[PATCH] Fix ICE with gimple clobber (PR tree-optimization/71405)

[Jakub Jelinek <jakub@redhat.com>]

Hi!

On this testcase execute_update_addresses_taken creates
VIEW_CONVERT_EXPR of a {CLOBBER}, which is of course invalid.
Instead, this patch just creates {CLOBBER} of the right type and let's
the following ssa update transform that to replacing uses with default def
or whatever else is appropriate.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2016-06-04  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/71405
	* tree-ssa.c (execute_update_addresses_taken): For clobber with
	incompatible type, build a new clobber with the right type instead
	of building a VIEW_CONVERT_EXPR around it.

	* g++.dg/torture/pr71405.C: New test.

--- gcc/tree-ssa.c.jj	2016-05-24 10:56:01.000000000 +0200
+++ gcc/tree-ssa.c	2016-06-04 11:59:36.561302230 +0200
@@ -1622,9 +1622,16 @@ execute_update_addresses_taken (void)
 		if (gimple_assign_lhs (stmt) != lhs
 		    && !useless_type_conversion_p (TREE_TYPE (lhs),
 						   TREE_TYPE (rhs)))
-		  rhs = fold_build1 (VIEW_CONVERT_EXPR,
-				     TREE_TYPE (lhs), rhs);
-
+		  {
+		    if (gimple_clobber_p (stmt))
+		      {
+			rhs = build_constructor (TREE_TYPE (lhs), NULL);
+			TREE_THIS_VOLATILE (rhs) = 1;
+		      }
+		    else
+		      rhs = fold_build1 (VIEW_CONVERT_EXPR,
+					 TREE_TYPE (lhs), rhs);
+		  }
 		if (gimple_assign_lhs (stmt) != lhs)
 		  gimple_assign_set_lhs (stmt, lhs);
 
--- gcc/testsuite/g++.dg/torture/pr71405.C.jj	2016-06-04 12:10:33.694768153 +0200
+++ gcc/testsuite/g++.dg/torture/pr71405.C	2016-06-04 12:09:28.000000000 +0200
@@ -0,0 +1,22 @@
+// PR tree-optimization/71405
+// { dg-do compile }
+
+struct C
+{
+  C () {}
+  int i;
+};
+
+void *
+operator new (__SIZE_TYPE__ x, void *y)
+{
+  return y;
+}
+
+int
+main ()
+{
+  int a;
+  new (&a) C;
+  return a; 
+}

	Jakub