[all-commits] [llvm/llvm-project] 44b865: [AMDGPU] Allow narrowing muti-dword loads

[Stanislav Mekhanoshin via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 44b865fa7fea8243126c489df6604ae7ecee072a
      https://github.com/llvm/llvm-project/commit/44b865fa7fea8243126c489df6604ae7ecee072a
  Author: Stanislav Mekhanoshin <Stanislav.Mekhanoshin at amd.com>
  Date:   2020-01-24 (Fri, 24 Jan 2020)

  Changed paths:
    M llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
    M llvm/test/CodeGen/AMDGPU/vector_shuffle.packed.ll

  Log Message:
  -----------
  [AMDGPU] Allow narrowing muti-dword loads

Currently BE allows only a little load narrowing because
of the fear it will produce sub-dword ext loads. However,
we can always allow narrowing if we are shrinking one
multi-dword load to another multi-dword load.

In particular we were unable to reduce s_load_dwordx8 into
s_load_dwordx4 if identity shuffle was used to extract
low 4 dwords.

Differential Revision: https://reviews.llvm.org/D73133