Make operator swapping depend on IGNORE_OVERLOADING flag

Add MUL back to the list and instead make the entire optimization
depend on IGNORE_OVERLOADING, which is there exactly so we can make
these kinds of assumptions.

Author: nikic

ext/opcache/Optimizer/pass3.c

@@ -50,7 +50,7 @@
 	}										\
 	jmp_hitlist[jmp_hitlist_count++] = ZEND_OP2_JMP_ADDR(target);
 
-void zend_optimizer_pass3(zend_op_array *op_array)
+void zend_optimizer_pass3(zend_op_array *op_array, zend_optimizer_ctx *ctx)
 {
 	zend_op *opline;
 	zend_op *end = op_array->opcodes + op_array->last;
@@ -90,15 +90,17 @@ void zend_optimizer_pass3(zend_op_array *op_array)
 						break;
 					}
 
-					if ((opline->op2_type & (IS_VAR | IS_CV))
+					/* change $i=expr+$i to $i=$i+expr so that the following optimization
+					 * works on it. Only do this if we are ignoring operator overloading,
+					 * as operand order might be significant otherwise. */
+					if ((ctx->optimization_level & ZEND_OPTIMIZER_IGNORE_OVERLOADING)
+						&& (opline->op2_type & (IS_VAR | IS_CV))
 						&& opline->op2.var == next_opline->op1.var &&
 						(opline->opcode == ZEND_ADD ||
+						 opline->opcode == ZEND_MUL ||
 						 opline->opcode == ZEND_BW_OR ||
 						 opline->opcode == ZEND_BW_AND ||
 						 opline->opcode == ZEND_BW_XOR)) {
-						/* change $i=expr+$i to $i=$i+expr so that the next
-						* optimization works on it
-						*/
 						zend_uchar tmp_type = opline->op1_type;
 						znode_op tmp = opline->op1;
 
@@ -110,6 +112,7 @@ void zend_optimizer_pass3(zend_op_array *op_array)
 							COPY_NODE(opline->op2, tmp);
 						}
 					}
+
 					if ((opline->op1_type & (IS_VAR | IS_CV))
 						&& opline->op1.var == next_opline->op1.var
 						&& opline->op1_type == next_opline->op1_type) {

ext/opcache/Optimizer/zend_optimizer.c

@@ -1131,7 +1131,7 @@ static void zend_optimize(zend_op_array      *op_array,
 	 * - change $i++ to ++$i where possible
 	 */
 	if (ZEND_OPTIMIZER_PASS_3 & ctx->optimization_level) {
-		zend_optimizer_pass3(op_array);
+		zend_optimizer_pass3(op_array, ctx);
 		if (ctx->debug_level & ZEND_DUMP_AFTER_PASS_3) {
 			zend_dump_op_array(op_array, 0, "after pass 3", NULL);
 		}

ext/opcache/Optimizer/zend_optimizer_internal.h

@@ -95,7 +95,7 @@ void zend_optimizer_remove_live_range(zend_op_array *op_array, uint32_t var);
 void zend_optimizer_remove_live_range_ex(zend_op_array *op_array, uint32_t var, uint32_t start);
 void zend_optimizer_pass1(zend_op_array *op_array, zend_optimizer_ctx *ctx);
 void zend_optimizer_pass2(zend_op_array *op_array);
-void zend_optimizer_pass3(zend_op_array *op_array);
+void zend_optimizer_pass3(zend_op_array *op_array, zend_optimizer_ctx *ctx);
 void zend_optimize_func_calls(zend_op_array *op_array, zend_optimizer_ctx *ctx);
 void zend_optimize_cfg(zend_op_array *op_array, zend_optimizer_ctx *ctx);
 void zend_optimize_dfa(zend_op_array *op_array, zend_optimizer_ctx *ctx);