carbon-lang/toolchain/sem_ir/import_ir.h

// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#ifndef CARBON_TOOLCHAIN_SEM_IR_IMPORT_IR_H_
#define CARBON_TOOLCHAIN_SEM_IR_IMPORT_IR_H_

#include "llvm/ADT/FoldingSet.h"
#include "toolchain/sem_ir/ids.h"
#include "toolchain/sem_ir/inst.h"

namespace Carbon::SemIR {

// A reference to an imported IR.
struct ImportIR : public Printable<ImportIR> {
  auto Print(llvm::raw_ostream& out) const -> void;

  // The `import` declaration.
  InstId decl_id;
  // True if this is part of an `export import`.
  bool is_export;
  // The imported IR.
  const File* sem_ir;
};

static_assert(sizeof(ImportIR) == 8 + sizeof(uintptr_t), "Unexpected size");

// A reference to an instruction in an imported IR. Used for diagnostics with
// LocId. For a `Cpp` import, points to a Clang source location.
class ImportIRInst : public Printable<ImportIRInst> {
 public:
  // Constructor for a non-`Cpp` import.
  explicit ImportIRInst(ImportIRId ir_id, InstId inst_id)
      : ir_id_(ir_id), inst_id_(inst_id) {
    CARBON_CHECK(ir_id != ImportIRId::Cpp);
  }

  // Constructor for a `Cpp` import.
  explicit ImportIRInst(ClangSourceLocId clang_source_loc_id)
      : ir_id_(ImportIRId::Cpp), clang_source_loc_id_(clang_source_loc_id) {}

  auto Print(llvm::raw_ostream& out) const -> void;

  friend auto operator==(const ImportIRInst& lhs, const ImportIRInst& rhs)
      -> bool {
    return lhs.ir_id() == rhs.ir_id() &&
           (lhs.ir_id() == ImportIRId::Cpp
                ? lhs.clang_source_loc_id() == rhs.clang_source_loc_id()
                : lhs.inst_id() == rhs.inst_id());
  }

  auto ir_id() const -> ImportIRId { return ir_id_; }
  auto inst_id() const -> InstId {
    CARBON_CHECK(ir_id() != ImportIRId::Cpp);
    return inst_id_;
  }
  auto clang_source_loc_id() const -> ClangSourceLocId {
    CARBON_CHECK(ir_id() == ImportIRId::Cpp);
    return clang_source_loc_id_;
  }

 private:
  ImportIRId ir_id_;
  union {
    // Set iff `ir_id != ImportIRId::Cpp`.
    InstId inst_id_;

    // Set iff `ir_id == ImportIRId::Cpp`.
    ClangSourceLocId clang_source_loc_id_;
  };
};

// Returns the canonical `File` and `InstId` for an entity, tracing imported
// instructions. Note the returned `File` might not be directly imported by the
// input `sem_ir`.
auto GetCanonicalFileAndInstId(const File* sem_ir, SemIR::InstId inst_id)
    -> std::pair<const File*, InstId>;

}  // namespace Carbon::SemIR

#endif  // CARBON_TOOLCHAIN_SEM_IR_IMPORT_IR_H_