Re: [Qemu-devel] [PATCH 09/16] tcg: Use per-temp state data in liveness

[Richard Henderson]

On 06/27/2017 01:57 AM, Alex Bennée wrote:
> > -            /* Note this unsigned test catches TCG_CALL_ARG_DUMMY too.  */
> > -            if (arg < nb_globals) {
>
> This test is gone but....
>
> > -                dir = dir_temps[arg];
> > -                if (dir != 0 && temp_state[arg] == TS_DEAD) {
> > -                    TCGTemp *its = arg_temp(arg);
> > -                    TCGOpcode lopc = (its->type == TCG_TYPE_I32
> > -                                      ? INDEX_op_ld_i32
> > -                                      : INDEX_op_ld_i64);
> > -                    TCGOp *lop = tcg_op_insert_before(s, op, lopc, 3);
> > -
> > -                    lop->args[0] = dir;
> > -                    lop->args[1] = temp_arg(its->mem_base);
> > -                    lop->args[2] = its->mem_offset;
> > -
> > -                    /* Loaded, but synced with memory.  */
> > -                    temp_state[arg] = TS_MEM;
> > -                }
> > +            arg_ts = arg_temp(op->args[i]);
> > +            dir_ts = arg_ts->state_ptr;
> > +            if (dir_ts && arg_ts->state == TS_DEAD) {
>
> ...we de-ref arg_ts here. So what if it was a TCG_CALL_ARG_DUMMY?

Good catch.  I need to do more testing on a host that actually uses this 
padding...


r~