c90-const-expr-8.c: Look for overflow on INT_MIN % -1.

2013-11-27  Kenneth Zadeck  <zadeck@naturalbridge.com>

	* gcc.dg/c90-const-expr-8.c: Look for overflow on INT_MIN % -1.
	* gcc.dg/c99-const-expr-8.c: Look for overflow on INT_MIN % -1.

2013-11-27  Kenneth Zadeck  <zadeck@naturalbridge.com>

	* fold-const.c
	(int_const_binop_1): Make INT_MIN % -1 return 0 with the overflow
	bit set.

From-SVN: r205448

gcc/ChangeLog

+2013-11-27  Kenneth Zadeck  <zadeck@naturalbridge.com>
+
+	* fold-const.c
+	(int_const_binop_1): Make INT_MIN % -1 return 0 with the overflow
+	bit set.
+
 2013-11-27  Richard Biener  <rguenther@suse.de>
 
 	PR middle-end/58723

gcc/fold-const.c

@@ -1110,7 +1110,22 @@ int_const_binop_1 (enum tree_code code, const_tree arg1, const_tree arg2,
     case ROUND_MOD_EXPR:
       if (op2.is_zero ())
 	return NULL_TREE;
-      tmp = op1.divmod_with_overflow (op2, uns, code, &res, &overflow);
+
+      /* Check for the case the case of INT_MIN % -1 and return
+       overflow and result = 0.  The TImode case is handled properly
+       in double-int.  */
+      if (TYPE_PRECISION (type) <= HOST_BITS_PER_WIDE_INT 
+	  && !uns
+          && op2.is_minus_one () 
+	  && op1.high == (HOST_WIDE_INT) -1
+	  && (HOST_WIDE_INT) op1.low 
+	  == (((HOST_WIDE_INT)-1) << (TYPE_PRECISION (type) - 1)))
+	{
+	  overflow = 1;
+	  res = double_int_zero;
+	}
+      else
+	tmp = op1.divmod_with_overflow (op2, uns, code, &res, &overflow);
       break;
 
     case MIN_EXPR:

gcc/testsuite/ChangeLog

+2013-11-27  Kenneth Zadeck  <zadeck@naturalbridge.com>
+
+	* gcc.dg/c90-const-expr-8.c: Look for overflow on INT_MIN % -1.
+	* gcc.dg/c99-const-expr-8.c: Look for overflow on INT_MIN % -1.
+
 2013-11-27  Marek Polacek  <polacek@redhat.com>
 
 	PR sanitizer/59306

gcc/testsuite/gcc.dg/c90-const-expr-8.c

@@ -23,5 +23,6 @@ enum e {
   /* { dg-error "3:overflow in constant expression" "constant" { target *-*-* } 22 } */
   E6 = 0 * !-INT_MIN, /* { dg-warning "13:integer overflow in expression" } */
   /* { dg-error "8:not an integer constant" "constant" { target *-*-* } 24 } */
-  E7 = INT_MIN % -1 /* Not an overflow.  */
+  E7 = INT_MIN % -1 /* { dg-warning "16:integer overflow in expression" } */
+  /* { dg-error "1:overflow in constant expression" "constant" { target *-*-* } 28 } */
 };

gcc/testsuite/gcc.dg/c99-const-expr-8.c

@@ -23,5 +23,6 @@ enum e {
   /* { dg-error "overflow in constant expression" "constant" { target *-*-* } 22 } */
   E6 = 0 * !-INT_MIN, /* { dg-warning "integer overflow in expression" } */
   /* { dg-error "not an integer constant" "constant" { target *-*-* } 24 } */
-  E7 = INT_MIN % -1 /* Not an overflow.  */
+  E7 = INT_MIN % -1 /* { dg-warning "16:integer overflow in expression" } */
+  /* { dg-error "1:overflow in constant expression" "constant" { target *-*-* } 28 } */
 };