On Mon, 15 Dec 2025 06:52:22 GMT, Eric Fang <[email protected]> wrote:

>> src/hotspot/share/opto/vectornode.cpp line 1063:
>> 
>>> 1061:       break;
>>> 1062:     }
>>> 1063:     assert(n->as_Vector()->length() == in1->as_Vector()->length(), 
>>> "vector length must match");
>> 
>> While assertions are good to add, but mask cast is a lanewise operation, 
>> i.e. length compatibility is implied, and adding an assertion for IR 
>> invariants is redundant.
>
> My main concern here is that the requirement for `VectorMaskCastNode` to have 
> the same length for both input and output might have been removed in the 
> future. I'm not sure, but we do require the lengths to be the same here, so I 
> added this assertion. @eme64  has a similar comment; see 
> https://github.com/openjdk/jdk/pull/28313/changes#r2614577536. So, if you all 
> think that the requirement for lane length in `VectorMaskCastNode` won't be 
> removed, then we can delete this assertion and the condition below.

I think assertion here is redundant.

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

PR Review Comment: https://git.openjdk.org/jdk/pull/28313#discussion_r2618311660

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