===================================================================
@@ -3901,13 +3901,10 @@ visit_phi (gimple *phi)
if only a single edge is exectuable use its value. */
if (n_executable <= 1)
result = seen_undef ? seen_undef : sameval;
- /* If we saw only undefined values create a new undef SSA name to
- avoid false equivalences. */
+ /* If we saw only undefined values and VN_TOP use one of the
+ undefined values. */
else if (sameval == VN_TOP)
- {
- gcc_assert (seen_undef);
- result = seen_undef;
- }
+ result = seen_undef ? seen_undef : sameval;
/* First see if it is equivalent to a phi node in this block. We prefer
this as it allows IV elimination - see PRs 66502 and 67167. */
else if ((result = vn_phi_lookup (phi)))
===================================================================
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+
+int a, b, c;
+
+void fn1 ()
+{
+ while (1)
+ {
+ if (c)
+ goto L2;
+ break;
+ }
+ if (c)
+ {
+L1:
+ {
+ int g[1];
+ if (b)
+ goto L1;
+ goto L1;
+L2:
+ for (a = 0; a;)
+ goto L1;
+ }
+ }
+}
+
+int main ()
+{
+ fn1 ();
+ return 0;
+}