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From "cannibal wang" <cannibal.w...@gmail.com>
Subject Re: [drlvm][opt][translator] What dose JavaLabelPrepass do?
Date Fri, 18 Jan 2008 01:31:42 GMT
2008/1/17, Simon Chow <simon.harmony@gmail.com>:
>
> Actually, we are targeting at x86 platform :)  IPF is not concerned until
> now.
> I am sorry that I did not make this clear before.


Agree, we will graduate next year, so we have only one year at most to do
so, unless our future work
involves Harmony,:)

Now we just plan to enhance OPT using Open64 only for loops and other
> computation-intensive sections.
> Does it have some opportunities for performance improving?


Initially, we planned to compile a java program to WHIRL using Open64,
then translate WHIRL to OPT HIR, because WHIRL has five levels, and it can
deal with more detailed information.
in the end, dynamical optimization in Harmony will be utilized.
Is this idea feasible?

As you said, code motion and prefetch optimizations is more helpful in C
> compilers,
> and what is the advantaging we can take using JIT compiler? profiling?
> and?
> I have little experience here.
>
> And I have not tried DRLVM on IPF yet...
>
> Thanks
>
> On 17 Jan 2008 15:41:08 +0300, Egor Pasko <egor.pasko@gmail.com> wrote:
> >
> > On the 0x3CE day of Apache Harmony Simon Chow wrote:
> > > On 17 Jan 2008 13:31:05 +0300, Egor Pasko <egor.pasko@gmail.com>
> wrote:
> > > >
> > > > 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.
> > >
> > >
> > > There is no document for this yet, but I will write one in the next
> few
> > days
> > > after having a discussion with others in my group.
> > > Our static compilation platform is Open64, some of my teammates are
> > working
> > > on it.
> >
> > just to make sure.. is the primary goal to replace/enhance Jitrino.OPT
> > on IPF machines? Oh, those itanics..
> >
> > > I only have a little understanding of jitrino.OPT.
> > > For achieving higher performance, which part or phases of
> jitrino.OPTcould
> > > be refined or replaced by Open64 optimization?
> > > Could you give me some suggestion?
> >
> > I am afraid I am not familiar with Open64 at all, and there are
> > concerns using a mix of Jitrino.OPT and Open64 since the latter is
> > licensed under GPL. So, do not show me their code :)
> >
> > Jitrino.OPT/IPF is rather immature/experimental/untested/etc. So, if
> > using Jitrino.OPT on IPF consider throwing away the code generator
> > (but take care about generating the right calling convention and
> > VM-related stuff like threading)
> >
> > As for the High-level optimizations, I do not know, where Open64 is
> > better, maybe Xiaofeng knows? :)
> >
> > I may try to forsee something: Fortran & C compilers have more freedom
> > for code motion and prefetch optimizations than a Java JIT compiler
> > (which has a more dynamic nature), so, when ported to Java realities a
> > C compiler is likely to behave not very cool.
> >
> > I would suggest you to enhance Jitrino IPF codegenerator in
> > if-conversion and register allocation, that looks like more
> > interesting and performance-beneficial. However, I am not sure if it
> > suits you good as a subject of research.
> >
> > Did you try running DRLVM on IPF? Does it work? Does it even compile?
> >
> > > By the way, This idea is original from Xiaofeng :)
> > >
> > > Thank you every much!
> > >
> > > > 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
> > > >
> > > >
> > >
> > >
> > > --
> > > From : Simon.Chow@Software School of Fudan University
> >
> > --
> > Egor Pasko
> >
> >
>
>
> --
> From : Simon.Chow@Software School of Fudan University
>



-- 
Cannibal
CS.Fudan University

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