From: Xinchen Hui <laruence@gmail.com>
Date: Sat, 17 Feb 2018 15:19:31 +0000 (+0800)
Subject: Optimized strrev with SSSE3
X-Git-Tag: php-7.3.0alpha1~380
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c79f2de2cfe5a6b24a890269920d7714663d2ec9;p=php

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 585495b715..2a79378c4b 100644
--- 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';