re PR ipa/78644 (ICE: SIGSEGV in is_gimple_reg_type with -Og -fipa-cp)

2017-03-28  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/78644
	* tree-ssa-ccp.c (evaluate_stmt): When we may not use the value
	of a simplification result we may not use it at all.

	* gcc.dg/pr78644-1.c: New testcase.
	* gcc.dg/pr78644-2.c: Likewise.

From-SVN: r246534

gcc/ChangeLog

 2017-03-28  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/78644
+	* tree-ssa-ccp.c (evaluate_stmt): When we may not use the value
+	of a simplification result we may not use it at all.
+
+2017-03-28  Richard Biener  <rguenther@suse.de>
+
 	PR ipa/80205
 	* tree-inline.c (copy_phis_for_bb): Do not create PHI node
 	without arguments, generate default definition of a SSA name.

gcc/testsuite/ChangeLog

+2017-03-28  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/78644
+	* gcc.dg/pr78644-1.c: New testcase.
+	* gcc.dg/pr78644-2.c: Likewise.
+
 2017-03-28  Toma Tabacu  <toma.tabacu@imgtec.com>
 
 	* gcc.dg/pic-3.c: Skip for mips*-*-linux-*.

gcc/testsuite/gcc.dg/pr78644-1.c

+/* { dg-do compile { target int128 } } */
+/* { dg-options "-Og -fipa-cp -w -Wno-psabi" } */
+
+typedef unsigned __int128 u128;
+typedef unsigned __int128 V __attribute__ ((vector_size (64)));
+
+V x4;
+
+static V
+bar (u128 x2, u128 x3)
+{
+  while (x4[0]--)
+    x2 /= x3 >>= 1;
+  return x2 + x3 + x4;
+}
+
+void
+foo (void)
+{
+  bar (0, 0);
+}

gcc/testsuite/gcc.dg/pr78644-2.c

+/* { dg-do compile { target int128 } } */
+/* { dg-options "-Og -finline-functions-called-once -w -Wno-psabi" } */
+
+typedef unsigned V __attribute__ ((vector_size (64)));
+typedef unsigned __int128 U __attribute__ ((vector_size (64)));
+
+U
+bar4 (U u0, U u1)
+{
+  if (u1[0])
+    u1 <<= 1;
+  return u0 + u1;
+}
+
+V
+foo (U u, V v)
+{
+  v |= (unsigned)bar4(u, (U){})[0];
+  return v;
+}

gcc/tree-ssa-ccp.c

@@ -1749,18 +1749,24 @@ evaluate_stmt (gimple *stmt)
       fold_defer_overflow_warnings ();
       simplified = ccp_fold (stmt);
       if (simplified
-	  && TREE_CODE (simplified) == SSA_NAME
+	  && TREE_CODE (simplified) == SSA_NAME)
+	{
 	  /* We may not use values of something that may be simulated again,
 	     see valueize_op_1.  */
-	  && (SSA_NAME_IS_DEFAULT_DEF (simplified)
-	      || ! prop_simulate_again_p (SSA_NAME_DEF_STMT (simplified))))
-	{
-	  ccp_prop_value_t *val = get_value (simplified);
-	  if (val && val->lattice_val != VARYING)
+	  if (SSA_NAME_IS_DEFAULT_DEF (simplified)
+	      || ! prop_simulate_again_p (SSA_NAME_DEF_STMT (simplified)))
 	    {
-	      fold_undefer_overflow_warnings (true, stmt, 0);
-	      return *val;
+	      ccp_prop_value_t *val = get_value (simplified);
+	      if (val && val->lattice_val != VARYING)
+		{
+		  fold_undefer_overflow_warnings (true, stmt, 0);
+		  return *val;
+		}
 	    }
+	  else
+	    /* We may also not place a non-valueized copy in the lattice
+	       as that might become stale if we never re-visit this stmt.  */
+	    simplified = NULL_TREE;
 	}
       is_constant = simplified && is_gimple_min_invariant (simplified);
       fold_undefer_overflow_warnings (is_constant, stmt, 0);