[CodeGen] Model machine debug metadata

Replace marker-based metadata operands with scoped references and inline DIExpression values. Add structured DILocation chains, instruction debug attachments, stack variable records, and entry values with unified verification, builder support, and deterministic cloning.

1 files changed, 154 insertions, 0 deletions

diff --git a/backend/include/rcc/CodeGen/MachineDebugInfo.h b/backend/include/rcc/CodeGen/MachineDebugInfo.h
new file mode 100644
index 0000000..0d95e96
--- /dev/null
+++ b/backend/include/rcc/CodeGen/MachineDebugInfo.h
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_CODEGEN_MACHINEDEBUGINFO_H
+#define RCC_CODEGEN_MACHINEDEBUGINFO_H
+
+#include "rcc/CodeGen/MachineMetadata.h"
+#include "rcc/Support/Error.h"
+
+#include <cstdint>
+#include <optional>
+#include <span>
+#include <utility>
+#include <variant>
+#include <vector>
+
+namespace rcc {
+
+class MachineDIExpression final {
+public:
+  MachineDIExpression() = default;
+  explicit MachineDIExpression(std::vector<std::uint64_t> Elements)
+      : Elements(std::move(Elements)) {}
+
+  [[nodiscard]] std::span<const std::uint64_t> elements() const noexcept {
+    return Elements;
+  }
+
+  friend bool operator==(const MachineDIExpression &Left,
+                         const MachineDIExpression &Right) = default;
+
+private:
+  std::vector<std::uint64_t> Elements;
+};
+
+class MachineMetadataValue final {
+public:
+  MachineMetadataValue() = default;
+
+  [[nodiscard]] static Expected<MachineMetadataValue> reference(MachineMetadataReference Reference);
+  [[nodiscard]] static MachineMetadataValue expression(MachineDIExpression Expression);
+
+  [[nodiscard]] bool isValid() const noexcept {
+    return !std::holds_alternative<std::monostate>(Storage);
+  }
+
+  [[nodiscard]] const MachineMetadataReference *reference() const noexcept {
+    return std::get_if<MachineMetadataReference>(&Storage);
+  }
+
+  [[nodiscard]] const MachineDIExpression *expression() const noexcept {
+    return std::get_if<MachineDIExpression>(&Storage);
+  }
+
+  [[nodiscard]] Expected<void> verify(const MachineMetadataInfo &Metadata) const;
+
+  friend bool operator==(const MachineMetadataValue &Left,
+                         const MachineMetadataValue &Right) = default;
+
+private:
+  explicit MachineMetadataValue(MachineMetadataReference Reference) : Storage(Reference) {}
+  explicit MachineMetadataValue(MachineDIExpression Expression) : Storage(std::move(Expression)) {}
+
+  std::variant<std::monostate, MachineMetadataReference, MachineDIExpression> Storage;
+};
+
+struct MachineDILocationFrame final {
+  std::uint32_t Line = 0;
+  std::uint16_t Column = 0;
+  MachineMetadataReference Scope;
+  bool IsImplicitCode = false;
+  std::uint64_t AtomGroup = 0;
+  std::uint8_t AtomRank = 0;
+
+  friend constexpr bool operator==(MachineDILocationFrame Left,
+                                   MachineDILocationFrame Right) noexcept = default;
+};
+
+class MachineDILocation final {
+public:
+  static constexpr std::uint64_t MaxAtomGroup = (std::uint64_t{1} << 61) - 1;
+
+  [[nodiscard]] static Expected<MachineDILocation>
+  create(std::vector<MachineDILocationFrame> InlineChain,
+         std::optional<MachineMetadataReference> TerminalInlinedAt = std::nullopt);
+
+  [[nodiscard]] std::span<const MachineDILocationFrame> inlineChain() const noexcept {
+    return InlineChain;
+  }
+
+  [[nodiscard]] std::optional<MachineMetadataReference> terminalInlinedAt() const noexcept {
+    return TerminalInlinedAt;
+  }
+
+  [[nodiscard]] Expected<void> verify(const MachineMetadataInfo &Metadata) const;
+
+  friend bool operator==(const MachineDILocation &Left, const MachineDILocation &Right) = default;
+
+private:
+  MachineDILocation(std::vector<MachineDILocationFrame> InlineChain,
+                    std::optional<MachineMetadataReference> TerminalInlinedAt)
+      : InlineChain(std::move(InlineChain)), TerminalInlinedAt(TerminalInlinedAt) {}
+
+  [[nodiscard]] Expected<void> verifyStructure() const;
+
+  std::vector<MachineDILocationFrame> InlineChain;
+  std::optional<MachineMetadataReference> TerminalInlinedAt;
+};
+
+class MachineDebugLocation final {
+public:
+  MachineDebugLocation() = default;
+
+  [[nodiscard]] static Expected<MachineDebugLocation> reference(MachineMetadataReference Reference);
+  [[nodiscard]] static MachineDebugLocation inlineLocation(MachineDILocation Location);
+
+  [[nodiscard]] bool isValid() const noexcept {
+    return !std::holds_alternative<std::monostate>(Storage);
+  }
+
+  [[nodiscard]] const MachineMetadataReference *reference() const noexcept {
+    return std::get_if<MachineMetadataReference>(&Storage);
+  }
+
+  [[nodiscard]] const MachineDILocation *inlineLocation() const noexcept {
+    return std::get_if<MachineDILocation>(&Storage);
+  }
+
+  [[nodiscard]] Expected<void> verify(const MachineMetadataInfo &Metadata) const;
+
+  friend bool operator==(const MachineDebugLocation &Left,
+                         const MachineDebugLocation &Right) = default;
+
+private:
+  explicit MachineDebugLocation(MachineMetadataReference Reference) : Storage(Reference) {}
+  explicit MachineDebugLocation(MachineDILocation Location) : Storage(std::move(Location)) {}
+
+  std::variant<std::monostate, MachineMetadataReference, MachineDILocation> Storage;
+};
+
+struct MachineVariableDebugInfo final {
+  std::optional<MachineMetadataReference> Variable;
+  std::optional<MachineMetadataValue> Expression;
+  std::optional<MachineDebugLocation> Location;
+
+  [[nodiscard]] Expected<void> verifyStructure() const;
+  [[nodiscard]] Expected<void> verify(const MachineMetadataInfo &Metadata) const;
+
+  friend bool operator==(const MachineVariableDebugInfo &Left,
+                         const MachineVariableDebugInfo &Right) = default;
+};
+
+} // namespace rcc
+
+#endif // RCC_CODEGEN_MACHINEDEBUGINFO_H