8266967: debug.cpp utility find() should print Java Object fields.

[kevinjwalls]

This change enables debug.cpp's find() utility to print Java Objects with their fields.

find() calls os::print_location, and Java heap objects are printed with instanceKlass oop_print_on.
Removing the ifdef for defining oop_print_on for instanceKlass, and also on methods in FieldPrinter and FieldDescriptor, make this work.

Checking other uses of os::print_location this might affect:

macroAssembler_x86.cpp has MacroAssembler::print_state32 and MacroAssembler::print_state64
which use os::print_location to print register contents and print words at top of stack.
These will be more verbose, as it already is in non-PRODUCT builds.

vmError uses os::print_location when showing the stack, i.e. this output:

Stack slot to memory mapping:
stack at sp + 0 slots: 0x0000000000000002 is an unknown value
..etc...

...will be more verbose when Java object references are found (for the 8 stack slots it tries to show).

Shenandoah uses os::print_location once, but for non-Java heap objects so nothing changes.

Manual testing on Linux-x64 and Windows: old behaviour shows these two lines only:

"Executing find"
0x00000000ff0a03e0 is an oop: jdk.internal.loader.ClassLoaders$AppClassLoader
{0x00000000ff0a03e0} - klass: 'jdk/internal/loader/ClassLoaders$AppClassLoader'

...then with the change the full info:

"Executing find"
0x00000000ff0a03e0 is an oop: jdk.internal.loader.ClassLoaders$AppClassLoader
{0x00000000ff0a03e0} - klass: 'jdk/internal/loader/ClassLoaders$AppClassLoader'

• ---- fields (total size 13 words):
• private 'defaultAssertionStatus' 'Z' @12 false
• private final 'parent' 'Ljava/lang/ClassLoader;' @24 a 'jdk/internal/loader/ClassLoaders$PlatformClassLoader'{0x00000000ff0a0a
  40} (ff0a0a40)
• private final 'name' 'Ljava/lang/String;' @28 "app"{0x00000000ff0d0060} (ff0d0060)
• private final 'unnamedModule' 'Ljava/lang/Module;' @32 a 'java/lang/Module'{0x00000000ff0a0448} (ff0a044)
  ...etc...

---

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Issue

• JDK-8266967: debug.cpp utility find() should print Java Object fields.

Reviewers

• Serguei Spitsyn (@sspitsyn - Reviewer) ⚠️ Review applies to f645429
• Coleen Phillimore (@coleenp - Reviewer) ⚠️ Review applies to f645429

Reviewing

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[bridgekeeper]

👋 Welcome back kevinw! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

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[mlbridge]

Webrevs

• 02: Full - Incremental (a1170727)
• 01: Full - Incremental (f6454294)
• 00: Full (10005d11)

[kevinjwalls]

Oops the #ifndef PRODUCT move in instanceKlass.hpp made more than just the oop printers visible, moving it to line 1270, above print_dependent_nmethods.

[kevinjwalls]

/label serviceability

[openjdk]

@kevinjwalls
The serviceability label was successfully added.

[sspitsyn]

Hi Kevin,
The fix looks okay to me.
Thanks,
Serguei

[openjdk]

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

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8266967: debug.cpp utility find() should print Java Object fields.

Reviewed-by: sspitsyn, coleenp

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[coleenp]

This looks good!

[kevinjwalls]

Thanks Serguei and Coleen!

[kevinjwalls]

/integrate

[openjdk]

@kevinjwalls Since your change was applied there has been 1 commit pushed to the master branch:

• c7c77fd: 8255557: Decouple GCM from CipherCore

Your commit was automatically rebased without conflicts.

Pushed as commit 5e557d8.

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