mirror of https://github.com/python/cpython
214eb2cce5
* Add support for the BOLT post-link binary optimizer Using [bolt](https://github.com/llvm/llvm-project/tree/main/bolt) provides a fairly large speedup without any code or functionality changes. It provides roughly a 1% speedup on pyperformance, and a 4% improvement on the Pyston web macrobenchmarks. It is gated behind an `--enable-bolt` configure arg because not all toolchains and environments are supported. It has been tested on a Linux x86_64 toolchain, using llvm-bolt built from the LLVM 14.0.6 sources (their binary distribution of this version did not include bolt). Compared to [a previous attempt](https://github.com/faster-cpython/ideas/issues/224), this commit uses bolt's preferred "instrumentation" approach, as well as adds some non-PIE flags which enable much better optimizations from bolt. The effects of this change are a bit more dependent on CPU microarchitecture than other changes, since it optimizes i-cache behavior which seems to be a bit more variable between architectures. The 1%/4% numbers were collected on an Intel Skylake CPU, and on an AMD Zen 3 CPU I got a slightly larger speedup (2%/4%), and on a c6i.xlarge EC2 instance I got a slightly lower speedup (1%/3%). The low speedup on pyperformance is not entirely unexpected, because BOLT improves i-cache behavior, and the benchmarks in the pyperformance suite are small and tend to fit in i-cache. This change uses the existing pgo profiling task (`python -m test --pgo`), though I was able to measure about a 1% macrobenchmark improvement by using the macrobenchmarks as the training task. I personally think that both the PGO and BOLT tasks should be updated to use macrobenchmarks, but for the sake of splitting up the work this PR uses the existing pgo task. * Simplify the build flags * Add a NEWS entry * Update Makefile.pre.in Co-authored-by: Dong-hee Na <donghee.na92@gmail.com> * Update configure.ac Co-authored-by: Dong-hee Na <donghee.na92@gmail.com> * Add myself to ACKS * Add docs * Other review comments * fix tab/space issue * Make it more clear that --enable-bolt is experimental * Add link to bolt's github page Co-authored-by: Dong-hee Na <donghee.na92@gmail.com> |
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| .. | ||
| cmdline.rst | ||
| configure.rst | ||
| editors.rst | ||
| index.rst | ||
| mac.rst | ||
| unix.rst | ||
| venv-create.inc | ||
| win_installer.png | ||
| windows.rst | ||
