double-int.c (div_and_round_double): Use the proper predicate to detect a negative quotient.

	* double-int.c (div_and_round_double) <ROUND_DIV_EXPR>: Use the proper
	predicate to detect a negative quotient.

From-SVN: r210981

gcc/ChangeLog

 2014-05-27  Eric Botcazou  <ebotcazou@adacore.com>
 
+	* double-int.c (div_and_round_double) <ROUND_DIV_EXPR>: Use the proper
+	predicate to detect a negative quotient.
+
+2014-05-27  Eric Botcazou  <ebotcazou@adacore.com>
+
 	* fold-const.c (fold_comparison): Clean up and extend X +- C1 CMP C2
 	to X CMP C2 -+ C1 transformation to EQ_EXPR/NE_EXPR.
 	Add X - Y CMP 0 to X CMP Y transformation.

gcc/double-int.c

@@ -588,7 +588,7 @@ div_and_round_double (unsigned code, int uns,
 		 == (unsigned HOST_WIDE_INT) htwice)
 		&& (labs_den <= ltwice)))
 	  {
-	    if (*hquo < 0)
+	    if (quo_neg)
 	      /* quo = quo - 1;  */
 	      add_double (*lquo, *hquo,
 			  (HOST_WIDE_INT) -1, (HOST_WIDE_INT) -1, lquo, hquo);

gcc/testsuite/ChangeLog

+2014-05-27  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gnat.dg/overflow_fixed.adb: New test.
+
 2014-05-27  Marek Polacek  <polacek@redhat.com>
 
 	PR c/56724

gcc/testsuite/gnat.dg/overflow_fixed.adb

+-- { dg-do run }
+-- { dg-options "-gnato -O" }
+
+procedure Overflow_Fixed is
+
+  type Unsigned_8_Bit is mod 2**8;
+
+  procedure Fixed_To_Eight (Value : Duration) is
+    Item : Unsigned_8_Bit;
+  begin
+    Item := Unsigned_8_Bit(Value);
+    raise Program_Error;
+  exception
+    when Constraint_Error => null; -- expected case
+  end;
+
+begin
+  Fixed_To_Eight (-0.5);
+end;