Commit Graph

3 Commits

Author SHA1 Message Date
Tobias Grosser 7a93d94a8f Revert "Currently broken by recent LLVM upstream changes"
This reverts commit r296579, which is not needed anymore as the relevant changes
in trunk have been reverted.

llvm-svn: 296817
2017-03-02 21:43:50 +00:00
Tobias Grosser 6f9b60cf38 Currently broken by recent LLVM upstream changes
We mark it as XFAIL to get buildbots back to green, until the upstream changes
have been addressed.

llvm-svn: 296579
2017-03-01 04:34:44 +00:00
Tobias Grosser 349d1c3368 [ScopDetection] Remove redundant checks for endless loops
Summary:
Both `canUseISLTripCount()` and `addOverApproximatedRegion()` contained checks
to reject endless loops which are now removed and replaced by a single check
in `isValidLoop()`.

For reporting such loops the `ReportLoopOverlapWithNonAffineSubRegion` is
renamed to `ReportLoopHasNoExit`. The test case
`ReportLoopOverlapWithNonAffineSubRegion.ll` is adapted and renamed as well.

The schedule generation in `buildSchedule()` is based on the following
assumption:

Given some block B that is contained in a loop L and a SESE region R,
we assume that L is contained in R or the other way around.

However, this assumption is broken in the presence of endless loops that are
nested inside other loops. Therefore, in order to prevent erroneous behavior
in `buildSchedule()`, r265280 introduced a corresponding check in
`canUseISLTripCount()` to reject endless loops. Unfortunately, it was possible
to bypass this check with -polly-allow-nonaffine-loops which was fixed by adding
another check to reject endless loops in `allowOverApproximatedRegion()` in
r273905. Hence there existed two separate locations that handled this case.

Thank you Johannes Doerfert for helping to provide the above background
information.

Reviewers: Meinersbur, grosser

Subscribers: _jdoerfert, pollydev

Differential Revision: https://reviews.llvm.org/D24560

Contributed-by: Matthias Reisinger <d412vv1n@gmail.com>
llvm-svn: 281987
2016-09-20 17:05:22 +00:00