[Polly] Run-time alias check construction hangs

[Quuxplusone]

Bugzilla Link	PR21166
Status	RESOLVED FIXED
Importance	P normal
Reported by	Tobias Grosser (tobias@grosser.es)
Reported on	2014-10-06 04:29:12 -0700
Last modified on	2016-01-18 17:01:43 -0800
Version	unspecified
Hardware	PC Linux
CC	jdoerfert@anl.gov, llvm-bugs@lists.llvm.org
Fixed by commit(s)
Attachments	test-case.ll (2004 bytes, application/octet-stream)
Blocks
Blocked by
See also

Running

alias polly-opt='opt -load LLVMPolly.so'

polly-opt -polly-code-generator=isl test-case.ll

causes a time out for me.

My first investigations point to:

commit 61337345c7fbc77f04a816d5ca45631a013132f9
Author: Johannes Doerfert <doerfert@cs.uni-saarland.de>
Date:   Wed Oct 1 12:42:37 2014 +0000

    [RTC] Use the domain to split alias groups.

      We use a parametric abstraction of the domain to split alias groups
      if accesses cannot be executed under the same parameter evaluation.

      The two test cases check that we can remove alias groups if the
      pointers which might alias are never accessed under the same parameter
      evaluation and that the minimal/maximal accesses are not global but
      with regards to the parameter evaluation.

    Differential Revision: http://reviews.llvm.org/D5436

[Quuxplusone]

Attached test-case.ll (2004 bytes, application/octet-stream): Test case

[Quuxplusone]

When you dump the SCoP before we build alias groups you see:

       Stmt_for_body9
            Domain :=
                { Stmt_for_body9[i0, i1] : 1 = 0 };

and that's why the splitting procedure doesn't converge.

Fix: http://reviews.llvm.org/D5623

[Quuxplusone]

Fixed in r219131.

[Quuxplusone]

Move to Polly Product.