[llvm] yaml2obj: Implement Coverage mapping format (PR #129472)

[Jessica Paquette via llvm-commits]

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+//===- CovMap.h - ObjectYAML Interface for coverage map ---------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// - llvm::coverage::yaml
+//
+//   Describes binary file formats and YAML structures of coverage map.
+//
+// - llvm::yaml
+//
+//   Attachments for YAMLTraits.
+//
+// - llvm::covmap
+//
+//   Provides YAML encoder for coverage map.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_OBJECTYAML_COVMAP_H
+#define LLVM_OBJECTYAML_COVMAP_H
+
+#include "llvm/ADT/StringRef.h"
+#include "llvm/ObjectYAML/ELFYAML.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/YAMLTraits.h"
+#include <array>
+#include <cstdint>
+#include <memory>
+#include <optional>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace llvm {
+class raw_ostream;
+} // namespace llvm
+
+namespace llvm::coverage::yaml {
+
+/// Base Counter, corresponding to coverage::Counter.
+struct CounterTy {
+  enum TagTy : uint8_t {
+    Zero = 0,
+    Ref,
+    Sub,
+    Add,
+  };
+
+  TagTy Tag;
+  uint64_t Val;
+
+  virtual ~CounterTy() {}
+
+  virtual void mapping(llvm::yaml::IO &IO);
+
+  void encode(raw_ostream &OS) const;
+};
+
+/// Holds a pair of both hands but doesn't hold ops(add or sub).
+/// Ops is stored in CounterTy::Tag.
+using ExpressionTy = std::array<CounterTy, 2>;
+
+/// {True, False}
+using BranchTy = std::array<CounterTy, 2>;
+
+/// {ID, TrueID, FalseID}
+/// Note: This has +1 offset unlike mcdc::ConditionID.
+using MCDCBranchTy = std::array<uint16_t, 3>;
+
+struct DecisionTy {
+  uint64_t BIdx; ///< Bitmap index
+  uint64_t NC;   ///< NumConds
+
+  void mapping(llvm::yaml::IO &IO);
+
+  void encode(raw_ostream &OS) const;
+};
+
+/// {LineStart, ColumnStart, LineEnd, ColumnEnd}
+using LocTy = std::array<uint64_t, 4>;
+
+///
+struct RecTy : CounterTy {
+  enum ExtTagTy : uint8_t {
+    Skip = 2,
+    Branch = 4,
+    Decision = 5,
+    MCDCBranch = 6,
+  };
+
+  /// This is optional in detailed view.
+  std::optional<ExtTagTy> ExtTag;
+
+  // Options for extensions.
+  std::optional<uint64_t> Expansion; ///< Doesn't have ExtTag.
+  std::optional<BranchTy> BranchOpt; ///< Optionally has MCDC.
+  std::optional<MCDCBranchTy> MCDC;
+  std::optional<DecisionTy> DecisionOpt;
+
+  /// True or None.
+  /// Stored in ColumnEnd:31.
+  std::optional<bool> isGap;
+
+  LocTy dLoc; ///< Differential line numbers.
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ornata wrote:

LLVM naming conventions

https://github.com/llvm/llvm-project/pull/129472