[llvm] [NVPTX] Add NVPTXIncreaseAligmentPass to improve vectorization (PR #144958)

[Alex MacLean via llvm-commits]

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@@ -0,0 +1,131 @@
+//===-- NVPTXIncreaseAlignment.cpp - Increase alignment for local arrays --===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// A simple pass that looks at local memory arrays that are statically
+// sized and sets an appropriate alignment for them. This enables vectorization
+// of loads/stores to these arrays if not explicitly specified by the client.
+//
+// TODO: Ideally we should do a bin-packing of local arrays to maximize
+// alignments while minimizing holes.
+//
+//===----------------------------------------------------------------------===//
+
+#include "NVPTX.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/MathExtras.h"
+
+using namespace llvm;
+
+static cl::opt<bool>
+    MaxLocalArrayAlignment("nvptx-use-max-local-array-alignment",
+                           cl::init(false), cl::Hidden,
+                           cl::desc("Use maximum alignment for local memory"));
+
+static constexpr Align MaxPTXArrayAlignment = Align::Constant<16>();
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AlexMaclean wrote:

Yup. While it won't get us much I agree it is better to reduce the number of places we define constants like this. 

https://github.com/llvm/llvm-project/pull/144958