1 //===-- ClangUserExpression.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_CLANGUSEREXPRESSION_H
10 #define LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGUSEREXPRESSION_H
11 
12 #include <vector>
13 
14 #include "ASTResultSynthesizer.h"
15 #include "ASTStructExtractor.h"
16 #include "ClangExpressionDeclMap.h"
17 #include "ClangExpressionHelper.h"
18 #include "ClangExpressionSourceCode.h"
19 #include "ClangExpressionVariable.h"
20 #include "IRForTarget.h"
21 
22 #include "lldb/Core/Address.h"
23 #include "lldb/Expression/LLVMUserExpression.h"
24 #include "lldb/Expression/Materializer.h"
25 #include "lldb/Target/ExecutionContext.h"
26 #include "lldb/lldb-forward.h"
27 #include "lldb/lldb-private.h"
28 
29 namespace lldb_private {
30 
31 class ClangExpressionParser;
32 
33 /// \class ClangUserExpression ClangUserExpression.h
34 /// "lldb/Expression/ClangUserExpression.h" Encapsulates a single expression
35 /// for use with Clang
36 ///
37 /// LLDB uses expressions for various purposes, notably to call functions
38 /// and as a backend for the expr command.  ClangUserExpression encapsulates
39 /// the objects needed to parse and interpret or JIT an expression.  It uses
40 /// the Clang parser to produce LLVM IR from the expression.
41 class ClangUserExpression : public LLVMUserExpression {
42   // LLVM RTTI support
43   static char ID;
44 
45 public:
46   bool isA(const void *ClassID) const override {
47     return ClassID == &ID || LLVMUserExpression::isA(ClassID);
48   }
49   static bool classof(const Expression *obj) { return obj->isA(&ID); }
50 
51   enum { kDefaultTimeout = 500000u };
52 
53   class ClangUserExpressionHelper : public ClangExpressionHelper {
54   public:
55     ClangUserExpressionHelper(Target &target, bool top_level)
56         : m_target(target), m_top_level(top_level) {}
57 
58     ~ClangUserExpressionHelper() override = default;
59 
60     /// Return the object that the parser should use when resolving external
61     /// values.  May be NULL if everything should be self-contained.
62     ClangExpressionDeclMap *DeclMap() override {
63       return m_expr_decl_map_up.get();
64     }
65 
66     void ResetDeclMap() { m_expr_decl_map_up.reset(); }
67 
68     void ResetDeclMap(ExecutionContext &exe_ctx,
69                       Materializer::PersistentVariableDelegate &result_delegate,
70                       bool keep_result_in_memory,
71                       ValueObject *ctx_obj);
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     void CommitPersistentDecls() override;
83 
84   private:
85     Target &m_target;
86     std::unique_ptr<ClangExpressionDeclMap> m_expr_decl_map_up;
87     std::unique_ptr<ASTStructExtractor> m_struct_extractor_up; ///< The class
88                                                                ///that generates
89                                                                ///the argument
90                                                                ///struct layout.
91     std::unique_ptr<ASTResultSynthesizer> m_result_synthesizer_up;
92     bool m_top_level;
93   };
94 
95   /// Constructor
96   ///
97   /// \param[in] expr
98   ///     The expression to parse.
99   ///
100   /// \param[in] prefix
101   ///     If non-NULL, a C string containing translation-unit level
102   ///     definitions to be included when the expression is parsed.
103   ///
104   /// \param[in] language
105   ///     If not eLanguageTypeUnknown, a language to use when parsing
106   ///     the expression.  Currently restricted to those languages
107   ///     supported by Clang.
108   ///
109   /// \param[in] desired_type
110   ///     If not eResultTypeAny, the type to use for the expression
111   ///     result.
112   ///
113   /// \param[in] options
114   ///     Additional options for the expression.
115   ///
116   /// \param[in] ctx_obj
117   ///     The object (if any) in which context the expression
118   ///     must be evaluated. For details see the comment to
119   ///     `UserExpression::Evaluate`.
120   ClangUserExpression(ExecutionContextScope &exe_scope, llvm::StringRef expr,
121                       llvm::StringRef prefix, lldb::LanguageType language,
122                       ResultType desired_type,
123                       const EvaluateExpressionOptions &options,
124                       ValueObject *ctx_obj);
125 
126   ~ClangUserExpression() override;
127 
128   /// Parse the expression
129   ///
130   /// \param[in] diagnostic_manager
131   ///     A diagnostic manager to report parse errors and warnings to.
132   ///
133   /// \param[in] exe_ctx
134   ///     The execution context to use when looking up entities that
135   ///     are needed for parsing (locations of functions, types of
136   ///     variables, persistent variables, etc.)
137   ///
138   /// \param[in] execution_policy
139   ///     Determines whether interpretation is possible or mandatory.
140   ///
141   /// \param[in] keep_result_in_memory
142   ///     True if the resulting persistent variable should reside in
143   ///     target memory, if applicable.
144   ///
145   /// \return
146   ///     True on success (no errors); false otherwise.
147   bool Parse(DiagnosticManager &diagnostic_manager, ExecutionContext &exe_ctx,
148              lldb_private::ExecutionPolicy execution_policy,
149              bool keep_result_in_memory, bool generate_debug_info) override;
150 
151   bool Complete(ExecutionContext &exe_ctx, CompletionRequest &request,
152                 unsigned complete_pos) override;
153 
154   ExpressionTypeSystemHelper *GetTypeSystemHelper() override {
155     return &m_type_system_helper;
156   }
157 
158   ClangExpressionDeclMap *DeclMap() { return m_type_system_helper.DeclMap(); }
159 
160   void ResetDeclMap() { m_type_system_helper.ResetDeclMap(); }
161 
162   void ResetDeclMap(ExecutionContext &exe_ctx,
163                     Materializer::PersistentVariableDelegate &result_delegate,
164                     bool keep_result_in_memory) {
165     m_type_system_helper.ResetDeclMap(exe_ctx, result_delegate,
166                                       keep_result_in_memory,
167                                       m_ctx_obj);
168   }
169 
170   lldb::ExpressionVariableSP
171   GetResultAfterDematerialization(ExecutionContextScope *exe_scope) override;
172 
173   /// Returns true iff this expression is using any imported C++ modules.
174   bool DidImportCxxModules() const { return !m_imported_cpp_modules.empty(); }
175 
176 private:
177   /// Populate m_in_cplusplus_method and m_in_objectivec_method based on the
178   /// environment.
179 
180   /// Contains the actual parsing implementation.
181   /// The parameter have the same meaning as in ClangUserExpression::Parse.
182   /// \see ClangUserExpression::Parse
183   bool TryParse(DiagnosticManager &diagnostic_manager,
184                 ExecutionContextScope *exe_scope, ExecutionContext &exe_ctx,
185                 lldb_private::ExecutionPolicy execution_policy, bool keep_result_in_memory,
186                 bool generate_debug_info);
187 
188   void SetupCppModuleImports(ExecutionContext &exe_ctx);
189 
190   void ScanContext(ExecutionContext &exe_ctx,
191                    lldb_private::Status &err) override;
192 
193   bool AddArguments(ExecutionContext &exe_ctx, std::vector<lldb::addr_t> &args,
194                     lldb::addr_t struct_address,
195                     DiagnosticManager &diagnostic_manager) override;
196 
197   void CreateSourceCode(DiagnosticManager &diagnostic_manager,
198                         ExecutionContext &exe_ctx,
199                         std::vector<std::string> modules_to_import,
200                         bool for_completion);
201 
202   lldb::addr_t GetCppObjectPointer(lldb::StackFrameSP frame,
203                                    ConstString &object_name, Status &err);
204 
205   /// Defines how the current expression should be wrapped.
206   ClangExpressionSourceCode::WrapKind GetWrapKind() const;
207   bool SetupPersistentState(DiagnosticManager &diagnostic_manager,
208                                    ExecutionContext &exe_ctx);
209   bool PrepareForParsing(DiagnosticManager &diagnostic_manager,
210                          ExecutionContext &exe_ctx, bool for_completion);
211 
212   ClangUserExpressionHelper m_type_system_helper;
213 
214   class ResultDelegate : public Materializer::PersistentVariableDelegate {
215   public:
216     ResultDelegate(lldb::TargetSP target) : m_target_sp(target) {}
217     ConstString GetName() override;
218     void DidDematerialize(lldb::ExpressionVariableSP &variable) override;
219 
220     void RegisterPersistentState(PersistentExpressionState *persistent_state);
221     lldb::ExpressionVariableSP &GetVariable();
222 
223   private:
224     PersistentExpressionState *m_persistent_state;
225     lldb::ExpressionVariableSP m_variable;
226     lldb::TargetSP m_target_sp;
227   };
228 
229   /// The include directories that should be used when parsing the expression.
230   std::vector<std::string> m_include_directories;
231 
232   /// The absolute character position in the transformed source code where the
233   /// user code (as typed by the user) starts. If the variable is empty, then we
234   /// were not able to calculate this position.
235   llvm::Optional<size_t> m_user_expression_start_pos;
236   ResultDelegate m_result_delegate;
237   ClangPersistentVariables *m_clang_state;
238   std::unique_ptr<ClangExpressionSourceCode> m_source_code;
239   /// The parser instance we used to parse the expression.
240   std::unique_ptr<ClangExpressionParser> m_parser;
241   /// File name used for the expression.
242   std::string m_filename;
243 
244   /// The object (if any) in which context the expression is evaluated.
245   /// See the comment to `UserExpression::Evaluate` for details.
246   ValueObject *m_ctx_obj;
247 
248   /// A list of module names that should be imported when parsing.
249   /// \see CppModuleConfiguration::GetImportedModules
250   std::vector<std::string> m_imported_cpp_modules;
251 
252   /// True if the expression parser should enforce the presence of a valid class
253   /// pointer in order to generate the expression as a method.
254   bool m_enforce_valid_object = true;
255   /// True if the expression is compiled as a C++ member function (true if it
256   /// was parsed when exe_ctx was in a C++ method).
257   bool m_in_cplusplus_method = false;
258   /// True if the expression is compiled as an Objective-C method (true if it
259   /// was parsed when exe_ctx was in an Objective-C method).
260   bool m_in_objectivec_method = false;
261   /// True if the expression is compiled as a static (or class) method
262   /// (currently true if it was parsed when exe_ctx was in an Objective-C class
263   /// method).
264   bool m_in_static_method = false;
265   /// True if "this" or "self" must be looked up and passed in.  False if the
266   /// expression doesn't really use them and they can be NULL.
267   bool m_needs_object_ptr = false;
268 };
269 
270 } // namespace lldb_private
271 
272 #endif // LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGUSEREXPRESSION_H
273