[IRA] Fix PR91052 by skipping multiple_sets insn in combine_and_move_insns

As PR91052's comments show, commit r272731 exposed one issue in function
combine_and_move_insns.  Function combine_and_move_insns perform the
unexpected movement which alter live interval of some register, leading
incorrect value to be used.  See PR91052 for details.

2020-02-12  Kewen Lin  <linkw@gcc.gnu.org>
    PR target/91052
    * ira.c (combine_and_move_insns): Skip multiple_sets def_insn.

gcc/ChangeLog

+2020-02-12  Kewen Lin  <linkw@gcc.gnu.org>
+
+	PR target/91052
+	* ira.c (combine_and_move_insns): Skip multiple_sets def_insn.
+
 2020-02-12  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	* config/rs6000/rs6000.c (rs6000_debug_print_mode): Don't use sizeof

gcc/ira.c

@@ -3784,6 +3784,11 @@ combine_and_move_insns (void)
       if (can_throw_internal (def_insn))
 	continue;
 
+      /* Instructions with multiple sets can only be moved if DF analysis is
+	 performed for all of the registers set.  See PR91052.  */
+      if (multiple_sets (def_insn))
+	continue;
+
       basic_block use_bb = BLOCK_FOR_INSN (use_insn);
       basic_block def_bb = BLOCK_FOR_INSN (def_insn);
       if (bb_loop_depth (use_bb) > bb_loop_depth (def_bb))