Re: Sigh. Inlining heuristics.

[Daniel Berlin <dan at cgsoftware dot com>]

Mark Mitchell <mark@codesourcery.com> writes:

>> I'm using -O3.
>> At -O2, it doesn't inline it.
> 
> That's what -O3 means.  It means treat all functions as candidates for
> inlining.  I think that behavior dates to handling C89, where `inline'
> is not a keyword, but sometimes you want the compiler to inline things
> anyhow.

Yes, yes,  I know, it was 3:30am, and my brain failed to work
properly.

> 
> I've never personally found -O3 to be useful for anything, in C or C++,
> ever, precisely because of this problem; clearly ACT has had the same
> experience.  So, it's good if you find a way to impose heuristics that do
> the right thing more often.

O3 will become important when we have a better inlining
architecture. Like I said, once diego's basic blocks on trees stuff is
there, we'll have the basis for doing profile guided inlining (with
fake or real profile info).

> 
> Anyhow, this has nothing to do with flag_default_inline; it's a
> different flag.
> 
> Would you try just cranking down the limit?  I bet that is an 85%
> solution, i.e., one that may make this not a big issue any more.  That
> is good, because there are lots of other big issues. :-)
Sure, i'll give it a try.
-- 
"Babies don't need a vacation, but I still see them at the
beach...  It pisses me off!  I'll go over to a little baby and
say, "What are you doing here?  You haven't worked a day in your
life!"
"-Steven Wright