re PR tree-optimization/79666 (wrong code (SIGFPE) at -O2 on x86_64-linux-gnu…

re PR tree-optimization/79666 (wrong code (SIGFPE) at -O2 on x86_64-linux-gnu (in both 32-bit and 64-bit modes))

2017-02-22  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/79666
	* tree-vrp.c (extract_range_from_binary_expr_1): Make sure
	to not symbolically negate if that may introduce undefined
	overflow.

	* gcc.dg/torture/pr79666.c: New testcase.

From-SVN: r245648

gcc/ChangeLog

+2017-02-22  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/79666
+	* tree-vrp.c (extract_range_from_binary_expr_1): Make sure
+	to not symbolically negate if that may introduce undefined
+	overflow.
+
 2017-02-22  Martin Liska  <mliska@suse.cz>
 
 	PR lto/79587

gcc/testsuite/ChangeLog

+2017-02-22  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/79666
+	* gcc.dg/torture/pr79666.c: New testcase.
+
 2017-02-22  Martin Liska  <mliska@suse.cz>
 
 	PR lto/79587

gcc/testsuite/gcc.dg/torture/pr79666.c

+/* { dg-do run } */
+
+struct
+{
+  unsigned a:6;
+} b;
+
+int c, e, g = 7;
+signed char d, f = 6, h = -10;
+
+void fn1 ()
+{
+  for (; c < 9; c++)
+    {
+      if (f)
+	g = ~(~0 / (g ^ e));
+      b.a = ~0;
+      d = ~((h ^ b.a) & 132 & (~(f && g) | (d && 1)));
+      e = ~0;
+      if (d < 127 || f < 1)
+	continue;
+      g = 0;
+    }
+}
+
+int main ()
+{
+  fn1 ();
+  return 0; 
+}

gcc/tree-vrp.c

@@ -2631,8 +2631,17 @@ extract_range_from_binary_expr_1 (value_range *vr,
 	    min = build_symbolic_expr (expr_type, sym_min_op0,
 				       neg_min_op0, min);
 	  else if (sym_min_op1)
-	    min = build_symbolic_expr (expr_type, sym_min_op1,
-				       neg_min_op1 ^ minus_p, min);
+	    {
+	      /* We may not negate if that might introduce
+		 undefined overflow.  */
+	      if (! minus_p
+		  || neg_min_op1
+		  || TYPE_OVERFLOW_WRAPS (expr_type))
+		min = build_symbolic_expr (expr_type, sym_min_op1,
+					   neg_min_op1 ^ minus_p, min);
+	      else
+		min = NULL_TREE;
+	    }
 
 	  /* Likewise for the upper bound.  */
 	  if (sym_max_op0 == sym_max_op1)
@@ -2641,8 +2650,17 @@ extract_range_from_binary_expr_1 (value_range *vr,
 	    max = build_symbolic_expr (expr_type, sym_max_op0,
 				       neg_max_op0, max);
 	  else if (sym_max_op1)
-	    max = build_symbolic_expr (expr_type, sym_max_op1,
-				       neg_max_op1 ^ minus_p, max);
+	    {
+	      /* We may not negate if that might introduce
+		 undefined overflow.  */
+	      if (! minus_p
+		  || neg_max_op1
+		  || TYPE_OVERFLOW_WRAPS (expr_type))
+		max = build_symbolic_expr (expr_type, sym_max_op1,
+					   neg_max_op1 ^ minus_p, max);
+	      else
+		max = NULL_TREE;
+	    }
 	}
       else
 	{