[llvm] [RISCV] Port Gather/Scatter Lowering to NewPM (PR #215669)

[Aiden Grossman via llvm-commits]

================
@@ -0,0 +1,40 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file declares the RISC-V gather/scatter lowering passes.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_RISCV_RISCVGATHERSCATTERLOWERING_H
----------------
boomanaiden154 wrote:

Do we want separate headers for the passes?

I know AMDGPU did this, but I haven't been doing it for other targets, and I think it probably makes more sense to keep all the headers in `RISCV.h`. That's what I've done for MSP430/Lanai/BPF/WebAssembly/X86/AArch64, and NVPTX is doing the same. AMDGPU should probably be cleaned up.

https://github.com/llvm/llvm-project/pull/215669