On Thu, 9 Aug 2012, Andrey Belevantsev wrote:

> Hello,
> 
> The problem in question is uncovered by the recent speculation patch, it is in
> the handling of expressions blocked by bookkeeping.  Those are expressions
> that become unavailable due to the newly created bookkeeping copies.  In the
> original algorithm the supported insns and transformations cannot lead to this
> result, but when handling non-separable insns or creating speculative checks
> that unpredictably block certain insns the situation can arise.  We just
> filter out all such expressions from the final availability set for
> correctness.
> 
> The PR happens because the expression being filtered out can be transformed
> while being moved up, thus we need to look up not only its exact pattern but
> also all its previous forms saved in its history of changes.  The patch does
> exactly that, I also clarified the comments w.r.t. this situation.
> 
> Bootstrapped and tested on ia64 and x86-64, the PR testcase is minimized, too.
> OK for trunk?  Also need to backport this to 4.7 with PR 53975, say on the
> next week.

This is OK.

Thanks.

Alexander
  • Fix PR 53701 Andrey Belevantsev
    • Re: Fix PR 53701 Alexander Monakov

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