re PR tree-optimization/87402 (ICE in set_ssa_val_to, at tree-ssa-sccvn.c:3645)

2018-09-25  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/87402
	* tree-ssa-sccvn.c (SSA_VISITED): Remove unused function.
	(visit_phi): Re-instantiate handling of supposed to be VARYING
	but non-VARYING backedge value.

	* gcc.dg/torture/pr87402.c: New testcase.

From-SVN: r264566

gcc/ChangeLog

 2018-09-25  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/87402
+	* tree-ssa-sccvn.c (SSA_VISITED): Remove unused function.
+	(visit_phi): Re-instantiate handling of supposed to be VARYING
+	but non-VARYING backedge value.
+
+2018-09-25  Richard Biener  <rguenther@suse.de>
+
 	PR debug/83941
 	* dwarf2out.c (struct sym_off_pair): New.
 	(external_die_map): New global.

gcc/testsuite/ChangeLog

+2018-09-25  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/87402
+	* gcc.dg/torture/pr87402.c: New testcase.
+
 2018-09-25  H.J. Lu  <hongjiu.lu@intel.com>
 
 	PR testsuite/70150

gcc/testsuite/gcc.dg/torture/pr87402.c

+/* { dg-do compile } */
+
+void
+xl (int co)
+{
+  int ar = 0;
+
+  if (ar != 0)
+    {
+      int pp, ll = 0;
+      int *zx;
+
+      if (co == 0)
+	{
+	}
+      else
+	{
+	  zx = &pp;
+
+	  if (co < 0)
+	    while (co < 1)
+	      {
+to:
+		while (ll < 1)
+		  ++ll;
+	      }
+
+	  *zx = (__INTPTR_TYPE__)&ar;
+	}
+    }
+
+  goto to;
+}

gcc/tree-ssa-sccvn.c

@@ -464,15 +464,6 @@ SSA_VAL (tree x, bool *visited = NULL)
   return tem && tem->visited ? tem->valnum : x;
 }
 
-/* Return whether X was visited.  */
-
-inline bool
-SSA_VISITED (tree x)
-{
-  vn_ssa_aux_t tem = vn_ssa_aux_hash->find_with_hash (x, SSA_NAME_VERSION (x));
-  return tem && tem->visited;
-}
-
 /* Return the SSA value of the VUSE x, supporting released VDEFs
    during elimination which will value-number the VDEF to the
    associated VUSE (but not substitute in the whole lattice).  */
@@ -4196,7 +4187,10 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p)
 	  }
       }
 
-  /* If we value-number a virtual operand never value-number to the
+  /* If the value we want to use is flowing over the backedge and we
+     should take it as VARYING but it has a non-VARYING value drop to
+     VARYING.
+     If we value-number a virtual operand never value-number to the
      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.  */
@@ -4204,7 +4198,8 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p)
       && !seen_non_backedge
       && TREE_CODE (backedge_val) == SSA_NAME
       && sameval == backedge_val
-      && SSA_NAME_IS_VIRTUAL_OPERAND (backedge_val))
+      && (SSA_NAME_IS_VIRTUAL_OPERAND (backedge_val)
+	  || SSA_VAL (backedge_val) != backedge_val))
     /* Note this just drops to VARYING without inserting the PHI into
        the hashes.  */
     result = PHI_RESULT (phi);