Fix handling of non-final loop var free in sccp

We only need to preserve the FE_FREE that marks the end of the
loop range. Skip FE_FREEs with the FREE_ON_RETURN flag.

Author: nikic

ext/opcache/Optimizer/scdf.c

@@ -195,8 +195,7 @@ static zend_bool kept_alive_by_loop_var_free(scdf_ctx *scdf, uint32_t block_idx)
 	}
 	for (i = block->start; i < block->start + block->len; i++) {
 		zend_op *opline = &op_array->opcodes[i];
-		if (opline->opcode == ZEND_FE_FREE ||
-				(opline->opcode == ZEND_FREE && opline->extended_value == ZEND_FREE_SWITCH)) {
+		if (zend_optimizer_is_loop_var_free(opline)) {
 			int ssa_var = scdf->ssa->ops[i].op1_use;
 			if (ssa_var >= 0) {
 				int op_num = scdf->ssa->vars[ssa_var].definition;

ext/opcache/Optimizer/zend_cfg.c

@@ -208,9 +208,7 @@ static void zend_mark_reachable_blocks(const zend_op_array *op_array, zend_cfg *
 
 			for (j = b->start; j < b->start + b->len; j++) {
 				zend_op *opline = &op_array->opcodes[j];
-				if (opline->opcode == ZEND_FE_FREE ||
-					(opline->opcode == ZEND_FREE && opline->extended_value == ZEND_FREE_SWITCH)
-				) {
+				if (zend_optimizer_is_loop_var_free(opline)) {
 					zend_op *def_opline = zend_optimizer_get_loop_var_def(op_array, opline);
 					if (def_opline) {
 						uint32_t def_block = block_map[def_opline - op_array->opcodes];

ext/opcache/Optimizer/zend_optimizer.c

@@ -918,8 +918,7 @@ uint32_t zend_optimizer_classify_function(zend_string *name, uint32_t num_args)
 
 zend_op *zend_optimizer_get_loop_var_def(const zend_op_array *op_array, zend_op *free_opline) {
 	uint32_t var = free_opline->op1.var;
-	ZEND_ASSERT(free_opline->opcode == ZEND_FE_FREE ||
-		(free_opline->opcode == ZEND_FREE && free_opline->extended_value == ZEND_FREE_SWITCH));
+	ZEND_ASSERT(zend_optimizer_is_loop_var_free(free_opline));
 
 	while (--free_opline >= op_array->opcodes) {
 		if ((free_opline->result_type & (IS_TMP_VAR|IS_VAR)) && free_opline->result.var == var) {

ext/opcache/Optimizer/zend_optimizer_internal.h

@@ -71,6 +71,11 @@ typedef struct _zend_optimizer_ctx {
 		target = src; \
 	} while (0)
 
+static inline zend_bool zend_optimizer_is_loop_var_free(const zend_op *opline) {
+	return (opline->opcode == ZEND_FE_FREE && opline->extended_value != ZEND_FREE_ON_RETURN)
+		|| (opline->opcode == ZEND_FREE && opline->extended_value == ZEND_FREE_SWITCH);
+}
+
 int  zend_optimizer_add_literal(zend_op_array *op_array, zval *zv);
 int  zend_optimizer_get_persistent_constant(zend_string *name, zval *result, int copy);
 void zend_optimizer_collect_constant(zend_optimizer_ctx *ctx, zval *name, zval* value);

ext/opcache/tests/sccp_loop_var_free.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Check that SCCP correctly handles non-terminating frees of loop variables
+--FILE--
+<?php
+function test() {
+    $arr = [];
+    foreach ($arr as $item) {
+        if (!empty($result)) {
+            return $result;
+        }
+    }
+    return 2;
+}
+
+var_dump(test());
+?>
+--EXPECT--
+int(2)