[llvm] [LV] Add initial support for vectorizing literal struct return values (PR #109833)

[Benjamin Maxwell via llvm-commits]

================
@@ -0,0 +1,53 @@
+//===----------- VectorUtils.h -  Vector type utility functions -*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/DerivedTypes.h"
+
+namespace llvm {
+
+/// A helper function for converting Scalar types to vector types. If
+/// the incoming type is void, we return void. If the EC represents a
+/// scalar, we return the scalar type.
+inline Type *ToVectorTy(Type *Scalar, ElementCount EC) {
+  if (Scalar->isVoidTy() || Scalar->isMetadataTy() || EC.isScalar())
+    return Scalar;
+  return VectorType::get(Scalar, EC);
+}
+
+inline Type *ToVectorTy(Type *Scalar, unsigned VF) {
+  return ToVectorTy(Scalar, ElementCount::getFixed(VF));
+}
+
+/// A helper for converting to wider (vector) types. For scalar types, this is
+/// equivalent to calling `ToVectorTy`. For struct types, this returns a new
+/// struct where each element type has been widened to a vector type. Note: Only
+/// unpacked literal struct types are supported.
+Type *ToWideTy(Type *Ty, ElementCount EC);
+
+/// A helper for converting wide types to narrow (non-vector) types. For vector
+/// types, this is equivalent to calling .getScalarType(). For struct types,
+/// this returns a new struct where each element type has been converted to a
+/// scalar type. Note: Only unpacked literal struct types are supported.
+Type *ToNarrowTy(Type *Ty);
----------------
MacDue wrote:

Similar comments to above, the input type here can be a `VectorType` or a wide `StructType`. So, "narrow" means the result type is either a scalar or a struct literal of scalars.

https://github.com/llvm/llvm-project/pull/109833