[webkit-dev] Fwd: Difference between jit/JITArithmetic32_64 and jit/JITArithmetic

wingoog moon wingoog91 at gmail.com
Sat Feb 18 05:41:59 PST 2012

---------- Forwarded message ----------
From: wingoog moon <wingoog91 at gmail.com>
Date: Sat, Feb 18, 2012 at 4:44 AM
Subject: Re: [webkit-dev] Difference between jit/JITArithmetic32_64 and
To: squirrelfish-dev at lists.webkit.org

Thanks for answer!!
But what you mean when say 32_64 value representation?  Do you mean it must
work for 32 bit architecture??

On Fri, Feb 17, 2012 at 10:47 AM, Filip Pizlo <fpizlo at apple.com> wrote:

> The JIT class is quite large, and so its implementation is broken up into
> multiple files.  The manner in which it is broken up is somewhat arbitrary,
> with the main goal being to not have any outrageously large .cpp files.
>  Here's the intuition I use for finding what I want:
> JIT.cpp: the harness that runs the JIT and a few utility functions that
> are not related to any particular bytecode opcode.
> JITArithmetic.cpp: implementation of arithmetic instructions.
> JITCall.cpp: implementation of calling convention, including call
> instructions.
> JITPropertyAccess.cpp: implementation of heap access instructions.
> JITOpcodes.cpp: implementation of miscellaneous instructions that don't
> fit into the above.
> But there is also a second split: the JIT can either be generating code
> that uses the 32_64 value representation, or the 64-bit value
> representation.  These two representations require two completely different
> code generators and most of the code in the JIT is specialized on one or
> the other.  Hence any file that is marked 32_64 (like JITArithmetic32_64)
> contains implementations for the 32_64 value representation, whereas files
> that do not have "32_64" in them are implementing either the 64-bit value
> representation, or code that is agnostic towards value representation.
> -Filip
> On Feb 17, 2012, at 7:02 AM, wingoog moon wrote:
> > HI All.
> > Can't understand difference between jit/JITArithmetic32_64 and
> jit/JITArithmetic.
> > Both of them are implementing JIT class. So when program calls functions
> from JITArithmetic and when JITArithmetic32_64.
> >
> > I also noticed that that there is JITOpcodes class, which is also
> implementing JIT class. Why we need this class.
> >
> > P.s
> > Sorry for bad English
> > thanks for answers.
> > _______________________________________________
> > webkit-dev mailing list
> > webkit-dev at lists.webkit.org
> > http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev
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