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Re: [PATCH AutoFDO]Restoring indirect call value profile transformation


On Wed, Dec 19, 2018 at 5:27 AM Andi Kleen <ak@linux.intel.com> wrote:
>
> > Yes, take g++.dg/tree-prof/morefunc.C as an example:
> > -  int i;
> > -  for (i = 0; i < 1000; i++)
> > +  int i, j;
> > +  for (i = 0; i < 1000000; i++)
> > +    for (j = 0; j < 50; j++)
> >       g += tc->foo();
> >     if (g<100) g++;
> >  }
> > @@ -27,8 +28,9 @@ void test1 (A *tc)
> >  static __attribute__((always_inline))
> >  void test2 (B *tc)
> >  {
> > -  int i;
> > +  int i, j;
> >    for (i = 0; i < 1000000; i++)
> > +    for (j = 0; j < 50; j++)
> >
> > I have to increase loop count like this to get stable pass on my
> > machine.  The original count (1000) is too small to be sampled.
>
> IIRC It was originally higher, but people running on slow simulators complained,
> so it was reduced.  Perhaps we need some way to detect in the test suite
> that the test runs on a real CPU.
Is there concise way to do this, given gcc may be run on all kinds of
virtual scenarios?

>
> >
> > > > FYI, an update about AutoFDO status:
> > > > All AutoFDO ICEs in regtest are fixed, while several tests still failing fall in below
> > > > three categories:
> > >
> > > Great!
> > >
> > > Of course it still ICEs with LTO?
> > >
> > > Right now there is no test case for this I think. Probably one should be added.
>
>
> Any comments on this?
We'd like to further investigate AutoFDO+LTO, may I ask what the
status is (or was)?  Any background elaboration about this would be
appreciated.

Thanks,
bin
>
> -Andi


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