RFR: 8373615: Improve HotSpot debug functions findclass() and findmethod

[Ashutosh Mehra]

On Fri, 12 Dec 2025 16:40:24 GMT, Ioi Lam <iklam at openjdk.org> wrote:

> I used the `findclass` and `findmethod` functions in debug.cpp  a lot when debugging problems with class metadata.
> 
> https://github.com/openjdk/jdk/blob/6ec36d348b1eaeedb993a905e42650242fac0918/src/hotspot/share/utilities/debug.cpp#L583-L603 
> 
> This REF improves these functions by:
> 
> - Sorting the names of classes and methods
> - Allow "." to be used in class names. So both `findclass("java.lang.Object")` and `findclass("java/lang/Object")` would work
> - Print the C++/Java objects that represent classes and methods.

src/hotspot/share/classfile/classPrinter.cpp line 96:

> 94:       return;
> 95:     }
> 96:     _klasses.append(InstanceKlass::cast(k));

It doesn't really matter much as these are for debugging, but it would be more efficient if filtering based on `_class_name_pattern` is done here before adding the class to the array.

src/hotspot/share/classfile/classPrinter.cpp line 164:

> 162:         oop mirror = ik->java_mirror();
> 163:         if (mirror != nullptr) {
> 164:         _st->print("\nJava mirror oop for %s: ", ik->name()->as_C_string());

Indentation is off

src/hotspot/share/classfile/classPrinter.hpp line 56:

> 54:     PRINT_METHOD_HANDLE     = 1 << 4, // extra information for invokehandle
> 55:     PRINT_CLASS_DETAILS     = 1 << 5, // print details of the C++ and Java objects that represent classes
> 56:     PRINT_METHOD_DETAILS    = 1 << 6, // print details of the C++ that represent methods

Suggestion:

    PRINT_METHOD_DETAILS    = 1 << 6, // print details of the C++ objects that represent methods

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/28796#discussion_r2615512327
PR Review Comment: https://git.openjdk.org/jdk/pull/28796#discussion_r2615512117
PR Review Comment: https://git.openjdk.org/jdk/pull/28796#discussion_r2615512521