2010/4/20 Blue Swirl <blauwir...@gmail.com>: > On 4/20/10, Artyom Tarasenko <atar4q...@googlemail.com> wrote: >> /* XXX: potentially incorrect if dynamic npc */ >> static void do_branch >> >> There are few comments like this in target-sparc/translate.c . >> In what case is it incorrect? >> >> Can do_branch functions be called with dynamic npc? > > Maybe, if there are two branches or jumps in a row. The last time I > checked, at least for successive branches we do the correct thing. > It's pretty obscure, no compiler will generate such sequences and > nobody with asm skills either.
Why not? That's how you can implement a very compact 'case' operator in asm. It is used in OBP. But you are right, this seems to work (at least with ss-5 and ss-20 OBP). > Another corner case that IIRC we don't handle is where a jump > instruction is at the end of the page and its delay slot instruction > is at next page. Do you mean that npc is dynamic in this case, or that if npc is dynamic and the instruction is at the end of the page we have a problem? > I think one commit for Microblaze added support for > this case. -- Regards, Artyom Tarasenko solaris/sparc under qemu blog: http://tyom.blogspot.com/
