egcs 1.1b and "volatile"

egcs 1.1b and "volatile"

[erik.ivanenko]

Is there some way to guarantee that a volatile variable will remain
volatile regardless of optimization level?  This is critical when
writing a device driver that modifies CPU memory. eg. i82596.

Re: egcs 1.1b and "volatile"

[Jeffrey A Law]

  In message < 3637A2D7.3B01A550@utoronto.ca >you write:
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  > Is there some way to guarantee that a volatile variable will remain
  > volatile regardless of optimization level?  This is critical when
  > writing a device driver that modifies CPU memory. eg. i82596.
A load to or store from a volatile variable can never be deleted regardless
of the optimization level.

jeff

Re: egcs 1.1b and "volatile"

[erik.ivanenko]

Eric Norum wrote:

> erik.ivanenko@utoronto.ca wrote:
>
> >Is there some way to guarantee that a volatile variable will remain
> >volatile regardless of optimization level?  This is critical when
> >writing a device driver that modifies CPU memory. eg. i82596.
>
> The volatile keyword tells the optimizer that the value of the variable in
> question may change in ways that can not be inferred from the C statements.
>

While I was composing my response, ( which included code references ) I
noticed that I had placed the volatile qualifier on only one of two required
places.   Sorry for the confusion.