[Mono-dev] JIT and Inlining - why doesn't it happen?

[Zoltan Varga]

Hi,

> I get an 10% performance boost (give or take). Surely if the method was
> getting inlined, that wouldn't be the case. Could it be that the temp
> variables (25->28) aren't being dropped and there is excess variable copying
> going on?

Yes, the current JIT is not very good at getting rid of copies.

              Zoltan

>
> Alan.
>
>
>
> On Thu, May 1, 2008 at 12:47 PM, Zoltan Varga <vargaz at gmail.com> wrote:
> > Hi,
> >
> >  On my amd64 machine, that method does get inlined. You can check the
> > output of mono -v -v -v -v for INLINE lines to see what gets inlined.
> >
> >                        Zoltan
> >
> >
> >
> >
> > 2008/4/30 Alan McGovern <alan.mcgovern at gmail.com>:
> > > This method does not get inlined:
> > >
> > > private uint Ch (uint u, uint v, uint w)
> > > {
> > >     return (u&v) ^ (~u&w);
> > > }
> > >
> > > If that isn't inlined then don't ask me what kind of method *could* be
> > > inlined by the JIT.
> > >
> > > Alan.
> > >
> > >
> > >
> > > On Wed, Apr 30, 2008 at 11:32 PM, Rodrigo Kumpera <kumpera at gmail.com>
> wrote:
> > > > Mono only inline very short methods. Right now methods must have a
> body at
> > > most 20 bytes long.
> > > >
> > > >
> > > >
> > > >
> > > > 2008/4/30 Alan McGovern <alan.mcgovern at gmail.com>:
> > > >
> > > > >
> > > > >
> > > > >
> > > > > I recently started doing a bit of optimisation work on the
> > > hashing/cryptography classes in mono. When working on the managed SHA256
> > > class[1], i noticed that mono isn't inlining what i'd consider some
> *very*
> > > simple methods.
> > > > >
> > > > > The helper methods which do the bitshifting (Ro0, Ro1, Ch, Maj etc)
> > > aren't inlined! Each of these methods is only called once in the code.
> By
> > > manually inlining those method calls, performance increased
> significantly -
> > > about 70%. Why isn't mono inlining these methods? Can mono be made
> inline
> > > these?
> > > > >
> > > > > Alan.
> > > > >
> > > > >
> > >
> [1]http://anonsvn.mono-project.com/viewcvs/trunk/mcs/class/corlib/System.Security.Cryptography/SHA256Managed.cs?rev=46462&view=markup
> > > > >
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> > > >
> > >
> > >
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