llvm-6502/include/llvm/Object/StringTableBuilder.h
Hans Wennborg a8febf2283 ELFObjectWriter: deduplicate suffices in strtab
We already do this for shstrtab, so might as well do it for strtab. This
extracts the string table building code into a separate class. The idea
is to use it for other object formats too.

I mostly wanted to do this for the general principle, but it does save a
little bit on object file size. I tried this on a clang bootstrap and
saved 0.54% on the sum of object file sizes (1.14 MB out of 212 MB for
a release build).

Differential Revision: http://reviews.llvm.org/D3533

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207670 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-30 16:25:02 +00:00

60 lines
1.6 KiB
C++

//===-- StringTableBuilder.h - String table building utility ------*- C++ -*-=//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_OBJECT_STRINGTABLE_BUILDER_H
#define LLVM_OBJECT_STRINGTABLE_BUILDER_H
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringMap.h"
#include <cassert>
namespace llvm {
/// \brief Utility for building string tables with deduplicated suffixes.
class StringTableBuilder {
SmallString<256> StringTable;
StringMap<size_t> StringIndexMap;
public:
/// \brief Add a string to the builder. Returns a StringRef to the internal
/// copy of s. Can only be used before the table is finalized.
StringRef add(StringRef s) {
assert(!isFinalized());
return StringIndexMap.GetOrCreateValue(s, 0).getKey();
}
/// \brief Analyze the strings and build the final table. No more strings can
/// be added after this point.
void finalize();
/// \brief Retrieve the string table data. Can only be used after the table
/// is finalized.
StringRef data() {
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) {
assert(isFinalized());
assert(StringIndexMap.count(s) && "String is not in table!");
return StringIndexMap[s];
}
private:
bool isFinalized() {
return !StringTable.empty();
}
};
} // end llvm namespace
#endif