Coverage Report

Created: 2022-01-18 06:27

/Users/buildslave/jenkins/workspace/coverage/llvm-project/lldb/include/lldb/Expression/FunctionCaller.h
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//===-- FunctionCaller.h ----------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLDB_EXPRESSION_FUNCTIONCALLER_H
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#define LLDB_EXPRESSION_FUNCTIONCALLER_H
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#include <list>
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#include <memory>
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#include <string>
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#include <vector>
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#include "lldb/Core/Address.h"
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#include "lldb/Core/Value.h"
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#include "lldb/Expression/Expression.h"
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#include "lldb/Expression/ExpressionParser.h"
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#include "lldb/Symbol/CompilerType.h"
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namespace lldb_private {
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/// \class FunctionCaller FunctionCaller.h "lldb/Expression/FunctionCaller.h"
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/// Encapsulates a function that can be called.
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///
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/// A given FunctionCaller object can handle a single function signature.
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/// Once constructed, it can set up any number of concurrent calls to
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/// functions with that signature.
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///
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/// It performs the call by synthesizing a structure that contains the pointer
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/// to the function and the arguments that should be passed to that function,
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/// and producing a special-purpose JIT-compiled function that accepts a void*
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/// pointing to this struct as its only argument and calls the function in the
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/// struct with the written arguments.  This method lets Clang handle the
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/// vagaries of function calling conventions.
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///
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/// The simplest use of the FunctionCaller is to construct it with a function
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/// representative of the signature you want to use, then call
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/// ExecuteFunction(ExecutionContext &, Stream &, Value &).
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///
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/// If you need to reuse the arguments for several calls, you can call
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/// InsertFunction() followed by WriteFunctionArguments(), which will return
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/// the location of the args struct for the wrapper function in args_addr_ref.
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///
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/// If you need to call the function on the thread plan stack, you can also
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/// call InsertFunction() followed by GetThreadPlanToCallFunction().
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///
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/// Any of the methods that take arg_addr_ptr or arg_addr_ref can be passed a
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/// pointer set to LLDB_INVALID_ADDRESS and new structure will be allocated
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/// and its address returned in that variable.
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///
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/// Any of the methods that take arg_addr_ptr can be passed nullptr, and the
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/// argument space will be managed for you.
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class FunctionCaller : public Expression {
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  // LLVM RTTI support
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  static char ID;
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public:
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  bool isA(const void *ClassID) const override { return ClassID == &ID; }
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  static bool classof(const Expression *obj) { return obj->isA(&ID); }
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  /// Constructor
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  ///
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  /// \param[in] exe_scope
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  ///     An execution context scope that gets us at least a target and
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  ///     process.
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  ///
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  /// \param[in] return_type
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  ///     An opaque Clang QualType for the function result.  Should be
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  ///     defined in ast_context.
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  ///
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  /// \param[in] function_address
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  ///     The address of the function to call.
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  ///
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  /// \param[in] arg_value_list
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  ///     The default values to use when calling this function.  Can
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  ///     be overridden using WriteFunctionArguments().
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  FunctionCaller(ExecutionContextScope &exe_scope,
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                 const CompilerType &return_type,
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                 const Address &function_address,
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                 const ValueList &arg_value_list, const char *name);
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  /// Destructor
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  ~FunctionCaller() override;
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  /// Compile the wrapper function
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  ///
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  /// \param[in] thread_to_use_sp
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  ///     Compilation might end up calling functions.  Pass in the thread you
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  ///     want the compilation to use.  If you pass in an empty ThreadSP it will
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  ///     use the currently selected thread.
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  ///
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  /// \param[in] diagnostic_manager
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  ///     The diagnostic manager to report parser errors to.
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  ///
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  /// \return
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  ///     The number of errors.
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  virtual unsigned CompileFunction(lldb::ThreadSP thread_to_use_sp,
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                                   DiagnosticManager &diagnostic_manager) = 0;
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  /// Insert the default function wrapper and its default argument struct
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  ///
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  /// \param[in] exe_ctx
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  ///     The execution context to insert the function and its arguments
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  ///     into.
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  ///
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  /// \param[in,out] args_addr_ref
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  ///     The address of the structure to write the arguments into.  May
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  ///     be LLDB_INVALID_ADDRESS; if it is, a new structure is allocated
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  ///     and args_addr_ref is pointed to it.
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  ///
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  /// \param[in] diagnostic_manager
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  ///     The diagnostic manager to report errors to.
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  ///
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  /// \return
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  ///     True on success; false otherwise.
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  bool InsertFunction(ExecutionContext &exe_ctx, lldb::addr_t &args_addr_ref,
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                      DiagnosticManager &diagnostic_manager);
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  /// Insert the default function wrapper (using the JIT)
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  ///
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  /// \param[in] exe_ctx
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  ///     The execution context to insert the function and its arguments
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  ///     into.
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  ///
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  /// \param[in] diagnostic_manager
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  ///     The diagnostic manager to report errors to.
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  ///
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  /// \return
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  ///     True on success; false otherwise.
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  bool WriteFunctionWrapper(ExecutionContext &exe_ctx,
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                            DiagnosticManager &diagnostic_manager);
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  /// Insert the default function argument struct
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  ///
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  /// \param[in] exe_ctx
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  ///     The execution context to insert the function and its arguments
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  ///     into.
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  ///
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  /// \param[in,out] args_addr_ref
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  ///     The address of the structure to write the arguments into.  May
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  ///     be LLDB_INVALID_ADDRESS; if it is, a new structure is allocated
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  ///     and args_addr_ref is pointed to it.
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  ///
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  /// \param[in] diagnostic_manager
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  ///     The diagnostic manager to report errors to.
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  ///
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  /// \return
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  ///     True on success; false otherwise.
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  bool WriteFunctionArguments(ExecutionContext &exe_ctx,
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                              lldb::addr_t &args_addr_ref,
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                              DiagnosticManager &diagnostic_manager);
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  /// Insert an argument struct with a non-default function address and non-
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  /// default argument values
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  ///
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  /// \param[in] exe_ctx
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  ///     The execution context to insert the function and its arguments
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  ///     into.
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  ///
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  /// \param[in,out] args_addr_ref
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  ///     The address of the structure to write the arguments into.  May
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  ///     be LLDB_INVALID_ADDRESS; if it is, a new structure is allocated
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  ///     and args_addr_ref is pointed at it.
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  ///
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  /// \param[in] arg_values
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  ///     The values of the function's arguments.
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  ///
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  /// \param[in] diagnostic_manager
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  ///     The diagnostic manager to report errors to.
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  ///
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  /// \return
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  ///     True on success; false otherwise.
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  bool WriteFunctionArguments(ExecutionContext &exe_ctx,
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                              lldb::addr_t &args_addr_ref,
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                              ValueList &arg_values,
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                              DiagnosticManager &diagnostic_manager);
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  /// Run the function this FunctionCaller was created with.
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  ///
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  /// This is the full version.
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  ///
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  /// \param[in] exe_ctx
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  ///     The thread & process in which this function will run.
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  ///
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  /// \param[in] args_addr_ptr
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  ///     If nullptr, the function will take care of allocating & deallocating
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  ///     the wrapper
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  ///     args structure.  Otherwise, if set to LLDB_INVALID_ADDRESS, a new
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  ///     structure
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  ///     will be allocated, filled and the address returned to you.  You are
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  ///     responsible
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  ///     for deallocating it.  And if passed in with a value other than
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  ///     LLDB_INVALID_ADDRESS,
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  ///     this should point to an already allocated structure with the values
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  ///     already written.
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  ///
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  /// \param[in] diagnostic_manager
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  ///     The diagnostic manager to report errors to.
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  ///
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  /// \param[in] options
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  ///     The options for this expression execution.
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  ///
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  /// \param[out] results
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  ///     The result value will be put here after running the function.
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  ///
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  /// \return
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  ///     Returns one of the ExpressionResults enum indicating function call
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  ///     status.
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  lldb::ExpressionResults
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  ExecuteFunction(ExecutionContext &exe_ctx, lldb::addr_t *args_addr_ptr,
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                  const EvaluateExpressionOptions &options,
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                  DiagnosticManager &diagnostic_manager, Value &results);
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  /// Get a thread plan to run the function this FunctionCaller was created
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  /// with.
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  ///
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  /// \param[in] exe_ctx
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  ///     The execution context to insert the function and its arguments
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  ///     into.
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  ///
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  /// \param[in] args_addr
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  ///     The address of the argument struct.
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  ///
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  /// \param[in] diagnostic_manager
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  ///     The diagnostic manager to report errors to.
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  ///
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  /// \return
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  ///     A ThreadPlan shared pointer for executing the function.
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  lldb::ThreadPlanSP
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  GetThreadPlanToCallFunction(ExecutionContext &exe_ctx, lldb::addr_t args_addr,
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                              const EvaluateExpressionOptions &options,
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                              DiagnosticManager &diagnostic_manager);
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  /// Get the result of the function from its struct
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  ///
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  /// \param[in] exe_ctx
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  ///     The execution context to retrieve the result from.
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  ///
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  /// \param[in] args_addr
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  ///     The address of the argument struct.
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  ///
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  /// \param[out] ret_value
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  ///     The value returned by the function.
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  ///
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  /// \return
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  ///     True on success; false otherwise.
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  bool FetchFunctionResults(ExecutionContext &exe_ctx, lldb::addr_t args_addr,
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                            Value &ret_value);
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  /// Deallocate the arguments structure
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  ///
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  /// \param[in] exe_ctx
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  ///     The execution context to insert the function and its arguments
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  ///     into.
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  ///
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  /// \param[in] args_addr
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  ///     The address of the argument struct.
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  void DeallocateFunctionResults(ExecutionContext &exe_ctx,
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                                 lldb::addr_t args_addr);
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  /// Interface for ClangExpression
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  /// Return the string that the parser should parse.  Must be a full
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  /// translation unit.
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  const char *Text() override { return m_wrapper_function_text.c_str(); }
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  /// Return the function name that should be used for executing the
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  /// expression.  Text() should contain the definition of this function.
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  const char *FunctionName() override {
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    return m_wrapper_function_name.c_str();
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  }
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  /// Return the object that the parser should use when registering local
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  /// variables. May be nullptr if the Expression doesn't care.
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  ExpressionVariableList *LocalVariables() { return nullptr; }
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  /// Return true if validation code should be inserted into the expression.
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  bool NeedsValidation() override { return false; }
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  /// Return true if external variables in the expression should be resolved.
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  bool NeedsVariableResolution() override { return false; }
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  ValueList GetArgumentValues() const { return m_arg_values; }
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protected:
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  // Note: the parser needs to be destructed before the execution unit, so
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  // declare the execution unit first.
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  std::shared_ptr<IRExecutionUnit> m_execution_unit_sp;
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  std::unique_ptr<ExpressionParser>
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      m_parser; ///< The parser responsible for compiling the function.
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                ///< This will get made in CompileFunction, so it is
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                ///< safe to access it after that.
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  lldb::ModuleWP m_jit_module_wp;
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  std::string
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      m_name; ///< The name of this clang function - for debugging purposes.
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  Function *m_function_ptr; ///< The function we're going to call. May be
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                            ///nullptr if we don't have debug info for the
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                            ///function.
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  Address m_function_addr;  ///< If we don't have the FunctionSP, we at least
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                            ///need the address & return type.
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  CompilerType m_function_return_type; ///< The opaque clang qual type for the
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                                       ///function return type.
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  std::string m_wrapper_function_name; ///< The name of the wrapper function.
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  std::string
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      m_wrapper_function_text;       ///< The contents of the wrapper function.
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  std::string m_wrapper_struct_name; ///< The name of the struct that contains
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                                     ///the target function address, arguments,
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                                     ///and result.
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  std::list<lldb::addr_t> m_wrapper_args_addrs; ///< The addresses of the
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                                                ///arguments to the wrapper
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                                                ///function.
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  bool m_struct_valid; ///< True if the ASTStructExtractor has populated the
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                       ///variables below.
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  /// These values are populated by the ASTStructExtractor
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  size_t m_struct_size; ///< The size of the argument struct, in bytes.
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  std::vector<uint64_t>
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      m_member_offsets; ///< The offset of each member in the struct, in bytes.
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  uint64_t m_return_size;   ///< The size of the result variable, in bytes.
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  uint64_t m_return_offset; ///< The offset of the result variable in the
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                            ///struct, in bytes.
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  ValueList m_arg_values; ///< The default values of the arguments.
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  bool m_compiled; ///< True if the wrapper function has already been parsed.
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  bool
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      m_JITted; ///< True if the wrapper function has already been JIT-compiled.
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};
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} // namespace lldb_private
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#endif // LLDB_EXPRESSION_FUNCTIONCALLER_H