[polly] r229252 - Overaproximate divisions in for the alias checks.

[Johannes Doerfert]

On 02/14, Tobias Grosser wrote:
> On 14.02.2015 13:00, Johannes Doerfert wrote:
> >Author: jdoerfert
> >Date: Sat Feb 14 06:00:06 2015
> >New Revision: 229252
> >
> >URL: http://llvm.org/viewvc/llvm-project?rev=229252&view=rev
> >Log:
> >Overaproximate divisions in for the alias checks.
> >
> >   Alias checks might become costly if there are divisions that complicate the
> >   description of the accessed locations. By overaproximating them we get fairly
> >   accurate results without the huge compile time cost.
> 
> A test case would be nice here.
I don't have a test case at the moment but I'll try to get one. The idea
is that we want to check ranges anyway and alias check creation times
out on lnt since we allowed signed divisions.

> Also, can you explain why this approximation is always save?
The isl manual states that the result is an overapproximation. I will
add a comment to the code.

> Tobisa

-- 

Johannes Doerfert
Researcher / PhD Student

Compiler Design Lab (Prof. Hack)
Saarland University, Computer Science
Building E1.3, Room 4.31

Tel. +49 (0)681 302-57521 : doerfert at cs.uni-saarland.de
Fax. +49 (0)681 302-3065  : http://www.cdl.uni-saarland.de/people/doerfert
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 213 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20150214/c73cf9b8/attachment.sig>