On Mon, 16 Aug 2021 20:59:55 GMT, TatWai Chong <github.com+78814694+tatwaich...@openjdk.org> wrote:
> This patch implements string_compare intrinsic in SVE. > It supports all LL, LU, UL and UU comparisons. > > As we haven't found an existing benchmark to measure performance impact, > we created a benchmark derived from the test [1] for this evaluation. > This benchmark is attached to this patch. > > Besides, remove the unused temporary register `vtmp3` from the existing > match rules for StrCmp. > > The result below shows all varients can be benefited largely. > Command: make exploded-test TEST="micro:StringCompareToDifferentLength" > > Benchmark (size) Mode Cnt Score Speedup Units > compareToLL 24 avgt 10 1.0x ms/op > compareToLL 36 avgt 10 1.0x ms/op > compareToLL 72 avgt 10 1.0x ms/op > compareToLL 128 avgt 10 1.4x ms/op > compareToLL 256 avgt 10 1.8x ms/op > compareToLL 512 avgt 10 2.7x ms/op > compareToLU 24 avgt 10 1.6x ms/op > compareToLU 36 avgt 10 1.8x ms/op > compareToLU 72 avgt 10 2.3x ms/op > compareToLU 128 avgt 10 3.8x ms/op > compareToLU 256 avgt 10 4.7x ms/op > compareToLU 512 avgt 10 6.3x ms/op > compareToUL 24 avgt 10 1.6x ms/op > compareToUL 36 avgt 10 1.7x ms/op > compareToUL 72 avgt 10 2.2x ms/op > compareToUL 128 avgt 10 3.3x ms/op > compareToUL 256 avgt 10 4.4x ms/op > compareToUL 512 avgt 10 6.1x ms/op > compareToUU 24 avgt 10 1.0x ms/op > compareToUU 36 avgt 10 1.0x ms/op > compareToUU 72 avgt 10 1.4x ms/op > compareToUU 128 avgt 10 2.2x ms/op > compareToUU 256 avgt 10 2.6x ms/op > compareToUU 512 avgt 10 3.7x ms/op > > [1] > https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/compiler/intrinsics/string/TestStringCompareToDifferentLength.java src/hotspot/cpu/aarch64/aarch64.ad line 16515: > 16513: instruct string_compareUL(iRegP_R1 str1, iRegI_R2 cnt1, iRegP_R3 str2, > iRegI_R4 cnt2, > 16514: iRegI_R0 result, iRegP_R10 tmp1, iRegL_R11 > tmp2, > 16515: vRegD_V0 vtmp1, vRegD_V1 vtmp2, vRegD_V2 > vtmp3, rFlagsReg cr) I think vtmp3 (=V2) is still used by the non-SVE compare-long-strings stub? (see `generate_compare_long_string_different_encoding`) ------------- PR: https://git.openjdk.java.net/jdk/pull/5129
