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author | Hans Wennborg <hans@hanshq.net> | 2014-04-30 16:25:02 +0000 |
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committer | Hans Wennborg <hans@hanshq.net> | 2014-04-30 16:25:02 +0000 |
commit | a8febf2283921157da1539c079cd74a55bf89a5a (patch) | |
tree | 9d35112077dfea406ecb273ab0ea1ee2e99292e1 /include | |
parent | b1c1b8a78dce82d3740316ddf94029696ba68674 (diff) | |
download | llvm-a8febf2283921157da1539c079cd74a55bf89a5a.tar.gz llvm-a8febf2283921157da1539c079cd74a55bf89a5a.tar.bz2 llvm-a8febf2283921157da1539c079cd74a55bf89a5a.tar.xz |
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
Diffstat (limited to 'include')
-rw-r--r-- | include/llvm/Object/StringTableBuilder.h | 59 |
1 files changed, 59 insertions, 0 deletions
diff --git a/include/llvm/Object/StringTableBuilder.h b/include/llvm/Object/StringTableBuilder.h new file mode 100644 index 0000000000..c61e216bdf --- /dev/null +++ b/include/llvm/Object/StringTableBuilder.h @@ -0,0 +1,59 @@ +//===-- 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 |