RFR: 8353175: Eliminate double iteration of stream in FieldDescriptor reinitialization [v6]

[Radim Vansa]

On Thu, 10 Apr 2025 08:38:35 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Radim Vansa has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Remove outdated comment
>
> src/hotspot/share/oops/instanceKlass.cpp line 1945:
> 
>> 1943:     fields_sorted.sort(compare_fields_by_offset);
>> 1944:     fieldDescriptor fd;
>> 1945:     for (auto it = fields_sorted.begin(); it != fields_sorted.end(); ++it) {
> 
> Ah, that's not what I meant :) There is no need to use iterators here, just pull `length` out of `fields_stored.length()`, and use the same old indexed loop:
> 
> 
>  int length = fields_stored.length();
>  if (length > 0) {
>     fields_sorted.sort(compare_fields_by_offset);
>     for (int i = 0; i < length; i++) {
>       ...

I know you haven't asked specifically for iterators, but to me this seems 'the' cleaner way, rather than plain old indexed loop. Or do you have doubts about this being inlined to effectively the same code?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24290#discussion_r2037152642