cse.c (simplify_relational_operation): If MODE specifies a mode wider than HOST_WIDE_INT...

        * cse.c (simplify_relational_operation): If MODE specifies a
        mode wider than HOST_WIDE_INT, then the high word of a CONST_INT
        is derived from the sign bit of the low word.

Brought over from r5900 branch.

From-SVN: r15454

gcc/ChangeLog

+Mon Sep 15 15:39:26 1997  Jeffrey A Law  (law@cygnus.com)
+
+	* cse.c (simplify_relational_operation): If MODE specifies a
+	mode wider than HOST_WIDE_INT, then the high word of a CONST_INT
+	is derived from the sign bit of the low word.
+
 1997-09-15  Brendan Kehoe  <brendan@cygnus.com>
 
 	* except.c (find_exception_handler_labels): Use xmalloc instead of

gcc/cse.c

@@ -4482,7 +4482,14 @@ simplify_relational_operation (code, mode, op0, op1)
       else
 	{
 	  l0u = l0s = INTVAL (op0);
-	  h0u = 0, h0s = l0s < 0 ? -1 : 0;
+	  h0s = l0s < 0 ? -1 : 0;
+	  /* If WIDTH is nonzero and larger than HOST_BITS_PER_WIDE_INT,
+	     then the high word is derived from the sign bit of the low
+	     word, else the high word is zero.  */
+	  if (width != 0 && width > HOST_BITS_PER_WIDE_INT)
+	    h0u = l0s < 0 ? -1 : 0;
+	  else
+	    h0u = 0;
 	}
 	  
       if (GET_CODE (op1) == CONST_DOUBLE)
@@ -4493,7 +4500,14 @@ simplify_relational_operation (code, mode, op0, op1)
       else
 	{
 	  l1u = l1s = INTVAL (op1);
-	  h1u = 0, h1s = l1s < 0 ? -1 : 0;
+	  h1s = l1s < 0 ? -1 : 0;
+	  /* If WIDTH is nonzero and larger than HOST_BITS_PER_WIDE_INT,
+	     then the high word is derived from the sign bit of the low
+	     word, else the high word is zero.  */
+	  if (width != 0 && width > HOST_BITS_PER_WIDE_INT)
+	    h1u = l1s < 0 ? -1 : 0;
+	  else
+	    h1u = 0;
 	}
 
       /* If WIDTH is nonzero and smaller than HOST_BITS_PER_WIDE_INT,