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Re: [PATCH] Fix PR23744, VRP not merging discontinuous ranges of PHIs
- From: Daniel Berlin <dberlin at dberlin dot org>
- To: Diego Novillo <dnovillo at redhat dot com>
- Cc: Duncan Sands <baldrick at free dot fr>, gcc-patches at gcc dot gnu dot org
- Date: Mon, 15 May 2006 12:31:11 -0400
- Subject: Re: [PATCH] Fix PR23744, VRP not merging discontinuous ranges of PHIs
- References: <200605051110.04479.baldrick@free.fr> <4468A969.7090105@redhat.com>
Diego Novillo wrote:
> Duncan Sands wrote on 05/05/06 05:10:
>
>>> PR tree-optimization/23744
>>> * tree-vrp.c (vrp_meet): do not require ranges to intersect.
>>>
> This will be more appropriate for the next stage 1. In the meantime, I
> would like to see compile time impact analysis on real code (I can help
> out with the usual suspects I have around: cc1-i-files, DLV, MICO, SPEC,
> etc).
>
> You are lengthening the simulation by slowing down the decay into
> VR_VARYING.
However, I expect this will enable folding of a large number of
predicates that are currently missed.
I tried it on some C++ code I have that heavily uses enums and tests
against them, and it helped enormously.