remove unnecessary memset in strcoll

This patch avoids some initialization overhead in the hot path of strcoll by
replacing a memset with zero assignments. It improves the file listing benchmark
by 15% on x86. Tests are ok.

filelist#C              -1.30%
filelist#en_US.UTF-8    -15.08%
lorem_ipsum#vi_VN.UTF-8 -15.04%
lorem_ipsum#ar_SA.UTF-8 -11.83%
lorem_ipsum#en_US.UTF-8 -9.66%
lorem_ipsum#zh_CN.UTF-8 -8.63%
lorem_ipsum#cs_CZ.UTF-8 -8.28%
lorem_ipsum#en_GB.UTF-8 -18.07%
lorem_ipsum#da_DK.UTF-8 -11.13%
lorem_ipsum#pl_PL.UTF-8 -15.31%
lorem_ipsum#fr_FR.UTF-8 -12.26%
lorem_ipsum#pt_PT.UTF-8 -10.64%
lorem_ipsum#el_GR.UTF-8 -8.19%
lorem_ipsum#ru_RU.UTF-8 -0.65%
lorem_ipsum#iw_IL.UTF-8 -14.92%
lorem_ipsum#es_ES.UTF-8 -11.47%
lorem_ipsum#hi_IN.UTF-8 -1.05%
lorem_ipsum#sv_SE.UTF-8  6.44%
lorem_ipsum#hu_HU.UTF-8 -9.85%
lorem_ipsum#tr_TR.UTF-8 -14.96%
lorem_ipsum#is_IS.UTF-8 -10.35%
lorem_ipsum#it_IT.UTF-8 -11.33%
lorem_ipsum#sr_RS.UTF-8 -9.88%
lorem_ipsum#ja_JP.UTF-8 -3.23%

        * string/strcoll_l.c (STRCOLL): Remove unnecessary memset.

diff --git a/ChangeLog b/ChangeLog
index 7b9ab6a6434c3d8487ac396cbb97c6b0aa5dfc0e..1150ec5d2ebaa15e205b3b8ea76a5d7de96fe21a 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
 2015-06-22  Leonhard Holz  <leonhard.holz@web.de>
 
+       * string/strcoll_l.c (STRCOLL): Remove unnecessary memset.
+
        * string/strcoll_l.c: Remove unused struct element idxnow.
 
 2015-06-21  Joseph Myers  <joseph@codesourcery.com>

diff --git a/string/strcoll_l.c b/string/strcoll_l.c
index 967bbba231c129bc7bdf4cf1a08dadfcb9079052..8f1225fc7aefcf304e69c348657d23cbfba8ad13 100644 (file)
--- a/string/strcoll_l.c
+++ b/string/strcoll_l.c
@@ -315,8 +315,11 @@ STRCOLL (const STRING_TYPE *s1, const STRING_TYPE *s2, __locale_t l)
   int result = 0, rule = 0;
 
   coll_seq seq1, seq2;
-  memset (&seq1, 0, sizeof (seq1));
-  seq2 = seq1;
+  seq1.len = 0;
+  seq1.idxmax = 0;
+  seq1.rule = 0;
+  seq2.len = 0;
+  seq2.idxmax = 0;
 
   for (int pass = 0; pass < nrules; ++pass)
     {