2019-08-30  Jakub Jelinek  <jakub@redhat.com>

	Backported from mainline
	2019-02-20  Jakub Jelinek  <jakub@redhat.com>
		    David Malcolm  <dmalcolm@redhat.com>

	PR middle-end/89091
	* fold-const.c (decode_field_reference): Return NULL_TREE if
	lang_hooks.types.type_for_size returns NULL.  Check it before
	overwriting *exp_.  Use return NULL_TREE instead of return 0.

	* gcc.dg/torture/pr89091.c: New test.

--- gcc/fold-const.c	(revision 270712)
+++ gcc/fold-const.c	(revision 270713)
@@ -4239,7 +4239,7 @@ decode_field_reference (location_t loc,
      There are problems with FP fields since the type_for_size call
      below can fail for, e.g., XFmode.  */
   if (! INTEGRAL_TYPE_P (TREE_TYPE (exp)))
-    return 0;
+    return NULL_TREE;
 
   /* We are interested in the bare arrangement of bits, so strip everything
      that doesn't affect the machine mode.  However, record the type of the
@@ -4255,7 +4255,7 @@ decode_field_reference (location_t loc,
       exp = TREE_OPERAND (exp, 0);
       STRIP_NOPS (exp); STRIP_NOPS (and_mask);
       if (TREE_CODE (and_mask) != INTEGER_CST)
-	return 0;
+	return NULL_TREE;
     }
 
   poly_int64 poly_bitsize, poly_bitpos;
@@ -4271,7 +4271,11 @@ decode_field_reference (location_t loc,
       || (! AGGREGATE_TYPE_P (TREE_TYPE (inner))
 	  && compare_tree_int (TYPE_SIZE (TREE_TYPE (inner)),
 			       *pbitpos + *pbitsize) < 0))
-    return 0;
+    return NULL_TREE;
+
+  unsigned_type = lang_hooks.types.type_for_size (*pbitsize, 1);
+  if (unsigned_type == NULL_TREE)
+    return NULL_TREE;
 
   *exp_ = exp;
 
@@ -4282,7 +4286,6 @@ decode_field_reference (location_t loc,
     *punsignedp = TYPE_UNSIGNED (outer_type);
 
   /* Compute the mask to access the bitfield.  */
-  unsigned_type = lang_hooks.types.type_for_size (*pbitsize, 1);
   precision = TYPE_PRECISION (unsigned_type);
 
   mask = build_int_cst_type (unsigned_type, -1);
--- gcc/testsuite/gcc.dg/torture/pr89091.c	(nonexistent)
+++ gcc/testsuite/gcc.dg/torture/pr89091.c	(revision 270713)
@@ -0,0 +1,10 @@
+/* PR middle-end/89091 */
+/* { dg-do compile { target int128 } } */
+
+struct S { unsigned __int128 s : 65; };
+
+int
+foo (struct S *x, int y)
+{
+  return y && x->s;
+}