tree.def (CEIL_DIV_EXPR, [...]): Tweak comments.

	* tree.def (CEIL_DIV_EXPR, FLOOR_DIV_EXPR, ROUND_DIV_EXPR): Tweak
	comments.
	(TRUNC_MOD_EXPR, CEIL_MOD_EXPR, FLOOR_MOD_EXPR, ROUND_MOD_EXPR):
	Add comments on sign of the result.
	* fold-const.c (tree_binary_nonnegative_warnv_p) <FLOOR_MOD_EXPR>:
	Recurse on operand #1 instead of operand #0.
	<CEIL_MOD_EXPR>: Do not recurse.
	<ROUND_MOD_EXPR>: Likewise.

From-SVN: r229146

gcc/ChangeLog

+2015-10-21  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* tree.def (CEIL_DIV_EXPR, FLOOR_DIV_EXPR, ROUND_DIV_EXPR): Tweak
+	comments.
+	(TRUNC_MOD_EXPR, CEIL_MOD_EXPR, FLOOR_MOD_EXPR, ROUND_MOD_EXPR):
+	Add comments on sign of the result.
+	* fold-const.c (tree_binary_nonnegative_warnv_p) <FLOOR_MOD_EXPR>:
+	Recurse on operand #1 instead of operand #0.
+	<CEIL_MOD_EXPR>: Do not recurse.
+	<ROUND_MOD_EXPR>: Likewise.
+
 2015-10-21  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>
 
 	* cfgrtl.c (pass_free_cfg::execute): Adjust.

gcc/fold-const.c

@@ -12908,11 +12908,13 @@ tree_binary_nonnegative_warnv_p (enum tree_code code, tree type, tree op0,
       return RECURSE (op0) && RECURSE (op1);
 
     case TRUNC_MOD_EXPR:
-    case CEIL_MOD_EXPR:
-    case FLOOR_MOD_EXPR:
-    case ROUND_MOD_EXPR:
       return RECURSE (op0);
 
+    case FLOOR_MOD_EXPR:
+      return RECURSE (op1);
+
+    case CEIL_MOD_EXPR:
+    case ROUND_MOD_EXPR:
     default:
       return tree_simple_nonnegative_warnv_p (code, type);
     }

gcc/tree.def

@@ -685,19 +685,27 @@ DEFTREECODE (MULT_HIGHPART_EXPR, "mult_highpart_expr", tcc_binary, 2)
 /* Division for integer result that rounds the quotient toward zero.  */
 DEFTREECODE (TRUNC_DIV_EXPR, "trunc_div_expr", tcc_binary, 2)
 
-/* Division for integer result that rounds the quotient toward infinity.  */
+/* Division for integer result that rounds it toward plus infinity.  */
 DEFTREECODE (CEIL_DIV_EXPR, "ceil_div_expr", tcc_binary, 2)
 
-/* Division for integer result that rounds toward minus infinity.  */
+/* Division for integer result that rounds it toward minus infinity.  */
 DEFTREECODE (FLOOR_DIV_EXPR, "floor_div_expr", tcc_binary, 2)
 
-/* Division for integer result that rounds toward nearest integer.  */
+/* Division for integer result that rounds it toward nearest integer.  */
 DEFTREECODE (ROUND_DIV_EXPR, "round_div_expr", tcc_binary, 2)
 
-/* Four kinds of remainder that go with the four kinds of division.  */
+/* Four kinds of remainder that go with the four kinds of division:  */
+
+/* The sign of the remainder is that of the dividend.  */
 DEFTREECODE (TRUNC_MOD_EXPR, "trunc_mod_expr", tcc_binary, 2)
+
+/* The sign of the remainder is the opposite of that of the divisor.  */
 DEFTREECODE (CEIL_MOD_EXPR, "ceil_mod_expr", tcc_binary, 2)
+
+/* The sign of the remainder is that of the divisor.  */
 DEFTREECODE (FLOOR_MOD_EXPR, "floor_mod_expr", tcc_binary, 2)
+
+/* The sign of the remainder is not predictable.  */
 DEFTREECODE (ROUND_MOD_EXPR, "round_mod_expr", tcc_binary, 2)
 
 /* Division for real result.  */