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| author |   Noah Goldstein <goldstein.w.n@gmail.com> | 2021-11-10 16:18:56 -0600 |
|---|---|---|
| committer | Noah Goldstein <goldstein.w.n@gmail.com> | 2021-11-10 20:12:10 -0600 |
| commit | 2f9062d7171850451e6044ef78d91ff8c017b9c0 (patch) | |
| tree | e17665196e1f1d851601c54ad794b0bae8d5e50f /scripts/build-many-glibcs.py | |
| parent | Support C2X printf %b, %B (diff) | |
| download | glibc-2f9062d7171850451e6044ef78d91ff8c017b9c0.tar.xz glibc-2f9062d7171850451e6044ef78d91ff8c017b9c0.zip | |
x86: Shrink memcmp-sse4.S code size
No bug.
This implementation refactors memcmp-sse4.S primarily with minimizing
code size in mind. It does this by removing the lookup table logic and
removing the unrolled check from (256, 512] bytes.
memcmp-sse4 code size reduction : -3487 bytes
wmemcmp-sse4 code size reduction: -1472 bytes
The current memcmp-sse4.S implementation has a large code size
cost. This has serious adverse affects on the ICache / ITLB. While
in micro-benchmarks the implementations appears fast, traces of
real-world code have shown that the speed in micro benchmarks does not
translate when the ICache/ITLB are not primed, and that the cost
of the code size has measurable negative affects on overall
application performance.
See https://research.google/pubs/pub48320/ for more details.
Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Diffstat (limited to 'scripts/build-many-glibcs.py')
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