//===-- FunctionCaller.h ----------------------------------------*- 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

//

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

#ifndef LLDB_EXPRESSION_FUNCTIONCALLER_H

#define LLDB_EXPRESSION_FUNCTIONCALLER_H

#include <list>

#include <memory>

#include <string>

#include <vector>

#include "lldb/Core/Address.h"

#include "lldb/Core/Value.h"

#include "lldb/Expression/Expression.h"

#include "lldb/Expression/ExpressionParser.h"

#include "lldb/Symbol/CompilerType.h"

namespace lldb_private {

/// \class FunctionCaller FunctionCaller.h "lldb/Expression/FunctionCaller.h"

/// Encapsulates a function that can be called.

///

/// A given FunctionCaller object can handle a single function signature.

/// Once constructed, it can set up any number of concurrent calls to

/// functions with that signature.

///

/// It performs the call by synthesizing a structure that contains the pointer

/// to the function and the arguments that should be passed to that function,

/// and producing a special-purpose JIT-compiled function that accepts a void*

/// pointing to this struct as its only argument and calls the function in the

/// struct with the written arguments.  This method lets Clang handle the

/// vagaries of function calling conventions.

///

/// The simplest use of the FunctionCaller is to construct it with a function

/// representative of the signature you want to use, then call

/// ExecuteFunction(ExecutionContext &, Stream &, Value &).

///

/// If you need to reuse the arguments for several calls, you can call

/// InsertFunction() followed by WriteFunctionArguments(), which will return

/// the location of the args struct for the wrapper function in args_addr_ref.

///

/// If you need to call the function on the thread plan stack, you can also

/// call InsertFunction() followed by GetThreadPlanToCallFunction().

///

/// Any of the methods that take arg_addr_ptr or arg_addr_ref can be passed a

/// pointer set to LLDB_INVALID_ADDRESS and new structure will be allocated

/// and its address returned in that variable.

///

/// Any of the methods that take arg_addr_ptr can be passed nullptr, and the

/// argument space will be managed for you.

class FunctionCaller : public Expression {

  // LLVM RTTI support

  static char ID;

public:

  bool isA(const void *ClassID) const override { return ClassID == &ID; }

  static bool classof(const Expression *obj) { return obj->isA(&ID); }

  /// Constructor

  ///

  /// \param[in] exe_scope

  ///     An execution context scope that gets us at least a target and

  ///     process.

  ///

  /// \param[in] return_type

  ///     An opaque Clang QualType for the function result.  Should be

  ///     defined in ast_context.

  ///

  /// \param[in] function_address

  ///     The address of the function to call.

  ///

  /// \param[in] arg_value_list

  ///     The default values to use when calling this function.  Can

  ///     be overridden using WriteFunctionArguments().

  FunctionCaller(ExecutionContextScope &exe_scope,

                 const CompilerType &return_type,

                 const Address &function_address,

                 const ValueList &arg_value_list, const char *name);

  /// Destructor

  ~FunctionCaller() override;

  /// Compile the wrapper function

  ///

  /// \param[in] thread_to_use_sp

  ///     Compilation might end up calling functions.  Pass in the thread you

  ///     want the compilation to use.  If you pass in an empty ThreadSP it will

  ///     use the currently selected thread.

  ///

  /// \param[in] diagnostic_manager

  ///     The diagnostic manager to report parser errors to.

  ///

  /// \return

  ///     The number of errors.

  virtual unsigned CompileFunction(lldb::ThreadSP thread_to_use_sp,

                                   DiagnosticManager &diagnostic_manager) = 0;

  /// Insert the default function wrapper and its default argument struct

  ///

  /// \param[in] exe_ctx

  ///     The execution context to insert the function and its arguments

  ///     into.

  ///

  /// \param[in,out] args_addr_ref

  ///     The address of the structure to write the arguments into.  May

  ///     be LLDB_INVALID_ADDRESS; if it is, a new structure is allocated

  ///     and args_addr_ref is pointed to it.

  ///

  /// \param[in] diagnostic_manager

  ///     The diagnostic manager to report errors to.

  ///

  /// \return

  ///     True on success; false otherwise.

  bool InsertFunction(ExecutionContext &exe_ctx, lldb::addr_t &args_addr_ref,

                      DiagnosticManager &diagnostic_manager);

  /// Insert the default function wrapper (using the JIT)

  ///

  /// \param[in] exe_ctx

  ///     The execution context to insert the function and its arguments

  ///     into.

  ///

  /// \param[in] diagnostic_manager

  ///     The diagnostic manager to report errors to.

  ///

  /// \return

  ///     True on success; false otherwise.

  bool WriteFunctionWrapper(ExecutionContext &exe_ctx,

                            DiagnosticManager &diagnostic_manager);

  /// Insert the default function argument struct

  ///

  /// \param[in] exe_ctx

  ///     The execution context to insert the function and its arguments

  ///     into.

  ///

  /// \param[in,out] args_addr_ref

  ///     The address of the structure to write the arguments into.  May

  ///     be LLDB_INVALID_ADDRESS; if it is, a new structure is allocated

  ///     and args_addr_ref is pointed to it.

  ///

  /// \param[in] diagnostic_manager

  ///     The diagnostic manager to report errors to.

  ///

  /// \return

  ///     True on success; false otherwise.

  bool WriteFunctionArguments(ExecutionContext &exe_ctx,

                              lldb::addr_t &args_addr_ref,

                              DiagnosticManager &diagnostic_manager);

  /// Insert an argument struct with a non-default function address and non-

  /// default argument values

  ///

  /// \param[in] exe_ctx

  ///     The execution context to insert the function and its arguments

  ///     into.

  ///

  /// \param[in,out] args_addr_ref

  ///     The address of the structure to write the arguments into.  May

  ///     be LLDB_INVALID_ADDRESS; if it is, a new structure is allocated

  ///     and args_addr_ref is pointed at it.

  ///

  /// \param[in] arg_values

  ///     The values of the function's arguments.

  ///

  /// \param[in] diagnostic_manager

  ///     The diagnostic manager to report errors to.

  ///

  /// \return

  ///     True on success; false otherwise.

  bool WriteFunctionArguments(ExecutionContext &exe_ctx,

                              lldb::addr_t &args_addr_ref,

                              ValueList &arg_values,

                              DiagnosticManager &diagnostic_manager);

  /// Run the function this FunctionCaller was created with.

  ///

  /// This is the full version.

  ///

  /// \param[in] exe_ctx

  ///     The thread & process in which this function will run.

  ///

  /// \param[in] args_addr_ptr

  ///     If nullptr, the function will take care of allocating & deallocating

  ///     the wrapper

  ///     args structure.  Otherwise, if set to LLDB_INVALID_ADDRESS, a new

  ///     structure

  ///     will be allocated, filled and the address returned to you.  You are

  ///     responsible

  ///     for deallocating it.  And if passed in with a value other than

  ///     LLDB_INVALID_ADDRESS,

  ///     this should point to an already allocated structure with the values

  ///     already written.

  ///

  /// \param[in] diagnostic_manager

  ///     The diagnostic manager to report errors to.

  ///

  /// \param[in] options

  ///     The options for this expression execution.

  ///

  /// \param[out] results

  ///     The result value will be put here after running the function.

  ///

  /// \return

  ///     Returns one of the ExpressionResults enum indicating function call

  ///     status.

  lldb::ExpressionResults

  ExecuteFunction(ExecutionContext &exe_ctx, lldb::addr_t *args_addr_ptr,

                  const EvaluateExpressionOptions &options,

                  DiagnosticManager &diagnostic_manager, Value &results);

  /// Get a thread plan to run the function this FunctionCaller was created

  /// with.

  ///

  /// \param[in] exe_ctx

  ///     The execution context to insert the function and its arguments

  ///     into.

  ///

  /// \param[in] args_addr

  ///     The address of the argument struct.

  ///

  /// \param[in] diagnostic_manager

  ///     The diagnostic manager to report errors to.

  ///

  /// \return

  ///     A ThreadPlan shared pointer for executing the function.

  lldb::ThreadPlanSP

  GetThreadPlanToCallFunction(ExecutionContext &exe_ctx, lldb::addr_t args_addr,

                              const EvaluateExpressionOptions &options,

                              DiagnosticManager &diagnostic_manager);

  /// Get the result of the function from its struct

  ///

  /// \param[in] exe_ctx

  ///     The execution context to retrieve the result from.

  ///

  /// \param[in] args_addr

  ///     The address of the argument struct.

  ///

  /// \param[out] ret_value

  ///     The value returned by the function.

  ///

  /// \return

  ///     True on success; false otherwise.

  bool FetchFunctionResults(ExecutionContext &exe_ctx, lldb::addr_t args_addr,

                            Value &ret_value);

  /// Deallocate the arguments structure

  ///

  /// \param[in] exe_ctx

  ///     The execution context to insert the function and its arguments

  ///     into.

  ///

  /// \param[in] args_addr

  ///     The address of the argument struct.

  void DeallocateFunctionResults(ExecutionContext &exe_ctx,

                                 lldb::addr_t args_addr);

  /// Interface for ClangExpression

  /// Return the string that the parser should parse.  Must be a full

  /// translation unit.

  const char *Text() override { return m_wrapper_function_text.c_str(); }

  /// Return the function name that should be used for executing the

  /// expression.  Text() should contain the definition of this function.

  const char *FunctionName() override {

    return m_wrapper_function_name.c_str();

  }

  /// Return the object that the parser should use when registering local

  /// variables. May be nullptr if the Expression doesn't care.

  ExpressionVariableList *LocalVariables() { return nullptr; }

  /// Return true if validation code should be inserted into the expression.

  bool NeedsValidation() override { return false; }

  /// Return true if external variables in the expression should be resolved.

  bool NeedsVariableResolution() override { return false; }

  ValueList GetArgumentValues() const { return m_arg_values; }

protected:

  // Note: the parser needs to be destructed before the execution unit, so

  // declare the execution unit first.

  std::shared_ptr<IRExecutionUnit> m_execution_unit_sp;

  std::unique_ptr<ExpressionParser>

      m_parser; ///< The parser responsible for compiling the function.

                ///< This will get made in CompileFunction, so it is

                ///< safe to access it after that.

  lldb::ModuleWP m_jit_module_wp;

  std::string

      m_name; ///< The name of this clang function - for debugging purposes.

  Function *m_function_ptr; ///< The function we're going to call. May be

                            ///nullptr if we don't have debug info for the

                            ///function.

  Address m_function_addr;  ///< If we don't have the FunctionSP, we at least

                            ///need the address & return type.

  CompilerType m_function_return_type; ///< The opaque clang qual type for the

                                       ///function return type.

  std::string m_wrapper_function_name; ///< The name of the wrapper function.

  std::string

      m_wrapper_function_text;       ///< The contents of the wrapper function.

  std::string m_wrapper_struct_name; ///< The name of the struct that contains

                                     ///the target function address, arguments,

                                     ///and result.

  std::list<lldb::addr_t> m_wrapper_args_addrs; ///< The addresses of the

                                                ///arguments to the wrapper

                                                ///function.

  bool m_struct_valid; ///< True if the ASTStructExtractor has populated the

                       ///variables below.

  /// These values are populated by the ASTStructExtractor

  size_t m_struct_size; ///< The size of the argument struct, in bytes.

  std::vector<uint64_t>

      m_member_offsets; ///< The offset of each member in the struct, in bytes.

  uint64_t m_return_size;   ///< The size of the result variable, in bytes.

  uint64_t m_return_offset; ///< The offset of the result variable in the

                            ///struct, in bytes.

  ValueList m_arg_values; ///< The default values of the arguments.

  bool m_compiled; ///< True if the wrapper function has already been parsed.

  bool

      m_JITted; ///< True if the wrapper function has already been JIT-compiled.

};

} // namespace lldb_private

#endif // LLDB_EXPRESSION_FUNCTIONCALLER_H