re PR rtl-optimization/52528 (combine bug (powerpc testcase))

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().

From-SVN: r185175

gcc/ChangeLog

+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().
+
 2012-03-09  Sandra Loosemore  <sandra@codesourcery.com>
 
 	* doc/invoke.texi: Use correct names/markup for "GCC", "GDB", "ld",

gcc/combine.c

@@ -1822,6 +1822,10 @@ can_combine_p (rtx insn, rtx i3, rtx pred ATTRIBUTE_UNUSED,
   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);