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| author | Ondřej Bílka <neleai@seznam.cz> | 2014-03-18 11:01:38 +0100 |
|---|---|---|
| committer | Ondřej Bílka <neleai@seznam.cz> | 2015-05-12 20:18:51 +0200 |
| commit | 0f4840be2528b3e3f2ecea009ab08e753701e9be (patch) | |
| tree | fc4eafdf024c8eccba2724f48153a6ccc7166121 /sysdeps/x86_64 | |
| parent | 7327b333e56926d7d79bb9e01b839d3618bf750f (diff) | |
| download | glibc-0f4840be2528b3e3f2ecea009ab08e753701e9be.zip glibc-0f4840be2528b3e3f2ecea009ab08e753701e9be.tar.gz glibc-0f4840be2528b3e3f2ecea009ab08e753701e9be.tar.bz2 | |
Use strspn/strcspn/strpbrk ifunc in internal calls.
To make a strtok faster and improve performance in general we need to do one
additional change.
A comment:
/* It doesn't make sense to send libc-internal strcspn calls through a PLT.
The speedup we get from using SSE4.2 instruction is likely eaten away
by the indirect call in the PLT. */
Does not make sense at all because nobody bothered to check it. Gap
between these implementations is quite big, when haystack is empty a
sse2 is around 40 cycles slower because it needs to populate a lookup
table and difference only increases with size. That is much bigger than
plt slowdown which is few cycles.
Even benchtest show a gap which also may be reverse by branch
misprediction but my internal benchmark shown.
simple_strspn stupid_strspn __strspn_sse42 __strspn_sse2
Length 0, alignment 0, acc len 6: 18.6562 35.2344 17.0469 61.6719
Length 6, alignment 0, acc len 6: 59.5469 72.5781 16.4219 73.625
This patch also handles strpbrk which is implemented by including a
x86_64/multiarch/strcspn.S file.
* sysdeps/x86_64/multiarch/strspn.S: Remove plt indirection.
* sysdeps/x86_64/multiarch/strcspn.S: Likewise.
Diffstat (limited to 'sysdeps/x86_64')
| -rw-r--r-- | sysdeps/x86_64/multiarch/strcspn.S | 7 | ||||
| -rw-r--r-- | sysdeps/x86_64/multiarch/strspn.S | 6 |
2 files changed, 0 insertions, 13 deletions
diff --git a/sysdeps/x86_64/multiarch/strcspn.S b/sysdeps/x86_64/multiarch/strcspn.S index 00e4617..95e882c 100644 --- a/sysdeps/x86_64/multiarch/strcspn.S +++ b/sysdeps/x86_64/multiarch/strcspn.S @@ -65,14 +65,7 @@ END(STRCSPN) # undef END # define END(name) \ cfi_endproc; .size STRCSPN_SSE2, .-STRCSPN_SSE2 -# undef libc_hidden_builtin_def -/* It doesn't make sense to send libc-internal strcspn calls through a PLT. - The speedup we get from using SSE4.2 instruction is likely eaten away - by the indirect call in the PLT. */ -# define libc_hidden_builtin_def(name) \ - .globl __GI_STRCSPN; __GI_STRCSPN = STRCSPN_SSE2 #endif - #endif /* HAVE_SSE4_SUPPORT */ #ifdef USE_AS_STRPBRK diff --git a/sysdeps/x86_64/multiarch/strspn.S b/sysdeps/x86_64/multiarch/strspn.S index aea8e4c..b734c17 100644 --- a/sysdeps/x86_64/multiarch/strspn.S +++ b/sysdeps/x86_64/multiarch/strspn.S @@ -50,12 +50,6 @@ END(strspn) # undef END # define END(name) \ cfi_endproc; .size __strspn_sse2, .-__strspn_sse2 -# undef libc_hidden_builtin_def -/* It doesn't make sense to send libc-internal strspn calls through a PLT. - The speedup we get from using SSE4.2 instruction is likely eaten away - by the indirect call in the PLT. */ -# define libc_hidden_builtin_def(name) \ - .globl __GI_strspn; __GI_strspn = __strspn_sse2 #endif #endif /* HAVE_SSE4_SUPPORT */ |