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authorNoah Goldstein <goldstein.w.n@gmail.com>2022-02-06 00:54:18 -0600
committerNoah Goldstein <goldstein.w.n@gmail.com>2022-02-06 20:58:07 -0600
commitb62ace2740a106222e124cc86956448fa07abf4d (patch)
tree33113f4227f89fc389d82ec9a14834bb364704bb /nptl
parentd7fca835e064ead5a46914d5f3a2eda3cad5649f (diff)
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x86: Improve vec generation in memset-vec-unaligned-erms.S
No bug.

Split vec generation into multiple steps. This allows the
broadcast in AVX2 to use 'xmm' registers for the L(less_vec)
case. This saves an expensive lane-cross instruction and removes
the need for 'vzeroupper'.

For SSE2 replace 2x 'punpck' instructions with zero-idiom 'pxor' for
byte broadcast.

Results for memset-avx2 small (geomean of N = 20 benchset runs).

size, New Time, Old Time, New / Old
   0,    4.100,    3.831,     0.934
   1,    5.074,    4.399,     0.867
   2,    4.433,    4.411,     0.995
   4,    4.487,    4.415,     0.984
   8,    4.454,    4.396,     0.987
  16,    4.502,    4.443,     0.987

All relevant string/wcsmbs tests are passing.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Diffstat (limited to 'nptl')
0 files changed, 0 insertions, 0 deletions