Re: [PATCH] Fix PR 50971 and PR 35629: Only one loop detected when there should be two

[Andrew Pinski <pinskia at gmail dot com>]

Ping?  Rebootstrapped on x86_64-linux-gnu with no regressions.

Thanks,
Andrew Pinski

On Sat, Jan 21, 2012 at 1:21 PM, Andrew Pinski <pinskia@gmail.com> wrote:
> The problem with these two bug reports is that the cfgloop does not do
> a good job for disambiguating some loops. ÂThis patch rewrites
> find_subloop_latch_edge_by_ivs to be better. ÂIt is able to detect
> much more loops and gets the ones which are referenced in PR 50971 and
> PR 35629. ÂIt does make sure the loops it finds are really loops and
> not ones where the continue would cause a loop not to be done.
>
> OK for 4.8 when stage 1 comes? ÂBootstrapped and tested on
> x86_64-linux-gnu with no regressions.
>
> ChangeLog:
> cfgloop.c (skip_to_exit): New function.
> (find_subloop_latch_edge_by_ivs): Rewrite to better detect subloop latches by
> IVs. ÂAlso look at the cfg for those IVs to check for a better choice.
>
> testsuite/ChangeLog:
> * gcc.dg/tree-ssa/loop-25.c: Remove xfails and remove "Found latch
> edge"/"Merged latch edges" tests.
> * gcc.dg/tree-ssa/loop-38.c: New testcase.

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