Re: Woo hoo ... a whole new set of compiler headaches!!

On Fri, Apr 22, 2005 at 11:46:04AM -0300, Marc G. Fournier wrote:

> Actually, what I'm more "worried" about is the optimizations added to 4.x 
> ... I know, for instance, that with FreeBSD's kernel, for the longest time 
> you couldn't use the higher optimizations in 3.x, since it would cause 
> "unexpected results" ...

For a long time, the Linux kernel was meant to be compiled with specific
versions of GCC, because some assembly code was written in such a way
that the specific bugs in that compiler version made it write the exact
code they needed.  So a new GCC release would fix the bugs, therefore
breaking Linux; they had to create new, specially crafted buggy code to
account for the bugs in the new compiler ;-)  I think nowadays
those issues are pretty much settled.  (Not sure if you can compile the
Linux kernel with GCC 4 anyway.)

Maybe this was the issue with the FreeBSD kernel as well, I don't know.


I wonder if this new GCC release could allow us to examine the strict
aliasing issue again.

-- 
Alvaro Herrera (<alvherre[@]dcc.uchile.cl>)
"Amanece.                                               (Ignacio Reyes)El Cerro San Cristóbal me mira, cínicamente, con
ojosde virgen"