8269559: AArch64: Implement string_compare intrinsic in SVE #5129
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  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  https://github.com/openjdk/jdk/blob/master/test/hotspot/jtreg/compiler/intrinsics/string/TestStringCompareToDifferentLength.java
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… compare-long-strings stub. And remove the assertion in `string_compare` since it won't help as the registers used in the stub are fixed.
@tatwaichong This change now passes all automated pre-integration checks.
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@tatwaichong this pull request can not be integrated into
git checkout sve_compareto git fetch https://git.openjdk.java.net/jdk master git merge FETCH_HEAD # resolve conflicts and follow the instructions given by git merge git commit -m "Merge master" git push
We are seeing a large number of Aarch64 test failures in our CI after
I think we will need to back this change out while this is investigated
On 14/10/2021 3:30 pm, TatWai Chong wrote:
On 14/10/2021 4:28 pm, Nick Gasson wrote:
If a backout is needed then it should be converted to a "backout" issue per: