| Message ID | 20221003195944.3274548-1-aurelien@aurel32.net |
|---|---|
| Headers | show |
| Series | x86: Fix AVX2 string functions requiring BMI1, BMI2 or LZCNT (BZ #29611) | expand |
v3 looks good to me. On Mon, Oct 3, 2022 at 12:59 PM Aurelien Jarno <aurelien@aurel32.net> wrote: > > Some early Intel Haswell CPU have AVX2 instructions, but do not have > BMI1 and BMI2 instructions. Some AVX2 string functions only check for > AVX2, but use BMI1, BMI2 or LZCNT instructions. This patchset tries to > fix that. > > While most fixes only change ifunc-impl-list.c, and thus only concerns > the testsuite, the changes to str*cmp and wcs(n)cmp are a real issue > affecting early Intel Haswell CPU, reported to affect Debian Sid and > Fedora Rawhide. > > On the other hand, the check for LZCNT in memrchr is purely for > correctness, I am not aware of a CPU implementing AVX2 without LZCNT. > > This has been tested by remplacing all BMI1 and BMI2 instructions in the > source code by the "ud2" instruction and disabling the BMI1, BMI2 > feature detection, and running the testsuite. > > Resolves: BZ #29611 > > Changes v2 -> v3: > - Change the way patches are split. No code change. > > Change v1 -> v2: > - Better scan for BMI2 instructions (shlx and shrx) and BMI1 > instructions (blsmsk) instructions following the feedback from Noah > Goldstein > > Aurelien Jarno (8): > x86: include BMI1 and BMI2 in x86-64-v3 level > x86-64: Require BMI2 for AVX2 str(n)casecmp implementations > x86-64: Require BMI2 for AVX2 strcmp implementation > x86-64: Require BMI2 for AVX2 strncmp implementation > x86-64: Require BMI2 for AVX2 wcs(n)cmp implementations > x86-64: Require BMI2 for AVX2 (raw|w)memchr implementations > x86-64: Require BMI2 and LZCNT for AVX2 memrchr implementation > x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations > > sysdeps/x86/get-isa-level.h | 2 + > sysdeps/x86/isa-level.h | 2 + > sysdeps/x86_64/multiarch/ifunc-avx2.h | 2 + > sysdeps/x86_64/multiarch/ifunc-impl-list.c | 86 ++++++++++++++++----- > sysdeps/x86_64/multiarch/ifunc-strcasecmp.h | 1 + > sysdeps/x86_64/multiarch/strcmp.c | 4 +- > sysdeps/x86_64/multiarch/strncmp.c | 4 +- > 7 files changed, 76 insertions(+), 25 deletions(-) > > -- > 2.35.1 >
On Mon, Oct 3, 2022 at 12:59 PM Aurelien Jarno <aurelien@aurel32.net> wrote: > > Some early Intel Haswell CPU have AVX2 instructions, but do not have > BMI1 and BMI2 instructions. Some AVX2 string functions only check for > AVX2, but use BMI1, BMI2 or LZCNT instructions. This patchset tries to > fix that. > > While most fixes only change ifunc-impl-list.c, and thus only concerns > the testsuite, the changes to str*cmp and wcs(n)cmp are a real issue > affecting early Intel Haswell CPU, reported to affect Debian Sid and > Fedora Rawhide. > > On the other hand, the check for LZCNT in memrchr is purely for > correctness, I am not aware of a CPU implementing AVX2 without LZCNT. > > This has been tested by remplacing all BMI1 and BMI2 instructions in the > source code by the "ud2" instruction and disabling the BMI1, BMI2 > feature detection, and running the testsuite. > > Resolves: BZ #29611 > > Changes v2 -> v3: > - Change the way patches are split. No code change. > > Change v1 -> v2: > - Better scan for BMI2 instructions (shlx and shrx) and BMI1 > instructions (blsmsk) instructions following the feedback from Noah > Goldstein > > Aurelien Jarno (8): > x86: include BMI1 and BMI2 in x86-64-v3 level > x86-64: Require BMI2 for AVX2 str(n)casecmp implementations > x86-64: Require BMI2 for AVX2 strcmp implementation > x86-64: Require BMI2 for AVX2 strncmp implementation > x86-64: Require BMI2 for AVX2 wcs(n)cmp implementations > x86-64: Require BMI2 for AVX2 (raw|w)memchr implementations > x86-64: Require BMI2 and LZCNT for AVX2 memrchr implementation > x86-64: Require BMI1/BMI2 for AVX2 strrchr and wcsrchr implementations > > sysdeps/x86/get-isa-level.h | 2 + > sysdeps/x86/isa-level.h | 2 + > sysdeps/x86_64/multiarch/ifunc-avx2.h | 2 + > sysdeps/x86_64/multiarch/ifunc-impl-list.c | 86 ++++++++++++++++----- > sysdeps/x86_64/multiarch/ifunc-strcasecmp.h | 1 + > sysdeps/x86_64/multiarch/strcmp.c | 4 +- > sysdeps/x86_64/multiarch/strncmp.c | 4 +- > 7 files changed, 76 insertions(+), 25 deletions(-) > > -- > 2.35.1 > LGTM. Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>