[PATCH] D130146: [RISCV] Add isel pattern for (mul (and X, 0xffffffff), 3<<C) with Zba.

[Philip Reames via Phabricator via llvm-commits]

reames added a comment.

Went and glanced at surrounding code again, a couple of thoughts for follow up.

There's a whole bunch of mul by constant patterns.  It'd be really nice to sink the shift before those for e.g. 11 << 2 and variants.

Not sure how to write this, but the general form of this would be something like:
if (is interesting constant after shifting and not before) {

  emit shift
  match shifted constant pattern

}

Not sure how worthwhile this is, just thinking about generality of code structure.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D130146/new/

https://reviews.llvm.org/D130146