From: Nikita Popov <nikic@php.net>
Date: Tue, 7 Jun 2016 18:36:54 +0000 (+0200)
Subject: Use LCA for object(ce) type joins
X-Git-Tag: php-7.1.0alpha3~42^2~53
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=be37de1ff153c4ac51d14177572aa332612ae8e1;p=php

Use LCA for object(ce) type joins

For B, C extending A the join of object(B) and object(C) should
be object(instanceof A). For simplicity we only handle the class
hierarchy, as computing the least common unique ancestor for
interfaces would be more involved.

Also ignore phi sources that don't have an object type: The join
of null and object(A) is now null|object(A) rather than
null|object.
---

diff --git a/ext/opcache/Optimizer/zend_inference.c b/ext/opcache/Optimizer/zend_inference.c
index 56fcfdb393..cb8540c64b 100644
--- a/ext/opcache/Optimizer/zend_inference.c
+++ b/ext/opcache/Optimizer/zend_inference.c
@@ -2017,11 +2017,11 @@ static int zend_infer_ranges(const zend_op_array *op_array, zend_ssa *ssa) /* {{
 #define UPDATE_SSA_OBJ_TYPE(_ce, _is_instanceof, var)				    \
 	do {                                                                \
 		if (var >= 0) {													\
-			if (ssa_var_info[var].ce != _ce ||                          \
-			    ssa_var_info[var].is_instanceof != _is_instanceof) {    \
-				ssa_var_info[var].ce = _ce;						        \
-				ssa_var_info[var].is_instanceof = _is_instanceof;       \
-				add_usages(op_array, ssa, worklist, var);					\
+			if (ssa_var_info[var].ce != (_ce) ||                        \
+			    ssa_var_info[var].is_instanceof != (_is_instanceof)) {  \
+				ssa_var_info[var].ce = (_ce);						    \
+				ssa_var_info[var].is_instanceof = (_is_instanceof);     \
+				add_usages(op_array, ssa, worklist, var);				\
 			}															\
 			/*zend_bitset_excl(worklist, var);*/						\
 		}																\
@@ -3364,6 +3364,50 @@ unknown_opcode:
 	}
 }
 
+static uint32_t get_class_entry_rank(zend_class_entry *ce) {
+	uint32_t rank = 0;
+	while (ce->parent) {
+		rank++;
+		ce = ce->parent;
+	}
+	return rank;
+}
+
+/* Compute least common ancestor on class inheritance tree only */
+static zend_class_entry *join_class_entries(
+		zend_class_entry *ce1, zend_class_entry *ce2, int *is_instanceof) {
+	uint32_t rank1, rank2;
+	if (ce1 == ce2) {
+		return ce1;
+	}
+	if (!ce1 || !ce2) {
+		return NULL;
+	}
+
+	rank1 = get_class_entry_rank(ce1);
+	rank2 = get_class_entry_rank(ce2);
+
+	while (rank1 != rank2) {
+		if (rank1 > rank2) {
+			ce1 = ce1->parent;
+			rank1--;
+		} else {
+			ce2 = ce2->parent;
+			rank2--;
+		}
+	}
+
+	while (ce1 != ce2) {
+		ce1 = ce1->parent;
+		ce2 = ce2->parent;
+	}
+
+	if (ce1) {
+		*is_instanceof = 1;
+	}
+	return ce1;
+}
+
 int zend_infer_types_ex(const zend_op_array *op_array, const zend_script *script, zend_ssa *ssa, zend_bitset worklist)
 {
 	zend_basic_block *blocks = ssa->cfg.blocks;
@@ -3399,20 +3443,21 @@ int zend_infer_types_ex(const zend_op_array *op_array, const zend_script *script
 				}
 				UPDATE_SSA_TYPE(tmp, j);
 				for (i = 0; i < blocks[p->block].predecessors_count; i++) {
-					if (get_ssa_var_info(ssa, p->sources[i])) {
-						if (first) {
-							ce = ssa_var_info[p->sources[i]].ce;
-							is_instanceof = ssa_var_info[p->sources[i]].is_instanceof;
-							first = 0;
-						} else if (ce != ssa_var_info[p->sources[i]].ce) {
-							ce = NULL;
-							is_instanceof = 0;
-						} else if (is_instanceof != ssa_var_info[p->sources[i]].is_instanceof) {
-							is_instanceof = 1;
+					if (p->sources[i] >= 0) {
+						zend_ssa_var_info *info = &ssa_var_info[p->sources[i]];
+						if (info->type & MAY_BE_OBJECT) {
+							if (first) {
+								ce = info->ce;
+								is_instanceof = info->is_instanceof;
+								first = 0;
+							} else {
+								is_instanceof |= info->is_instanceof;
+								ce = join_class_entries(ce, info->ce, &is_instanceof);
+							}
 						}
 					}
 				}
-				UPDATE_SSA_OBJ_TYPE(ce, is_instanceof, j);
+				UPDATE_SSA_OBJ_TYPE(ce, ce ? is_instanceof : 0, j);
 			}
 		} else if (ssa_vars[j].definition >= 0) {
 			i = ssa_vars[j].definition;