Extend min/max array fast path to doubles

Author: mehmetcansahin

UPGRADING

@@ -392,6 +392,8 @@ PHP 8.6 UPGRADE NOTES
   . Improved performance of array_map() with multiple arrays passed.
   . Improved performance of array_sum() and array_product() for
     integer-only arrays.
+  . Improved performance of min() and max() for integer-only and float-only
+    arrays.
   . Improved performance of array_unshift().
   . Improved performance of array_walk().
   . Improved performance of intval('+0b...', 2) and intval('0b...', 2).

ext/standard/array.c

@@ -1095,63 +1095,73 @@ static int php_data_compare(const void *f, const void *s) /* {{{ */
 }
 /* }}} */
 
-static zend_always_inline bool php_array_minmax_long(HashTable *array, zval *return_value, bool max) /* {{{ */
+static zend_always_inline bool php_array_minmax(HashTable *array, zval *return_value, bool max) /* {{{ */
 {
 	zval *entry, *result = NULL;
-	zend_long result_lval;
-	bool long_mode = false;
+	zend_long result_lval = 0;
+	double result_dval = 0.0;
+	/* IS_LONG or IS_DOUBLE while every value scanned so far has that exact type,
+	 * IS_UNDEF once a value forces the generic php_data_compare() fallback. */
+	uint8_t fast_type = IS_UNDEF;
 
 	ZEND_HASH_FOREACH_VAL(array, entry) {
 		zval *value = entry;
-		zend_long value_lval;
 
 		ZVAL_DEREF(value);
-		if (!result) {
-			if (Z_TYPE_P(value) != IS_LONG) {
-				return false;
-			}
 
-			result = value;
-			result_lval = Z_LVAL_P(value);
-			long_mode = true;
+		if (fast_type == IS_LONG && EXPECTED(Z_TYPE_P(value) == IS_LONG)) {
+			zend_long value_lval = Z_LVAL_P(value);
+			if (max ? result_lval < value_lval : result_lval > value_lval) {
+				result = value;
+				result_lval = value_lval;
+			}
 			continue;
 		}
 
-		if (long_mode && EXPECTED(Z_TYPE_P(value) == IS_LONG)) {
-			value_lval = Z_LVAL_P(value);
-			if (max) {
-				if (result_lval < value_lval) {
+		if (fast_type == IS_DOUBLE && EXPECTED(Z_TYPE_P(value) == IS_DOUBLE)) {
+			double value_dval = Z_DVAL_P(value);
+			/* NaN ordering differs from zend_compare(); hand it to the fallback. */
+			if (EXPECTED(!zend_isnan(value_dval))) {
+				if (max ? result_dval < value_dval : result_dval > value_dval) {
 					result = value;
-					result_lval = value_lval;
-				}
-			} else {
-				if (result_lval > value_lval) {
-					result = value;
-					result_lval = value_lval;
+					result_dval = value_dval;
 				}
+				continue;
 			}
-			continue;
 		}
 
-		long_mode = false;
-
-		if (max) {
-			if (php_data_compare(result, value) < 0) {
+		if (!result) {
+			if (Z_TYPE_P(value) == IS_LONG) {
 				result = value;
+				result_lval = Z_LVAL_P(value);
+				fast_type = IS_LONG;
+				continue;
 			}
-		} else {
-			if (php_data_compare(result, value) > 0) {
+			if (Z_TYPE_P(value) == IS_DOUBLE && !zend_isnan(Z_DVAL_P(value))) {
 				result = value;
+				result_dval = Z_DVAL_P(value);
+				fast_type = IS_DOUBLE;
+				continue;
 			}
+			return false;
+		}
+
+		fast_type = IS_UNDEF;
+
+		int cmp = php_data_compare(result, value);
+		if (max ? cmp < 0 : cmp > 0) {
+			result = value;
 		}
 	} ZEND_HASH_FOREACH_END();
 
 	if (!result) {
 		return false;
 	}
 
-	if (long_mode) {
+	if (fast_type == IS_LONG) {
 		ZVAL_LONG(return_value, result_lval);
+	} else if (fast_type == IS_DOUBLE) {
+		ZVAL_DOUBLE(return_value, result_dval);
 	} else {
 		ZVAL_COPY_DEREF(return_value, result);
 	}
@@ -1179,7 +1189,7 @@ PHP_FUNCTION(min)
 			RETURN_THROWS();
 		} else {
 			HashTable *array = Z_ARRVAL(args[0]);
-			if (php_array_minmax_long(array, return_value, false)) {
+			if (php_array_minmax(array, return_value, false)) {
 				return;
 			}
 
@@ -1312,7 +1322,7 @@ PHP_FUNCTION(max)
 			RETURN_THROWS();
 		} else {
 			HashTable *array = Z_ARRVAL(args[0]);
-			if (php_array_minmax_long(array, return_value, true)) {
+			if (php_array_minmax(array, return_value, true)) {
 				return;
 			}
 

ext/standard/tests/array/min_max_array_fast_path.phpt

@@ -0,0 +1,107 @@
+--TEST--
+min() and max() array long/double fast path preserves comparison behavior
+--FILE--
+<?php
+
+$cases = [];
+
+$cases["packed long"] = [4, 1, 7, -3, 2];
+
+$long_sparse = [4, 1, 7];
+unset($long_sparse[1]);
+$long_sparse[5] = -2;
+$cases["sparse long"] = $long_sparse;
+
+$la = 4;
+$lb = 9;
+$cases["long refs"] = [&$la, &$lb, 3];
+
+$cases["packed double"] = [4.5, 1.5, 7.5, -3.5, 2.5];
+
+$dbl_sparse = [4.5, 1.5, 7.5];
+unset($dbl_sparse[1]);
+$dbl_sparse[5] = -2.5;
+$cases["sparse double"] = $dbl_sparse;
+
+$da = 4.5;
+$db = 9.5;
+$cases["double refs"] = [&$da, &$db, 3.5];
+
+$cases["double equal"] = [2.5, 2.5, 2.5];
+
+$cases["nan first"] = [NAN, 1.0, 2.0];
+$cases["nan middle"] = [3.0, NAN, 1.0];
+$cases["nan last"] = [3.0, 1.0, NAN];
+$cases["inf"] = [INF, -INF, 0.0, 5.0];
+
+$cases["single long"] = [7];
+$cases["single double"] = [7.5];
+
+$cases["first non-long"] = ["5", 3, 4];
+$cases["fallback after longs"] = [5, 4, "3", 2];
+$cases["fallback after doubles"] = [5.5, 4.5, "3", 2.5];
+$cases["long then double"] = [5, 4, 2.5, 9];
+$cases["double then long"] = [5.5, 4.5, 2, 9];
+
+foreach ($cases as $name => $values) {
+    echo "-- $name --\n";
+    var_dump(min($values));
+    var_dump(max($values));
+}
+
+?>
+--EXPECT--
+-- packed long --
+int(-3)
+int(7)
+-- sparse long --
+int(-2)
+int(7)
+-- long refs --
+int(3)
+int(9)
+-- packed double --
+float(-3.5)
+float(7.5)
+-- sparse double --
+float(-2.5)
+float(7.5)
+-- double refs --
+float(3.5)
+float(9.5)
+-- double equal --
+float(2.5)
+float(2.5)
+-- nan first --
+float(1)
+float(NAN)
+-- nan middle --
+float(1)
+float(3)
+-- nan last --
+float(NAN)
+float(3)
+-- inf --
+float(-INF)
+float(INF)
+-- single long --
+int(7)
+int(7)
+-- single double --
+float(7.5)
+float(7.5)
+-- first non-long --
+int(3)
+string(1) "5"
+-- fallback after longs --
+int(2)
+int(5)
+-- fallback after doubles --
+float(2.5)
+float(5.5)
+-- long then double --
+float(2.5)
+int(9)
+-- double then long --
+int(2)
+int(9)