re PR sanitizer/58413 (ubsan constant folding)

2013-09-20  Marek Polacek  <polacek@redhat.com>

	PR sanitizer/58413
	* ubsan.c (get_ubsan_type_info_for_type): Use TYPE_SIZE instead of
	TYPE_PRECISION.  Add asserts.

testsuite/
	* c-c++-common/ubsan/shift-4.c: New test.

From-SVN: r202776

gcc/ChangeLog

+2013-09-20  Marek Polacek  <polacek@redhat.com>
+
+	PR sanitizer/58413
+	* ubsan.c (get_ubsan_type_info_for_type): Use TYPE_SIZE instead of
+	TYPE_PRECISION.  Add asserts.
+
 2013-09-20  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/58453

gcc/testsuite/ChangeLog

+2013-09-20  Marek Polacek  <polacek@redhat.com>
+
+	PR sanitizer/58413
+	* c-c++-common/ubsan/shift-4.c: New test.
+
 2013-09-20  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/58453

gcc/testsuite/c-c++-common/ubsan/shift-4.c

+/* { dg-do run } */
+/* { dg-options "-fsanitize=shift -w" } */
+
+struct S { unsigned long long int b:40; } s;
+
+int
+main ()
+{
+  s.b = 2;
+  s.b <<= 120;
+  return 0;
+}
+
+/* { dg-output "shift exponent 120 is too large\[^\n\r]*(\n|\r\n|\r)" } */

gcc/ubsan.c

@@ -233,10 +233,9 @@ ubsan_source_location (location_t loc)
 static unsigned short
 get_ubsan_type_info_for_type (tree type)
 {
-  int prec = exact_log2 (TYPE_PRECISION (type));
-  if (prec == -1)
-    error ("unexpected size of type %qT", type);
-
+  gcc_assert (TYPE_SIZE (type) && host_integerp (TYPE_SIZE (type), 1));
+  int prec = exact_log2 (tree_low_cst (TYPE_SIZE (type), 1));
+  gcc_assert (prec != -1);
   return (prec << 1) | !TYPE_UNSIGNED (type);
 }