On 18/04/16 20:51, Sergey Fedorov wrote: > On 18/04/16 20:17, Alex Bennée wrote: >> Sergey Fedorov <serge.f...@gmail.com> writes: >>> On 18/04/16 17:09, Alex Bennée wrote: >>>> Sergey Fedorov <sergey.fedo...@linaro.org> writes: >>>>> diff --git a/cpu-exec.c b/cpu-exec.c >>> (snip) >>>>> @@ -507,14 +510,12 @@ int cpu_exec(CPUState *cpu) >>>>> } >>>>> tb_lock(); >>>>> tb = tb_find_fast(cpu); >>>>> - /* Note: we do it here to avoid a gcc bug on Mac OS X >>>>> when >>>>> - doing it in tb_find_slow */ >>>> Is this still true? Would it make more sense to push the patching down >>>> to the gen_code? >>> This comment comes up to the commit: >>> >>> commit 1538800276aa7228d74f9d00bf275f54dc9e9b43 >>> Author: bellard <bellard@c046a42c-6fe2-441c-8c8c-71466251a162> >>> Date: Mon Dec 19 01:42:32 2005 +0000 >>> >>> workaround for gcc bug on PowerPC >>> >>> >>> It was added more than ten years ago. Anyway, now this code is here not >>> because of the bug: we need to reset 'next_tb' which is a local variable >>> in cpu_exec(). Personally, I don't think it would be neater to hide it >>> into gen_code(). Do you have some thoughts on how we could benefit from >>> doing so? BTW, I had a feeling that it may be useful to reorganize >>> cpu_exec() a bit, although I don't have a solid idea of how to do this >>> so far. >> I'm mainly eyeing the tb_lock/unlock which would be nice to push further >> down the call chain if we can, especially if the need to lock >> tb_find_fast can be removed later on. > Yes, it would be nice to possibly have all tb_lock/unlock() calls (or at > least their pairs) in the same block. There is a lot to be thought over :)
It's not so simple because tb_find_fast() is also called in replay mode to find a TB for cpu_exec_nocache()... I'm not sure it's worth touching it now. Although it may be possible to improve the code structure of cpu_exec() in some other way. (It's really scary, indeed.) Actually, I've been keeping that in mind for some time. Do you think if MTTCG would benefit from some cpu_exec() refactoring to make it more clear and easy to understand? Kind regards, Sergey
