# Monday, 02 March 2009
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New Development Snapshot

In keeping with the recent coincidental trend of releasing a development snapshot every ten days, here's the next one. This time a got a little side tracked and decided to do some optimizations.

A cute one is that Object.getClass() is now an intrinsic in two specific scenarios. The first scenario is trivial, when it is used to do a null reference check (javac uses this pattern, both in its source and in the code it generates), the second scenario is a little more interesting:

boolean equals(Object other)
{
  if (other.getClass() != this.getClass())
    return false;
  ...
}

Is now compiled into:

boolean equals(Object other)
{
  if (Type.GetTypeHandle(other).Value != Type.GetTypeHandle(this).Value)
    return false;
  ...
}

This removes the need to create (and lookup) the System.Type and java.lang.Class objects entirely.

Changes:

  • Added wildcard exports for assemblies referenced by non-main assembly in shared class loader group.
  • Intrinsified two uses of Object.getClass().
  • Minor optimization to TypeWrapper.ClassObject.
  • Added optimization to reflective instantiation to use Activator.CreateInstance() when that is almost as fast as our LCG based implementation (which has a far higher initial cost).
  • Removed some unnecessary initializations from java.lang.Class.
  • Changed runtime calls to AccessController.doPrivileged() to explicitly pass callerID.
  • Added support for multi level stack tracking to CodeEmitter.
  • Made most Pop emitting lazy to enable optimizing them away (together with corresponding push).
  • Made loading class literal lazy, to enable optimizing them away when they aren't used (e.g. because an atomic intrinsic).
  • Made Class.desiredAssertionStatus() into an intrinsic, to be able to optimize it away when -removeassertions is used.
  • Avoid constructing AssemblyName objects when reading the export map (it turns out that constructing an AssemblyName is pretty expensive).
  • Made the export map reading lazy.

As always with a development snapshot, don't use this in production, but please do try it out and let me know about it. The sources are available in cvs and the binaries here: ikvmbin-0.39.3348.zip
 

Monday, 02 March 2009 06:43:55 (W. Europe Standard Time, UTC+01:00)  #    Comments [0]
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I apologize for the lameness of this, but the comment spam was driving me nuts. In order to be able to post a comment, you need to answer a simple question. Hopefully this question is easy enough not to annoy serious commenters, but hard enough to keep the spammers away.

Anti-Spam Question: What method on java.lang.System returns an object's original hashcode (i.e. the one that would be returned by java.lang.Object.hashCode() if it wasn't overridden)? (case is significant)

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