RFR: 8364588: Export the NPE backtracking functionality to general null-checking APIs [v4]

[David Holmes]

On Tue, 5 Aug 2025 10:16:32 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> src/hotspot/share/interpreter/bytecodeUtils.cpp line 1483:
>> 
>>> 1481:   // Is an explicit slot given?
>>> 1482:   bool explicit_search = slot >= 0;
>>> 1483:   if (explicit_search) {
>> 
>> Suggestion:
>> 
>>   if (slot >= 0) {
>> 
>> No need for the temporary local.
>
> If we don't adopt the enum I suggested, then I do prefer the naming of the condition through a variable. It gives you a hint of what the check is looking for, and not only what the check does.

That is what comments are for.

>> src/java.base/share/classes/java/lang/NullPointerException.java line 78:
>> 
>>> 76:     NullPointerException(int stackOffset, int searchSlot) {
>>> 77:         extendedMessageState = setupCustomBackTrace(stackOffset, searchSlot);
>>> 78:         this();
>> 
>> I thought `this()` had to come first in a constructor? Is this new in 25 or 26?
>
> https://openjdk.org/jeps/492

And now final - https://openjdk.org/jeps/513

Thanks

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PR Review Comment: https://git.openjdk.org/jdk/pull/26600#discussion_r2256053422
PR Review Comment: https://git.openjdk.org/jdk/pull/26600#discussion_r2256047794