[pypy-dev] Rough draft of x86-64 JIT backend GSoC proposal

[Jason Creighton]

Hi Guys,

I am a student planning on applying to GSoC to create an x86-64 backend 
for the JIT. I have a (very) rough draft of my proposal, and I was 
hoping to get some feedback on it.

Specifically, I'm wondering about operating system support. I've written 
the proposal as if I would support Linux/Mac OS X/Windows.

I would be developing on Linux, so I think we can assume that would be 
fairly well supported, but obviously I would like it to work on Mac OS X 
and Windows as well. (I'm not sure if I would have the time/motivation 
to care about obscure BSDs). OTOH, if there are already a lot of 
outstanding issues on one of those platforms, I don't know that I would 
be able to get it working. So what do you think would be a reasonable 
goal here?

Secondly, my timeline is pretty vague. The PSF proposal template 
recommends a week-by-week timeline, but honestly, I'm not sure how the 
time usage would break down. Any comments on that would be greatly 
appreciated.

Here's the draft:

=== Proposal ===

The PyPy JIT, which has shown substantial performance improvements over
CPython, often several times faster, does not currently support the
x86-64 instruction set, making it impractical to use on 64-bit x86
systems.

My proposal is to extend the existing x86 JIT backend to support x86-64
as well.

=== Deliverables ===

Stable, tested 64-bit JIT for PyPy on Linux, Mac OS X and Windows merged
into PyPy trunk.

=== Implementation plan ===

This is not a research proposal. The goal is simply to have a PyPy JIT
that works out of the box on 64-bit CPUs, implemented as conservatively
as possible.

As such, I will attempt to reuse as much of the existing x86 backend
that I can. In fact, the architectural similarities between x86 and
x86-64 are large enough that I hope to implement a unified x86/x86-64
backend with the majority of the code working for either platform.

There is an existing branch that, while very incomplete, has the
beginnings of a unified x86/x86-64 instruction encoding module. I intend
to use that branch as a starting point.

Rough outline:

1. Take the existing "remove-ri386-multimethod-2" branch and use it as a 
basis for instruction encoding.

2. Port the existing 32-bit backend to use the new instruction encoding 
scheme.

3. Add 64-bit support to the backend,
         A) Modify register allocator to use new general purpose and
         floating point registers.
         B) Port "ResOperation" operations to 64-bit
         C) Port guard failure handling to 64-bit

4. Test 64-bit on Mac OS X and Windows and fix inevitable issues.

=== About Me ===

I am a first-year Computer Science student at Flathead Valley Community
College planning to transfer to Montana State University.

I have several years of professional development experience. I am
comfortable programming in Python, C and x86 assembly.

Starting May 17th, I will be able to commit 40 hours/week to the project
until the end of August. I may travel for a few weeks at some point in
the summer, but I will have a laptop with me with the expectation of
continuing full-time work.

=== Contact information ===

Email: jcreigh at gmail.com
IRC:   "jcreigh" on Freenode
Phone: (will be given on request, but not preferred)