[llvm] [BOLT][DWARF] Add support for .debug_names (PR #81062)

[Maksim Panchenko via llvm-commits]

================
@@ -0,0 +1,173 @@
+//===- bolt/Core/DebugNames.h - Debug names 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 declaration of classes required for generation of
+// .debug_names section.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef BOLT_CORE_DEBUG_NAMES_H
+#define BOLT_CORE_DEBUG_NAMES_H
+
+#include "DebugData.h"
+#include "llvm/CodeGen/AccelTable.h"
+
+namespace llvm {
+namespace bolt {
+class BOLTDWARF5AccelTableData : public DWARF5AccelTableData {
+public:
+  BOLTDWARF5AccelTableData(const uint64_t DieOffset,
+                           const std::optional<uint64_t> DefiningParentOffset,
+                           const unsigned DieTag, const unsigned UnitID,
+                           const bool IsTU,
+                           const std::optional<unsigned> SecondUnitID)
+      : DWARF5AccelTableData(DieOffset, DefiningParentOffset, DieTag, UnitID,
+                             IsTU),
+        SecondUnitID(SecondUnitID) {}
+
+  uint64_t getDieOffset() const { return DWARF5AccelTableData::getDieOffset(); }
+  unsigned getDieTag() const { return DWARF5AccelTableData::getDieTag(); }
+  unsigned getUnitID() const { return DWARF5AccelTableData::getUnitID(); }
+  bool isTU() const { return DWARF5AccelTableData::isTU(); }
+  std::optional<unsigned> getSecondUnitID() const { return SecondUnitID; }
+
+private:
+  std::optional<unsigned> SecondUnitID;
+};
+
+class DWARF5AcceleratorTable {
+public:
+  DWARF5AcceleratorTable(const bool CreateDebugNames, BinaryContext &BC,
+                         DebugStrWriter &MainBinaryStrWriter);
+  ~DWARF5AcceleratorTable() {
+    for (DebugNamesAbbrev *Abbrev : AbbreviationsVector)
+      Abbrev->~DebugNamesAbbrev();
+  }
+  /// Add DWARF5 Accelerator table entry.
+  /// Input is DWARFUnit being processed, DIE that belongs to it, and potential
+  /// SkeletonCU if the Unit comes from a DWO section.
+  void addAccelTableEntry(DWARFUnit &Unit, const DIE &Die,
+                          const std::optional<uint64_t> &DWOID);
+  /// Set current unit being processed.
+  void setCurrentUnit(DWARFUnit &Unit, const uint64_t UnitStartOffset);
+  /// Emit Accelerator table.
+  void emitAccelTable();
+  /// Returns true if the table was crated.
+  bool isCreated() const { return NeedToCreate; }
+  /// Returns buffer containing the accelerator table.
+  std::unique_ptr<DebugBufferVector> releaseBuffer() {
+    return std::move(FullTableBuffer);
+  }
+
+private:
+  BinaryContext &BC;
+  bool NeedToCreate = false;
+  BumpPtrAllocator Allocator;
+  DebugStrWriter &MainBinaryStrWriter;
+  StringRef StrSection;
+  uint64_t CurrentUnitOffset = 0;
+  const DWARFUnit *CurrentUnit = nullptr;
+  std::unordered_map<uint32_t, uint32_t> AbbrevTagToIndexMap;
+
+  /// Represents a group of entries with identical name (and hence, hash value).
+  struct HashData {
+    uint64_t StrOffset;
+    uint32_t HashValue;
+    uint32_t EntryOffset;
+    std::vector<BOLTDWARF5AccelTableData *> Values;
+  };
+  using HashList = std::vector<HashData *>;
+  using BucketList = std::vector<HashList>;
+  /// Contains all the offsets of CUs.
+  SmallVector<uint32_t, 1> CUList;
+  /// Contains all the offsets of local TUs.
+  SmallVector<uint32_t, 1> LocalTUList;
+  /// Contains all the type hashes for split dwarf TUs.
+  SmallVector<uint64_t, 1> ForeignTUList;
+  using StringEntries =
+      MapVector<std::string, HashData, llvm::StringMap<unsigned>>;
+  StringEntries Entries;
+  /// FoldingSet that uniques the abbreviations.
+  FoldingSet<DebugNamesAbbrev> AbbreviationsSet;
+  /// Vector containing DebugNames abbreviations for iteration in order.
+  SmallVector<DebugNamesAbbrev *, 5> AbbreviationsVector;
+  /// The bump allocator to use when creating DIEAbbrev objects in the uniqued
+  /// storage container.
+  BumpPtrAllocator Alloc;
+  uint32_t BucketCount = 0;
+  uint32_t UniqueHashCount = 0;
+  uint32_t AbbrevTableSize = 0;
+  uint32_t CUIndexEncodingSize = 4;
+  uint32_t TUIndexEncodingSize = 4;
+  uint32_t AugmentationStringSize = 0;
+  dwarf::Form CUIndexForm = dwarf::DW_FORM_data4;
+  dwarf::Form TUIndexForm = dwarf::DW_FORM_data4;
+
+  BucketList Buckets;
+
+  std::unique_ptr<DebugBufferVector> FullTableBuffer;
+  std::unique_ptr<raw_svector_ostream> FullTableStream;
+  std::unique_ptr<DebugBufferVector> StrBuffer;
+  std::unique_ptr<raw_svector_ostream> StrStream;
+  std::unique_ptr<DebugBufferVector> EntriesBuffer;
+  std::unique_ptr<raw_svector_ostream> Entriestream;
+  std::unique_ptr<DebugBufferVector> AugStringBuffer;
+  std::unique_ptr<raw_svector_ostream> AugStringtream;
+  llvm::DenseMap<llvm::hash_code, uint64_t> StrCacheToOffsetMap;
+  // Contains DWO ID to CUList Index.
+  llvm::DenseMap<uint64_t, uint32_t> CUOffsetsToPatch;
+  /// Adds Unit to either CUList, LocalTUList or ForeignTUList.
+  /// Input Unit being processed, and DWO ID if Unit is being processed comes
+  /// from a DWO section.
+  void addUnit(DWARFUnit &Unit, const std::optional<uint64_t> &DWOID);
+  /// Returns number of buckets in .debug_name table.
+  ArrayRef<HashList> getBuckets() const { return Buckets; }
+  /// Get encoding for a given attribute.
+  std::optional<DWARF5AccelTable::UnitIndexAndEncoding>
+  getIndexForEntry(const BOLTDWARF5AccelTableData &Value) const;
+  /// Get encoding for a given attribute for second index.
+  /// Returns nullopt if there is no second index.
+  std::optional<DWARF5AccelTable::UnitIndexAndEncoding>
+  getSecondIndexForEntry(const BOLTDWARF5AccelTableData &Value) const;
+  /// Uniquify Entries.
+  void finalize();
+  /// Computes bucket count.
+  void computeBucketCount();
+  /// Populate Abbreviations Map.
+  void populateAbbrevsMap();
+  /// Write Entries.
+  void writeEntries();
+  /// Write an Entry;
----------------
maksfb wrote:

s/;/./

https://github.com/llvm/llvm-project/pull/81062