> I'd like to throw one more suggestion into this discussion: add a > register to indicate whether r0 is writable or hard-wired to 0. If it's > not writable, it's a waste to clear it at every syscall and this can be > optimized out; if it is writable, then you can use it for clever > optimizations (carefully).
I don't think the extra complication is worth it. At the very minimum, that would be another special case to test. I would just let R0 be like any other register, and move its usage as a constant zero to the ABI spec. Cheers, Ruben _______________________________________________ OpenRISC mailing list [email protected] http://lists.openrisc.net/listinfo/openrisc
