local volatiles live on stack (I believe this is in docs).
but where is volatile declaration in your code?
As I can see from your example there is simple 'constant propagation'
technique being used.
~d
On Wednesday 23 June 2004 21:05, Matthias Weingart wrote:
> Hi,
>
> again a problem with volatile - or too much optimizing of the compiler.
> With "volatile uint n;" my code will work as expected, but it uses space on
> the stack and it wastes cycles. I want registers for my purpose.
>
> This is the code (Stripped down to something useless :-)
>
> #define VALUE 8
>
> void foo(void)
> {
> {
> uint n;
> n=VALUE;
> __asm__ __volatile__("dec %0\n jnz $-2\n" :: "r" (n));
> }
> //do someth.
> {
> uint n;
> n=VALUE;
> __asm__ __volatile__("dec %0\n jnz $-2\n" :: "r" (n));
> }
> //do someth.
> }
>
> The compiler is setting N=2*VALUE before the first loop:
>
> mov #16, r15
> dec r15
> jnz $-2
>
> ... ;do smth.
>
> dec r15
> jnz $-2
>
> ... ;do smth.
> ret
>
> but I want it to look like this:
> mov #8, r15
> dec r15
> jnz $-2
>
> ... ;do smth.
>
> mov #8, r15
> dec r15
> jnz $-2
>
> ... ;do smth.
> ret
>
> any ideas?
>
> thx
>
> M.
>
>
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