Bit test optimization

onion83 · May 8, 2018 · 4ad9cf4 · 4ad9cf4
1 parent dc796b0
commit 4ad9cf4
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Showing 6 changed files with 18 additions and 11 deletions.
diff --git a/Zend/zend_alloc.c b/Zend/zend_alloc.c
@@ -587,7 +587,7 @@ static zend_always_inline int zend_mm_bitset_find_zero_and_set(zend_mm_bitset *b
 
 static zend_always_inline int zend_mm_bitset_is_set(zend_mm_bitset *bitset, int bit)
 {
-	return (bitset[bit / ZEND_MM_BITSET_LEN] & (Z_L(1) << (bit & (ZEND_MM_BITSET_LEN-1)))) != 0;
+	return ZEND_BIT_TEST(bitset, bit);
 }
 
 static zend_always_inline void zend_mm_bitset_set_bit(zend_mm_bitset *bitset, int bit)

diff --git a/Zend/zend_bitset.h b/Zend/zend_bitset.h
@@ -86,7 +86,7 @@ static inline uint32_t zend_bitset_len(uint32_t n)
 
 static inline zend_bool zend_bitset_in(zend_bitset set, uint32_t n)
 {
-	return (set[ZEND_BITSET_ELM_NUM(n)] & (Z_UL(1) << ZEND_BITSET_BIT_NUM(n))) != Z_UL(0);
+	return ZEND_BIT_TEST(set, n);
 }
 
 static inline void zend_bitset_incl(zend_bitset set, uint32_t n)

diff --git a/Zend/zend_portability.h b/Zend/zend_portability.h
@@ -442,6 +442,13 @@ char *alloca();
 #define MAX(a, b)  (((a)>(b))?(a):(b))
 #define MIN(a, b)  (((a)<(b))?(a):(b))
 
+/* x86 instructions BT, SHL, SHR don't require masking */
+#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
+# define ZEND_BIT_TEST(bits, bit) (((bits)[(bit) / (sizeof((bits)[0])*8)] >> (bit)) & 1)
+#else
+# define ZEND_BIT_TEST(bits, bit) (((bits)[(bit) / (sizeof((bits)[0])*8)] >> ((bit) & (sizeof((bits)[0])*8-1))) & 1)
+#endif
+
 /* We always define a function, even if there's a macro or expression we could
  * alias, so that using it in contexts where we can't make function calls
  * won't fail to compile on some machines and not others.

diff --git a/ext/json/json_encoder.c b/ext/json/json_encoder.c
@@ -350,7 +350,7 @@ static int php_json_escape_string(
 				0xffffffff, 0x500080c4, 0x10000000, 0x00000000};
 
 			pos++;
-			if (EXPECTED(!((charmap[us >> 5] >> (us & 0x1f)) & 1))) {
+			if (EXPECTED(!ZEND_BIT_TEST(charmap, us))) {
 				smart_str_appendc(buf, (unsigned char) us);
 			} else {
 				switch (us) {

diff --git a/ext/mysqlnd/mysqlnd_result.c b/ext/mysqlnd/mysqlnd_result.c
@@ -108,7 +108,7 @@ MYSQLND_METHOD(mysqlnd_result_buffered_c, initialize_result_set_rest)(MYSQLND_RE
 
 		for (i = 0; i < result->row_count; i++) {
 			/* (i / 8) & the_bit_for_i*/
-			if ((initialized[i >> 3] >> (i & 7)) & 1) {
+			if (ZEND_BIT_TEST(initialized, i)) {
 				continue;
 			}
 
@@ -1151,7 +1151,7 @@ MYSQLND_METHOD(mysqlnd_result_buffered_c, fetch_row)(MYSQLND_RES * result, void
 		if (rc != PASS) {
 			DBG_RETURN(FAIL);
 		}
-		if (!((set->initialized[set->current_row >> 3] >> (set->current_row & 7)) & 1)) {
+		if (!ZEND_BIT_TEST(set->initialized, set->current_row)) {
 			set->initialized[set->current_row >> 3] |= (1 << (set->current_row & 7)); /* mark initialized */
 
 			++set->initialized_rows;

diff --git a/ext/standard/array.c b/ext/standard/array.c
@@ -1660,14 +1660,14 @@ static zend_always_inline int php_valid_var_name(const char *var_name, size_t va
 {
 #if 1
 	/* first 256 bits for first character, and second 256 bits for the next */
-	static const uint32_t charset[16] = {
+	static const uint32_t charset[8] = {
 	     /*  31      0   63     32   95     64   127    96 */
 			0x00000000, 0x00000000, 0x87fffffe, 0x07fffffe,
-			0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff,
+			0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff};
+	static const uint32_t charset2[8] = {
 	     /*  31      0   63     32   95     64   127    96 */
 			0x00000000, 0x03ff0000, 0x87fffffe, 0x07fffffe,
-			0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff
-		};
+			0xffffffff, 0xffffffff, 0xffffffff, 0xffffffff};
 #endif
 	size_t i;
 	uint32_t ch;
@@ -1679,7 +1679,7 @@ static zend_always_inline int php_valid_var_name(const char *var_name, size_t va
 	/* These are allowed as first char: [a-zA-Z_\x7f-\xff] */
 	ch = (uint32_t)((unsigned char *)var_name)[0];
 #if 1
-	if (UNEXPECTED(!((charset[ch >> 5] >> (ch & 0x1f)) & 1))) {
+	if (UNEXPECTED(!ZEND_BIT_TEST(charset, ch))) {
 #else
 	if (var_name[0] != '_' &&
 		(ch < 65  /* A    */ || /* Z    */ ch > 90)  &&
@@ -1696,7 +1696,7 @@ static zend_always_inline int php_valid_var_name(const char *var_name, size_t va
 		do {
 			ch = (uint32_t)((unsigned char *)var_name)[i];
 #if 1
-			if (UNEXPECTED(!((charset[8 + (ch >> 5)] >> (ch & 0x1f)) & 1))) {
+			if (UNEXPECTED(!ZEND_BIT_TEST(charset2, ch))) {
 #else
 			if (var_name[i] != '_' &&
 				(ch < 48  /* 0    */ || /* 9    */ ch > 57)  &&