[llvm] [SYCL][LLVM] Adding property set I/O library for SYCL (PR #110771)

[Arvind Sudarsanam via llvm-commits]

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+//==-- PropertySetIO.h -- models a sequence of property sets and their I/O -==//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+// Models a sequence of property sets and their input and output operations.
+// TODO use Yaml as I/O engine.
+// PropertyValue set format:
+//   '['<PropertyValue set name>']'
+//   <property name>=<property type>'|'<property value>
+//   <property name>=<property type>'|'<property value>
+//   ...
+//   '['<PropertyValue set name>']'
+//   <property name>=<property type>'|'<property value>
+// where
+//   <PropertyValue set name>, <property name> are strings
+//   <property type> - string representation of the property type
+//   <property value> - string representation of the property value.
+//
+// For example:
+// [Staff/Ages]
+// person1=1|20
+// person2=1|25
+// [Staff/Experience]
+// person1=1|1
+// person2=1|2
+// person3=1|12
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_PROPERTYSETIO_H
+#define LLVM_SUPPORT_PROPERTYSETIO_H
+
+#include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/xxhash.h"
+#include <variant>
+
+namespace llvm {
+namespace util {
+
+// Represents a property value. PropertyValue name is stored in the encompassing
+// container.
+class PropertyValue {
+public:
+  // Type of the size of the value. Value size gets serialized along with the
+  // value data in some cases for later reading at runtime, so size_t is not
+  // suitable as its size varies.
+  using SizeTy = uint64_t;
+  using byte = std::byte;
+
+  // Defines supported property types
+  enum Type { first = 0, NONE = first, UINT32, BYTE_ARRAY, last = BYTE_ARRAY };
+
+  // Translates C++ type to the corresponding type tag.
+  template <typename T> static Type getTypeTag();
+
+  // Casts from int value to a type tag.
+  static Expected<Type> getTypeTag(int T) {
+    if (T < first || T > last)
+      return createStringError(std::error_code(), "bad property type ", T);
+    return static_cast<Type>(T);
+  }
+
+  ~PropertyValue() {
+    if (std::holds_alternative<byte *>(Val)) {
+      byte *ByteArrayVal = std::get<byte *>(Val);
+      delete ByteArrayVal;
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asudarsa wrote:

We have used unique_ptr inside the 'read' routine. That's the only place where we allocate memory for 'Val'. So, by transferring the ownership back to caller from 'read' routine, the caller now has full ownership of the memory allocated to 'Val'.
Hope that's agreeable.
Thanks

https://github.com/llvm/llvm-project/pull/110771