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

[Alan McGovern]

Hi,

That makes sense. I was just quite surprised at the time that the methods
were not being inlined as they were only simple maths operations. I checked
monodis for one of the methods and it turned out to be 8 IL instructions,
which is probably 24 bytes, which would explain why it wasn't inlined.

Alan.

On Thu, May 1, 2008 at 12:24 AM, Rodrigo Kumpera <kumpera at gmail.com> wrote:

> Well, the inliner basically eliminates the penalty from using properties
> and empty constructors.
>
> Increasing the inline threshold is tricky and might now be worthy as there
> are too many situations that abort inlining. So it would significantly
> increase JIT time for diminishing gains.
>
>
>
> On Wed, Apr 30, 2008 at 6:38 PM, Alan McGovern <alan.mcgovern at gmail.com>
> wrote:
>
> > 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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> > > > Mono-devel-list at lists.ximian.com
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> > > >
> > > >
> > >
> >
>
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