Re: Is gcc thread-unsafe?

[Arjan van de Ven]

On Thu, 25 Oct 2007 13:24:49 +1000
Nick Piggin <nickpiggin@xxxxxxxxxxxx> wrote:

> Hi,
> 
> Andi spotted this exchange on the gcc list. I don't think he's
> brought it up here yet, but it worries me enough that I'd like
> to discuss it.
> 
> Starts here
> http://gcc.gnu.org/ml/gcc/2007-10/msg00266.html
> 
> Concrete example here
> http://gcc.gnu.org/ml/gcc/2007-10/msg00275.html
> 
> Basically, what the gcc developers are saying is that gcc is
> free to load and store to any memory location, so long as it
> behaves as if the instructions were executed in sequence.
> 


this optimization btw is a serious mis-optimization, it makes memory
more dirty and causes cachelines to become unshared.... I'm sure it
works great on microbenchmarks but it sucks bigtime for anything real
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