| commit | 4d64c6445735e9b34e2ac8e369312cbfc2f88e17 | |
| author | Aurelien Jarno <aurelien@aurel32.net> | |
| Mon, 3 Oct 2022 21:46:11 +0000 (3 23:46 +0200) | ||
| committer | Aurelien Jarno <aurelien@aurel32.net> | |
| Mon, 3 Oct 2022 21:46:11 +0000 (3 23:46 +0200) | ||
| tree | b7a3a4be592c3e14f661db4f209e337c6185f9ee | treesnapshot (tar.gz zip) |
| parent | 10f79d3670b036925da63dc532b122d27ce65ff8 | commitdiff |
x86-64: Require BMI2 for AVX2 strcmp implementation
The AVX2 strcmp implementation uses the 'bzhi' instruction, which
belongs to the BMI2 CPU feature.
NB: It also uses the 'tzcnt' BMI1 instruction, but it is executed as BSF
as BSF if the CPU doesn't support TZCNT, and produces the same result
for non-zero input.
Partially fixes: b77b06e0e296 ("x86: Optimize strcmp-avx2.S")
Partially resolves: BZ #29611
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
The AVX2 strcmp implementation uses the 'bzhi' instruction, which
belongs to the BMI2 CPU feature.
NB: It also uses the 'tzcnt' BMI1 instruction, but it is executed as BSF
as BSF if the CPU doesn't support TZCNT, and produces the same result
for non-zero input.
Partially fixes: b77b06e0e296 ("x86: Optimize strcmp-avx2.S")
Partially resolves: BZ #29611
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
| sysdeps/x86_64/multiarch/ifunc-impl-list.c | diffblobblamehistory | |
| sysdeps/x86_64/multiarch/strcmp.c | diffblobblamehistory |