[lld] [lld][ELF] Extend profile guided function ordering to ELF binaries (PR #117514)

[Ellis Hoag via llvm-commits]

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@@ -0,0 +1,76 @@
+//===- BPSectionOrdererBase.h ---------------------------------------------===//
+//
+// 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 defines the common interfaces which may be used by
+// BPSectionOrderer.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLD_COMMON_BP_SECTION_ORDERER_BASE_H
+#define LLD_COMMON_BP_SECTION_ORDERER_BASE_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/Support/xxhash.h"
+
+namespace lld {
+
+class BPSymbol {
+
+public:
+  virtual ~BPSymbol() = default;
+  virtual llvm::StringRef getName() const = 0;
+  virtual BPSymbol *asDefinedSymbol() = 0;
+  virtual std::optional<uint64_t> getValue() const = 0;
+  virtual std::optional<uint64_t> getSize() const = 0;
+};
+
+class BPSectionBase {
+public:
+  virtual ~BPSectionBase() = default;
+  virtual llvm::StringRef getName() const = 0;
+  virtual uint64_t getSize() const = 0;
+  virtual bool hasValidData() const = 0;
+  virtual bool isCodeSection() const = 0;
+  virtual llvm::ArrayRef<uint8_t> getSectionData() const = 0;
+  virtual llvm::ArrayRef<std::unique_ptr<BPSymbol>> getSymbols() const = 0;
+  virtual void
+  getSectionHash(llvm::SmallVectorImpl<uint64_t> &hashes) const = 0;
+  virtual bool needResolveLinkageName(llvm::StringRef &name) const = 0;
+  static llvm::StringRef getRootSymbol(llvm::StringRef Name) {
+    auto [P0, S0] = Name.rsplit(".llvm.");
+    auto [P1, S1] = P0.rsplit(".__uniq.");
+    return P1;
+  }
+
+  static uint64_t getRelocHash(llvm::StringRef kind, uint64_t sectionIdx,
+                               uint64_t offset, uint64_t addend) {
+    return llvm::xxHash64((kind + ": " + llvm::Twine::utohexstr(sectionIdx) +
+                           " + " + llvm::Twine::utohexstr(offset) + " + " +
+                           llvm::Twine::utohexstr(addend))
+                              .str());
+  }
+};
+/// Base class for Balanced Partitioning section ordering, providing common
+/// functionality for both ELF and MachO formats. This shared implementation
+/// reduces code duplication while handling function and data reordering.
+class BPSectionOrdererBase {
+public:
+  static llvm::DenseMap<const BPSectionBase *, size_t>
+  reorderSectionsByBalancedPartitioning(
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ellishg wrote:

It seems weird to have a class with a single static function. Can we move this to `BPSectionBase`?

https://github.com/llvm/llvm-project/pull/117514