Since wcsnlen.S uses pminud which is the part of SSE4.1, move wcsnlen.S
to multiarch/wcsnlen-sse4_1.S.
* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
wcsnlen-sse4_1 and wcsnlen-c.
* sysdeps/x86_64/multiarch/ifunc-impl-list.c
(__libc_ifunc_impl_list): Test __wcsnlen_sse4_1 and
__wcsnlen_sse2.
* sysdeps/x86_64/multiarch/ifunc-sse4_1.h: New file.
* sysdeps/x86_64/multiarch/wcsnlen-c.c: Likewise.
* sysdeps/x86_64/multiarch/wcsnlen-sse4_1.S: Likewise.
* sysdeps/x86_64/multiarch/wcsnlen.c: Likewise.
* sysdeps/x86_64/wcsnlen.S: Removed.
Optimize x86-64 memcmp/wmemcmp with AVX2. It uses vector compare as
much as possible. It is as fast as SSE4 memcmp for size <= 16 bytes
and up to 2X faster for size > 16 bytes on Haswell and Skylake. Select
AVX2 memcmp/wmemcmp on AVX2 machines where vzeroupper is preferred and
AVX unaligned load is fast.
NB: It uses TZCNT instead of BSF since TZCNT produces the same result
as BSF for non-zero input. TZCNT is faster than BSF and is executed
as BSF if machine doesn't support TZCNT.
Key features:
1. For size from 2 to 7 bytes, load as big endian with movbe and bswap
to avoid branches.
2. Use overlapping compare to avoid branch.
3. Use vector compare when size >= 4 bytes for memcmp or size >= 8
bytes for wmemcmp.
4. If size is 8 * VEC_SIZE or less, unroll the loop.
5. Compare 4 * VEC_SIZE at a time with the aligned first memory area.
6. Use 2 vector compares when size is 2 * VEC_SIZE or less.
7. Use 4 vector compares when size is 4 * VEC_SIZE or less.
8. Use 8 vector compares when size is 8 * VEC_SIZE or less.
* sysdeps/x86/cpu-features.h (index_cpu_MOVBE): New.
* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
memcmp-avx2 and wmemcmp-avx2.
* sysdeps/x86_64/multiarch/ifunc-impl-list.c
(__libc_ifunc_impl_list): Test __memcmp_avx2 and __wmemcmp_avx2.
* sysdeps/x86_64/multiarch/memcmp-avx2.S: New file.
* sysdeps/x86_64/multiarch/wmemcmp-avx2.S: Likewise.
* sysdeps/x86_64/multiarch/memcmp.S: Use __memcmp_avx2 on AVX
2 machines if AVX unaligned load is fast and vzeroupper is
preferred.
* sysdeps/x86_64/multiarch/wmemcmp.S: Use __wmemcmp_avx2 on AVX
2 machines if AVX unaligned load is fast and vzeroupper is
preferred.
If assembler doesn't support AVX512DQ, _dl_runtime_resolve_avx is used
to save the first 8 vector registers, which only saves the lower 256
bits of vector register, for lazy binding. When it is called on AVX512
platform, the upper 256 bits of ZMM registers are clobbered. Parameters
passed in ZMM registers will be wrong when the function is called the
first time. This patch requires binutils 2.24, whose assembler can store
and load ZMM registers, to build x86-64 glibc. Since mathvec library
needs assembler support for AVX512DQ, we disable mathvec if assembler
doesn't support AVX512DQ.
[BZ #20139]
* config.h.in (HAVE_AVX512_ASM_SUPPORT): Renamed to ...
(HAVE_AVX512DQ_ASM_SUPPORT): This.
* sysdeps/x86_64/configure.ac: Require assembler from binutils
2.24 or above.
(HAVE_AVX512_ASM_SUPPORT): Removed.
(HAVE_AVX512DQ_ASM_SUPPORT): New.
* sysdeps/x86_64/configure: Regenerated.
* sysdeps/x86_64/dl-trampoline.S: Make HAVE_AVX512_ASM_SUPPORT
check unconditional.
* sysdeps/x86_64/multiarch/ifunc-impl-list.c: Likewise.
* sysdeps/x86_64/multiarch/memcpy.S: Likewise.
* sysdeps/x86_64/multiarch/memcpy_chk.S: Likewise.
* sysdeps/x86_64/multiarch/memmove-avx512-no-vzeroupper.S:
Likewise.
* sysdeps/x86_64/multiarch/memmove-avx512-unaligned-erms.S:
Likewise.
* sysdeps/x86_64/multiarch/memmove.S: Likewise.
* sysdeps/x86_64/multiarch/memmove_chk.S: Likewise.
* sysdeps/x86_64/multiarch/mempcpy.S: Likewise.
* sysdeps/x86_64/multiarch/mempcpy_chk.S: Likewise.
* sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S:
Likewise.
* sysdeps/x86_64/multiarch/memset-avx512-unaligned-erms.S:
Likewise.
* sysdeps/x86_64/multiarch/memset.S: Likewise.
* sysdeps/x86_64/multiarch/memset_chk.S: Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_d_cos8_core_avx512.S: Check
HAVE_AVX512DQ_ASM_SUPPORT instead of HAVE_AVX512_ASM_SUPPORT.
* sysdeps/x86_64/fpu/multiarch/svml_d_exp8_core_avx512.S:
Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_d_log8_core_avx512.S:
Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_d_pow8_core_avx512.S:
Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_d_sin8_core_avx512.S:
Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_d_sincos8_core_avx512.:
Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_s_cosf16_core_avx512.S:
Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_s_expf16_core_avx512.S:
Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_s_logf16_core_avx512.S:
Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_s_powf16_core_avx512.S:
Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_s_sincosf16_core_avx51:
Likewise.
* sysdeps/x86_64/fpu/multiarch/svml_s_sinf16_core_avx512.S:
Likewise.
Since the new SSE2/AVX2 memcpy/memmove are faster than the previous ones,
we can remove the previous SSE2/AVX2 memcpy/memmove and replace them with
the new ones.
No change in IFUNC selection if SSE2 and AVX2 memcpy/memmove weren't used
before. If SSE2 or AVX2 memcpy/memmove were used, the new SSE2 or AVX2
memcpy/memmove optimized with Enhanced REP MOVSB will be used for
processors with ERMS. The new AVX512 memcpy/memmove will be used for
processors with AVX512 which prefer vzeroupper.
Since the new SSE2 memcpy/memmove are faster than the previous default
memcpy/memmove used in libc.a and ld.so, we also remove the previous
default memcpy/memmove and make them the default memcpy/memmove, except
that non-temporal store isn't used in ld.so.
Together, it reduces the size of libc.so by about 6 KB and the size of
ld.so by about 2 KB.
[BZ #19776]
* sysdeps/x86_64/memcpy.S: Make it dummy.
* sysdeps/x86_64/mempcpy.S: Likewise.
* sysdeps/x86_64/memmove.S: New file.
* sysdeps/x86_64/memmove_chk.S: Likewise.
* sysdeps/x86_64/multiarch/memmove.S: Likewise.
* sysdeps/x86_64/multiarch/memmove_chk.S: Likewise.
* sysdeps/x86_64/memmove.c: Removed.
* sysdeps/x86_64/multiarch/memcpy-avx-unaligned.S: Likewise.
* sysdeps/x86_64/multiarch/memcpy-sse2-unaligned.S: Likewise.
* sysdeps/x86_64/multiarch/memmove-avx-unaligned.S: Likewise.
* sysdeps/x86_64/multiarch/memmove-sse2-unaligned-erms.S:
Likewise.
* sysdeps/x86_64/multiarch/memmove.c: Likewise.
* sysdeps/x86_64/multiarch/memmove_chk.c: Likewise.
* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Remove
memcpy-sse2-unaligned, memmove-avx-unaligned,
memcpy-avx-unaligned and memmove-sse2-unaligned-erms.
* sysdeps/x86_64/multiarch/ifunc-impl-list.c
(__libc_ifunc_impl_list): Replace
__memmove_chk_avx512_unaligned_2 with
__memmove_chk_avx512_unaligned. Remove
__memmove_chk_avx_unaligned_2. Replace
__memmove_chk_sse2_unaligned_2 with
__memmove_chk_sse2_unaligned. Remove __memmove_chk_sse2 and
__memmove_avx_unaligned_2. Replace __memmove_avx512_unaligned_2
with __memmove_avx512_unaligned. Replace
__memmove_sse2_unaligned_2 with __memmove_sse2_unaligned.
Remove __memmove_sse2. Replace __memcpy_chk_avx512_unaligned_2
with __memcpy_chk_avx512_unaligned. Remove
__memcpy_chk_avx_unaligned_2. Replace
__memcpy_chk_sse2_unaligned_2 with __memcpy_chk_sse2_unaligned.
Remove __memcpy_chk_sse2. Remove __memcpy_avx_unaligned_2.
Replace __memcpy_avx512_unaligned_2 with
__memcpy_avx512_unaligned. Remove __memcpy_sse2_unaligned_2
and __memcpy_sse2. Replace __mempcpy_chk_avx512_unaligned_2
with __mempcpy_chk_avx512_unaligned. Remove
__mempcpy_chk_avx_unaligned_2. Replace
__mempcpy_chk_sse2_unaligned_2 with
__mempcpy_chk_sse2_unaligned. Remove __mempcpy_chk_sse2.
Replace __mempcpy_avx512_unaligned_2 with
__mempcpy_avx512_unaligned. Remove __mempcpy_avx_unaligned_2.
Replace __mempcpy_sse2_unaligned_2 with
__mempcpy_sse2_unaligned. Remove __mempcpy_sse2.
* sysdeps/x86_64/multiarch/memcpy.S (__new_memcpy): Support
__memcpy_avx512_unaligned_erms and __memcpy_avx512_unaligned.
Use __memcpy_avx_unaligned_erms and __memcpy_sse2_unaligned_erms
if processor has ERMS. Default to __memcpy_sse2_unaligned.
(ENTRY): Removed.
(END): Likewise.
(ENTRY_CHK): Likewise.
(libc_hidden_builtin_def): Likewise.
Don't include ../memcpy.S.
* sysdeps/x86_64/multiarch/memcpy_chk.S (__memcpy_chk): Support
__memcpy_chk_avx512_unaligned_erms and
__memcpy_chk_avx512_unaligned. Use
__memcpy_chk_avx_unaligned_erms and
__memcpy_chk_sse2_unaligned_erms if if processor has ERMS.
Default to __memcpy_chk_sse2_unaligned.
* sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S
Change function suffix from unaligned_2 to unaligned.
* sysdeps/x86_64/multiarch/mempcpy.S (__mempcpy): Support
__mempcpy_avx512_unaligned_erms and __mempcpy_avx512_unaligned.
Use __mempcpy_avx_unaligned_erms and __mempcpy_sse2_unaligned_erms
if processor has ERMS. Default to __mempcpy_sse2_unaligned.
(ENTRY): Removed.
(END): Likewise.
(ENTRY_CHK): Likewise.
(libc_hidden_builtin_def): Likewise.
Don't include ../mempcpy.S.
(mempcpy): New. Add a weak alias.
* sysdeps/x86_64/multiarch/mempcpy_chk.S (__mempcpy_chk): Support
__mempcpy_chk_avx512_unaligned_erms and
__mempcpy_chk_avx512_unaligned. Use
__mempcpy_chk_avx_unaligned_erms and
__mempcpy_chk_sse2_unaligned_erms if if processor has ERMS.
Default to __mempcpy_chk_sse2_unaligned.
Since the new SSE2/AVX2 memsets are faster than the previous ones, we
can remove the previous SSE2/AVX2 memsets and replace them with the
new ones. This reduces the size of libc.so by about 900 bytes.
No change in IFUNC selection if SSE2 and AVX2 memsets weren't used
before. If SSE2 or AVX2 memset was used, the new SSE2 or AVX2 memset
optimized with Enhanced REP STOSB will be used for processors with
ERMS. The new AVX512 memset will be used for processors with AVX512
which prefer vzeroupper.
[BZ #19881]
* sysdeps/x86_64/multiarch/memset-sse2-unaligned-erms.S: Folded
into ...
* sysdeps/x86_64/memset.S: This.
(__bzero): Removed.
(__memset_tail): Likewise.
(__memset_chk): Likewise.
(memset): Likewise.
(MEMSET_CHK_SYMBOL): New. Define only if MEMSET_SYMBOL isn't
defined.
(MEMSET_SYMBOL): Define only if MEMSET_SYMBOL isn't defined.
* sysdeps/x86_64/multiarch/memset-avx2.S: Removed.
(__memset_zero_constant_len_parameter): Check SHARED instead of
PIC.
* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Remove
memset-avx2 and memset-sse2-unaligned-erms.
* sysdeps/x86_64/multiarch/ifunc-impl-list.c
(__libc_ifunc_impl_list): Remove __memset_chk_sse2,
__memset_chk_avx2, __memset_sse2 and __memset_avx2_unaligned.
* sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S
(__bzero): Enabled.
* sysdeps/x86_64/multiarch/memset.S (memset): Replace
__memset_sse2 and __memset_avx2 with __memset_sse2_unaligned
and __memset_avx2_unaligned. Use __memset_sse2_unaligned_erms
or __memset_avx2_unaligned_erms if processor has ERMS. Support
__memset_avx512_unaligned_erms and __memset_avx512_unaligned.
(memset): Removed.
(__memset_chk): Likewise.
(MEMSET_SYMBOL): New.
(libc_hidden_builtin_def): Replace __memset_sse2 with
__memset_sse2_unaligned.
* sysdeps/x86_64/multiarch/memset_chk.S (__memset_chk): Replace
__memset_chk_sse2 and __memset_chk_avx2 with
__memset_chk_sse2_unaligned and __memset_chk_avx2_unaligned_erms.
Use __memset_chk_sse2_unaligned_erms or
__memset_chk_avx2_unaligned_erms if processor has ERMS. Support
__memset_chk_avx512_unaligned_erms and
__memset_chk_avx512_unaligned.
Implement x86-64 memset with unaligned store and rep movsb. Support
16-byte, 32-byte and 64-byte vector register sizes. A single file
provides 2 implementations of memset, one with rep stosb and the other
without rep stosb. They share the same codes when size is between 2
times of vector register size and REP_STOSB_THRESHOLD which defaults
to 2KB.
Key features:
1. Use overlapping store to avoid branch.
2. For size <= 4 times of vector register size, fully unroll the loop.
3. For size > 4 times of vector register size, store 4 times of vector
register size at a time.
[BZ #19881]
* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
memset-sse2-unaligned-erms, memset-avx2-unaligned-erms and
memset-avx512-unaligned-erms.
* sysdeps/x86_64/multiarch/ifunc-impl-list.c
(__libc_ifunc_impl_list): Test __memset_chk_sse2_unaligned,
__memset_chk_sse2_unaligned_erms, __memset_chk_avx2_unaligned,
__memset_chk_avx2_unaligned_erms, __memset_chk_avx512_unaligned,
__memset_chk_avx512_unaligned_erms, __memset_sse2_unaligned,
__memset_sse2_unaligned_erms, __memset_erms,
__memset_avx2_unaligned, __memset_avx2_unaligned_erms,
__memset_avx512_unaligned_erms and __memset_avx512_unaligned.
* sysdeps/x86_64/multiarch/memset-avx2-unaligned-erms.S: New
file.
* sysdeps/x86_64/multiarch/memset-avx512-unaligned-erms.S:
Likewise.
* sysdeps/x86_64/multiarch/memset-sse2-unaligned-erms.S:
Likewise.
* sysdeps/x86_64/multiarch/memset-vec-unaligned-erms.S:
Likewise.
Implement x86-64 memmove with unaligned load/store and rep movsb.
Support 16-byte, 32-byte and 64-byte vector register sizes. When
size <= 8 times of vector register size, there is no check for
address overlap bewteen source and destination. Since overhead for
overlap check is small when size > 8 times of vector register size,
memcpy is an alias of memmove.
A single file provides 2 implementations of memmove, one with rep movsb
and the other without rep movsb. They share the same codes when size is
between 2 times of vector register size and REP_MOVSB_THRESHOLD which
is 2KB for 16-byte vector register size and scaled up by large vector
register size.
Key features:
1. Use overlapping load and store to avoid branch.
2. For size <= 8 times of vector register size, load all sources into
registers and store them together.
3. If there is no address overlap bewteen source and destination, copy
from both ends with 4 times of vector register size at a time.
4. If address of destination > address of source, backward copy 8 times
of vector register size at a time.
5. Otherwise, forward copy 8 times of vector register size at a time.
6. Use rep movsb only for forward copy. Avoid slow backward rep movsb
by fallbacking to backward copy 8 times of vector register size at a
time.
7. Skip when address of destination == address of source.
[BZ #19776]
* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
memmove-sse2-unaligned-erms, memmove-avx-unaligned-erms and
memmove-avx512-unaligned-erms.
* sysdeps/x86_64/multiarch/ifunc-impl-list.c
(__libc_ifunc_impl_list): Test
__memmove_chk_avx512_unaligned_2,
__memmove_chk_avx512_unaligned_erms,
__memmove_chk_avx_unaligned_2, __memmove_chk_avx_unaligned_erms,
__memmove_chk_sse2_unaligned_2,
__memmove_chk_sse2_unaligned_erms, __memmove_avx_unaligned_2,
__memmove_avx_unaligned_erms, __memmove_avx512_unaligned_2,
__memmove_avx512_unaligned_erms, __memmove_erms,
__memmove_sse2_unaligned_2, __memmove_sse2_unaligned_erms,
__memcpy_chk_avx512_unaligned_2,
__memcpy_chk_avx512_unaligned_erms,
__memcpy_chk_avx_unaligned_2, __memcpy_chk_avx_unaligned_erms,
__memcpy_chk_sse2_unaligned_2, __memcpy_chk_sse2_unaligned_erms,
__memcpy_avx_unaligned_2, __memcpy_avx_unaligned_erms,
__memcpy_avx512_unaligned_2, __memcpy_avx512_unaligned_erms,
__memcpy_sse2_unaligned_2, __memcpy_sse2_unaligned_erms,
__memcpy_erms, __mempcpy_chk_avx512_unaligned_2,
__mempcpy_chk_avx512_unaligned_erms,
__mempcpy_chk_avx_unaligned_2, __mempcpy_chk_avx_unaligned_erms,
__mempcpy_chk_sse2_unaligned_2, __mempcpy_chk_sse2_unaligned_erms,
__mempcpy_avx512_unaligned_2, __mempcpy_avx512_unaligned_erms,
__mempcpy_avx_unaligned_2, __mempcpy_avx_unaligned_erms,
__mempcpy_sse2_unaligned_2, __mempcpy_sse2_unaligned_erms and
__mempcpy_erms.
* sysdeps/x86_64/multiarch/memmove-avx-unaligned-erms.S: New
file.
* sysdeps/x86_64/multiarch/memmove-avx512-unaligned-erms.S:
Likwise.
* sysdeps/x86_64/multiarch/memmove-sse2-unaligned-erms.S:
Likwise.
* sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:
Likwise.
It shows improvement up to 28% over AVX2 memset (performance results
attached at <https://sourceware.org/ml/libc-alpha/2015-12/msg00052.html>).
* sysdeps/x86_64/multiarch/memset-avx512-no-vzeroupper.S: New file.
* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Added new file.
* sysdeps/x86_64/multiarch/ifunc-impl-list.c: Added new tests.
* sysdeps/x86_64/multiarch/memset.S: Added new IFUNC branch.
* sysdeps/x86_64/multiarch/memset_chk.S: Likewise.
* sysdeps/x86/cpu-features.h (bit_Prefer_No_VZEROUPPER,
index_Prefer_No_VZEROUPPER): New.
* sysdeps/x86/cpu-features.c (init_cpu_features): Set the
Prefer_No_VZEROUPPER for Knights Landing.
There are configure tests for the -mavx2 compiler option. AVX2
support was added in GCC 4.7, so these tests are now obsolete; this
patch removes them.
Tested for x86_64 and x86 (testsuite, and that installed stripped
shared libraries are unchanged by the patch).
* sysdeps/i386/configure.ac (libc_cv_cc_avx2): Remove configure
test.
* sysdeps/i386/configure: Regenerated.
* sysdeps/x86_64/configure.ac (libc_cv_cc_avx2): Remove configure
test.
* sysdeps/x86_64/configure: Regenerated.
* config.h.in (HAVE_AVX2_SUPPORT): Remove #undef.
* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
memset-avx2 unconditionally instead of conditionally on
[$(config-cflags-avx2) = yes].
* sysdeps/x86_64/multiarch/ifunc-impl-list.c
(__libc_ifunc_impl_list) [HAVE_AVX2_SUPPORT]: Make code
unconditional.
* sysdeps/x86_64/multiarch/memset.S [HAVE_AVX2_SUPPORT]: Likewise.
* sysdeps/x86_64/multiarch/memset_chk.S
[IS_IN (libc) && SHARED && HAVE_AVX2_SUPPORT]: Change conditional
to [IS_IN (libc) && SHARED].
sysdeps/i386/i686/multiarch/strcasestr-c.c became unused after
commit 1818483b15
Author: Andreas Schwab <schwab@suse.de>
Date: Wed Dec 18 11:53:27 2013 +1000
Remove use of SSE4.2 functions for strstr on i686
which contains
-sysdep_routines += strcspn-c strpbrk-c strspn-c strstr-c strcasestr-c
+sysdep_routines += strcspn-c strpbrk-c strspn-c
sysdeps/x86_64/multiarch/strcasestr.c became useless after
t 584b18eb4d
Author: Ondřej Bílka <neleai@seznam.cz>
Date: Sat Dec 14 19:33:56 2013 +0100
Add strstr with unaligned loads. Fixes bug 12100.
which changes sysdeps/x86_64/multiarch/strcasestr.c to
libc_ifunc (__strcasestr, __strcasestr_sse2);
This patch removes these file.
* i386/i686/multiarch/strcasestr-c.c: Removed.
* x86_64/multiarch/strcasestr.c: Likewise.
* x86_64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list):
Remove strcasestr.
In this patch we take advantage of HSW memory bandwidth, manage to
reduce miss branch prediction by avoiding using branch instructions and
force destination to be aligned with avx instruction.
The CPU2006 403.gcc benchmark indicates this patch improves performance
from 2% to 10%.
* config.h.in (HAVE_AVX2_SUPPORT): New #undef.
* sysdeps/i386/configure.ac: Set HAVE_AVX2_SUPPORT and
config-cflags-avx2.
* sysdeps/x86_64/configure.ac: Likewise.
* sysdeps/i386/configure: Regenerated.
* sysdeps/x86_64/configure: Likewise.
* sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
memset-avx2 only if config-cflags-avx2 is yes.
* sysdeps/x86_64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list):
Tests for memset_chk and memset only if HAVE_AVX2_SUPPORT is
defined.
* sysdeps/x86_64/multiarch/memset.S: Define multiple versions
only if HAVE_AVX2_SUPPORT is defined.
* sysdeps/x86_64/multiarch/memset_chk.S: Likewise.
This patch adds ifunc tests for x86_64 memset_chk and memset. It also
defines HAS_AVX2 with AVX2_Usable since AVX2 may not be usable even if
processor has AVX2.
* sysdeps/x86_64/multiarch/ifunc-impl-list.c (__libc_ifunc_impl_list):
Add tests for memset_chk and memset.
* sysdeps/x86_64/multiarch/init-arch.h (HAS_AVX2): Defined
with AVX2_Usable.
A sse42 version of strstr used pcmpistr instruction which is quite
ineffective. A faster way is look for pairs of characters which is uses
sse2, is faster than pcmpistr and for real strings a pairs we look for
are relatively rare.
For linear time complexity we use buy or rent technique which switches
to two-way algorithm when superlinear behaviour is detected.
We add new memcpy version that uses unaligned loads which are fast
on modern processors. This allows second improvement which is avoiding
computed jump which is relatively expensive operation.
Tests available here:
http://kam.mff.cuni.cz/~ondra/memcpy_profile_result27_04_13.tar.bz2
