Optimized strrev with SSSE3

since strrev is not wildly used, and SSSE3 is defined default by some
compiler, so won't try to do ifunc here.

diff --git a/ext/standard/string.c b/ext/standard/string.c
index 585495b71556bd2df2a0324b9c67bb58d1d4bfcd..2a79378c4be9d2162d57ed48543b468551dec2c3 100644 (file)
--- a/ext/standard/string.c
+++ b/ext/standard/string.c
@@ -3511,10 +3511,13 @@ PHP_FUNCTION(strtr)
 
 /* {{{ proto string strrev(string str)
    Reverse a string */
+#if ZEND_INTRIN_SSSE3_NATIVE
+#include <tmmintrin.h>
+#endif
 PHP_FUNCTION(strrev)
 {
        zend_string *str;
-       char *e, *p;
+       char *s, *e, *p;
        zend_string *n;
 
        ZEND_PARSE_PARAMETERS_START(1, 1)
@@ -3524,10 +3527,24 @@ PHP_FUNCTION(strrev)
        n = zend_string_alloc(ZSTR_LEN(str), 0);
        p = ZSTR_VAL(n);
 
-       e = ZSTR_VAL(str) + ZSTR_LEN(str);
-
-       while (--e >= ZSTR_VAL(str)) {
-               *p++ = *e;
+       s = ZSTR_VAL(str);
+       e = s + ZSTR_LEN(str);
+       --e;
+#if ZEND_INTRIN_SSSE3_NATIVE
+       while (e - s > 15) {
+               const __m128i map = _mm_set_epi8(
+                               0, 1, 2, 3,
+                               4, 5, 6, 7,
+                               8, 9, 10, 11,
+                               12, 13, 14, 15);
+               const __m128i str = _mm_loadu_si128((__m128i *)(e - 15));
+               _mm_storeu_si128((__m128i *)p, _mm_shuffle_epi8(str, map));
+               p += 16;
+               e -= 16;
+       }
+#endif
+       while (e >= s) {
+               *p++ = *e--;
        }
 
        *p = '\0';