8340456: Reduce overhead of proxying Object methods in ProxyGenerator

[cl4es]

This PR changes proxy code gen to avoid generating Class.forName("java.lang.Object"), instead emitting an ldc for the class literal, ldc(CD_Object), java code equivalent Object.class.

More types could profitably use ldc(ClassDesc/-Entry), taking cues from InvokerBytecodeGenerator.isStaticallyInvocable, but just addressing the Object methods gets rid of most Class.forName emits. It's not terribly important for throughput performance since these are called in the generated clinit, so getting a quick win with few additional checks is a good starting point.

Added a few unrelated minor refactors/improvements, guided by diagnostic runs of the now fixed microbenchmark.

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Issue

• JDK-8340456: Reduce overhead of proxying Object methods in ProxyGenerator (Enhancement - P4)

Reviewers

• Chen Liang (@liach - Reviewer)

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@cl4es This change now passes all automated pre-integration checks.

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8340456: Reduce overhead of proxying Object methods in ProxyGenerator

Reviewed-by: liach

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At the time when this comment was updated there had been 9 new commits pushed to the master branch:

• 75d5e11: 8340400: Shenandoah: Whitebox breakpoint GC requests may cause assertions
• 15ae115: 8340166: [REDO] CDS: Trim down minimum GC region alignment
• ec3cba0: 8340399: Update comment in SourceVersion for language evolution history
• d1d8240: 8340308: PassFailJFrame: Make rows default to number of lines in instructions
• bc36ace: 8340271: Open source several AWT Robot tests
• 5f3e7aa: 8339735: Remove references to Applet in core-libs/security APIs
• 2ada313: 8340329: (fs) Message of NotLinkException thrown by FIles.readSymbolicLink does not include file name (win)
• 3bb8de3: 8338693: assert(Atomic::add(&ik->_shared_class_load_count, 1) == 1) failed: shared class loaded more than once
• d555f07: 8298614: Support CDS heap dumping for SerialGC and ParallelGC

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[liach]

This Class.forName is only necessary in a very small number of cases, namely when the overridden interface method has an unaccessible parameter type, usually a package-private type not accessible to the implementing class. Maybe we can always directly ldc if the class is public.

[cl4es]

Yeah, I'm just not sure what rules are quite right here. Wouldn't want to inadvertently regress this again, and not sure we have tests for all eventualities, so I started this off with the most conservative yet most beneficial improvement.

[mlbridge]

Webrevs

• 00: Full (1d6ed5b4)

[liach]

Replacing Class.forName with ldc or even condy is an esoteric topic. We can dive into that later and pick up the obvious gains.

[cl4es]

Thanks!

/integrate

[openjdk]

Going to push as commit a50440f.
Since your change was applied there have been 19 commits pushed to the master branch:

• 5d611c0: 8340439: AArch64: Extra entry declaration for assember test
• 9d76c7c: 8340418: GHA: MacOS AArch64 bundles can be removed prematurely
• 46b02f4: 8339906: Open source several AWT focus tests - series 4
• f4e4017: 8339984: Open source AWT MenuItem related tests
• 0f7d9e5: 8340436: Remove unused CompressedOops::AnyNarrowOopMode
• 94c3317: 8339895: Open source several AWT focus tests - series 3
• 969c2af: 8339192: Native annotation parsing code of deprecated annotations causes crash
• fdc16a3: 8340480: Bad copyright notices in changes from JDK-8339902
• 296b496: 8340353: Remove CompressedOops::ptrs_base
• fde8508: 8339902: Open source couple TextField related tests
• ... and 9 more: https://git.openjdk.org/jdk/compare/c9bee173d61f4accfc4adc280ab5d21600191756...master

Your commit was automatically rebased without conflicts.

[openjdk]

@cl4es Pushed as commit a50440f.

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