Re: Specially crafted binary chunks can cause Lua to crash

[David Given <dg@...>]

Ralph Hempel wrote:
[...]
> Hopefully your compiler won't optimize that out, and it's not
> actually atomic in the sense that it's thread safe :-)

The compiler *must not* optimize it out --- that's incorrect code! And I
mean 'atomic' in the this-is-a-fundamental-concept sense, rather than in
the synchronisation sense.

> Does the more verbose but clear (i ? true : false) generate better
> or worse code in terms of speed or size?

Personally, I find that rather less clear --- too wordy and doesn't
adequately encapsulate what it is I'm trying to do. I'd expect any
modern compiler to generate the same code for both. However, optimising
!! is a rather easier job that ?:; the latter is a conditional, and
would require the compiler to recognise the intent of the entire
operation and replace it with equivalent code, whereas optimising !!
merely requires it to know what happens when you perform ! twice.

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