[Sablevm-bugs] [ sablevm-Bugs-704345 ] optimization of method preparation

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Bugs item #704345, was opened at 2003-03-15 20:30
Message generated for change (Settings changed) made by egagnon
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Category: Wishlist
Group: SableVM
>Status: Deleted
>Resolution: Duplicate
Priority: 1
Submitted By: Chris Pickett (ihatemcgill)
Assigned to: Etienne M. Gagnon (egagnon)
Summary: optimization of method preparation

Initial Comment:
In Ch.2 of his thesis, Etienne explains the code
preparation technique to replace slow instructions that
must check for class initialization with faster ones
(patching in code from the end of the code array at
runtime).

However, once a class is initialized, then for future
preparation of methods that use this class, it is
unnecessary to have either the slow version or the patch.  

The only cost of this optimization is an extra check at
method preparation time for each instruction that
requires class initialization, to see if the class has
already been initialized.  

The savings are that 1) neither patching code nor slow
initialization code needs to be prepared 2) there is no
patching that ever takes place for that instruction and
3) (most importantly), we save at least one
synchronization on the slow initialization instruction.

This optimization is applicable to all three threading
modes, but it will of course be most interesting to see
if it improves inlined-threading.

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Comment By: Chris Pickett (cpickett)
Date: 2004-03-26 19:49

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I never got around to this, but I wouldn't mind trying it
out when I prepare a few changes from my tree for migration
to staging, after I have submitted an initial paper on my
spmt work.

Or it could serve as a good intro project to SableVM for
somebody.

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Comment By: Etienne M. Gagnon (egagnon)
Date: 2003-03-16 11:24

Message:
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Hi Chris,

You are highly encouraged to submit a patch as attachment to
this bug. :-)

Etienne

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