| commit | 65dc53baca60b7dd59de36c21f5f5176ea4f2be1 | [log] [tgz] |
|---|---|---|
| author | Luke Lau <luke@igalia.com> | Mon Sep 09 13:11:08 2024 +0800 |
| committer | GitHub <noreply@github.com> | Mon Sep 09 13:11:08 2024 +0800 |
| tree | 802e83444599ceb94d346fc24dd654655904aede | |
| parent | b5ee4639dee0fd74c1215547e35bd9a10cfc5925 [diff] |
[RISCV] Rematerialize vmv.v.i (#107550)
This continues the line of work started in #97520, and gives a 2.5%
reduction in the number of spills on SPEC CPU 2017.
Program regalloc.NumSpills
lhs rhs diff
605.mcf_s 141.00 141.00 0.0%
505.mcf_r 141.00 141.00 0.0%
519.lbm_r 73.00 73.00 0.0%
619.lbm_s 68.00 68.00 0.0%
631.deepsjeng_s 354.00 353.00 -0.3%
531.deepsjeng_r 354.00 353.00 -0.3%
625.x264_s 1896.00 1886.00 -0.5%
525.x264_r 1896.00 1886.00 -0.5%
508.namd_r 6665.00 6598.00 -1.0%
644.nab_s 761.00 753.00 -1.1%
544.nab_r 761.00 753.00 -1.1%
638.imagick_s 4287.00 4181.00 -2.5%
538.imagick_r 4287.00 4181.00 -2.5%
602.gcc_s 12771.00 12450.00 -2.5%
502.gcc_r 12771.00 12450.00 -2.5%
510.parest_r 43876.00 42740.00 -2.6%
500.perlbench_r 4297.00 4179.00 -2.7%
600.perlbench_s 4297.00 4179.00 -2.7%
526.blender_r 13503.00 13103.00 -3.0%
511.povray_r 2006.00 1937.00 -3.4%
620.omnetpp_s 984.00 946.00 -3.9%
520.omnetpp_r 984.00 946.00 -3.9%
657.xz_s 302.00 289.00 -4.3%
557.xz_r 302.00 289.00 -4.3%
541.leela_r 378.00 356.00 -5.8%
641.leela_s 378.00 356.00 -5.8%
623.xalancbmk_s 1646.00 1548.00 -6.0%
523.xalancbmk_r 1646.00 1548.00 -6.0%
Geomean difference -2.5%
I initially held off submitting this patch because it surprisingly
introduced a lot of spills in the test diffs, but after #107290 the
vmv.v.is that caused them are now gone.
The gist is that marking vmv.v.i as spillable decreased its spill
weight, which actually resulted in more m8 registers getting evicted and
spilled during register allocation.
The SPEC results show this isn't an issue in practice though, and I plan
on posting a separate patch to explain this in more detail.
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