df-scan: fix use of mw_order in df_mw_compare (PR 86096)

	PR rtl-optimization/86096
	* df-scan.c (df_mw_compare): Do not check mw_reg fields when
	comparing mw_order values.

From-SVN: r269189

gcc/ChangeLog

+2019-02-25  Alexander Monakov  <amonakov@ispras.ru>
+
+	PR rtl-optimization/86096
+	* df-scan.c (df_mw_compare): Do not check mw_reg fields when
+	comparing mw_order values.
+
 2019-02-25  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/89434

gcc/df-scan.c

@@ -2208,10 +2208,7 @@ df_mw_compare (const df_mw_hardreg *mw1, const df_mw_hardreg *mw2)
   if (mw1->end_regno != mw2->end_regno)
     return mw1->end_regno - mw2->end_regno;
 
-  if (mw1->mw_reg != mw2->mw_reg)
-    return mw1->mw_order - mw2->mw_order;
-
-  return 0;
+  return mw1->mw_order - mw2->mw_order;
 }
 
 /* Like df_mw_compare, but compare two df_mw_hardreg** pointers R1 and R2.  */