simplify-rtx.c (simplify_unary_operation): When simplifying (neg (lt X 0)) into…

simplify-rtx.c (simplify_unary_operation): When simplifying (neg (lt X 0)) into (ashiftrt X C) or (lshiftrt X C)...


	* simplify-rtx.c (simplify_unary_operation): When simplifying
	(neg (lt X 0)) into (ashiftrt X C) or (lshiftrt X C), make sure
	that we perform the right shift in the appropriate mode, and
	then extend or truncate the result to requested mode.

From-SVN: r111671

gcc/ChangeLog

+2006-03-02  Roger Sayle  <roger@eyesopen.com>
+
+	* simplify-rtx.c (simplify_unary_operation): When simplifying
+	(neg (lt X 0)) into (ashiftrt X C) or (lshiftrt X C), make sure
+	that we perform the right shift in the appropriate mode, and
+	then extend or truncate the result to requested mode.
+
 2006-03-03  Zdenek Dvorak <dvorakz@suse.cz>
 
 	* gengtype.c (main): Handle double_int type.
@@ -16,7 +23,8 @@
 
 2006-03-02  Zdenek Dvorak <dvorakz@suse.cz>
 
-	* tree-vrp.c (remove_range_assertions): Do not update statements unnecessarily.
+	* tree-vrp.c (remove_range_assertions): Do not update statements
+	unnecessarily.
 
 2006-03-02  Zdenek Dvorak <dvorakz@suse.cz>
 

gcc/simplify-rtx.c

@@ -590,12 +590,28 @@ simplify_unary_operation_1 (enum rtx_code code, enum machine_mode mode, rtx op)
       if (GET_CODE (op) == LT
 	  && XEXP (op, 1) == const0_rtx)
 	{
+	  enum machine_mode inner = GET_MODE (XEXP (op, 0));
+	  int isize = GET_MODE_BITSIZE (inner);
 	  if (STORE_FLAG_VALUE == 1)
-	    return simplify_gen_binary (ASHIFTRT, mode, XEXP (op, 0),
-					GEN_INT (GET_MODE_BITSIZE (mode) - 1));
+	    {
+	      temp = simplify_gen_binary (ASHIFTRT, inner, XEXP (op, 0),
+					  GEN_INT (isize - 1));
+	      if (mode == inner)
+		return temp;
+	      if (GET_MODE_BITSIZE (mode) > isize)
+		return simplify_gen_unary (SIGN_EXTEND, mode, temp, inner);
+	      return simplify_gen_unary (TRUNCATE, mode, temp, inner);
+	    }
 	  else if (STORE_FLAG_VALUE == -1)
-	    return simplify_gen_binary (LSHIFTRT, mode, XEXP (op, 0),
-					GEN_INT (GET_MODE_BITSIZE (mode) - 1));
+	    {
+	      temp = simplify_gen_binary (LSHIFTRT, inner, XEXP (op, 0),
+					  GEN_INT (isize - 1));
+	      if (mode == inner)
+		return temp;
+	      if (GET_MODE_BITSIZE (mode) > isize)
+		return simplify_gen_unary (ZERO_EXTEND, mode, temp, inner);
+	      return simplify_gen_unary (TRUNCATE, mode, temp, inner);
+	    }
 	}
       break;