[Bug middle-end/54146] Very slow compile at -O1 (expand vars)

[glisse at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54146

--- Comment #11 from Marc Glisse <glisse at gcc dot gnu.org> 2012-08-01 15:59:43 UTC ---
(In reply to comment #9)
> I'm beginning to think this is one of those cases of "Doctor it hurts if I ..."
> that should be closed as WONTFIX.

Indeed, might even call it INVALID. Thanks a lot for the investigation and
sorry for the bad example. Hopefully the patches you wrote are still useful.

> Marc, do you know where the use of the
> flatten attribute comes from in your code?

Comes from the Eigen library, I'll talk to them about it and see if they can
comment. They mostly deal with simple number types (double, float), so the
behavior with heavy types might have been unnoticed.