm/ADT/APInt.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/MemoryBuffer.h"
using namespace llvm;
using namespace object;
static const char *Magic = "!<arch>\n";
static bool isInternalMember(const ArchiveMemberHeader &amh) {
static const char *const internals[] = {
"/",
"//",
"#_LLVM_SYM_TAB_#"
};
StringRef name = amh.getName();
for (std::size_t i = 0; i < sizeof(internals) / sizeof(*internals); ++i) {
if (name == internals[i])
return true;
}
return false;
}
void Archive::anchor() { }
error_code Archive::Child::getName(StringRef &Result) const {
StringRef name = ToHeader(Data.data())->getName();
// Check if it's a special name.
if (name[0] == '/') {
if (name.size() == 1) { // Linker member.
Result = name;
return object_error::success;
}
if (name.size() == 2 && name[1] == '/') { // String table.
Result = name;
return object_error::success;
}
// It's a long name.
// Get the offset.
std::size_t offset;
if (name.substr(1).rtrim(" ").getAsInteger(10, offset))
llvm_unreachable("Long name offset is not an integer");
const char *addr = Parent->StringTable->Data.begin()
+ sizeof(ArchiveMemberHeader)
+ offset;
// Verify it.
if (Parent->StringTable == Parent->end_children()
|| addr < (Parent->StringTable->Data.begin()
+ sizeof(ArchiveMemberHeader))
|| addr > (Parent->StringTable->Data.begin()
+ sizeof(ArchiveMemberHeader)
+ Parent->StringTable->getSize()))
return object_error::parse_failed;
// GNU long file names end with a /.
if (Parent->kind() == K_GNU) {
StringRef::size_type End = StringRef(addr).find('/');
Result = StringRef(addr, End);
} else {
Result = addr;
}
return object_error::success;
} else 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 ingeter");
Result = Data.substr(sizeof(ArchiveMemberHeader), name_size);
return object_error::success;
}
// It's a simple name.
if (name[name.size() - 1] == '/')
Result = name.substr(0, name.size() - 1);
else
Result = name;
return object_error::success;
}
error_code Archive::Child::getAsBinary(OwningPtr<Binary> &Result) const {
OwningPtr<Binary> 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;
}
Archive::Archive(MemoryBuffer *source, error_code &ec)
: Binary(Binary::ID_Archive, source) {
// Check for sufficient magic.
if (!source || source->getBufferSize()
< (8 + sizeof(ArchiveMemberHeader) + 2) // Smallest archive.
|| StringRef(source->getBufferStart(), 8) != Magic) {
ec = object_error::invalid_file_type;
return;
}
// Get the special members.
child_iterator i = begin_children(false);
child_iterator e = end_children();
StringRef name;
if ((ec = i->getName(name)))
return;
// Below is the pattern that is used to figure out the archive format
// GNU archive format
// First member : / (points to the symbol table )
// Second member : // (may exist, if it exists, points to the string table)
// Note : The string table is used if the filename exceeds 15 characters
// BSD archive format
// First member : __.SYMDEF (points to the symbol table)
// There is no string table, if the filename exceeds 15 characters or has a
// embedded space, the filename has #1/<size>, The size represents the size
// of the filename that needs to be read after the archive header
// COFF archive format
// First member : /
// Second member : / (provides a directory of symbols)
// Third member : // contains the string table, this is present even if the
// string table is empty
if (name == "/") {
SymbolTable = i;
StringTable = e;
if (i != e) ++i;
if (i == e) {
ec = object_error::parse_failed;
return;
}
if ((ec = i->getName(name)))
return;
if (name[0] != '/') {
Format = K_GNU;
} else if ((name.size() > 1) && (name == "//")) {
Format = K_GNU;
StringTable = i;
++i;
} else {
Format = K_COFF;
if (i != e) {
SymbolTable = i;
++i;
}
if (i != e) {
StringTable = i;
}
}
} else if (name == "__.SYMDEF") {
Format = K_BSD;
SymbolTable = i;
StringTable = e;
}
ec = object_error::success;
}
Archive::child_iterator Archive::begin_children(bool skip_internal) const {
const char *Loc = Data->getBufferStart() + strlen(Magic);
size_t Size = sizeof(ArchiveMemberHeader) +
ToHeader(Loc)->getSize();
Child c(this, StringRef(Loc, Size));
// Skip internals at the beginning of an archive.
if (skip_internal && isInternalMember(*ToHeader(Loc)))
return c.getNext();
return c;
}
Archive::child_iterator Archive::end_children() const {
return Child(this, StringRef(0, 0));
}
error_code Archive::Symbol::getName(StringRef &Result) const {
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().begin();
const char *Offsets = Buf + 4;
uint32_t Offset = 0;
if (Parent->kind() == K_GNU) {
Offset = *(reinterpret_cast<const support::ubig32_t*>(Offsets)
+ SymbolIndex);
} else if (Parent->kind() == K_BSD) {
llvm_unreachable("BSD format is not supported");
} else {
uint32_t MemberCount = *reinterpret_cast<const support::ulittle32_t*>(Buf);
// Skip offsets.
Buf += sizeof(support::ulittle32_t)
+ (MemberCount * sizeof(support::ulittle32_t));
uint32_t SymbolCount = *reinterpret_cast<const support::ulittle32_t*>(Buf);
if (SymbolIndex >= SymbolCount)
return object_error::parse_failed;
// Skip SymbolCount to get to the indices table.
const char *Indices = Buf + sizeof(support::ulittle32_t);
// Get the index of the offset in the file member offset table for this
// symbol.
uint16_t OffsetIndex =
*(reinterpret_cast<const support::ulittle16_t*>(Indices)
+ SymbolIndex);
// Subtract 1 since OffsetIndex is 1 based.
--OffsetIndex;
if (OffsetIndex >= MemberCount)
return object_error::parse_failed;
Offset = *(reinterpret_cast<const support::ulittle32_t*>(Offsets)
+ OffsetIndex);
}
const char *Loc = Parent->getData().begin() + Offset;
size_t Size = sizeof(ArchiveMemberHeader) +
ToHeader(Loc)->getSize();
Result = Child(Parent, StringRef(Loc, Size));
return object_error::success;
}
Archive::Symbol Archive::Symbol::getNext() const {
Symbol t(*this);
// Go to one past next null.
t.StringIndex =
Parent->SymbolTable->getBuffer().find('\0', t.StringIndex) + 1;
++t.SymbolIndex;
return t;
}
Archive::symbol_iterator Archive::begin_symbols() const {
const char *buf = SymbolTable->getBuffer().begin();
if (kind() == K_GNU) {
uint32_t symbol_count = 0;
symbol_count = *reinterpret_cast<const support::ubig32_t*>(buf);
buf += sizeof(uint32_t) + (symbol_count * (sizeof(uint32_t)));
} else if (kind() == K_BSD) {
llvm_unreachable("BSD archive format is not supported");
} else {
uint32_t member_count = 0;
uint32_t symbol_count = 0;
member_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
buf += 4 + (member_count * 4); // Skip offsets.
symbol_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
buf += 4 + (symbol_count * 2); // Skip indices.
}
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().begin();
uint32_t symbol_count = 0;
if (kind() == K_GNU) {
symbol_count = *reinterpret_cast<const support::ubig32_t*>(buf);
buf += sizeof(uint32_t) + (symbol_count * (sizeof(uint32_t)));
} else if (kind() == K_BSD) {
llvm_unreachable("BSD archive format is not supported");
} else {
uint32_t member_count = 0;
member_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
buf += 4 + (member_count * 4); // Skip offsets.
symbol_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
}
return symbol_iterator(
Symbol(this, symbol_count, 0));
}
Archive::child_iterator Archive::findSym(StringRef name) const {
Archive::symbol_iterator bs = begin_symbols();
Archive::symbol_iterator es = end_symbols();
Archive::child_iterator result;
StringRef symname;
for (; bs != es; ++bs) {
if (bs->getName(symname))
return end_children();
if (symname == name) {
if (bs->getMember(result))
return end_children();
return result;
}
}
return end_children();
}