new file mode 100644
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O -ftree-pre -ftree-vectorize -fno-tree-pta" } */
+
+void
+qf (void);
+
+void
+mr (short int db)
+{
+ int vq;
+ short int *lp = &db;
+
+ for (vq = 0; vq < 1; ++vq)
+ qf ();
+
+ while (*lp < 2)
+ {
+ *lp = db;
+ lp = (short int *) &vq;
+ ++*lp;
+ }
+}
+
@@ -4194,12 +4194,19 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p)
value from the backedge as that confuses the alias-walking code.
See gcc.dg/torture/pr87176.c. If the value is the same on a
non-backedge everything is OK though. */
- if (backedge_val
- && !seen_non_backedge
- && TREE_CODE (backedge_val) == SSA_NAME
- && sameval == backedge_val
- && (SSA_NAME_IS_VIRTUAL_OPERAND (backedge_val)
- || SSA_VAL (backedge_val) != backedge_val))
+ bool visited_p;
+ if ((backedge_val
+ && !seen_non_backedge
+ && TREE_CODE (backedge_val) == SSA_NAME
+ && sameval == backedge_val
+ && (SSA_NAME_IS_VIRTUAL_OPERAND (backedge_val)
+ || SSA_VAL (backedge_val) != backedge_val))
+ /* Do not value-number a virtual operand to sth not visited though
+ given that allows us to escape a region in alias walking. */
+ || (sameval
+ && TREE_CODE (sameval) == SSA_NAME
+ && SSA_NAME_IS_VIRTUAL_OPERAND (sameval)
+ && (SSA_VAL (sameval, &visited_p), !visited_p)))
/* Note this just drops to VARYING without inserting the PHI into
the hashes. */
result = PHI_RESULT (phi);