PATCH: Use ADD if result isn't used in memory address

[H.J. Lu]

When result of ADD isn't used in memory address, we should use ADD
instead of LEA.  OK for trunk?

Thanks.


H.J.
---
2010-09-14  H.J. Lu  <hongjiu.lu@intel.com>

	* config/i386/i386.c (ix86_lea_for_add_ok): Return false if
	result isn't used in memory address.

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 734ff3d..0b542fa 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -14969,15 +14969,19 @@ ix86_lea_for_add_ok (rtx insn, rtx operands[])
   else
     {
       int dist_define, dist_use;
+
+      /* Return false if REGNO0 isn't used in memory address. */
+      dist_use = distance_agu_use (regno0, insn);
+      if (dist_use <= 0)
+	return false;
+
       dist_define = distance_non_agu_define (regno1, regno2, insn);
       if (dist_define <= 0)
         return true;
 
       /* If this insn has both backward non-agu dependence and forward
          agu dependence, the one with short distance take effect. */
-      dist_use = distance_agu_use (regno0, insn);
-      if (dist_use <= 0
-	  || (dist_define + IX86_LEA_PRIORITY) < dist_use)
+      if ((dist_define + IX86_LEA_PRIORITY) < dist_use)
         return false;
 
       return true;