re PR bootstrap/71071 (ICE --enable-checking=fold : fold check: original tree changed by fold)

	PR bootstrap/71071
	* fold-const.c (fold_checksum_tree): Allow modification
	of TYPE_ALIAS_SET during folding.

	* gcc.dg/pr71071.c: New test.

From-SVN: r236222

gcc/ChangeLog

 2016-05-13  Jakub Jelinek  <jakub@redhat.com>
 
+	PR bootstrap/71071
+	* fold-const.c (fold_checksum_tree): Allow modification
+	of TYPE_ALIAS_SET during folding.
+
 	* config/i386/i386.c (ix86_compute_frame_layout, ix86_expand_prologue,
 	ix86_expand_split_stack_prologue): Use HOST_WIDE_INT_C macro.
 	(ix86_split_to_parts): Likewise.  Fix up formatting.

gcc/fold-const.c

@@ -12130,7 +12130,8 @@ fold_checksum_tree (const_tree expr, struct md5_ctx *ctx,
 	       || TYPE_REFERENCE_TO (expr)
 	       || TYPE_CACHED_VALUES_P (expr)
 	       || TYPE_CONTAINS_PLACEHOLDER_INTERNAL (expr)
-	       || TYPE_NEXT_VARIANT (expr)))
+	       || TYPE_NEXT_VARIANT (expr)
+	       || TYPE_ALIAS_SET_KNOWN_P (expr)))
     {
       /* Allow these fields to be modified.  */
       tree tmp;
@@ -12140,6 +12141,7 @@ fold_checksum_tree (const_tree expr, struct md5_ctx *ctx,
       TYPE_POINTER_TO (tmp) = NULL;
       TYPE_REFERENCE_TO (tmp) = NULL;
       TYPE_NEXT_VARIANT (tmp) = NULL;
+      TYPE_ALIAS_SET (tmp) = -1;
       if (TYPE_CACHED_VALUES_P (tmp))
 	{
 	  TYPE_CACHED_VALUES_P (tmp) = 0;

gcc/testsuite/ChangeLog

+2016-05-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR bootstrap/71071
+	* gcc.dg/pr71071.c: New test.
+
 2016-05-13  Uros Bizjak  <ubizjak@gmail.com>
 
 	* gcc.dg/vect/tree-vect.h (check_vect): Handle AVX2,

gcc/testsuite/gcc.dg/pr71071.c

+/* PR bootstrap/71071 */
+/* { dg-do compile } *
+/* { dg-options "-O2" } */
+
+struct S { unsigned b : 1; } a;
+
+void
+foo ()
+{
+  if (a.b)
+    ;
+}