[llvm] [StaticDataLayout][PGO] Add profile format for static data layout, and the classes to operate on the profiles. (PR #138170)

[Mingming Liu via llvm-commits]

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@@ -0,0 +1,167 @@
+//===- DataAccessProf.h - Data access profile format support ---------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support to construct and use data access profiles.
+//
+// For the original RFC of this pass please see
+// https://discourse.llvm.org/t/rfc-profile-guided-static-data-partitioning/83744
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_PROFILEDATA_DATAACCESSPROF_H_
+#define LLVM_PROFILEDATA_DATAACCESSPROF_H_
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DenseMapInfoVariant.h"
+#include "llvm/ADT/MapVector.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ProfileData/InstrProf.h"
+#include "llvm/Support/Allocator.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/StringSaver.h"
+
+#include <cstdint>
+#include <variant>
+
+namespace llvm {
+
+namespace data_access_prof {
+// The location of data in the source code.
+struct DataLocation {
+  // The filename where the data is located.
+  StringRef FileName;
+  // The line number in the source code.
+  uint32_t Line;
+};
+
+// The data access profiles for a symbol.
+struct DataAccessProfRecord {
+  DataAccessProfRecord(uint64_t SymbolID, uint64_t AccessCount,
+                       bool IsStringLiteral)
+      : SymbolID(SymbolID), AccessCount(AccessCount),
+        IsStringLiteral(IsStringLiteral) {}
+
+  // Represents a data symbol. The semantic comes in two forms: a symbol index
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mingmingl-llvm wrote:

> I understood that, but my question was more about why in practice some would be string literals and some would be hashes.

This makes sense. Added comment at L55 to explain why two forms are used.

https://github.com/llvm/llvm-project/pull/138170