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Re: [PATCH] Fix for PR64081 in RTL loop unroller

From: Jeff Law <law at redhat dot com>
To: "Zamyatin, Igor" <igor dot zamyatin at intel 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: Tue, 13 Jan 2015 12:04:36 -0700
Subject: Re: [PATCH] Fix for PR64081 in RTL loop unroller
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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>

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. Ifthere was a reasonable way to factor that test into a single functionand call it from both places that would be even better.


Jeff

Follow-Ups:
- RE: [PATCH] Fix for PR64081 in RTL loop unroller
  - From: Zamyatin, Igor

References:
- Re: [PATCH] Fix for PR64081 in RTL loop unroller
  - From: Jeff Law
- RE: [PATCH] Fix for PR64081 in RTL loop unroller
  - From: Zamyatin, Igor

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