MyDeveloperDay added a comment. We don't really have any performance tests, but the following shows some analysis, all builds are release build:
- clang-format-ns is built with this change (compiled with VS2017) - clang-format is without (compiled with VS2017) - c:/Program\ Files/LLVM/bin/clang-format is the last Feb 2020 snapshot build version of clang-format (probably compiled with clang-cl) - build_release_cl/clang-format with this change (compiled with clang-cl from Fab2020 snapshot) _ build_2019/clang-format with this change (compiled with VS2019) The test is to run clang-format over the largest file in LLVM ./libcxxabi/test/test_demangle.pass.cpp is 5.2M in size = 30,000 lines, 29799 opening and closing braces For a file this size I think I'd expect IO to dominate (I'm running this test on an Intel i7-800 CPU @3,.20GHz with an SSD, Running cygwin in Windows 10) I've run these tests multiple times and they are often the same or similar timings (I'm running the base clang-format as a benchmark twice because the first run is often slower time /clang/build_release/bin/clang-format ../libcxxabi/test/test_demangle.pass.cpp > speed1 (Baseline to get test_demangle.pass.cpp into system cache) real 0m3.957s user 0m0.000s sys 0m0.000s time /clang/build_release/bin/clang-format-ns ../libcxxabi/test/test_demangle.pass.cpp > speed1 real 0m3.994s user 0m0.000s sys 0m0.000s time /clang/build_release/bin/clang-format ../libcxxabi/test/test_demangle.pass.cpp > speed1 real 0m3.990s user 0m0.000s sys 0m0.000s time c:/Program\ Files/LLVM/bin/clang-format ../libcxxabi/test/test_demangle.pass.cpp > speed1 real 0m3.793s user 0m0.000s sys 0m0.000s time /clang/build_release_cl/bin/clang-format ../libcxxabi/test/test_demangle.pass.cpp > speed1 real 0m3.442s user 0m0.000s sys 0m0.000s time /clang/build_2019/bin/clang-format ../libcxxabi/test/test_demangle.pass.cpp > speed1 real 0m3.820s user 0m0.000s sys 0m0.000s The speed difference of this change of clang-format is fairly negligible, varying by about +/-20ms one way or the other (often swinging the other between runs or depending on which goes first) I feel this change is relatively low impact, (perhaps the loop could be moved into some earlier equivalent loop but for clarity, I think it's ok here for now.) I'm not 100% sure how we could reliably test performance generally in clang-format, but I think it would be good to have something. The key takeaway is likely that clang-cl is quicker! and it obviously more about which compiler you choose. Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D80830/new/ https://reviews.llvm.org/D80830 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
