This patch adds mid-end support for vectorized min/max reduction operations for half floats. It also includes backend AArch64 support for these operations. Both floating point min/max reductions don’t require strict order, because they are associative.
It will generate NEON fminv/fmaxv reduction instructions when max vector length is 8B or 16B. On SVE supporting machines with vector lengths > 16B, it will generate the SVE fminv/fmaxv instructions. The patch also adds support for partial min/max reductions on SVE machines using fminv/fmaxv. Ratio of throughput(ops/ms) > 1 indicates the performance with this patch is better than the mainline. Neoverse N1 (UseSVE = 0, max vector length = 16B): Benchmark vectorDim Mode Cnt 8B 16B ReductionMaxFP16 256 thrpt 9 3.69 6.44 ReductionMaxFP16 512 thrpt 9 3.71 7.62 ReductionMaxFP16 1024 thrpt 9 4.16 8.64 ReductionMaxFP16 2048 thrpt 9 4.44 9.12 ReductionMinFP16 256 thrpt 9 3.69 6.43 ReductionMinFP16 512 thrpt 9 3.70 7.62 ReductionMinFP16 1024 thrpt 9 4.16 8.64 ReductionMinFP16 2048 thrpt 9 4.44 9.10 Neoverse V1 (UseSVE = 1, max vector length = 32B): Benchmark vectorDim Mode Cnt 8B 16B 32B ReductionMaxFP16 256 thrpt 9 3.96 8.62 8.02 ReductionMaxFP16 512 thrpt 9 3.54 9.25 11.71 ReductionMaxFP16 1024 thrpt 9 3.77 8.71 14.07 ReductionMaxFP16 2048 thrpt 9 3.88 8.44 14.69 ReductionMinFP16 256 thrpt 9 3.96 8.61 8.03 ReductionMinFP16 512 thrpt 9 3.54 9.28 11.69 ReductionMinFP16 1024 thrpt 9 3.76 8.70 14.12 ReductionMinFP16 2048 thrpt 9 3.87 8.45 14.70 Neoverse V2 (UseSVE = 2, max vector length = 16B): Benchmark vectorDim Mode Cnt 8B 16B ReductionMaxFP16 256 thrpt 9 4.78 10.00 ReductionMaxFP16 512 thrpt 9 3.74 11.33 ReductionMaxFP16 1024 thrpt 9 3.86 9.59 ReductionMaxFP16 2048 thrpt 9 3.94 8.71 ReductionMinFP16 256 thrpt 9 4.78 10.00 ReductionMinFP16 512 thrpt 9 3.74 11.29 ReductionMinFP16 1024 thrpt 9 3.86 9.58 ReductionMinFP16 2048 thrpt 9 3.94 8.71 Testing: hotspot_all, jdk (tier1-3) and langtools (tier1) all pass on Neoverse N1/V1/V2. ------------- Commit messages: - 8373344: Add support for FP16 min/max reduction operations Changes: https://git.openjdk.org/jdk/pull/28828/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28828&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8373344 Stats: 968 lines in 13 files changed: 296 ins; 22 del; 650 mod Patch: https://git.openjdk.org/jdk/pull/28828.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/28828/head:pull/28828 PR: https://git.openjdk.org/jdk/pull/28828
