local_storage_allocation.h

// Copyright (c) 2021-2023, David H. Hovemeyer <david.hovemeyer@gmail.com>
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
// OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
 
#ifndef LOCAL_STORAGE_ALLOCATION_H
#define LOCAL_STORAGE_ALLOCATION_H
 
#include "storage.h"
#include "ast_visitor.h"
#include "function.h"
 
// A LocalStorageAllocation object is responsible for allocating local
// storage for variables in exactly one function. The allocate_storage()
// member function will be called with a shared pointer to the
// Function containing the information about the function
// (including its AST). The Function object is also intended to
// the place where storage allocation decisions for the function
// are recorded.
class LocalStorageAllocation : public ASTVisitor {
public:
  // vr0 is the return value vreg
  static const int VREG_RETVAL = 0;
 
  // vr1 is 1st argument vreg
  static const int VREG_FIRST_ARG = 1;
 
  // local variable allocation starts at vr10
  static const int VREG_FIRST_LOCAL = 10;
 
private:
  std::shared_ptr<Function> m_function;
  StorageCalculator m_storage_calc;
  unsigned m_total_local_storage;
  int m_next_vreg;
 
public:
  LocalStorageAllocation();
  virtual ~LocalStorageAllocation();
 
  void allocate_storage(const std::shared_ptr<Function> &function);
 
  virtual void visit_declarator_list(Node *n);
  virtual void visit_function_definition(Node *n);
  virtual void visit_function_parameter(Node *n);
  virtual void visit_statement_list(Node *n);
  virtual void visit_struct_type_definition(Node *n);
 
private:
#ifdef SOLUTION
  StorageCalculator enter_scope();
  void leave_scope(StorageCalculator save);
  void visit_scope(Node *n);
  void allocate_storage(Node *n);
#else
  // TODO: add private member functions
#endif
};
 
#endif // LOCAL_STORAGE_ALLOCATION_H