[polly] r264118 - [ScopInfo] Fix domains after loops.

[Tobias Grosser via llvm-commits]

On 03/23/2016 12:27 AM, Michael Kruse via llvm-commits wrote:
> Author: meinersbur
> Date: Tue Mar 22 18:27:42 2016
> New Revision: 264118
>
> URL: http://llvm.org/viewvc/llvm-project?rev=264118&view=rev
> Log:
> [ScopInfo] Fix domains after loops.
>
> ISL can conclude additional conditions on parameters from restrictions
> on loop variables. Such conditions persist when leaving the loop and the
> loop variable is projected out. This results in a narrower domain for
> exiting the loop than entering it and is logically impossible for
> non-infinite loops.
>
> We fix this by not adding a lower bound i>=0 when constructing BB
> domains, but defer it to when also the upper bound it computed, which
> was done redundantly even before this patch.
>
> This reduces the number of LNT fails with -polly-process-unprofitable
> -polly-position=before-vectorizer from 8 to 6.

Nice finding!

Johannes, could you please give this a post-review when you have time again.

Best,
Tobias