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authorOndřej Bílka <neleai@seznam.cz>2014-03-18 11:01:38 +0100
committerOndřej Bílka <neleai@seznam.cz>2015-05-12 20:18:51 +0200
commit0f4840be2528b3e3f2ecea009ab08e753701e9be (patch)
treefc4eafdf024c8eccba2724f48153a6ccc7166121 /sysdeps
parent7327b333e56926d7d79bb9e01b839d3618bf750f (diff)
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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')
-rw-r--r--sysdeps/x86_64/multiarch/strcspn.S7
-rw-r--r--sysdeps/x86_64/multiarch/strspn.S6
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 */