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From "Xiao-Feng Li" <xiaofeng...@gmail.com>
Subject Re: [drlvm][jit] Code review of the following issue - [jira] Commented: (HARMONY-3246) [drlvm][jit][opt] Jitted code can not be executed on non-SSE2 platforms
Date Wed, 18 Apr 2007 07:56:16 GMT
On 4/18/07, Pavel Ozhdikhin <pavel.ozhdikhin@gmail.com> wrote:
> On 4/18/07, Alexey Varlamov <alexey.v.varlamov@gmail.com> wrote:
> >
> > 2007/4/18, Mikhail Fursov <mike.fursov@gmail.com>:
> > > Nathan,
> > > I checked the patch and it looks OK except a one issue.
> > >
> > > I do not really like that we have new p5.emconf in codebase and propose
> > the
> > > following improvement:
> > > 1) add p5 pass to all Jitrino.OPT codegen aliases in every emconf we
> > have.
> > > (I can update the patch if agreed)
> > I suppose you meant all ia32 configs :). This is neccesary step to
> > CPUID autodetection, so it a must actually.
> >
> > >
> > > 2) a. After the commit: Make it turned off by default and use additional
> > > cmd-line -XX:jit.arg.codegen.p5=on when run on PC without SSE2
> > >    b. Start discussion: Use CPUID to detect if SSE2 is available and
> > make
> > > JIT turn this pass on automatically if needed.
> > >
> > > We can implement CPUID check for SSE2 in JIT only (a couple of lines of
> > > assembly for Linux and Windows)
> > > The question is: would it be better if VM provides such service for
> > every
> > > client? E.g. cpuid_is_sse2_supported()-like methods.
> > I'm in serious doubt that it is needed. Too IA-centric, it would have
> > little sense in general case. So doing it right in Jit is the right
> > thing IMO.
>
>
>
> Why do you think this is not needed? We might have several JITs or
> interpreter that can use and extended set of instructions. It would be good
> to keep these checks in one place in VM.

This is architecture specific property, hence Alexey may think it
belongs to code generator (here JIT), since otherwise an interpreter
in C may not need it. I think Alexey's point is valid. To deal with
multiple JITs, probably we can put it into some JIT-common files. In
other words, although multiple JITs may query it, it is not
necessarily VM's duty to respond. (Or if we view the JIT-common
support as part of VM, then yes, it can be provided by VM.)

Thanks,
xiaofeng

> Thanks,
> Pavel
>
> >
> > >
> > > On 4/18/07, Nathan Beyer <ndbeyer@apache.org> wrote:
> > > >
> > > > Would anyone else like to review this patch? It's somewhat
> > > > significant. I've tested it on a P4/WinXP and DRLVM works without any
> > > > noticeable regressions. I've done some initial tests on a Quad
> > > > P3/Ubuntu and I can now run a simple Hello World with the default JIT,
> > > > which is a huge step.
> > > >
> > > > If no one has any issues, I'm going to commit this patch.
> > > >
> > > > -Nathan
> > > >
> > > > ---------- Forwarded message ----------
> > > > From: Nathan Beyer (JIRA) <jira@apache.org>
> > > > Date: Apr 18, 2007 12:49 AM
> > > > Subject: [jira] Commented: (HARMONY-3246) [drlvm][jit][opt] Jitted
> > > > code can not be executed on non-SSE2 platforms
> > > > To: commits@harmony.apache.org
> > > >
> > > >
> > > >
> > > >     [
> > > >
> > https://issues.apache.org/jira/browse/HARMONY-3246?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12489614
> > > > ]
> > > >
> > > > Nathan Beyer commented on HARMONY-3246:
> > > > ---------------------------------------
> > > >
> > > > I've test this on a Linux P3 and it seems to work. I'm now able to run
> > > > a simple hello world. Additionally, everything seems to work as it did
> > > > on a P4/WinXP.
> > > >
> > > > Let's see if we can get a few more people to review the code.
> > > >
> > > > > [drlvm][jit][opt] Jitted code can not be executed on non-SSE2
> > platforms
> > > > >
> > -----------------------------------------------------------------------
> > > > >
> > > > >                 Key: HARMONY-3246
> > > > >                 URL:
> > https://issues.apache.org/jira/browse/HARMONY-3246
> > > > >             Project: Harmony
> > > > >          Issue Type: Improvement
> > > > >          Components: DRLVM
> > > > >            Reporter: Nikolay Sidelnikov
> > > > >         Assigned To: Nathan Beyer
> > > > >         Attachments: p5_fixed_commented.patch
> > > > >
> > > > >
> > > > > Jitrino generates code with SSE and SSE2 instructions which can not
> > be
> > > > executed on processors older than Pentium 4.
> > > >
> > > > --
> > > > This message is automatically generated by JIRA.
> > > > -
> > > > You can reply to this email to add a comment to the issue online.
> > > >
> > >
> > >
> > >
> > > --
> > > Mikhail Fursov
> > >
> >
>


-- 
http://xiao-feng.blogspot.com

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