combine.c (simplify_comparison): When widening modes, ignore sign extension on CONST_INTs.

	* combine.c (simplify_comparison): When widening modes, ignore
	sign extension on CONST_INTs.

From-SVN: r51216

gcc/ChangeLog

+2002-03-23  Alan Modra  <amodra@bigpond.net.au>
+
+	* combine.c (simplify_comparison): When widening modes, ignore
+	sign extension on CONST_INTs.
+
 2002-03-22  Bob Wilson  <bob.wilson@acm.org>
 
 	* config/xtensa/xtensa.c (print_operand): Fix incorrect mode

gcc/combine.c

@@ -10975,14 +10975,22 @@ simplify_comparison (code, pop0, pop1)
 	 tmode = GET_MODE_WIDER_MODE (tmode))
       if (have_insn_for (COMPARE, tmode))
 	{
+	  int zero_extended;
+
 	  /* If the only nonzero bits in OP0 and OP1 are those in the
 	     narrower mode and this is an equality or unsigned comparison,
 	     we can use the wider mode.  Similarly for sign-extended
 	     values, in which case it is true for all comparisons.  */
-	  if (((code == EQ || code == NE
-		|| code == GEU || code == GTU || code == LEU || code == LTU)
-	       && (nonzero_bits (op0, tmode) & ~GET_MODE_MASK (mode)) == 0
-	       && (nonzero_bits (op1, tmode) & ~GET_MODE_MASK (mode)) == 0)
+	  zero_extended = ((code == EQ || code == NE
+			    || code == GEU || code == GTU
+			    || code == LEU || code == LTU)
+			   && (nonzero_bits (op0, tmode)
+			       & ~GET_MODE_MASK (mode)) == 0
+			   && ((GET_CODE (op1) == CONST_INT
+				|| (nonzero_bits (op1, tmode)
+				    & ~GET_MODE_MASK (mode)) == 0)));
+
+	  if (zero_extended
 	      || ((num_sign_bit_copies (op0, tmode)
 		   > GET_MODE_BITSIZE (tmode) - GET_MODE_BITSIZE (mode))
 		  && (num_sign_bit_copies (op1, tmode)
@@ -10999,6 +11007,8 @@ simplify_comparison (code, pop0, pop1)
 							   XEXP (op0, 1)));
 
 	      op0 = gen_lowpart_for_combine (tmode, op0);
+	      if (zero_extended && GET_CODE (op1) == CONST_INT)
+		op1 = GEN_INT (INTVAL (op1) & GET_MODE_MASK (mode));
 	      op1 = gen_lowpart_for_combine (tmode, op1);
 	      break;
 	    }