JDK-8068784 : Halve the function object creation code size
  • Type: Enhancement
  • Component: core-libs
  • Sub-Component: jdk.nashorn
  • Affected Version: 9
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2015-01-12
  • Updated: 2015-09-29
  • Resolved: 2015-01-12
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JDK 8 JDK 9
8u60Fixed 9 b46Fixed
Description
Currently we need 16 bytes to create a ScriptFunction in bytecode:

  new ScriptFunctionImpl
  dup
  getstatic Script$f.constants : [Object;
  iconst_1 
  aaload
  checkcast RecompilableScriptFunctionData
  aload_2
  invokespecial ScriptFunctionImpl.<init>(RecompilableScriptFunctionData;ScriptObject;)V

This can be reduced to 8 by introducing a factory method ScriptFunctionImpl.create(Object[] constants, int index, ScriptObject scope):

  getstatic Script$f.constants : [Object;
  iconst_1
  aload 2
  invokestatic ScriptFunctionImpl.create([Object;IScriptObject;)ScriptFunction;

For methods containing lots of function declarations (e.g. typically the top-level program) this is a significant reduction in bytecode size.