re PR middle-end/63879 (ICE compiling Linux Kernel fs/ext3/namei.c with -fsanitize=undefined)

	PR sanitizer/63879
	* fold-const.c (negate_expr_p) <case NEGATE_EXPR>: Return
	!TYPE_OVERFLOW_SANITIZED.
	(fold_negate_expr) <case INTEGER_CST>: Fold when overflow
	does not trap and when overflow wraps, or when SANITIZE_SI_OVERFLOW
	is 0.

	* c-c++-common/ubsan/pr63879-1.c: New test.
	* c-c++-common/ubsan/pr63879-2.c: New test.

From-SVN: r217766

gcc/ChangeLog

+2014-11-19  Marek Polacek  <polacek@redhat.com>
+
+	PR sanitizer/63879
+	* fold-const.c (negate_expr_p) <case NEGATE_EXPR>: Return
+	!TYPE_OVERFLOW_SANITIZED.
+	(fold_negate_expr) <case INTEGER_CST>: Fold when overflow
+	does not trap and when overflow wraps, or when SANITIZE_SI_OVERFLOW
+	is 0.
+
 2014-11-19  Ilya Tocar  <ilya.tocar@intel.com>
 
 	* collect2.c (main): Don't call fatal_error before

gcc/fold-const.c

@@ -408,9 +408,11 @@ negate_expr_p (tree t)
 	      && TYPE_OVERFLOW_WRAPS (type));
 
     case FIXED_CST:
-    case NEGATE_EXPR:
       return true;
 
+    case NEGATE_EXPR:
+      return !TYPE_OVERFLOW_SANITIZED (type);
+
     case REAL_CST:
       /* We want to canonicalize to positive real constants.  Pretend
          that only negative ones can be easily negated.  */
@@ -555,7 +557,8 @@ fold_negate_expr (location_t loc, tree t)
       tem = fold_negate_const (t, type);
       if (TREE_OVERFLOW (tem) == TREE_OVERFLOW (t)
 	  || (!TYPE_OVERFLOW_TRAPS (type)
-	      && (flag_sanitize & SANITIZE_SI_OVERFLOW) == 0))
+	      && TYPE_OVERFLOW_WRAPS (type))
+	  || (flag_sanitize & SANITIZE_SI_OVERFLOW) == 0)
 	return tem;
       break;
 

gcc/testsuite/ChangeLog

+2014-11-19  Marek Polacek  <polacek@redhat.com>
+
+	PR sanitizer/63879
+	* c-c++-common/ubsan/pr63879-1.c: New test.
+	* c-c++-common/ubsan/pr63879-2.c: New test.
+
 2014-11-19  Tom de Vries  <tom@codesourcery.com>
 
 	PR tree-optimization/62167

gcc/testsuite/c-c++-common/ubsan/pr63879-1.c

+/* PR sanitizer/63879 */
+/* { dg-do compile } */
+/* { dg-options "-fsanitize=undefined" } */
+
+struct A
+{
+  int inode;
+} * a;
+int b, c;
+void
+fn1 ()
+{
+  int d = 0;
+  while (b)
+    {
+      if (a->inode)
+        d++;
+      a = 0;
+    }
+  c = d - 1;
+  for (; c >= 0; c--)
+    ;
+}

gcc/testsuite/c-c++-common/ubsan/pr63879-2.c

+/* PR sanitizer/63879 */
+/* { dg-do compile } */
+/* { dg-options "-fsanitize=undefined" } */
+
+int a;
+void
+fn1 ()
+{
+  int b = 2;
+  for (; a;)
+    while (b >= 0)
+      b--;
+}