RFR: 8320347: Emulate vblendvp[sd] on ECore

[Sandhya Viswanathan]

On Fri, 17 Nov 2023 19:58:13 GMT, Volodymyr Paprotski <duke at openjdk.org> wrote:

> Splitting vblendvp[sd] into boolean operations is bit faster on ECore, get up to 30% gain
> 
> 
> =============== BEFORE ===============
> Benchmark                 (SIZE)  Mode  Cnt    Score   Error  Units
> VectorSignum.floatSignum     256  avgt    3   77.766 ± 0.049  ns/op
> VectorSignum.floatSignum     512  avgt    3  154.889 ± 0.242  ns/op
> VectorSignum.floatSignum    1024  avgt    3  306.130 ± 0.605  ns/op
> VectorSignum.floatSignum    2048  avgt    3  609.965 ± 0.927  ns/op
> VectorSignum.doubleSignum     256  avgt    3   151.874 ± 1.748  ns/op
> VectorSignum.doubleSignum     512  avgt    3   303.080 ± 0.310  ns/op
> VectorSignum.doubleSignum    1024  avgt    3   607.517 ± 0.597  ns/op
> VectorSignum.doubleSignum    2048  avgt    3  1214.282 ± 1.834  ns/op
> Benchmark                Mode  Cnt    Score   Error  Units
> MaxMinOptimizeTest.dAdd  avgt    3   77.240 ± 0.029  us/op
> MaxMinOptimizeTest.dMax  avgt    3  137.334 ± 0.128  us/op
> MaxMinOptimizeTest.dMin  avgt    3  137.160 ± 0.465  us/op
> MaxMinOptimizeTest.dMul  avgt    3   77.231 ± 0.051  us/op
> MaxMinOptimizeTest.fAdd  avgt    3   77.165 ± 0.003  us/op
> MaxMinOptimizeTest.fMax  avgt    3  107.428 ± 1.501  us/op
> MaxMinOptimizeTest.fMin  avgt    3  107.186 ± 0.022  us/op
> MaxMinOptimizeTest.fMul  avgt    3   77.164 ± 0.012  us/op
> 
> =============== AFTER ===============
> Benchmark                 (SIZE)  Mode  Cnt    Score   Error  Units
> VectorSignum.floatSignum     256  avgt    3   61.816 ± 1.980  ns/op
> VectorSignum.floatSignum     512  avgt    3  117.251 ± 0.052  ns/op
> VectorSignum.floatSignum    1024  avgt    3  231.356 ± 0.397  ns/op
> VectorSignum.floatSignum    2048  avgt    3  458.904 ± 0.774  ns/op
> VectorSignum.doubleSignum     256  avgt    3  121.449 ± 0.184  ns/op
> VectorSignum.doubleSignum     512  avgt    3  241.662 ± 0.189  ns/op
> VectorSignum.doubleSignum    1024  avgt    3  482.365 ± 0.165  ns/op
> VectorSignum.doubleSignum    2048  avgt    3  962.412 ± 1.401  ns/op
> Benchmark                Mode  Cnt    Score   Error  Units
> MaxMinOptimizeTest.dAdd  avgt    3   77.240 ± 0.029  us/op
> MaxMinOptimizeTest.dMax  avgt    3  125.701 ± 0.082  us/op
> MaxMinOptimizeTest.dMin  avgt    3  124.704 ± 0.119  us/op
> MaxMinOptimizeTest.dMul  avgt    3   77.232 ± 0.028  us/op
> MaxMinOptimizeTest.fAdd  avgt    3   77.169 ± 0.103  us/op
> MaxMinOptimizeTest.fMax  avgt    3   97.939 ± 0.477  us/op
> MaxMinOptimizeTest.fMin  avgt    3   98.012 ± 0.154  us/op
> MaxMinOptimizeTest.fMul  avgt    3   77.174 ± 0.012  us/op

src/hotspot/cpu/x86/macroAssembler_x86.cpp line 3488:

> 3486:   // WARN: Allow dst == (src1|src2), mask == scratch
> 3487:   bool scratch_available = scratch != xnoreg && scratch != src1 && scratch != src2 && scratch != dst;
> 3488:   bool dst_available = dst != src1 || dst != src2;

What if it is fully masked and dst==mask? In that case also dst_available should be false.

src/hotspot/cpu/x86/macroAssembler_x86.cpp line 3503:

> 3501:     }
> 3502:     vpor(dst, dst, scratch, vector_len);
> 3503:     // CASE dst==src1==src2

Should this comment be in the else part below or removed altogether?

src/hotspot/cpu/x86/macroAssembler_x86.cpp line 3513:

> 3511:   // WARN: Allow dst == (src1|src2), mask == scratch
> 3512:   bool scratch_available = scratch != xnoreg && scratch != src1 && scratch != src2 && scratch != dst && (fully_masked || scratch != mask);
> 3513:   bool dst_available = dst != src1 || dst != src2;

What if it is fully masked and dst==mask? In that case also dst_available should be false.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/16716#discussion_r1399757438
PR Review Comment: https://git.openjdk.org/jdk/pull/16716#discussion_r1399750936
PR Review Comment: https://git.openjdk.org/jdk/pull/16716#discussion_r1399760137