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 <optional>
13 #include <vector>
14 
15 #include "ASTResultSynthesizer.h"
16 #include "ASTStructExtractor.h"
17 #include "ClangExpressionDeclMap.h"
18 #include "ClangExpressionHelper.h"
19 #include "ClangExpressionSourceCode.h"
20 #include "ClangExpressionVariable.h"
21 #include "IRForTarget.h"
22 
23 #include "lldb/Core/Address.h"
24 #include "lldb/Expression/LLVMUserExpression.h"
25 #include "lldb/Expression/Materializer.h"
26 #include "lldb/Target/ExecutionContext.h"
27 #include "lldb/lldb-forward.h"
28 #include "lldb/lldb-private.h"
29 
30 namespace lldb_private {
31 
32 class ClangExpressionParser;
33 
34 /// \class ClangUserExpression ClangUserExpression.h
35 /// "lldb/Expression/ClangUserExpression.h" Encapsulates a single expression
36 /// for use with Clang
37 ///
38 /// LLDB uses expressions for various purposes, notably to call functions
39 /// and as a backend for the expr command.  ClangUserExpression encapsulates
40 /// the objects needed to parse and interpret or JIT an expression.  It uses
41 /// the Clang parser to produce LLVM IR from the expression.
42 class ClangUserExpression : public LLVMUserExpression {
43   // LLVM RTTI support
44   static char ID;
45 
46 public:
isA(const void * ClassID)47   bool isA(const void *ClassID) const override {
48     return ClassID == &ID || LLVMUserExpression::isA(ClassID);
49   }
classof(const Expression * obj)50   static bool classof(const Expression *obj) { return obj->isA(&ID); }
51 
52   enum { kDefaultTimeout = 500000u };
53 
54   class ClangUserExpressionHelper : public ClangExpressionHelper {
55   public:
ClangUserExpressionHelper(Target & target,bool top_level)56     ClangUserExpressionHelper(Target &target, bool top_level)
57         : m_target(target), m_top_level(top_level) {}
58 
59     ~ClangUserExpressionHelper() override = default;
60 
61     /// Return the object that the parser should use when resolving external
62     /// values.  May be NULL if everything should be self-contained.
DeclMap()63     ClangExpressionDeclMap *DeclMap() override {
64       return m_expr_decl_map_up.get();
65     }
66 
ResetDeclMap()67     void ResetDeclMap() { m_expr_decl_map_up.reset(); }
68 
69     void ResetDeclMap(ExecutionContext &exe_ctx,
70                       Materializer::PersistentVariableDelegate &result_delegate,
71                       bool keep_result_in_memory,
72                       ValueObject *ctx_obj);
73 
74     /// Return the object that the parser should allow to access ASTs. May be
75     /// NULL if the ASTs do not need to be transformed.
76     ///
77     /// \param[in] passthrough
78     ///     The ASTConsumer that the returned transformer should send
79     ///     the ASTs to after transformation.
80     clang::ASTConsumer *
81     ASTTransformer(clang::ASTConsumer *passthrough) override;
82 
83     void CommitPersistentDecls() override;
84 
85   private:
86     Target &m_target;
87     std::unique_ptr<ClangExpressionDeclMap> m_expr_decl_map_up;
88     std::unique_ptr<ASTStructExtractor> m_struct_extractor_up; ///< The class
89                                                                ///that generates
90                                                                ///the argument
91                                                                ///struct layout.
92     std::unique_ptr<ASTResultSynthesizer> m_result_synthesizer_up;
93     bool m_top_level;
94   };
95 
96   /// Constructor
97   ///
98   /// \param[in] expr
99   ///     The expression to parse.
100   ///
101   /// \param[in] prefix
102   ///     If non-NULL, a C string containing translation-unit level
103   ///     definitions to be included when the expression is parsed.
104   ///
105   /// \param[in] language
106   ///     If not eLanguageTypeUnknown, a language to use when parsing
107   ///     the expression.  Currently restricted to those languages
108   ///     supported by Clang.
109   ///
110   /// \param[in] desired_type
111   ///     If not eResultTypeAny, the type to use for the expression
112   ///     result.
113   ///
114   /// \param[in] options
115   ///     Additional options for the expression.
116   ///
117   /// \param[in] ctx_obj
118   ///     The object (if any) in which context the expression
119   ///     must be evaluated. For details see the comment to
120   ///     `UserExpression::Evaluate`.
121   ClangUserExpression(ExecutionContextScope &exe_scope, llvm::StringRef expr,
122                       llvm::StringRef prefix, lldb::LanguageType language,
123                       ResultType desired_type,
124                       const EvaluateExpressionOptions &options,
125                       ValueObject *ctx_obj);
126 
127   ~ClangUserExpression() override;
128 
129   /// Parse the expression
130   ///
131   /// \param[in] diagnostic_manager
132   ///     A diagnostic manager to report parse errors and warnings to.
133   ///
134   /// \param[in] exe_ctx
135   ///     The execution context to use when looking up entities that
136   ///     are needed for parsing (locations of functions, types of
137   ///     variables, persistent variables, etc.)
138   ///
139   /// \param[in] execution_policy
140   ///     Determines whether interpretation is possible or mandatory.
141   ///
142   /// \param[in] keep_result_in_memory
143   ///     True if the resulting persistent variable should reside in
144   ///     target memory, if applicable.
145   ///
146   /// \return
147   ///     True on success (no errors); false otherwise.
148   bool Parse(DiagnosticManager &diagnostic_manager, ExecutionContext &exe_ctx,
149              lldb_private::ExecutionPolicy execution_policy,
150              bool keep_result_in_memory, bool generate_debug_info) override;
151 
152   bool Complete(ExecutionContext &exe_ctx, CompletionRequest &request,
153                 unsigned complete_pos) override;
154 
GetTypeSystemHelper()155   ExpressionTypeSystemHelper *GetTypeSystemHelper() override {
156     return &m_type_system_helper;
157   }
158 
DeclMap()159   ClangExpressionDeclMap *DeclMap() { return m_type_system_helper.DeclMap(); }
160 
ResetDeclMap()161   void ResetDeclMap() { m_type_system_helper.ResetDeclMap(); }
162 
ResetDeclMap(ExecutionContext & exe_ctx,Materializer::PersistentVariableDelegate & result_delegate,bool keep_result_in_memory)163   void ResetDeclMap(ExecutionContext &exe_ctx,
164                     Materializer::PersistentVariableDelegate &result_delegate,
165                     bool keep_result_in_memory) {
166     m_type_system_helper.ResetDeclMap(exe_ctx, result_delegate,
167                                       keep_result_in_memory,
168                                       m_ctx_obj);
169   }
170 
171   lldb::ExpressionVariableSP
172   GetResultAfterDematerialization(ExecutionContextScope *exe_scope) override;
173 
174   /// Returns true iff this expression is using any imported C++ modules.
DidImportCxxModules()175   bool DidImportCxxModules() const { return !m_imported_cpp_modules.empty(); }
176 
177 private:
178   /// Populate m_in_cplusplus_method and m_in_objectivec_method based on the
179   /// environment.
180 
181   /// Contains the actual parsing implementation.
182   /// The parameter have the same meaning as in ClangUserExpression::Parse.
183   /// \see ClangUserExpression::Parse
184   bool TryParse(DiagnosticManager &diagnostic_manager,
185                 ExecutionContextScope *exe_scope, ExecutionContext &exe_ctx,
186                 lldb_private::ExecutionPolicy execution_policy, bool keep_result_in_memory,
187                 bool generate_debug_info);
188 
189   void SetupCppModuleImports(ExecutionContext &exe_ctx);
190 
191   void ScanContext(ExecutionContext &exe_ctx,
192                    lldb_private::Status &err) override;
193 
194   bool AddArguments(ExecutionContext &exe_ctx, std::vector<lldb::addr_t> &args,
195                     lldb::addr_t struct_address,
196                     DiagnosticManager &diagnostic_manager) override;
197 
198   void CreateSourceCode(DiagnosticManager &diagnostic_manager,
199                         ExecutionContext &exe_ctx,
200                         std::vector<std::string> modules_to_import,
201                         bool for_completion);
202 
203   lldb::addr_t GetCppObjectPointer(lldb::StackFrameSP frame,
204                                    ConstString &object_name, Status &err);
205 
206   /// Defines how the current expression should be wrapped.
207   ClangExpressionSourceCode::WrapKind GetWrapKind() const;
208   bool SetupPersistentState(DiagnosticManager &diagnostic_manager,
209                                    ExecutionContext &exe_ctx);
210   bool PrepareForParsing(DiagnosticManager &diagnostic_manager,
211                          ExecutionContext &exe_ctx, bool for_completion);
212 
213   ClangUserExpressionHelper m_type_system_helper;
214 
215   class ResultDelegate : public Materializer::PersistentVariableDelegate {
216   public:
ResultDelegate(lldb::TargetSP target)217     ResultDelegate(lldb::TargetSP target) : m_target_sp(target) {}
218     ConstString GetName() override;
219     void DidDematerialize(lldb::ExpressionVariableSP &variable) override;
220 
221     void RegisterPersistentState(PersistentExpressionState *persistent_state);
222     lldb::ExpressionVariableSP &GetVariable();
223 
224   private:
225     PersistentExpressionState *m_persistent_state;
226     lldb::ExpressionVariableSP m_variable;
227     lldb::TargetSP m_target_sp;
228   };
229 
230   /// The include directories that should be used when parsing the expression.
231   std::vector<std::string> m_include_directories;
232 
233   /// The absolute character position in the transformed source code where the
234   /// user code (as typed by the user) starts. If the variable is empty, then we
235   /// were not able to calculate this position.
236   std::optional<size_t> m_user_expression_start_pos;
237   ResultDelegate m_result_delegate;
238   ClangPersistentVariables *m_clang_state;
239   std::unique_ptr<ClangExpressionSourceCode> m_source_code;
240   /// The parser instance we used to parse the expression.
241   std::unique_ptr<ClangExpressionParser> m_parser;
242   /// File name used for the expression.
243   std::string m_filename;
244 
245   /// The object (if any) in which context the expression is evaluated.
246   /// See the comment to `UserExpression::Evaluate` for details.
247   ValueObject *m_ctx_obj;
248 
249   /// A list of module names that should be imported when parsing.
250   /// \see CppModuleConfiguration::GetImportedModules
251   std::vector<std::string> m_imported_cpp_modules;
252 
253   /// True if the expression parser should enforce the presence of a valid class
254   /// pointer in order to generate the expression as a method.
255   bool m_enforce_valid_object = true;
256   /// True if the expression is compiled as a C++ member function (true if it
257   /// was parsed when exe_ctx was in a C++ method).
258   bool m_in_cplusplus_method = false;
259   /// True if the expression is compiled as an Objective-C method (true if it
260   /// was parsed when exe_ctx was in an Objective-C method).
261   bool m_in_objectivec_method = false;
262   /// True if the expression is compiled as a static (or class) method
263   /// (currently true if it was parsed when exe_ctx was in an Objective-C class
264   /// method).
265   bool m_in_static_method = false;
266   /// True if "this" or "self" must be looked up and passed in.  False if the
267   /// expression doesn't really use them and they can be NULL.
268   bool m_needs_object_ptr = false;
269 };
270 
271 } // namespace lldb_private
272 
273 #endif // LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGUSEREXPRESSION_H
274