[all-commits] [llvm/llvm-project] 6e198a: [SelectionDAG] Prevent warnings when extracting fi...

[paulwalker-arm via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 6e198aae1d65906535aca3f5b4efbfe5b5cfa92c
      https://github.com/llvm/llvm-project/commit/6e198aae1d65906535aca3f5b4efbfe5b5cfa92c
  Author: Paul Walker <paul.walker at arm.com>
  Date:   2020-07-14 (Tue, 14 Jul 2020)

  Changed paths:
    M llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
    M llvm/test/CodeGen/AArch64/sve-fixed-length-subvector.ll

  Log Message:
  -----------
  [SelectionDAG] Prevent warnings when extracting fixed length vector from scalable.

ComputeNumSignBits and computeKnownBits both trigger "Scalable flag
may be dropped" warnings when a fixed length vector is extracted
from a scalable vector.  This patch assumes nothing about the
demanded elements thus matching the behaviour when extracting a
scalable vector from a scalable vector.

Differential Revision: https://reviews.llvm.org/D83642