Re: [avr-gcc-list] Re: loop deleted using optimization
Ben Jackson [EMAIL PROTECTED] wrote: It would probably work to add an empty asm, as long as you used the __volatile attribute to scare gcc away from reordering code in the loop. asm volatile(:::memory); works. However, as others already noted, the functions from util/delay.h are preferrable, as their execution cycle count is simply known beforehand. -- cheers, Jorg .-.-. --... ...-- -.. . DL8DTL http://www.sax.de/~joerg/NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-) ___ AVR-GCC-list mailing list AVR-GCC-list@nongnu.org http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
[avr-gcc-list] Re: loop deleted using optimization
Why does avr-gcc delete my empty for loops if I compile with
optimization on?
I am able to preserve the loop if I add a NOP in the loop but that will
eat up one clock cycle. Is there a way to preserve the empty loops
without adding any NOP clock cycles?
It would probably work to add an empty asm, as long as you used the
__volatile attribute to scare gcc away from reordering code in the
loop. So, for () { __asm __volatile () ; }
(I note I wasn't able to get gcc 3.3 to optimize away the loop on i386)
--
Ben Jackson AD7GD
[EMAIL PROTECTED]
http://www.ben.com/
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