[backport from gcc-4.8/trunk r185175 <mikpe@it.uu.se>]

gcc/

2012-03-10  Chung-Lin Tang  <cltang@codesourcery.com>

	PR rtl-optimization/52528
	* combine.c (can_combine_p): Add setting of subst_low_luid
	before call to expand_field_assignment().

--- gcc-4.7-20120225/gcc/combine.c.~1~	2012-02-07 16:48:52.000000000 +0100
+++ gcc-4.7-20120225/gcc/combine.c	2012-03-11 12:56:45.000000000 +0100
@@ -1822,6 +1822,10 @@ can_combine_p (rtx insn, rtx i3, rtx pre
   if (set == 0)
     return 0;
 
+  /* The simplification in expand_field_assignment may call back to
+     get_last_value, so set safe guard here.  */
+  subst_low_luid = DF_INSN_LUID (insn);
+
   set = expand_field_assignment (set);
   src = SET_SRC (set), dest = SET_DEST (set);