combine.c (expand_compound_operation): Make sure that zero_extend operation is profitable.

2003-05-15 Eric Christopher <echristo@redhat.com>

        * combine.c (expand_compound_operation): Make sure
        that zero_extend operation is profitable.

From-SVN: r66853

gcc/ChangeLog

+2003-05-15 Eric Christopher <echristo@redhat.com>
+
+        * combine.c (expand_compound_operation): Make sure
+        that zero_extend operation is profitable.
+
 2003-05-15  Richard Henderson  <rth@redhat.com>
 
 	* config/alpha/linux.h, config/alpha/linux-elf.h: Remove

gcc/combine.c

@@ -5802,7 +5802,15 @@ expand_compound_operation (x)
 	       == 0)))
     {
       rtx temp = gen_rtx_ZERO_EXTEND (GET_MODE (x), XEXP (x, 0));
-      return expand_compound_operation (temp);
+      rtx temp2 = expand_compound_operation (temp);
+
+      /* Make sure this is a profitable operation.  */
+      if (rtx_cost (x, SET) > rtx_cost (temp2, SET))
+       return temp2;
+      else if (rtx_cost (x, SET) > rtx_cost (temp, SET))
+       return temp;
+      else
+       return x;
     }
 
   /* We can optimize some special cases of ZERO_EXTEND.  */