On Fri, 18 Oct 2024 05:42:21 GMT, Jatin Bhateja <jbhat...@openjdk.org> wrote:
>>> The issue is that a node is not immutable. >> >> I don't see any issues with mutability here. >> `MulVLNode::_mult_lower_double_word` is constant, so you have to allocate >> new node if you want to change its value. (And that's exactly what >> `MulVLNode::Ideal()` does.) But I agree with you that a dedicated ideal >> node type (e.g., `MulVI2L`) is much cleaner than >> `MulVLNode::_mult_lower_double_word`. Still, I'd prefer to see the logic >> confined in matcher-related code instead. > > Hi @iwanowww , @merykitty , I am in process of addressing all your concerns. > > I still feel idealization is the right place to execute this pattern > detection, we just need to re-wire the effective inputs bypassing doubleword > clearing logic to newly annotated MulVL node and allow clearing IR to > sweepout during successive passes, moving it to final graph reshaping just > before instruction selection will prevent dead IR cleanups. @jatin-bhateja I think you can do it at the same place as `Compile::optimize_logic_cones`, we do perform IGVN there. Unless you think this information is needed early in the compiling process, currently I see it is used during matching only, which makes it unnecessary to repeatedly checking it in `Node::Ideal` ------------- PR Comment: https://git.openjdk.org/jdk/pull/21244#issuecomment-2421519087
