> Continuing the work initiated by @luhenry to unroll and then intrinsify > polynomial hash loops. > > I've rewired the library changes to route via a single `@IntrinsicCandidate` > method. To make this work I've harmonized how they are invoked so that > there's less special handling and checks in the intrinsic. Mainly do the > null-check outside of the intrinsic for `Arrays.hashCode` cases. > > Having a centralized entry point means it'll be easier to parameterize the > factor and start values which are now hard-coded (always 31, and a start > value of either one for `Arrays` or zero for `String`). It seems somewhat > premature to parameterize this up front. > > The current implementation is performance neutral on microbenchmarks on all > tested platforms (x64, aarch64) when not enabling the intrinsic. We do add a > few trivial method calls which increase the call stack depth, so surprises > cannot be ruled out on complex workloads. > > With the most recent fixes the x64 intrinsic results on my workstation look > like this: > > Benchmark (size) Mode Cnt Score Error > Units > StringHashCode.Algorithm.defaultLatin1 1 avgt 5 2.199 ± 0.017 > ns/op > StringHashCode.Algorithm.defaultLatin1 10 avgt 5 6.933 ± 0.049 > ns/op > StringHashCode.Algorithm.defaultLatin1 100 avgt 5 29.935 ± 0.221 > ns/op > StringHashCode.Algorithm.defaultLatin1 10000 avgt 5 1596.982 ± 7.020 > ns/op > > Baseline: > > Benchmark (size) Mode Cnt Score Error > Units > StringHashCode.Algorithm.defaultLatin1 1 avgt 5 2.200 ± 0.013 > ns/op > StringHashCode.Algorithm.defaultLatin1 10 avgt 5 9.424 ± 0.122 > ns/op > StringHashCode.Algorithm.defaultLatin1 100 avgt 5 90.541 ± 0.512 > ns/op > StringHashCode.Algorithm.defaultLatin1 10000 avgt 5 9425.321 ± 67.630 > ns/op > > I.e. no measurable overhead compared to baseline even for `size == 1`. > > The vectorized code now nominally works for all unsigned cases as well as > ints, though more testing would be good. > > Benchmark for `Arrays.hashCode`: > > Benchmark (size) Mode Cnt Score Error Units > ArraysHashCode.bytes 1 avgt 5 1.884 ± 0.013 ns/op > ArraysHashCode.bytes 10 avgt 5 6.955 ± 0.040 ns/op > ArraysHashCode.bytes 100 avgt 5 87.218 ± 0.595 ns/op > ArraysHashCode.bytes 10000 avgt 5 9419.591 ± 38.308 ns/op > ArraysHashCode.chars 1 avgt 5 2.200 ± 0.010 ns/op > ArraysHashCode.chars 10 avgt 5 6.935 ± 0.034 ns/op > ArraysHashCode.chars 100 avgt 5 30.216 ± 0.134 ns/op > ArraysHashCode.chars 10000 avgt 5 1601.629 ± 6.418 ns/op > ArraysHashCode.ints 1 avgt 5 2.200 ± 0.007 ns/op > ArraysHashCode.ints 10 avgt 5 6.936 ± 0.034 ns/op > ArraysHashCode.ints 100 avgt 5 29.412 ± 0.268 ns/op > ArraysHashCode.ints 10000 avgt 5 1610.578 ± 7.785 ns/op > ArraysHashCode.shorts 1 avgt 5 1.885 ± 0.012 ns/op > ArraysHashCode.shorts 10 avgt 5 6.961 ± 0.034 ns/op > ArraysHashCode.shorts 100 avgt 5 87.095 ± 0.417 ns/op > ArraysHashCode.shorts 10000 avgt 5 9420.617 ± 50.089 ns/op > > Baseline: > > Benchmark (size) Mode Cnt Score Error Units > ArraysHashCode.bytes 1 avgt 5 3.213 ± 0.207 ns/op > ArraysHashCode.bytes 10 avgt 5 8.483 ± 0.040 ns/op > ArraysHashCode.bytes 100 avgt 5 90.315 ± 0.655 ns/op > ArraysHashCode.bytes 10000 avgt 5 9422.094 ± 62.402 ns/op > ArraysHashCode.chars 1 avgt 5 3.040 ± 0.066 ns/op > ArraysHashCode.chars 10 avgt 5 8.497 ± 0.074 ns/op > ArraysHashCode.chars 100 avgt 5 90.074 ± 0.387 ns/op > ArraysHashCode.chars 10000 avgt 5 9420.474 ± 41.619 ns/op > ArraysHashCode.ints 1 avgt 5 2.827 ± 0.019 ns/op > ArraysHashCode.ints 10 avgt 5 7.727 ± 0.043 ns/op > ArraysHashCode.ints 100 avgt 5 89.405 ± 0.593 ns/op > ArraysHashCode.ints 10000 avgt 5 9426.539 ± 51.308 ns/op > ArraysHashCode.shorts 1 avgt 5 3.071 ± 0.062 ns/op > ArraysHashCode.shorts 10 avgt 5 8.168 ± 0.049 ns/op > ArraysHashCode.shorts 100 avgt 5 90.399 ± 0.292 ns/op > ArraysHashCode.shorts 10000 avgt 5 9420.171 ± 44.474 ns/op > > > As we can see the `Arrays` intrinsics are faster for small inputs, and faster > on large inputs for `char` and `int` (the ones currently vectorized). I aim > to fix `byte` and `short` cases before integrating, though it might be > acceptable to hand that off as follow-up enhancements to not further delay > integration of this enhancement.
Claes Redestad has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 64 commits: - Pass the constant mode node through, removing need for all but one instruct declarations - FLAG_SET_DEFAULT - Merge branch 'master' into 8282664-polyhash - Merge branch 'master' into 8282664-polyhash - Missing & 0xff in StringLatin1::hashCode - Qualified guess on shenandoahSupport fix-up - Whitespace - Final touch-ups, restored 2-stride with dependency chain breakage - Minor cleanup - Revert accidental ModuleHashes change - ... and 54 more: https://git.openjdk.org/jdk/compare/8dfb6d76...c9e7c561 ------------- Changes: https://git.openjdk.org/jdk/pull/10847/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10847&range=13 Stats: 1021 lines in 33 files changed: 962 ins; 8 del; 51 mod Patch: https://git.openjdk.org/jdk/pull/10847.diff Fetch: git fetch https://git.openjdk.org/jdk pull/10847/head:pull/10847 PR: https://git.openjdk.org/jdk/pull/10847
