Messages in this thread | | | Date | Wed, 14 Aug 2002 14:13:23 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [patch 4/21] fix ARCH_HAS_PREFETCH |
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Willy Tarreau wrote: >>> >> >>#define __nop() asm volatile("") > > and if you want to pass arguments, to guarantee that no optimization will > be done, even on loop constants ? > eg: > for (i = 0; i < N; i++) { > j++; > __nop(); > } > > -> might be optimized this way : > j = N; > for (i = 0; i < N; i++) { > __nop(); > } > > Perhaps using a volatile for j ? >
OK, what are you trying to accomplish by this?
But if you wanted to, you could do:
for ( i = 0 ; i < N ; i++ ) { j++; asm volatile("" : "=g" (j)); }
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