Remove tail call optimization

Author: nielsdos

Zend/Optimizer/zend_cfg.c

@@ -35,82 +35,67 @@ static void zend_mark_reachable(zend_op *opcodes, zend_cfg *cfg, zend_basic_bloc
 	zend_worklist_push(&work, b - cfg->blocks);
 
 	while (zend_worklist_len(&work)) {
+		int i;
 		b = cfg->blocks + zend_worklist_pop(&work);
 
-		bool finished = false;
-		while (!finished) {
-			int i;
-
-			b->flags |= ZEND_BB_REACHABLE;
-			if (b->successors_count == 0) {
-				b->flags |= ZEND_BB_EXIT;
-				break;
-			}
+		b->flags |= ZEND_BB_REACHABLE;
+		if (b->successors_count == 0) {
+			b->flags |= ZEND_BB_EXIT;
+			continue;
+		}
 
-			for (i = 0; i < b->successors_count; i++) {
-				zend_basic_block* succ = blocks + b->successors[i];
+		for (i = 0; i < b->successors_count; i++) {
+			zend_basic_block* succ = blocks + b->successors[i];
 
-				if (b->len != 0) {
-					uint8_t opcode = opcodes[b->start + b->len - 1].opcode;
-					if (opcode == ZEND_MATCH) {
+			if (b->len != 0) {
+				uint8_t opcode = opcodes[b->start + b->len - 1].opcode;
+				if (opcode == ZEND_MATCH) {
+					succ->flags |= ZEND_BB_TARGET;
+				} else if (opcode == ZEND_SWITCH_LONG || opcode == ZEND_SWITCH_STRING) {
+					if (i == b->successors_count - 1) {
+						succ->flags |= ZEND_BB_FOLLOW | ZEND_BB_TARGET;
+					} else {
 						succ->flags |= ZEND_BB_TARGET;
-					} else if (opcode == ZEND_SWITCH_LONG || opcode == ZEND_SWITCH_STRING) {
-						if (i == b->successors_count - 1) {
-							succ->flags |= ZEND_BB_FOLLOW | ZEND_BB_TARGET;
-						} else {
-							succ->flags |= ZEND_BB_TARGET;
-						}
-					} else if (b->successors_count == 1) {
-						if (opcode == ZEND_JMP) {
-							succ->flags |= ZEND_BB_TARGET;
-						} else {
-							succ->flags |= ZEND_BB_FOLLOW;
-
-							if ((cfg->flags & ZEND_CFG_STACKLESS)) {
-								if (opcode == ZEND_INCLUDE_OR_EVAL ||
-									opcode == ZEND_GENERATOR_CREATE ||
-									opcode == ZEND_YIELD ||
-									opcode == ZEND_YIELD_FROM ||
-									opcode == ZEND_DO_FCALL ||
-									opcode == ZEND_DO_UCALL ||
-									opcode == ZEND_DO_FCALL_BY_NAME) {
-									succ->flags |= ZEND_BB_ENTRY;
-								}
-							}
-							if ((cfg->flags & ZEND_CFG_RECV_ENTRY)) {
-								if (opcode == ZEND_RECV ||
-									opcode == ZEND_RECV_INIT) {
-									succ->flags |= ZEND_BB_RECV_ENTRY;
-								}
+					}
+				} else if (b->successors_count == 1) {
+					if (opcode == ZEND_JMP) {
+						succ->flags |= ZEND_BB_TARGET;
+					} else {
+						succ->flags |= ZEND_BB_FOLLOW;
+
+						if ((cfg->flags & ZEND_CFG_STACKLESS)) {
+							if (opcode == ZEND_INCLUDE_OR_EVAL ||
+								opcode == ZEND_GENERATOR_CREATE ||
+								opcode == ZEND_YIELD ||
+								opcode == ZEND_YIELD_FROM ||
+								opcode == ZEND_DO_FCALL ||
+								opcode == ZEND_DO_UCALL ||
+								opcode == ZEND_DO_FCALL_BY_NAME) {
+								succ->flags |= ZEND_BB_ENTRY;
 							}
 						}
-					} else {
-						ZEND_ASSERT(b->successors_count == 2);
-						if (i == 0) {
-							succ->flags |= ZEND_BB_TARGET;
-						} else {
-							succ->flags |= ZEND_BB_FOLLOW;
+						if ((cfg->flags & ZEND_CFG_RECV_ENTRY)) {
+							if (opcode == ZEND_RECV ||
+								opcode == ZEND_RECV_INIT) {
+								succ->flags |= ZEND_BB_RECV_ENTRY;
+							}
 						}
 					}
 				} else {
-					succ->flags |= ZEND_BB_FOLLOW;
-				}
-
-				if (i == b->successors_count - 1) {
-					/* Tail call optimization */
-					if (succ->flags & ZEND_BB_REACHABLE) {
-						finished = true;
-						break;
-					}
-
-					b = succ;
-					break;
-				} else {
-					/* Recursively check reachability */
-					if (!(succ->flags & ZEND_BB_REACHABLE)) {
-						zend_worklist_push(&work, succ - cfg->blocks);
+					ZEND_ASSERT(b->successors_count == 2);
+					if (i == 0) {
+						succ->flags |= ZEND_BB_TARGET;
+					} else {
+						succ->flags |= ZEND_BB_FOLLOW;
 					}
 				}
+			} else {
+				succ->flags |= ZEND_BB_FOLLOW;
+			}
+
+			/* Check reachability of successor */
+			if (!(succ->flags & ZEND_BB_REACHABLE)) {
+				zend_worklist_push(&work, succ - cfg->blocks);
 			}
 		}
 	}