re PR middle-end/20396 (TRULY_NOOP_TRUNCATION ignored)

2005-08-16  J"orn Rennecke <joern.rennecke@st.com>
            Richard Shann <rshann@superh.com>

	PR middle-end/20396:
	* optabs.c (expand_binop): Take TRULY_NOOP_TRUNCATION into account.

Co-Authored-By: Richard Shann <rshann@superh.com>

From-SVN: r103153

gcc/ChangeLog

+2005-08-16  J"orn Rennecke <joern.rennecke@st.com>
+            Richard Shann <rshann@superh.com>
+
+	PR middle-end/20396:
+	* optabs.c (expand_binop): Take TRULY_NOOP_TRUNCATION into account.
+
 2005-08-16  Sebastian Pop  <pop@cri.ensmp.fr>
 
 	* tree-ssa-loop-niter.c (scev_probably_wraps_p): Reword a comment.

gcc/optabs.c

@@ -1184,7 +1184,9 @@ expand_binop (enum machine_mode mode, optab binoptab, rtx op0, rtx op1,
 
       if (temp != 0)
 	{
-	  if (GET_MODE_CLASS (mode) == MODE_INT)
+	  if (GET_MODE_CLASS (mode) == MODE_INT
+	      && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
+                                        GET_MODE_BITSIZE (GET_MODE (temp))))
 	    return gen_lowpart (mode, temp);
 	  else
 	    return convert_to_mode (mode, temp, unsignedp);
@@ -1231,7 +1233,9 @@ expand_binop (enum machine_mode mode, optab binoptab, rtx op0, rtx op1,
 				 unsignedp, OPTAB_DIRECT);
 	    if (temp)
 	      {
-		if (class != MODE_INT)
+		if (class != MODE_INT
+                    || !TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
+                                               GET_MODE_BITSIZE (wider_mode)))
 		  {
 		    if (target == 0)
 		      target = gen_reg_rtx (mode);
@@ -1759,7 +1763,9 @@ expand_binop (enum machine_mode mode, optab binoptab, rtx op0, rtx op1,
 				   unsignedp, methods);
 	      if (temp)
 		{
-		  if (class != MODE_INT)
+		  if (class != MODE_INT
+		      || !TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (mode),
+						 GET_MODE_BITSIZE (wider_mode)))
 		    {
 		      if (target == 0)
 			target = gen_reg_rtx (mode);