On Thu, 23 Feb 2023 10:20:31 GMT, Maurizio Cimadamore <mcimadam...@openjdk.org> wrote:
> > Correct, `extsw` performs a `I2L` conversion. I had thought about this > > already, but I think my current implementation is more efficient as it > > combines register moves with the 64 bit extend. Your proposal would > > generate separate extend and move instructions, right? > > Would it be possible to generate a biding cast + move and the recognize the > pattern in the HS backend and optimize it away as a `extsw` ? At the moment, there is a forced indirection between the Java code and downcall stub, so the JIT can not do any optimizations that have to take both sides into account. The downcall stub is opaque to the JIT. (though, perhaps in the long run we can add intrinsification of `linkToNative` that can generate the code in the downcall stub as part of the JIT's own IR, which would solve this) ------------- PR: https://git.openjdk.org/jdk/pull/12708
