[llvm-dev] RFC: Import of Integer Set Library into LLVM source tree

[Michael Kruse via llvm-dev]

2018-01-18 6:40 GMT+01:00 Chris Lattner <clattner at nondot.org>:
> Great, I think that that would be a fine approach: you can have the cmake logic detect which version of isl is installed and fail if it is the wrong version.  This would address my concern.

> The motivation explained in the original email seemed to hinge around the fact that Polly’s unit tests depend on accidental details of ISL that change across releases.  If you can fix that, then it seems more plausible to unbundle it.
>
> If you can’t fix that, and can’t replace ISL, then the best approach seems to have CMake detect and reject incompatible versions.

This would require buildbot admins to regularly install new versions of isl.

Isl implements the main loop optimization algorithms, so any change in
isl may potentially change Polly's output. This is not accidental but
intended, to profit from improvements in isl's loop optimization
algorithms. With the side-effect of input/output pairs (unit tests) to
be version-locked to a specific version of isl.

Isl currently has 177052 lines in source files. We thought about
writing a C++ implementation of it, but then again it would take
years, introduce new bugs and split the isl community.

Michael