//===--- Function.h - Bytecode function 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 Function class which holds all bytecode function-specific data.

//

// The scope class which describes local variables is also defined here.

//

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

#ifndef LLVM_CLANG_AST_INTERP_FUNCTION_H

#define LLVM_CLANG_AST_INTERP_FUNCTION_H

#include "Pointer.h"

#include "Source.h"

#include "clang/AST/Decl.h"

#include "llvm/Support/raw_ostream.h"

namespace clang {

namespace interp {

class Program;

class ByteCodeEmitter;

enum PrimType : uint32_t;

/// Describes a scope block.

///

/// The block gathers all the descriptors of the locals defined in this block.

class Scope {

public:

  /// Information about a local's storage.

  struct Local {

    /// Offset of the local in frame.

    unsigned Offset;

    /// Descriptor of the local.

    Descriptor *Desc;

  };

  using LocalVectorTy = llvm::SmallVector<Local, 8>;

  Scope(LocalVectorTy &&Descriptors) : Descriptors(std::move(Descriptors)) {}

  llvm::iterator_range<LocalVectorTy::iterator> locals() {

    return llvm::make_range(Descriptors.begin(), Descriptors.end());

  }

private:

  /// Object descriptors in this block.

  LocalVectorTy Descriptors;

};

/// Bytecode function.

///

/// Contains links to the bytecode of the function, as well as metadata

/// describing all arguments and stack-local variables.

class Function {

public:

  using ParamDescriptor = std::pair<PrimType, Descriptor *>;

  /// Returns the size of the function's local stack.

  unsigned getFrameSize() const { return FrameSize; }

  /// Returns the size of the argument stackx

  unsigned getArgSize() const { return ArgSize; }

  /// Returns a pointer to the start of the code.

  CodePtr getCodeBegin() const;

  /// Returns a pointer to the end of the code.

  CodePtr getCodeEnd() const;

  /// Returns the original FunctionDecl.

  const FunctionDecl *getDecl() const { return F; }

  /// Returns the location.

  SourceLocation getLoc() const { return Loc; }

  /// Returns a parameter descriptor.

  ParamDescriptor getParamDescriptor(unsigned Offset) const;

  /// Checks if the first argument is a RVO pointer.

  bool hasRVO() const { return ParamTypes.size() != Params.size(); }

  /// Range over the scope blocks.

  llvm::iterator_range<llvm::SmallVector<Scope, 2>::iterator> scopes() {

    return llvm::make_range(Scopes.begin(), Scopes.end());

  }

  /// Range over argument types.

  using arg_reverse_iterator = SmallVectorImpl<PrimType>::reverse_iterator;

  llvm::iterator_range<arg_reverse_iterator> args_reverse() {

    return llvm::make_range(ParamTypes.rbegin(), ParamTypes.rend());

  }

  /// Returns a specific scope.

  Scope &getScope(unsigned Idx) { return Scopes[Idx]; }

  /// Returns the source information at a given PC.

  SourceInfo getSource(CodePtr PC) const;

  /// Checks if the function is valid to call in constexpr.

  bool isConstexpr() const { return IsValid; }

  /// Checks if the function is virtual.

  bool isVirtual() const;

  /// Checks if the function is a constructor.

  bool isConstructor() const { return isa<CXXConstructorDecl>(F); }

private:

  /// Construct a function representing an actual function.

  Function(Program &P, const FunctionDecl *F, unsigned ArgSize,

           llvm::SmallVector<PrimType, 8> &&ParamTypes,

           llvm::DenseMap<unsigned, ParamDescriptor> &&Params);

  /// Sets the code of a function.

  void setCode(unsigned NewFrameSize, std::vector<char> &&NewCode, SourceMap &&NewSrcMap,

               llvm::SmallVector<Scope, 2> &&NewScopes) {

    FrameSize = NewFrameSize;

    Code = std::move(NewCode);

    SrcMap = std::move(NewSrcMap);

    Scopes = std::move(NewScopes);

    IsValid = true;

  }

private:

  friend class Program;

  friend class ByteCodeEmitter;

  /// Program reference.

  Program &P;

  /// Location of the executed code.

  SourceLocation Loc;

  /// Declaration this function was compiled from.

  const FunctionDecl *F;

  /// Local area size: storage + metadata.

  unsigned FrameSize;

  /// Size of the argument stack.

  unsigned ArgSize;

  /// Program code.

  std::vector<char> Code;

  /// Opcode-to-expression mapping.

  SourceMap SrcMap;

  /// List of block descriptors.

  llvm::SmallVector<Scope, 2> Scopes;

  /// List of argument types.

  llvm::SmallVector<PrimType, 8> ParamTypes;

  /// Map from byte offset to parameter descriptor.

  llvm::DenseMap<unsigned, ParamDescriptor> Params;

  /// Flag to indicate if the function is valid.

  bool IsValid = false;

public:

  /// Dumps the disassembled bytecode to \c llvm::errs().

  void dump() const;

  void dump(llvm::raw_ostream &OS) const;

};

} // namespace interp

} // namespace clang

#endif