@@ -314,6 +314,15 @@ static inline int same_memop(struct instruction *a, struct instruction *b)
return a->offset == b->offset && a->size == b->size;
}
+static inline int distinct_symbols(pseudo_t a, pseudo_t b)
+{
+ if (a->type != PSEUDO_SYM)
+ return 0;
+ if (b->type != PSEUDO_SYM)
+ return 0;
+ return a->sym != b->sym;
+}
+
/*
* Return 1 if "dom" dominates the access to "pseudo"
* in "insn".
@@ -332,7 +341,7 @@ int dominates(pseudo_t pseudo, struct instruction *insn, struct instruction *dom
if (local)
return 0;
/* We don't think two explicitly different symbols ever alias */
- if (dom->src->type == PSEUDO_SYM)
+ if (distinct_symbols(insn->src, dom->src))
return 0;
/* We could try to do some alias analysis here */
return -1;
new file mode 100644
@@ -0,0 +1,17 @@
+extern int g;
+extern int h;
+
+static int foo(void)
+{
+ g = 1;
+ h = 2;
+ return g == 1;
+}
+
+/*
+ * check-name: alias distinct symbols
+ * check-command: test-linearize $file
+ * check-output-ignore
+ *
+ * check-output-contains: ret\\..* *\\$1
+ */
new file mode 100644
@@ -0,0 +1,30 @@
+extern int g;
+
+
+static int foo(int *p)
+{
+ *p = 1;
+ g = 2;
+ return *p == 1;
+}
+
+static int bar(int *p)
+{
+ g = 1;
+ *p = 2;
+ return g == 1;
+}
+
+static test(void)
+{
+ foo(&g);
+ bar(&g);
+}
+
+/*
+ * check-name: alias symbol/pointer
+ * check-command: test-linearize $file
+ * check-output-ignore
+ *
+ * check-output-excludes: ret\\..* *\\$1
+ */
new file mode 100644
@@ -0,0 +1,17 @@
+extern int g;
+
+
+static int foo(void)
+{
+ g = 1;
+ g = 2;
+ return g != 1;
+}
+
+/*
+ * check-name: alias same symbols
+ * check-command: test-linearize $file
+ * check-output-ignore
+ *
+ * check-output-contains: ret\\..* *\\$1
+ */
In dominates() there is the following comment: "We don't think two explicitly different symbols ever alias" but the corresponding test only check if the storage in the potentialy dominating instruction is a symbol and if so returns 0 meaning that it can't dominate. But that's without taking in account that a pointer can point to this symbol and thus that a store via this symbol can dominate a store via a pointer. Fix this by changing the test more in accordance to the comment: return 0 only if the 2 concerned location correspond to 2 *distinct* symbols (and thus do not return 0 if one of the location is not a symbol). Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com> --- flow.c | 11 ++++++++++- validation/alias-distinct.c | 17 +++++++++++++++++ validation/alias-mixed.c | 30 ++++++++++++++++++++++++++++++ validation/alias-same.c | 17 +++++++++++++++++ 4 files changed, 74 insertions(+), 1 deletion(-) create mode 100644 validation/alias-distinct.c create mode 100644 validation/alias-mixed.c create mode 100644 validation/alias-same.c