I've put some work into the Google Benchmark library in order to make it easier
to benchmark libc++. These changes have already been upstreamed into
Google Benchmark and this patch applies the changes to the in-tree version.
The main improvement in the addition of a 'compare_bench.py' script which
makes it very easy to compare benchmarks. For example to compare the native
STL to libc++ you would run:
`$ compare_bench.py ./util_smartptr.native.out ./util_smartptr.libcxx.out`
And the output would look like:
RUNNING: ./util_smartptr.native.out
Benchmark Time CPU Iterations
----------------------------------------------------------------
BM_SharedPtrCreateDestroy 62 ns 62 ns 10937500
BM_SharedPtrIncDecRef 31 ns 31 ns 23972603
BM_WeakPtrIncDecRef 28 ns 28 ns 23648649
RUNNING: ./util_smartptr.libcxx.out
Benchmark Time CPU Iterations
----------------------------------------------------------------
BM_SharedPtrCreateDestroy 46 ns 46 ns 14957265
BM_SharedPtrIncDecRef 31 ns 31 ns 22435897
BM_WeakPtrIncDecRef 34 ns 34 ns 21084337
Comparing ./util_smartptr.native.out to ./util_smartptr.libcxx.out
Benchmark Time CPU
-----------------------------------------------------
BM_SharedPtrCreateDestroy -0.26 -0.26
BM_SharedPtrIncDecRef +0.00 +0.00
BM_WeakPtrIncDecRef +0.21 +0.21
llvm-svn: 278147
Summary:
This patch does the following:
1. Checks in a copy of the Google Benchmark library into the libc++ repo under `utils/google-benchmark`.
2. Teaches libc++ how to build Google Benchmark against both (A) in-tree libc++ and (B) the platforms native STL.
3. Allows performance benchmarks to be built as part of the libc++ build.
Building the benchmarks (and Google Benchmark) is off by default. It must be enabled using the CMake option `-DLIBCXX_INCLUDE_BENCHMARKS=ON`. When this option is enabled the tests under `libcxx/benchmarks` can be built using the `libcxx-benchmarks` target.
On Linux platforms where libstdc++ is the default STL the CMake option `-DLIBCXX_BUILD_BENCHMARKS_NATIVE_STDLIB=ON` can be used to build each benchmark test against libstdc++ as well. This is useful for comparing performance between standard libraries.
Support for benchmarks is currently very minimal. They must be manually run by the user and there is no mechanism for detecting performance regressions.
Known Issues:
* `-DLIBCXX_INCLUDE_BENCHMARKS=ON` is only supported for Clang, and not GCC, since the `-stdlib=libc++` option is needed to build Google Benchmark.
Reviewers: danalbert, dberlin, chandlerc, mclow.lists, jroelofs
Subscribers: chandlerc, dberlin, tberghammer, danalbert, srhines, hfinkel
Differential Revision: https://reviews.llvm.org/D22240
llvm-svn: 276049
Summary:
Currently on most platforms you have to manually link the c++ abi library used with libc++ whenever you use libc++. So your typical libc++ command like invocation might look like:
```
clang++ -stdlib=libc++ foo.cpp -lc++abi
```
Having to manually link `libc++abi.so` makes it harder for libc++ to be used generically. This patch fixes that by generating a linker script for `libc++.so` that correctly links the ABI library. On linux the linker script for libc++abi would look like:
```
# libc++.so
INPUT(libc++.so.1 -lc++abi)
```
With the linker script you can now use libc++ using only `-stdlib=libc++`. This is the technique that is used on FreeBSD in ordered to link cxxrt and I think it's the best approach to make our users lives simpler.
The CMake option used to enable this is `LIBCXX_ENABLE_ABI_LINKER_SCRIPT`. In future I would like to enable this by default on all platforms except for Darwin.
Reviewers: mclow.lists, danalbert, rsmith, jroelofs, EricWF
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D12508
llvm-svn: 250319
Summary:
Add symbol checking scripts for extracting a list of symbols from shared libraries and for comparing symbol lists for differences.
Reviewers: mclow.lists, danalbert, EricWF
Reviewed By: EricWF
Subscribers: majnemer, emaste, cfe-commits
Differential Revision: http://reviews.llvm.org/D4946
llvm-svn: 232855
Summary:
This patch allows the use of LIT's ShTest format in the libc++ test suite. ShTests have the suffix '.sh.cpp'. It also introduces a series of other changes. These changes are:
- More functionality including parsing test metadata has been moved into LIT.
- LibcxxTestFormat now supports multi-part suffixes.
- the `CXXCompiler` functionality has been used to shrink the size of LibcxxTestFormat.
- The recursive loading of the site config has been turned into `libcxx.test.config.loadSiteConfig` so it can be used with libc++abi.
- Temporary files are now created in the build directory of libc++. This follows how it is down in ShTest.
- `not.py` was added as a utility executable that mirrors the functionality of LLVM's `not` executable.
- The first ShTest test was added under test/libcxx/double_include.sh.cpp
Reviewers: jroelofs, danalbert
Reviewed By: danalbert
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D7073
llvm-svn: 226844
Eric Fiselier