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From: Egor Pasko <egor.pasko@gmail.com>
Subject: Re: [drlvm][opt][translator] What dose JavaLabelPrepass do?
Date: 17 Jan 2008 13:31:05 +0300
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On the 0x3CE day of Apache Harmony Simon Chow wrote:
> On 17 Jan 2008 11:08:54 +0300, Egor Pasko <egor.pasko@gmail.com> wrote:
> >
> > On the 0x3CD day of Apache Harmony Simon Chow wrote:
> > > I am studying OPT in jitrino. For understanding the process of building
> > CFG,
> > > I have read some code of JavaByteCodeTranslator.
> > > In the constructor of JavaByteCodeTranslator, there is an additional
> > pass
> > > named JavaLabelPrepass,
> > > I would like to ask what is the exact purpose of this pass?
> >
> > the purpose is to mark basic blocks and inference stack variables and
> > local variables with their types.
> >
> > This information goes to the input of JavaByteCodeTranslator, which in
> > single pass goes through each bytecode instruction and converts it to
> > operand-based representation from the stack-based in bytecode.
> >
> > The problem is a little tricky (with variable merging logic) and
> > current design is poor.
> >
> > > Besides this, It is seems that the translator part will be refined,
> > which I
> > > saw in the wiki. Has it already been done in the current version?
> > > Thanks!
> >
> > no, translator is not refined, low priority task.
> >
> > Why do you study the process of building CFG? If you want to do
> > something with it, I would suggest to try some other place since all
> > JIT people here will agree that debugging JavalabelPrepass is
> > brain-damaging.
> 
> 
> Thank!
> I am doing a project for combining static compiler with dynamic compilation
> environment (jitrino.OPT)
> As first step, now I am planning to translate the Harmony IR to WHIRL.

hm, do you have a kind of draft design document on how you want to do
this? ..probably Harmony gurus can give some valuable input having
read this doc.

> But I can not find more information for the CFG structure in jitrino.OPT,
> which leads me to read the code in translation part. :(
> Any advice for this?

there is no complete reference guide for HIR instructions yet. Once I
gave advice on this:

http://article.gmane.org/gmane.comp.java.harmony.devel/24474/

feel free to ask specific questions on CFG and instructions :)

-- 
Egor Pasko