[llvm-branch-commits] [RISCV] Enable ShouldTrackLaneMasks when having vector instructions (PR #115843)

[Philip Reames via llvm-branch-commits]

preames wrote:

> Ping.

I went and dug through the diffs in the tests.  I see no obvious evidence of performance improvement, and a couple of regressions (see vector_interleave_nxv16f64_nxv8f64).  I don't think this patch should move forward unless we have a justification for why we think this is a net performance win.  The easiest way to make said argument is to share measurements from some benchmark set (e.g. spec) on some vector hardware (e.g. bp3).  

I'll note that from a conceptual standpoint this patch does seem to make sense.  My worry (triggered by the regression noted above) is that this may be exposing some other issue and that we need to unwind things a bit before this can land.  

https://github.com/llvm/llvm-project/pull/115843