Optimiser and memory mapped I/O

[Grant Edwards]

On Thu, Sep 25, 2003 at 06:53:40PM +0200, Toralf Lund wrote:

> OK, this time I think I've found a genuine problem with the
> optimiser.

No, you've found a problem with your source code. :)

> Consider the following code:

[...]

> Simply put, the optimizer seems to think this is equivalent to

[...]

Assuming that's C code, the two _are_ equivalent -- it says
that in the language definition.  IOW, your source code is
incorrect for what you're trying to do.

> Any ways around this (besides not optimising at all)?

You need to use the "volatile" qualifier.

-- 
Grant Edwards
grante@visi.com

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