combine.c (make_compound_operation): Use simplify_subreg.

2005-06-19  Andreas Krebbel  <krebbel1@de.ibm.com>

	* combine.c (make_compound_operation): Use simplify_subreg.  Delete
	a optimization already done by simplify_subreg.

From-SVN: r101183

gcc/ChangeLog

+2005-06-19  Andreas Krebbel  <krebbel1@de.ibm.com>
+
+	* combine.c (make_compound_operation): Use simplify_subreg.  Delete
+	a optimization already done by simplify_subreg.
+
 2005-06-19  Ulrich Weigand  <uweigand@de.ibm.com>
 
 	* loop.c (scan_loop): Do not consider insns setting the frame

gcc/combine.c

@@ -6732,6 +6732,15 @@ make_compound_operation (rtx x, enum rtx_code in_code)
 	 what it originally did, do this SUBREG as a force_to_mode.  */
 
       tem = make_compound_operation (SUBREG_REG (x), in_code);
+
+      {
+	rtx simplified;
+	simplified = simplify_subreg (GET_MODE (x), tem, GET_MODE (tem),
+				      SUBREG_BYTE (x));
+
+	if (simplified)
+	  tem = simplified;
+
 	if (GET_CODE (tem) != GET_CODE (SUBREG_REG (x))
 	    && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (tem))
 	    && subreg_lowpart_p (x))
@@ -6747,24 +6756,7 @@ make_compound_operation (rtx x, enum rtx_code in_code)
 	    return newer;
 	  }
 
-      /* If this is a paradoxical subreg, and the new code is a sign or
-	 zero extension, omit the subreg and widen the extension.  If it
-	 is a regular subreg, we can still get rid of the subreg by not
-	 widening so much, or in fact removing the extension entirely.  */
-      if ((GET_CODE (tem) == SIGN_EXTEND
-	   || GET_CODE (tem) == ZERO_EXTEND)
-	  && subreg_lowpart_p (x))
-	{
-	  if (GET_MODE_SIZE (mode) > GET_MODE_SIZE (GET_MODE (tem))
-	      || (GET_MODE_SIZE (mode) >
-		  GET_MODE_SIZE (GET_MODE (XEXP (tem, 0)))))
-	    {
-	      if (! SCALAR_INT_MODE_P (mode))
-		break;
-	      tem = gen_rtx_fmt_e (GET_CODE (tem), mode, XEXP (tem, 0));
-	    }
-	  else
-	    tem = gen_lowpart (mode, XEXP (tem, 0));
+	if (simplified)
 	  return tem;
       }
       break;