Commit 61f15c48 authored by Richard Henderson's avatar Richard Henderson
Browse files

tcg: Improve move ops in liveness_pass_2 



If the output of the move is dead, then the last use is in
the store.  If we propagate the input to the store, then we
can remove the move opcode entirely.

Signed-off-by: default avatarRichard Henderson <richard.henderson@linaro.org>
parent cea94ba3

tcg/tcg.c

+56 −22
Original line number Diff line number Diff line
@@ -2982,6 +2982,39 @@ static bool liveness_pass_2(TCGContext *s) 
        }



        /* Outputs become available.  */

        if (opc == INDEX_op_mov_i32 || opc == INDEX_op_mov_i64) {

            arg_ts = arg_temp(op->args[0]);

            dir_ts = arg_ts->state_ptr;

            if (dir_ts) {

                op->args[0] = temp_arg(dir_ts);

                changes = true;



                /* The output is now live and modified.  */

                arg_ts->state = 0;



                if (NEED_SYNC_ARG(0)) {

                    TCGOpcode sopc = (arg_ts->type == TCG_TYPE_I32

                                      ? INDEX_op_st_i32

                                      : INDEX_op_st_i64);

                    TCGOp *sop = tcg_op_insert_after(s, op, sopc);

                    TCGTemp *out_ts = dir_ts;



                    if (IS_DEAD_ARG(0)) {

                        out_ts = arg_temp(op->args[1]);

                        arg_ts->state = TS_DEAD;

                        tcg_op_remove(s, op);

                    } else {

                        arg_ts->state = TS_MEM;

                    }



                    sop->args[0] = temp_arg(out_ts);

                    sop->args[1] = temp_arg(arg_ts->mem_base);

                    sop->args[2] = arg_ts->mem_offset;

                } else {

                    tcg_debug_assert(!IS_DEAD_ARG(0));

                }

            }

        } else {

            for (i = 0; i < nb_oargs; i++) {

                arg_ts = arg_temp(op->args[i]);

                dir_ts = arg_ts->state_ptr;
@@ -3013,6 +3046,7 @@ static bool liveness_pass_2(TCGContext *s) 
                }

            }

        }

    }



    return changes;

}