[all-commits] [llvm/llvm-project] 72f1fb: [ARM] Combines for VMOVN

[David Green via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 72f1fb2edf596e6030f6b55439c732631edb4e91
      https://github.com/llvm/llvm-project/commit/72f1fb2edf596e6030f6b55439c732631edb4e91
  Author: David Green <david.green at arm.com>
  Date:   2020-05-16 (Sat, 16 May 2020)

  Changed paths:
    M llvm/lib/Target/ARM/ARMISelLowering.cpp
    M llvm/test/CodeGen/Thumb2/mve-satmul-loops.ll
    M llvm/test/CodeGen/Thumb2/mve-vqmovn-combine.ll

  Log Message:
  -----------
  [ARM] Combines for VMOVN

This adds two combines for VMOVN, one to fold
VMOVN[tb](c, VQMOVNb(a, b)) => VQMOVN[tb](c, b)
The other to perform demand bits analysis on the lanes of a VMOVN. We
know that only the bottom lanes of the second operand and the top or
bottom lanes of the Qd operand are needed in the result, depending on if
the VMOVN is bottom or top.

Differential Revision: https://reviews.llvm.org/D77718