string: Improve generic strrchr with memrchr and strlen

Now that both strlen and memrchr have word vectorized implementation,
it should be faster to implement strrchr based on memrchr over the
string length instead of calling strchr on a loop.

Checked on x86_64-linux-gnu, i686-linux-gnu, powerpc-linux-gnu,
and powerpc64-linux-gnu by removing the arch-specific assembly
implementation and disabling multi-arch (it covers both LE and BE
for 64 and 32 bits).

diff --git a/string/strrchr.c b/string/strrchr.c
index 3c6e715d3b4b9759e2b13d7cd98248131c6ac11a..7b76dea4e0586c74455227fd6d43e43bae867d09 100644 (file)
--- a/string/strrchr.c
+++ b/string/strrchr.c
@@ -27,23 +27,7 @@
 char *
 STRRCHR (const char *s, int c)
 {
-  const char *found, *p;
-
-  c = (unsigned char) c;
-
-  /* Since strchr is fast, we use it rather than the obvious loop.  */
-
-  if (c == '\0')
-    return strchr (s, '\0');
-
-  found = NULL;
-  while ((p = strchr (s, c)) != NULL)
-    {
-      found = p;
-      s = p + 1;
-    }
-
-  return (char *) found;
+  return __memrchr (s, c, strlen (s) + 1);
 }
 
 #ifdef weak_alias