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Re: 100x perfomance regression between gcc 3.4.5 and gcc 4.X


On 3/13/06, Richard Guenther <richard.guenther@gmail.com> wrote:
> On 3/13/06, tbp <tbptbp@gmail.com> wrote:
> > On 3/13/06, Richard Guenther <richard.guenther@gmail.com> wrote:
> >  > Starting with gcc 4.1.0 we have inline heuristics in place that will _always_
> > > inline such simple "wrappers".  So, if this still happens, there is a bug in the
> > > heuristics and that should be reported.  Before 4.1.0 the heuristics were bogus
> > > and wrappers were not inlined all the time.
> > > So, can you verify you are happy with the heuristics in 4.1.0
> > No i'm not, and i've used a pristine 4.1.0 in
> > http://gcc.gnu.org/ml/gcc/2006-03/msg00410.html
>
> For the testcase in this message, I get (I removed the always_inline)
> all wrappers inlined to bloatit.  Of course bloatit does not get inlined
> w/o always_inline - it's a huge function and not a simple wrapper.  With
> always_inline on it, the wrappers are no longer inlined - this is a bug and
> should be reported.  Of course from 4.1.0 on you can easier stick an
> __attribute__((flatten)) on the function you want everything inlined to
> (finalblow) and get everything inlined into it.

I see the bug and will have a fix in a moment.

Richard.


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