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

[rguenth at gcc dot gnu.org]

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

--- Comment #10 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-08-01 14:32:15 UTC ---
(In reply to comment #9)
> clang compiles the test case with attribute((flatten)) because it doesn't
> support that attribute (http://llvm.org/bugs/show_bug.cgi?id=7559).
> 
> I'm beginning to think this is one of those cases of "Doctor it hurts if I ..."
> that should be closed as WONTFIX. Marc, do you know where the use of the
> flatten attribute comes from in your code?

indeed "flatten" will override any inlining heuristic that avoids creating
gigant function bodies.  Still eventually improving worst-case performance
of some of our algorithms sounds good, even if it will never fix all issues
that pop up when you for example put flatten on main () ;)