8b3f623582
Summary:
Summary: Keep history of macro definitions and #undefs with corresponding source locations, so that we can later find out all macros active in a specified source location. We don't save the history in PCH (no need currently). Memory overhead is about sizeof(void*)*3*<number of macro definitions and #undefs>+<in-memory size of all #undef'd macros>
I've run a test on a file composed of 109 .h files from boost 1.49 on x86-64 linux.
Stats before this patch:
*** Preprocessor Stats:
73222 directives found:
19171 #define.
4345 #undef.
#include/#include_next/#import:
5233 source files entered.
27 max include stack depth
19210 #if/#ifndef/#ifdef.
2384 #else/#elif.
6891 #endif.
408 #pragma.
14466 #if/#ifndef#ifdef regions skipped
80023/451669/1270 obj/fn/builtin macros expanded, 85724 on the fast path.
127145 token paste (##) operations performed, 11008 on the fast path.
Preprocessor Memory: 5874615B total
BumpPtr: 4399104
Macro Expanded Tokens: 417768
Predefines Buffer: 8135
Macros: 1048576
#pragma push_macro Info: 0
Poison Reasons: 1024
Comment Handlers: 8
Stats with this patch:
...
Preprocessor Memory: 7541687B total
BumpPtr: 6066176
Macro Expanded Tokens: 417768
Predefines Buffer: 8135
Macros: 1048576
#pragma push_macro Info: 0
Poison Reasons: 1024
Comment Handlers: 8
In my test increase in memory usage is about 1.7Mb, which is ~28% of initial preprocessor's memory usage and about 0.8% of clang's total VMM allocation.
As for CPU overhead, it should only be noticeable when iterating over all macros, and should mostly consist of couple extra dereferences and one comparison per macro + skipping of #undef'd macros. It's less trivial to measure, though, as the preprocessor consumes a very small fraction of compilation time.
Reviewers: doug.gregor, klimek, rsmith, djasper
Reviewed By: doug.gregor
CC: cfe-commits, chandlerc
Differential Revision: http://llvm-reviews.chandlerc.com/D28
llvm-svn: 162810
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| examples | ||
| include | ||
| lib | ||
| runtime | ||
| test | ||
| tools | ||
| unittests | ||
| utils | ||
| www | ||
| .gitignore | ||
| CMakeLists.txt | ||
| INSTALL.txt | ||
| LICENSE.TXT | ||
| Makefile | ||
| ModuleInfo.txt | ||
| NOTES.txt | ||
| README.txt | ||
README.txt
//===----------------------------------------------------------------------===// // C Language Family Front-end //===----------------------------------------------------------------------===// Welcome to Clang. This is a compiler front-end for the C family of languages (C, C++, Objective-C, and Objective-C++) which is built as part of the LLVM compiler infrastructure project. Unlike many other compiler frontends, Clang is useful for a number of things beyond just compiling code: we intend for Clang to be host to a number of different source level tools. One example of this is the Clang Static Analyzer. If you're interested in more (including how to build Clang) it is best to read the relevant web sites. Here are some pointers: Information on Clang: http://clang.llvm.org/ Building and using Clang: http://clang.llvm.org/get_started.html Clang Static Analyzer: http://clang-analyzer.llvm.org/ Information on the LLVM project: http://llvm.org/ If you have questions or comments about Clang, a great place to discuss them is on the Clang development mailing list: http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev If you find a bug in Clang, please file it in the LLVM bug tracker: http://llvm.org/bugs/