[backport from gcc-4.7.3 r193867, without the indentation changes <mikpe@it.uu.se>]

gcc/

2012-11-27  Paolo Bonzini  <pbonzini@redhat.com>

	PR rtl-optimization/55489
	* gcse.c (compute_transp): Precompute a canonical version
	of XEXP (x, 0), and pass it to canon_true_dependence.

--- gcc-4.6.3/gcc/gcse.c.~1~	2011-02-03 07:04:04.000000000 +0100
+++ gcc-4.6.3/gcc/gcse.c	2012-12-02 18:05:59.000000000 +0100
@@ -2144,6 +2144,10 @@ compute_transp (const_rtx x, int indx, s
 	{
 	  bitmap_iterator bi;
 	  unsigned bb_index;
+	  rtx x_addr;
+
+	  x_addr = get_addr (XEXP (x, 0));
+	  x_addr = canon_rtx (x_addr);
 
 	  /* First handle all the blocks with calls.  We don't need to
 	     do any list walking for them.  */
@@ -2175,7 +2179,7 @@ compute_transp (const_rtx x, int indx, s
 		    dest_addr = XEXP (list_entry, 0);
 
 		    if (canon_true_dependence (dest, GET_MODE (dest), dest_addr,
-					       x, NULL_RTX, rtx_addr_varies_p))
+					       x, x_addr, rtx_addr_varies_p))
 		      {
 			if (set_p)
 			  SET_BIT (bmap[bb_index], indx);