On Mon, 1 Jun 2026 02:04:13 GMT, Eric Fang <[email protected]> wrote:
> This PR introduces the basic Ideal/Identity transformations for > `VectorBlendNode`. > > The semantic of `VectorBlend(X, Y, M)` is: `M ? Y : X`. > > **Identity**: > > (VectorBlend X Y (Replicate -1)) => Y > (VectorBlend X Y (MaskAll -1)) => Y > (VectorBlend X Y (Replicate 0)) => X > (VectorBlend X Y (MaskAll 0)) => X > > > **Ideal**: > > (VectorBlend (VectorBlend X A M) B M) => (VectorBlend X B M) > (VectorBlend A (VectorBlend B X M) M) => (VectorBlend A X M) > (VectorBlend A B (XorV/XorVMask M -1)) => (VectorBlend B A M) > > > Also corrects the VectorBlendNode header comment: across all backends (X86 > SSE/AVX, AArch64 NEON/SVE, RISC-V V) the active mask lane selects `vec2` > (in(2)), and the inactive lane selects `vec1` (in(1)). > > JTReg and JMH tests are also added for each optimization pattern. All tests > (tier1, tier2, and tier3) passed on AArch64 and X86 platforms. > > JMH benchmark test results: > > On a Nvidia Grace (Neoverse-V2) machine with 128-bit SVE2: > > Benchmark Unit Before Error After Error > Uplift > blendNegatedMaskInt ops/ms 7990.6 2.8 10215.2 > 11.0 1.3 > identityAllOnesInt ops/ms 3574.8 2.6 7967.1 > 0.3 2.2 > identityAllZerosLong ops/ms 3575.6 1.0 7966.0 3.6 > 2.2 > nestedBlendInnerLong ops/ms 3533.8 2.8 478573.0 3178.5 135.4 > nestedBlendOuterInt ops/ms 3537.6 3.4 472242.2 3034.2 > 133.5 > > > On an AWS Graviton3 (Neoverse-V1) machine with 256-bit SVE1: > > Benchmark Unit Before Error After Error > Uplift > blendNegatedMaskInt ops/ms 5171.9 5.2 8129.0 > 17.3 1.6 > identityAllOnesInt ops/ms 2722.0 0.1 5891.3 > 0.1 2.2 > identityAllZerosLong ops/ms 2722.4 0.1 5891.1 0.3 > 2.2 > nestedBlendInnerLong ops/ms 2697.6 0.0 312148.7 2366.4 115.7 > nestedBlendOuterInt ops/ms 2702.7 0.1 308686.0 2709.8 > 114.2 > > > On a Nvidia Grace (Neoverse-V2) machine with `-XX:UseSVE=0`: > > Benchmark Unit Before Error After Error > Uplift > blendNegatedMaskInt ops/ms 7718.1 1.9 9515.9 > 54.0 1.2 > identityAllOnesInt ops/ms 3581.9 0.6 8062.5 > 0.5 2.3 > identityAllZerosLong ops/ms 3582.7 0.6 8058.5 11.9 > 2.2 > nestedBlendInnerLong ops/ms 3529.6 1.4 476029.8 5190.2 134.9 > nestedBlendOuterInt ops/ms 3536.9 2.1 486060.0 3442.1 > 137.4 > > > On an AMD EPYC 9124 16-Core Processor with option `-XX:UseAVX=3`: > > Benchmark Unit Before Error After Error > Uplift > blendNegatedMaskInt ops/ms 36773.6 541.7 46467.4 499.4 > 1.3 > identityAllOnesInt ops/ms 5262.7 3.7 13644.7 > 12.1 2.6 > identityAllZerosLong ... Thanks for the clarifications @erifan ------------- Marked as reviewed by galder (Committer). PR Review: https://git.openjdk.org/jdk/pull/31333#pullrequestreview-4661161522
