Subj : Re: What does Memory Barriers mean ??
To   : comp.programming.threads
From : Alexander Terekhov
Date : Tue Jan 11 2005 12:28 pm


David Schwartz wrote:
[...]
>     You guys are construing "standards" very narrowly. When I say
> "standards", I mean all the relevant documentation that accompanies all the
> interfaces and extensions you are using. If you use GCC's inline assembly
> correctly, according to the documentation, your code will work perfectly at

According to the GCC's documentation, "Even a volatile asm 
instruction can be moved in ways that appear insignificant to the 
compiler". GCC's notion of full-stop barrier via memory clobbers
and "asm volatile" sucks miserably... even if we assume that it 
works "as expected" (i.e. as a real bidirectional compiler fence).

> every level of optimization without you having to do anything other than
> correctly follow the documentation. Black magic is not needed.

Yeah, just a bit of luck.

regards,
alexander.

.