//===--- ByteCodeEmitter.h - Instruction emitter for the VM ---------*- 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

//

//===----------------------------------------------------------------------===//

//

// Defines the instruction emitters.

//

//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_AST_INTERP_LINKEMITTER_H

#define LLVM_CLANG_AST_INTERP_LINKEMITTER_H

#include "Context.h"

#include "PrimType.h"

#include "Program.h"

#include "Source.h"

#include "llvm/Support/Error.h"

namespace clang {

namespace interp {

enum Opcode : uint32_t;

/// An emitter which links the program to bytecode for later use.

class ByteCodeEmitter {

protected:

  using LabelTy = uint32_t;

  using AddrTy = uintptr_t;

  using Local = Scope::Local;

public:

  /// Compiles the function into the module.

  llvm::Expected<Function *> compileFunc(const FunctionDecl *FuncDecl);

protected:

  ByteCodeEmitter(Context &Ctx, Program &P) : Ctx(Ctx), P(P) {}

  virtual ~ByteCodeEmitter() {}

  /// Define a label.

  void emitLabel(LabelTy Label);

  /// Create a label.

  LabelTy getLabel() { return ++NextLabel; }

  /// Methods implemented by the compiler.

  virtual bool visitFunc(const FunctionDecl *E) = 0;

  virtual bool visitExpr(const Expr *E) = 0;

  virtual bool visitDecl(const VarDecl *E) = 0;

  /// Bails out if a given node cannot be compiled.

  bool bail(const Stmt *S) { return bail(S->getBeginLoc()); }

  bool bail(const Decl *D) { return bail(D->getBeginLoc()); }

  bool bail(const SourceLocation &Loc);

  /// Emits jumps.

  bool jumpTrue(const LabelTy &Label);

  bool jumpFalse(const LabelTy &Label);

  bool jump(const LabelTy &Label);

  bool fallthrough(const LabelTy &Label);

  /// Callback for local registration.

  Local createLocal(Descriptor *D);

  /// Parameter indices.

  llvm::DenseMap<const ParmVarDecl *, ParamOffset> Params;

  /// Lambda captures.

  llvm::DenseMap<const ValueDecl *, ParamOffset> LambdaCaptures;

  /// Offset of the This parameter in a lambda record.

  unsigned LambdaThisCapture = 0;

  /// Local descriptors.

  llvm::SmallVector<SmallVector<Local, 8>, 2> Descriptors;

private:

  /// Current compilation context.

  Context &Ctx;

  /// Program to link to.

  Program &P;

  /// Index of the next available label.

  LabelTy NextLabel = 0;

  /// Offset of the next local variable.

  unsigned NextLocalOffset = 0;

  /// Location of a failure.

  std::optional<SourceLocation> BailLocation;

  /// Label information for linker.

  llvm::DenseMap<LabelTy, unsigned> LabelOffsets;

  /// Location of label relocations.

  llvm::DenseMap<LabelTy, llvm::SmallVector<unsigned, 5>> LabelRelocs;

  /// Program code.

  std::vector<std::byte> Code;

  /// Opcode to expression mapping.

  SourceMap SrcMap;

  /// Returns the offset for a jump or records a relocation.

  int32_t getOffset(LabelTy Label);

  /// Emits an opcode.

  template <typename... Tys>

  bool emitOp(Opcode Op, const Tys &... Args, const SourceInfo &L);

protected:

#define GET_LINK_PROTO

#include "Opcodes.inc"

#undef GET_LINK_PROTO

};

} // namespace interp

} // namespace clang

#endif