re PR sanitizer/80932 (UBSAN: false positive as a result of distribution:…

re PR sanitizer/80932 (UBSAN: false positive as a result of distribution: c1*(c2*v1-c3*v2)=>c1*c2*v1-c1*c3*v2)

	PR sanitizer/80932
	* fold-const.c (extract_muldiv_1) <case MINUS_EXPR>: Add
	TYPE_OVERFLOW_WRAPS check. 

	* c-c++-common/ubsan/pr80932.c: New test.

From-SVN: r248961

gcc/ChangeLog

+2017-06-07  Marek Polacek  <polacek@redhat.com>
+
+	PR sanitizer/80932
+	* fold-const.c (extract_muldiv_1) <case MINUS_EXPR>: Add
+	TYPE_OVERFLOW_WRAPS check. 
+
 2017-06-07  Bin Cheng  <bin.cheng@arm.com>
 
 	* tree-vect-loop-manip.c (vect_do_peeling): Don't skip vector loop

gcc/fold-const.c

@@ -6178,6 +6178,7 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
       t1 = extract_muldiv (op0, c, code, wide_type, &sub_strict_overflow_p);
       t2 = extract_muldiv (op1, c, code, wide_type, &sub_strict_overflow_p);
       if (t1 != 0 && t2 != 0
+	  && TYPE_OVERFLOW_WRAPS (ctype)
 	  && (code == MULT_EXPR
 	      /* If not multiplication, we can only do this if both operands
 		 are divisible by c.  */

gcc/testsuite/ChangeLog

+2017-06-07  Marek Polacek  <polacek@redhat.com>
+
+	PR sanitizer/80932
+	* c-c++-common/ubsan/pr80932.c: New test.
+
 2017-06-07  Bin Cheng  <bin.cheng@arm.com>
 
 	* gcc.target/i386/l_fma_double_1.c: Adjust test strings.

gcc/testsuite/c-c++-common/ubsan/pr80932.c

+/* PR sanitizer/80932 */
+/* { dg-do run } */
+/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */
+
+int x = 1;
+
+long int
+foo (void)
+{
+  return ((long) (13801962912760474560ULL * x) - (long) (15334142073106273231ULL * x)) * -6;
+}
+
+int
+main ()
+{
+  foo ();
+}