combine.c (simplify_logical): Only simplify logical expressions of the form…

combine.c (simplify_logical): Only simplify logical expressions of the form ior(and(x,y),z) by the inverse...


	* combine.c (simplify_logical): Only simplify logical expressions
	of the form ior(and(x,y),z) by the inverse distributive law if the
	result is cheaper than the original.

Co-Authored-By: Eric Botcazou <ebotcazou@libertysurf.fr>

From-SVN: r94114

gcc/ChangeLog

+2005-01-23  Roger Sayle  <roger@eyesopen.com>
+	    Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+	* combine.c (simplify_logical): Only simplify logical expressions
+	of the form ior(and(x,y),z) by the inverse distributive law if the
+	result is cheaper than the original.
+
 2005-01-23  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* alias.c, c-common.h, c-incpath.c, c-incpath.h, expr.c,

gcc/combine.c

@@ -5574,26 +5574,28 @@ simplify_logical (rtx x)
 
       if (GET_CODE (op0) == AND)
 	{
-	  x = apply_distributive_law
+	  rtx tmp = apply_distributive_law
 	    (gen_binary (AND, mode,
 			 gen_binary (IOR, mode, XEXP (op0, 0), op1),
 			 gen_binary (IOR, mode, XEXP (op0, 1),
 				     copy_rtx (op1))));
 
-	  if (GET_CODE (x) != IOR)
-	    return x;
+	  if (GET_CODE (tmp) != IOR
+	      && rtx_cost (tmp, SET) < rtx_cost (x, SET))
+	    return tmp;
 	}
 
       if (GET_CODE (op1) == AND)
 	{
-	  x = apply_distributive_law
+	  rtx tmp = apply_distributive_law
 	    (gen_binary (AND, mode,
 			 gen_binary (IOR, mode, XEXP (op1, 0), op0),
 			 gen_binary (IOR, mode, XEXP (op1, 1),
 				     copy_rtx (op0))));
 
-	  if (GET_CODE (x) != IOR)
-	    return x;
+	  if (GET_CODE (tmp) != IOR
+	      && rtx_cost (tmp, SET) < rtx_cost (x, SET))
+	    return tmp;
 	}
 
       /* Convert (ior (ashift A CX) (lshiftrt A CY)) where CX+CY equals the