[Sablevm-bugs] [ sablevm-Bugs-925087 ] optimization of method preparation

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Bugs item #925087, was opened at 2004-03-28 18:00
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Category: Wishlist
Group: SableVM
Status: Open
Resolution: None
Priority: 1
Submitted By: Etienne M. Gagnon (egagnon)
Assigned to: Nobody/Anonymous (nobody)
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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