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RE: [PATCH] Fix for PR64081 in RTL loop unroller
- From: "Zamyatin, Igor" <igor dot zamyatin at intel dot com>
- To: Jeff Law <law at redhat dot com>, "GCC Patches (gcc-patches at gcc dot gnu dot org)" <gcc-patches at gcc dot gnu dot org>
- Cc: "ysrumyan at gmail dot com" <ysrumyan at gmail dot com>
- Date: Thu, 15 Jan 2015 16:36:41 +0000
- Subject: RE: [PATCH] Fix for PR64081 in RTL loop unroller
- Authentication-results: sourceware.org; auth=none
- References: <0EFAB2BDD0F67E4FB6CCC8B9F87D756969CF7BFC at IRSMSX101 dot ger dot corp dot intel dot com> <54AF707D dot 6080800 at redhat dot com> <CAEoMCqTzzMz-qO5x1q=5Htjxe1Von02iB_BpW7umXyQy_nVxtw at mail dot gmail dot com> <CAKdSQZnrxfXcUMXwNW=c0PPaFgFe6rUKhkW+2T1U8BKop8K8=A at mail dot gmail dot com> <0EFAB2BDD0F67E4FB6CCC8B9F87D756969D345EB at IRSMSX101 dot ger dot corp dot intel dot com> <54B56C44 dot 8090707 at redhat dot com>
>
> On 01/13/15 11:01, Zamyatin, Igor wrote:
> >>
> >> Is it really sufficient here to verify that all the defs are on latch
> >> predecessors, what about the case where there is a predecessor
> >> without a def. How do you guarantee domination in that case?
> >>
> >> ISTM that given the structure for the code you're writing that you'd
> >> want to verify that in the event of multiple definitions that all of
> >> them appear on immediate predecessors of the latch *and* that each
> >> immediate predecessor has a definition.
> >
> > Yes, do you think it's better to check exactly immediate predecessors?
> I'd use the same structure that you have in iv_get_reaching_def. If there
> was a reasonable way to factor that test into a single function and call it from
> both places that would be even better.
Not sure it's possible to merge DF_REG_DEF_CHAIN walk and DF_REF_CHAIN walk...
Thanks,
Igor
>
> Jeff