re PR middle-end/52493 (tree check fail in ptr_derefs_may_alias_p)

2012-03-06  Richard Guenther  <rguenther@suse.de>

	PR middle-end/52493
	* tree-ssa-alias.c (ptr_derefs_may_alias_p): Robustify.

	* gcc.dg/torture/pr52493.c: New testcase.

From-SVN: r184987

4 files changed, 57 insertions, 13 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 4f629fa..3b88179 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2012-03-06  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/52493
+	* tree-ssa-alias.c (ptr_derefs_may_alias_p): Robustify.
+
 2012-03-06  Tristan Gingold  <gingold@adacore.com>
 
 	* config/vms/vms-c.c (vms_pragma_nomember_alignment): Handle
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 45b04e9..25b446b 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2012-03-06  Richard Guenther  <rguenther@suse.de>
 
+	PR middle-end/52493
+	* gcc.dg/torture/pr52493.c: New testcase.
+
+2012-03-06  Richard Guenther  <rguenther@suse.de>
+
 	PR lto/52097
 	* gcc.dg/lto/pr52097_0.c: New testcase.
 
diff --git a/gcc/testsuite/gcc.dg/torture/pr52493.c b/gcc/testsuite/gcc.dg/torture/pr52493.c
new file mode 100644
index 0000000..b04ac5c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr52493.c
@@ -0,0 +1,38 @@
+/* { dg-do compile } */
+
+struct Time {
+    long int sec;
+    long usec;
+};
+struct Flow {
+    unsigned short iif;
+    struct Time mtime;
+};
+struct NetFlow {
+    unsigned MaxFlows;
+    unsigned HeaderFields;
+    unsigned short *HeaderFormat;
+};
+static struct NetFlow *netflow;
+static struct Time start_time;
+static unsigned char emit_packet[1500];
+inline long int cmpmtime(struct Time *t1, struct Time *t2)
+{
+  return (t1->sec - t2->sec) * 1000 + (t1->usec - t2->usec) / 1000;
+}
+static void fill(int fields, unsigned short *format,
+		  struct Flow *flow, void *p)
+{
+  int i;
+  for (i = 0; i < fields; i++)
+    if (format[i] == 21)
+      {
+	unsigned int __v;
+	__v = cmpmtime(&flow->mtime, &start_time);
+	*((unsigned int *) p) = __v;
+      }
+}
+void emit_thread()
+{
+  fill(netflow->HeaderFields, netflow->HeaderFormat, 0, &emit_packet);
+}
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c
index 54badda..dd90432 100644
--- a/gcc/tree-ssa-alias.c
+++ b/gcc/tree-ssa-alias.c
@@ -236,17 +236,6 @@ ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
   STRIP_NOPS (ptr1);
   STRIP_NOPS (ptr2);
 
-  /* Anything we do not explicilty handle aliases.  */
-  if ((TREE_CODE (ptr1) != SSA_NAME
-       && TREE_CODE (ptr1) != ADDR_EXPR
-       && TREE_CODE (ptr1) != POINTER_PLUS_EXPR)
-      || (TREE_CODE (ptr2) != SSA_NAME
-	  && TREE_CODE (ptr2) != ADDR_EXPR
-	  && TREE_CODE (ptr2) != POINTER_PLUS_EXPR)
-      || !POINTER_TYPE_P (TREE_TYPE (ptr1))
-      || !POINTER_TYPE_P (TREE_TYPE (ptr2)))
-    return true;
-
   /* Disregard pointer offsetting.  */
   if (TREE_CODE (ptr1) == POINTER_PLUS_EXPR)
     {
@@ -275,7 +264,7 @@ ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
       if (base
 	  && (TREE_CODE (base) == MEM_REF
 	      || TREE_CODE (base) == TARGET_MEM_REF))
-	ptr1 = TREE_OPERAND (base, 0);
+	return ptr_derefs_may_alias_p (TREE_OPERAND (base, 0), ptr2);
       else if (base
 	       && DECL_P (base))
 	return ptr_deref_may_alias_decl_p (ptr2, base);
@@ -288,7 +277,7 @@ ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
       if (base
 	  && (TREE_CODE (base) == MEM_REF
 	      || TREE_CODE (base) == TARGET_MEM_REF))
-	ptr2 = TREE_OPERAND (base, 0);
+	return ptr_derefs_may_alias_p (ptr1, TREE_OPERAND (base, 0));
       else if (base
 	       && DECL_P (base))
 	return ptr_deref_may_alias_decl_p (ptr1, base);
@@ -296,6 +285,13 @@ ptr_derefs_may_alias_p (tree ptr1, tree ptr2)
 	return true;
     }
 
+  /* From here we require SSA name pointers.  Anything else aliases.  */
+  if (TREE_CODE (ptr1) != SSA_NAME
+      || TREE_CODE (ptr2) != SSA_NAME
+      || !POINTER_TYPE_P (TREE_TYPE (ptr1))
+      || !POINTER_TYPE_P (TREE_TYPE (ptr2)))
+    return true;
+
   /* We may end up with two empty points-to solutions for two same pointers.
      In this case we still want to say both pointers alias, so shortcut
      that here.  */