Method Fusion proposal

[Flavio Brasil]

Thank you for the quick feedback, Gilles.

Yes, building the frame state is currently where I'm stuck at. Would you be
able to give some details on how the optimization that fuses sequential
`StringBuilder.append` on Graal EE works? Are there plans to open source it?

Best,

Flavio

On Fri, Jun 15, 2018 at 8:54 AM Gilles Duboscq <gilles.m.duboscq at oracle.com>
wrote:

> Hi Flavio,
>
> Usually, the difficult part of this kind of transforms are the stacks
> ("framestates") that your are going to give to the VM along with the
> compiled code.
>
> In principle they should represent stacks and states that are possible to
> reach through the bytecodes that are being compiled so that things like
> deoptimization can work.
>
> In previous experimentation we concluded that HotSpot really doesn't like
> fake framestates.
> Maybe some of these HotSpot limitations could be lifted with some C++
> changes??
>
> Overall getting FrameState nodes that will work will be your biggest
> challenge:
> - what will be the bci of the FrameState for the introduced calls?
> - what values will be on the stack if deoptimization occurs for while the
> new calls or the re-written calls are on the stack? can execution proceed
> correctly?
>
>  Gilles
>
> On 15/06/18 16:27, Flavio Brasil wrote:
> > *Hi Graal developers,We’ve been exploring a new JIT optimization at
> Twitter
> > that could significantly improve the efficiency of some of the high-level
> > abstractions normally used in Scala. The project is at its early stage so
> > we thought it’d be best to have your feedback on it sooner rather than
> > later since you might be interested in collaborating on it.The initial
> > design doc is available at *https://docs.google.com/document/d/139XJhODDMfcWBNi80-jSWNGrBEmggch72oaNA5LXF2I/edit#heading=h.uqhewhqfc5rs
> <https://docs.google.com/document/d/139XJhODDMfcWBNi80-jSWNGrBEmggch72oaNA5LXF2I/edit#heading=h.uqhewhqfc5rs>* and
> open for comments.Thank you,Flavio
> > BrasilVM Team @ Twitter*
> >
>