* re.c (rb_memsearch_ss): performance improvement by using memmem(3) if

  possible. [ruby-dev:45530] [Feature #6311]

* configure.in: check existence of memmem(3) and that it is not broken.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37634 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 56 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 1586239bcf..957552f63a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Tue Nov 13 11:03:47 2012  Masaki Matsushita  <glass.saga@gmail.com>
+
+	* re.c (rb_memsearch_ss): performance improvement by using memmem(3) if
+	  possible. [ruby-dev:45530] [Feature #6311]
+
+	* configure.in: check existence of memmem(3) and that it is not broken.
+
 Tue Nov 13 06:50:02 2012  Aaron Patterson <aaron@tenderlovemaking.com>
 
 	* probes.d: add DTrace probe declarations. [ruby-core:27448]
diff --git a/configure.in b/configure.in
index aafada5e03..d2ba707a7b 100644
--- a/configure.in
+++ b/configure.in
@@ -2900,6 +2900,42 @@ if test "${universal_binary-no}" = yes ; then
     ])])
 fi
 
+AC_CHECK_FUNC(memmem, [
+  AC_CACHE_CHECK(for broken memmem, rb_cv_broken_memmem, [
+    AC_TRY_RUN([
+#include <string.h>
+
+int
+main()
+{
+  char *str = "hogefugafoobar";
+  char *rs = "foo";
+  char *empty = "";
+  char *p;
+
+  p = memmem(str, strlen(str), rs, strlen(rs));
+  if (p == str+8) {
+    p = memmem(str, strlen(str), empty, strlen(empty));
+    if (p == str)
+      return 0;
+    else
+      return 1;
+  }
+  else {
+    return 1;
+  }
+}
+    ],
+    rb_cv_broken_memmem=no,
+    rb_cv_broken_memmem=yes,
+    rb_cv_broken_memmem=yes)
+  ])
+  if test "$rb_cv_broken_memmem" = no; then
+    AC_DEFINE(HAVE_MEMMEM, 1)
+  fi
+])
+
+
 CPPFLAGS="$CPPFLAGS "'$(DEFS)'
 test -z "$CPPFLAGS" || CPPFLAGS="$CPPFLAGS "; CPPFLAGS="$CPPFLAGS"'${cppflags}'
 if test -n "${cflags+set}"; then
diff --git a/re.c b/re.c
index ea11f1c015..97803d4e38 100644
--- a/re.c
+++ b/re.c
@@ -97,6 +97,18 @@ rb_memcmp(const void *p1, const void *p2, long len)
     return memcmp(p1, p2, len);
 }
 
+#ifdef HAVE_MEMMEM
+static inline long
+rb_memsearch_ss(const unsigned char *xs, long m, const unsigned char *ys, long n)
+{
+    const unsigned char *y;
+
+    if (y = memmem(ys, n, xs, m))
+	return y - ys;
+    else
+	return -1;
+}
+#else
 static inline long
 rb_memsearch_ss(const unsigned char *xs, long m, const unsigned char *ys, long n)
 {
@@ -132,6 +144,7 @@ rb_memsearch_ss(const unsigned char *xs, long m, const unsigned char *ys, long n
     }
     return y - ys - m;
 }
+#endif
 
 static inline long
 rb_memsearch_qs(const unsigned char *xs, long m, const unsigned char *ys, long n)