On Tue, 16 Jan 2024 23:51:15 GMT, Scott Gibbons <sgibb...@openjdk.org> wrote:
>> 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. Thank you for explanation. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/16753#discussion_r1454238988