1 files changed, 210 insertions, 0 deletions
diff --git a/backend/include/rcc/CodeGen/TargetFunctionState.h b/backend/include/rcc/CodeGen/TargetFunctionState.h
new file mode 100644
index 0000000..b11c91b
--- /dev/null
+++ b/backend/include/rcc/CodeGen/TargetFunctionState.h
@@ -0,0 +1,210 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef RCC_CODEGEN_TARGETFUNCTIONSTATE_H
+#define RCC_CODEGEN_TARGETFUNCTIONSTATE_H
+
+#include "rcc/CodeGen/MachineIRTypes.h"
+#include "rcc/Support/Error.h"
+
+#include <concepts>
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <optional>
+#include <span>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace rcc {
+
+class MachineFunctionCloneContext;
+
+struct EncodedTargetFunctionState final {
+  TargetFunctionStateTypeID TypeID;
+  std::uint32_t Version = 0;
+  std::vector<std::byte> Payload;
+
+  friend bool operator==(const EncodedTargetFunctionState &Left,
+                         const EncodedTargetFunctionState &Right) = default;
+};
+
+template <typename ValueT>
+concept TargetFunctionStateValue =
+    std::move_constructible<ValueT> &&
+    requires(const ValueT &Value, const ValueT &Other,
+             const MachineFunctionCloneContext &CloneContext, std::uint32_t Version,
+             std::span<const std::byte> Payload) {
+      { ValueT::stableTypeID() } -> std::same_as<TargetFunctionStateTypeID>;
+      { ValueT::schemaVersion() } -> std::same_as<std::uint32_t>;
+      { Value.verify() } -> std::same_as<Expected<void>>;
+      { Value.clone(CloneContext) } -> std::same_as<Expected<ValueT>>;
+      { Value.print() } -> std::same_as<std::string>;
+      { Value.encode() } -> std::same_as<Expected<std::vector<std::byte>>>;
+      { Value == Other } -> std::convertible_to<bool>;
+      { ValueT::decode(Version, Payload) } -> std::same_as<Expected<ValueT>>;
+    };
+
+class TargetFunctionState final {
+public:
+  TargetFunctionState() = default;
+  TargetFunctionState(const TargetFunctionState &) = delete;
+  TargetFunctionState &operator=(const TargetFunctionState &) = delete;
+  TargetFunctionState(TargetFunctionState &&) noexcept;
+  TargetFunctionState &operator=(TargetFunctionState &&) noexcept;
+  ~TargetFunctionState();
+
+  template <TargetFunctionStateValue ValueT>
+  [[nodiscard]] static Expected<TargetFunctionState> create(ValueT Value) {
+    if (ValueT::stableTypeID().value() == 0) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "target function state TypeID must be nonzero");
+    }
+    if (ValueT::schemaVersion() == 0) {
+      return makeUnexpected(ErrorCode::InvalidArgument,
+                            "target function state schema version must be nonzero");
+    }
+    auto Verification = Value.verify();
+    if (!Verification)
+      return std::unexpected(Verification.error());
+
+    std::unique_ptr<Concept> NewStorage = std::make_unique<Model<ValueT>>(std::move(Value));
+    return TargetFunctionState(std::move(NewStorage));
+  }
+
+  template <TargetFunctionStateValue ValueT>
+  [[nodiscard]] static Expected<TargetFunctionState>
+  decode(const EncodedTargetFunctionState &Encoded) {
+    if (Encoded.TypeID != ValueT::stableTypeID()) {
+      return makeUnexpected(
+          ErrorCode::ParseError,
+          "encoded target function state TypeID does not match its target schema");
+    }
+    if (Encoded.Version == 0) {
+      return makeUnexpected(ErrorCode::ParseError, "target function state version must be nonzero");
+    }
+    auto Value = ValueT::decode(Encoded.Version, Encoded.Payload);
+    if (!Value)
+      return std::unexpected(Value.error());
+    return create<ValueT>(std::move(*Value));
+  }
+
+  [[nodiscard]] bool hasValue() const noexcept {
+    return Storage != nullptr;
+  }
+
+  [[nodiscard]] std::optional<TargetFunctionStateTypeID> typeID() const noexcept;
+  [[nodiscard]] std::optional<std::uint32_t> schemaVersion() const noexcept;
+  [[nodiscard]] Expected<void> verify() const;
+  [[nodiscard]] Expected<TargetFunctionState>
+  clone(const MachineFunctionCloneContext &CloneContext) const;
+  [[nodiscard]] Expected<std::string> print() const;
+  [[nodiscard]] Expected<EncodedTargetFunctionState> encode() const;
+  [[nodiscard]] bool equals(const TargetFunctionState &Other) const noexcept;
+
+  template <TargetFunctionStateValue ValueT> [[nodiscard]] ValueT *getIf() noexcept {
+    if (!hasType<ValueT>())
+      return nullptr;
+    return &static_cast<Model<ValueT> *>(Storage.get())->value();
+  }
+
+  template <TargetFunctionStateValue ValueT> [[nodiscard]] const ValueT *getIf() const noexcept {
+    if (!hasType<ValueT>())
+      return nullptr;
+    return &static_cast<const Model<ValueT> *>(Storage.get())->value();
+  }
+
+private:
+  class Concept {
+  public:
+    Concept() = default;
+    Concept(const Concept &) = delete;
+    Concept &operator=(const Concept &) = delete;
+    Concept(Concept &&) = delete;
+    Concept &operator=(Concept &&) = delete;
+    virtual ~Concept() = default;
+
+    [[nodiscard]] virtual TargetFunctionStateTypeID typeID() const noexcept = 0;
+    [[nodiscard]] virtual std::uint32_t schemaVersion() const noexcept = 0;
+    [[nodiscard]] virtual const void *localTypeToken() const noexcept = 0;
+    [[nodiscard]] virtual Expected<void> verify() const = 0;
+    [[nodiscard]] virtual Expected<std::unique_ptr<Concept>>
+    cloneStorage(const MachineFunctionCloneContext &CloneContext) const = 0;
+    [[nodiscard]] virtual std::string print() const = 0;
+    [[nodiscard]] virtual Expected<std::vector<std::byte>> encodePayload() const = 0;
+    [[nodiscard]] virtual bool equals(const Concept &Other) const noexcept = 0;
+  };
+
+  template <typename ValueT> [[nodiscard]] static const void *typeToken() noexcept {
+    static const std::byte Token{};
+    return &Token;
+  }
+
+  template <TargetFunctionStateValue ValueT> class Model final : public Concept {
+  public:
+    explicit Model(ValueT Value) : Value(std::move(Value)) {}
+
+    [[nodiscard]] TargetFunctionStateTypeID typeID() const noexcept override {
+      return ValueT::stableTypeID();
+    }
+
+    [[nodiscard]] std::uint32_t schemaVersion() const noexcept override {
+      return ValueT::schemaVersion();
+    }
+
+    [[nodiscard]] const void *localTypeToken() const noexcept override {
+      return TargetFunctionState::typeToken<ValueT>();
+    }
+
+    [[nodiscard]] Expected<void> verify() const override {
+      return Value.verify();
+    }
+
+    [[nodiscard]] Expected<std::unique_ptr<Concept>>
+    cloneStorage(const MachineFunctionCloneContext &CloneContext) const override {
+      auto Cloned = Value.clone(CloneContext);
+      if (!Cloned)
+        return std::unexpected(Cloned.error());
+      std::unique_ptr<Concept> Result = std::make_unique<Model<ValueT>>(std::move(*Cloned));
+      return Result;
+    }
+
+    [[nodiscard]] std::string print() const override {
+      return Value.print();
+    }
+
+    [[nodiscard]] Expected<std::vector<std::byte>> encodePayload() const override {
+      return Value.encode();
+    }
+
+    [[nodiscard]] bool equals(const Concept &Other) const noexcept override {
+      if (Other.localTypeToken() != TargetFunctionState::typeToken<ValueT>())
+        return false;
+      return Value == static_cast<const Model<ValueT> &>(Other).Value;
+    }
+
+    [[nodiscard]] ValueT &value() noexcept {
+      return Value;
+    }
+
+    [[nodiscard]] const ValueT &value() const noexcept {
+      return Value;
+    }
+
+  private:
+    ValueT Value;
+  };
+
+  explicit TargetFunctionState(std::unique_ptr<Concept> Storage) : Storage(std::move(Storage)) {}
+
+  template <TargetFunctionStateValue ValueT> [[nodiscard]] bool hasType() const noexcept {
+    return Storage != nullptr && Storage->typeID() == ValueT::stableTypeID() &&
+           Storage->localTypeToken() == typeToken<ValueT>();
+  }
+
+  std::unique_ptr<Concept> Storage;
+};
+
+} // namespace rcc
+
+#endif // RCC_CODEGEN_TARGETFUNCTIONSTATE_H