RFR: 8353216: Improve VerifyMethodHandles for method handle linkers [v2]

[Vladimir Ivanov]

On Fri, 28 Mar 2025 23:11:14 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Vladimir Ivanov has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - assert_different_registers on x86
>>  - jcc->jccb
>
> src/hotspot/cpu/x86/methodHandles_x86.cpp line 131:
> 
>> 129:     Label L_ok;
>> 130: 
>> 131:     const Register method_holder = temp;
> 
> `assert_different_registers` missing. Or you don't need it?

Added.

> src/hotspot/cpu/x86/methodHandles_x86.cpp line 139:
> 
>> 137:         // Require compiled LambdaForm class to be fully initialized.
>> 138:         __ cmpb(Address(method_holder, InstanceKlass::init_state_offset()), InstanceKlass::fully_initialized);
>> 139:         __ jccb(Assembler::equal, L_ok);
> 
> Should this also be long jump?

It jumps over the code generated by `MacroAssembler::stop`, so a short jump instruction should be fine here.

I did the opposite: turned the jump for other linkers from `jcc` to `jccb`.

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PR Review Comment: https://git.openjdk.org/jdk/pull/23950#discussion_r2019647257
PR Review Comment: https://git.openjdk.org/jdk/pull/23950#discussion_r2019647780