RFR: 8369448: C2 SuperWord: refactor VTransform to do move_unordered_reduction_out_of_loop during VTransform::optimize [v2]

[Christian Hagedorn]

On Mon, 13 Oct 2025 08:45:30 GMT, Christian Hagedorn <chagedorn at openjdk.org> wrote:

>> Emanuel Peter has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   For Vladimir K7
>
> src/hotspot/share/opto/vtransform.cpp line 46:
> 
>> 44:   TRACE_OPTIMIZE( tty->print_cr("\nVTransformGraph::optimize"); )
>> 45: 
>> 46:   while (true) {
> 
> Could we also just do `while (progress)`? You always seem to check `!progress` at the very end of the loop.

If there is a bug and we keep setting `progress` to true, we might loop endlessly. Is there another always true upper-bound condition? We could additionally add an assert for catching issues when we bail out.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/27704#discussion_r2425601345