RE: Arrays oddities
- From: Alain Meunier <deco33@xxxxxxxxxx>
- To: "luajit@xxxxxxxxxxxxx" <luajit@xxxxxxxxxxxxx>
- Date: Mon, 31 Mar 2014 11:34:58 +0200
Ok..
So basically anything my bytes[5] may be lost if the system need that memory
space, right ?
Obviously it will not be the case with bytes[2] because it is in the bounds.
Actually, i don't really care the access time, I just want the fastest as a
whole. And even if faster access, the whole code is slower. That is odd to me.
If faster in one cycle, 1000 cycles should be faster too.
I don't get it Mike, I am sorry.
And this code is realistic enough to be used in production. I just try to
fasten it.
> Date: Mon, 31 Mar 2014 11:24:39 +0200
> From: mike-1403@xxxxxxxxxx
> To: luajit@xxxxxxxxxxxxx
> Subject: Re: Arrays oddities
>
> Alain Meunier wrote:
> > 1) Why can we allocate a value in an array out of the bound ?
>
> Allocate? You mean access. The FFI is a low-level interface. It
> doesn't do bounds-checking (which isn't possible on C types in
> general, anyway). http://luajit.org/ext_ffi_semantics.html#policy
>
> > 2) Should not an array be faster than a table ?
>
> It is. If properly used in a realistic benchmark that actually
> tests array accesses (which is a single-cycle op) and not the
> random variations in something else (~ thousands of cycles).
>
> --Mike
>
Other related posts:
