On Tue, 16 Jan 2024 22:27:52 GMT, Vladimir Kozlov <k...@openjdk.org> wrote:
>> Scott Gibbons has updated the pull request with a new target base due to a >> merge or a rebase. The pull request now contains 22 commits: >> >> - Merge branch 'openjdk:master' into indexof >> - Merge branch 'openjdk:master' into indexof >> - Addressing review comments. >> - Fix for JDK-8321599 >> - Support UU IndexOf >> - Only use optimization when EnableX86ECoreOpts is true >> - Fix whitespace >> - Merge branch 'openjdk:master' into indexof >> - Comments; added exhaustive-ish test >> - Subtracting 0x10 twice. >> - ... and 12 more: https://git.openjdk.org/jdk/compare/8e12053e...3e58d0c2 > > src/hotspot/cpu/x86/stubGenerator_x86_64.cpp line 4111: > >> 4109: if ((UseAVX == 2) && EnableX86ECoreOpts && >> VM_Version::supports_avx2()) { >> 4110: StubRoutines::_string_indexof = generate_string_indexof(); >> 4111: } > > What motivation for this extensive new code only for avx2? 30% is nice (for > some cases) but it is enabled only for AVX2 and not for avx512 which all > modern x86 CPUs have so the code will not be used. > > Or it is typo? This is acceleration for AVX2, replacing the pcmpestri instruction which is microcoded on E-cores and causes significant performance impact. I am working on a pared-down implementation and should update this PR in a couple of days. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1454217437
