lldb/source/Plugins/ExpressionParser/Clang/ClangFunctionCaller.h

   1 //===-- ClangFunctionCaller.h -----------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGFUNCTIONCALLER_H
  10 #define LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGFUNCTIONCALLER_H
  11
  12 #include "ClangExpressionHelper.h"
  13
  14 #include "lldb/Core/Address.h"
  15 #include "lldb/Core/Value.h"
  16 #include "lldb/Core/ValueObjectList.h"
  17 #include "lldb/Expression/FunctionCaller.h"
  18 #include "lldb/Symbol/CompilerType.h"
  19 #include "lldb/Target/Process.h"
  20
  21 namespace lldb_private {
  22
  23 class ASTStructExtractor;
  24
  25 /// \class ClangFunctionCaller ClangFunctionCaller.h
  26 /// "lldb/Expression/ClangFunctionCaller.h" Encapsulates a function that can
  27 /// be called.
  28 ///
  29 /// A given ClangFunctionCaller object can handle a single function signature.
  30 /// Once constructed, it can set up any number of concurrent calls to
  31 /// functions with that signature.
  32 ///
  33 /// It performs the call by synthesizing a structure that contains the pointer
  34 /// to the function and the arguments that should be passed to that function,
  35 /// and producing a special-purpose JIT-compiled function that accepts a void*
  36 /// pointing to this struct as its only argument and calls the function in the
  37 /// struct with the written arguments.  This method lets Clang handle the
  38 /// vagaries of function calling conventions.
  39 ///
  40 /// The simplest use of the ClangFunctionCaller is to construct it with a
  41 /// function representative of the signature you want to use, then call
  42 /// ExecuteFunction(ExecutionContext &, Stream &, Value &).
  43 ///
  44 /// If you need to reuse the arguments for several calls, you can call
  45 /// InsertFunction() followed by WriteFunctionArguments(), which will return
  46 /// the location of the args struct for the wrapper function in args_addr_ref.
  47 ///
  48 /// If you need to call the function on the thread plan stack, you can also
  49 /// call InsertFunction() followed by GetThreadPlanToCallFunction().
  50 ///
  51 /// Any of the methods that take arg_addr_ptr or arg_addr_ref can be passed a
  52 /// pointer set to LLDB_INVALID_ADDRESS and new structure will be allocated
  53 /// and its address returned in that variable.
  54 ///
  55 /// Any of the methods that take arg_addr_ptr can be passed NULL, and the
  56 /// argument space will be managed for you.
  57 class ClangFunctionCaller : public FunctionCaller {
  58   friend class ASTStructExtractor;
  59
  60   class ClangFunctionCallerHelper
  61       : public llvm::RTTIExtends<ClangFunctionCallerHelper,
  62                                  ClangExpressionHelper> {
  63   public:
  64     // LLVM RTTI support
  65     static char ID;
  66
  67     ClangFunctionCallerHelper(ClangFunctionCaller &owner) : m_owner(owner) {}
  68
  69     /// Return the object that the parser should use when resolving external
  70     /// values.  May be NULL if everything should be self-contained.
  71     ClangExpressionDeclMap *DeclMap() override { return nullptr; }
  72
  73     /// Return the object that the parser should allow to access ASTs. May be
  74     /// NULL if the ASTs do not need to be transformed.
  75     ///
  76     /// \param[in] passthrough
  77     ///     The ASTConsumer that the returned transformer should send
  78     ///     the ASTs to after transformation.
  79     clang::ASTConsumer *
  80     ASTTransformer(clang::ASTConsumer *passthrough) override;
  81
  82   private:
  83     ClangFunctionCaller &m_owner;
  84     std::unique_ptr<ASTStructExtractor> m_struct_extractor; ///< The class that
  85                                                             ///generates the
  86                                                             ///argument struct
  87                                                             ///layout.
  88   };
  89
  90   // LLVM RTTI support
  91   static char ID;
  92
  93 public:
  94   bool isA(const void *ClassID) const override {
  95     return ClassID == &ID || FunctionCaller::isA(ClassID);
  96   }
  97   static bool classof(const Expression *obj) { return obj->isA(&ID); }
  98
  99   /// Constructor
 100   ///
 101   /// \param[in] exe_scope
 102   ///     An execution context scope that gets us at least a target and
 103   ///     process.
 104   ///
 105   /// \param[in] return_type
 106   ///     A compiler type for the function result.  Should be
 107   ///     defined in ast_context.
 108   ///
 109   /// \param[in] function_address
 110   ///     The address of the function to call.
 111   ///
 112   /// \param[in] arg_value_list
 113   ///     The default values to use when calling this function.  Can
 114   ///     be overridden using WriteFunctionArguments().
 115   ClangFunctionCaller(ExecutionContextScope &exe_scope,
 116                       const CompilerType &return_type,
 117                       const Address &function_address,
 118                       const ValueList &arg_value_list, const char *name);
 119
 120   ~ClangFunctionCaller() override;
 121
 122   /// Compile the wrapper function
 123   ///
 124   /// \param[in] thread_to_use_sp
 125   ///     Compilation might end up calling functions.  Pass in the thread you
 126   ///     want the compilation to use.  If you pass in an empty ThreadSP it will
 127   ///     use the currently selected thread.
 128   ///
 129   /// \param[in] diagnostic_manager
 130   ///     The diagnostic manager to report parser errors to.
 131   ///
 132   /// \return
 133   ///     The number of errors.
 134   unsigned CompileFunction(lldb::ThreadSP thread_to_use_sp,
 135                            DiagnosticManager &diagnostic_manager) override;
 136
 137   ExpressionTypeSystemHelper *GetTypeSystemHelper() override {
 138     return &m_type_system_helper;
 139   }
 140
 141 protected:
 142   const char *GetWrapperStructName() { return m_wrapper_struct_name.c_str(); }
 143
 144 private:
 145   // For ClangFunctionCaller only
 146
 147   // Note: the parser needs to be destructed before the execution unit, so
 148   // declare the execution unit first.
 149   ClangFunctionCallerHelper m_type_system_helper;
 150 };
 151
 152 } // namespace lldb_private
 153
 154 #endif // LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGFUNCTIONCALLER_H