Use ZEND_FUNC_FREE_LOOP_VAR flag to avoid useless iterations.

Author: dstogov

ext/opcache/Optimizer/scdf.c

@@ -213,6 +213,9 @@ int scdf_remove_unreachable_blocks(scdf_ctx *scdf) {
 	int i;
 	int removed_ops = 0;
 
+	if (!(ssa->cfg.flags & ZEND_FUNC_FREE_LOOP_VAR)) {
+		return 0;
+	}
 	for (i = 0; i < ssa->cfg.blocks_count; i++) {
 		if (!zend_bitset_in(scdf->executable_blocks, i)
 				&& (ssa->cfg.blocks[i].flags & ZEND_BB_REACHABLE)

ext/opcache/Optimizer/zend_cfg.c

@@ -110,7 +110,7 @@ static void zend_mark_reachable_blocks(const zend_op_array *op_array, zend_cfg *
 	blocks[start].flags = ZEND_BB_START;
 	zend_mark_reachable(op_array->opcodes, cfg, blocks + start);
 
-	if (op_array->last_live_range || op_array->last_try_catch) {
+	if (op_array->last_try_catch) {
 		zend_basic_block *b;
 		int j, changed;
 		uint32_t *block_map = cfg->map;
@@ -193,6 +193,12 @@ static void zend_mark_reachable_blocks(const zend_op_array *op_array, zend_cfg *
 				}
 			}
 		} while (changed);
+	}
+
+	if (cfg->flags & ZEND_FUNC_FREE_LOOP_VAR) {
+		zend_basic_block *b;
+		int j;
+		uint32_t *block_map = cfg->map;
 
 		/* Mark blocks that are unreachable, but free a loop var created in a reachable block. */
 		for (b = blocks; b < blocks + cfg->blocks_count; b++) {
@@ -417,6 +423,14 @@ int zend_build_cfg(zend_arena **arena, const zend_op_array *op_array, uint32_t b
 			case ZEND_EXT_FCALL_END:
 				flags |= ZEND_FUNC_HAS_EXTENDED_INFO;
 				break;
+			case ZEND_FREE:
+				if (opline->extended_value == ZEND_FREE_SWITCH) {
+					flags |= ZEND_FUNC_FREE_LOOP_VAR;
+				}
+				break;
+			case ZEND_FE_FREE:
+				flags |= ZEND_FUNC_FREE_LOOP_VAR;
+				break;
 		}
 	}
 

ext/opcache/Optimizer/zend_func_info.h

@@ -27,6 +27,7 @@
 #define ZEND_FUNC_VARARG                   (1<<2)  /* uses func_get_args()        */
 #define ZEND_FUNC_NO_LOOPS                 (1<<3)
 #define ZEND_FUNC_IRREDUCIBLE              (1<<4)
+#define ZEND_FUNC_FREE_LOOP_VAR            (1<<5)
 #define ZEND_FUNC_RECURSIVE                (1<<7)
 #define ZEND_FUNC_RECURSIVE_DIRECTLY       (1<<8)
 #define ZEND_FUNC_RECURSIVE_INDIRECTLY     (1<<9)