On Mon, 9 Dec 2024 08:10:20 GMT, Emanuel Peter <epe...@openjdk.org> wrote:
>> Quan Anh Mai has updated the pull request incrementally with one additional >> commit since the last revision: >> >> add comment, extract cast into local variable > > src/hotspot/share/opto/vectornode.hpp line 1696: > >> 1694: // shuffle vector into 1 that we can do byte rearrange such that it >> would provide the same result. >> 1695: // This can be done in VectorRearrangeNode during code emission but we >> eagerly expand out this >> 1696: // because it is often the case that an index vector is reused in many >> rearrange operations. > > Thanks for this explanation! > > `This can be done in VectorRearrangeNode` -> **could have** be done, because > we now don't do it, right? > What do you mean by `expand out this`? Do you mean we have a separate > dedicated node, so that it could possibly fold away with other nodes, such as > index vector? Thanks for the reviews, I have added another comment sentence. Basically, by separating into a dedicated node, the preparation of the index vector can be GVN-ed across multiple rearrange operations as well as hoisted out of loops if the index vector is a loop invariant. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/21042#discussion_r1875985223
