[PATCH] D108355: [AggressiveInstCombine] Add arithmetic shift right instr to `TruncInstCombine` DAG

[Anton Afanasyev via Phabricator via llvm-commits]

anton-afanasyev added a comment.

In D108355#2954130 <https://reviews.llvm.org/D108355#2954130>, @lebedev.ri wrote:

> I'm pretty sure we should count the number of sign bits here, much like how we count the number of leading zeros:
> https://godbolt.org/z/vGsf664Gf => https://alive2.llvm.org/ce/z/gIc43E

Ok, I've extended both `lshr` and `ashr` to use `countMinSignBits()`, unifying both cases, but we have to `computeKnownBits()` one more time here.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D108355/new/

https://reviews.llvm.org/D108355