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ASTStructExtractor.h
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1 //===-- ASTStructExtractor.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 liblldb_ASTStructExtractor_h_
10 #define liblldb_ASTStructExtractor_h_
11 
13 #include "ClangFunctionCaller.h"
14 
15 #include "lldb/Core/ClangForward.h"
16 #include "clang/Sema/SemaConsumer.h"
17 
18 namespace lldb_private {
19 
20 /// \class ASTStructExtractor ASTStructExtractor.h
21 /// "lldb/Expression/ASTStructExtractor.h" Extracts and describes the argument
22 /// structure for a wrapped function.
23 ///
24 /// This pass integrates with ClangFunctionCaller, which calls functions with
25 /// custom sets of arguments. To avoid having to implement the full calling
26 /// convention for the target's architecture, ClangFunctionCaller writes a
27 /// simple wrapper function that takes a pointer to an argument structure that
28 /// contains room for the address of the function to be called, the values of
29 /// all its arguments, and room for the function's return value.
30 ///
31 /// The definition of this struct is itself in the body of the wrapper
32 /// function, so Clang does the structure layout itself. ASTStructExtractor
33 /// reads through the AST for the wrapper function and finds the struct.
34 class ASTStructExtractor : public clang::SemaConsumer {
35 public:
36  /// Constructor
37  ///
38  /// \param[in] passthrough
39  /// Since the ASTs must typically go through to the Clang code generator
40  /// in order to produce LLVM IR, this SemaConsumer must allow them to
41  /// pass to the next step in the chain after processing. Passthrough is
42  /// the next ASTConsumer, or NULL if none is required.
43  ///
44  /// \param[in] struct_name
45  /// The name of the structure to extract from the wrapper function.
46  ///
47  /// \param[in] function
48  /// The caller object whose members should be populated with information
49  /// about the argument struct. ClangFunctionCaller friends
50  /// ASTStructExtractor
51  /// for this purpose.
52  ASTStructExtractor(clang::ASTConsumer *passthrough, const char *struct_name,
53  ClangFunctionCaller &function);
54 
55  /// Destructor
56  ~ASTStructExtractor() override;
57 
58  /// Link this consumer with a particular AST context
59  ///
60  /// \param[in] Context
61  /// This AST context will be used for types and identifiers, and also
62  /// forwarded to the passthrough consumer, if one exists.
63  void Initialize(clang::ASTContext &Context) override;
64 
65  /// Examine a list of Decls to find the function $__lldb_expr and transform
66  /// its code
67  ///
68  /// \param[in] D
69  /// The list of Decls to search. These may contain LinkageSpecDecls,
70  /// which need to be searched recursively. That job falls to
71  /// TransformTopLevelDecl.
72  bool HandleTopLevelDecl(clang::DeclGroupRef D) override;
73 
74  /// Passthrough stub
75  void HandleTranslationUnit(clang::ASTContext &Ctx) override;
76 
77  /// Passthrough stub
78  void HandleTagDeclDefinition(clang::TagDecl *D) override;
79 
80  /// Passthrough stub
81  void CompleteTentativeDefinition(clang::VarDecl *D) override;
82 
83  /// Passthrough stub
84  void HandleVTable(clang::CXXRecordDecl *RD) override;
85 
86  /// Passthrough stub
87  void PrintStats() override;
88 
89  /// Set the Sema object to use when performing transforms, and pass it on
90  ///
91  /// \param[in] S
92  /// The Sema to use. Because Sema isn't externally visible, this class
93  /// casts it to an Action for actual use.
94  void InitializeSema(clang::Sema &S) override;
95 
96  /// Reset the Sema to NULL now that transformations are done
97  void ForgetSema() override;
98 
99 private:
100  /// Hunt the given FunctionDecl for the argument struct and place
101  /// information about it into m_function
102  ///
103  /// \param[in] F
104  /// The FunctionDecl to hunt.
105  void ExtractFromFunctionDecl(clang::FunctionDecl *F);
106 
107  /// Hunt the given Decl for FunctionDecls named the same as the wrapper
108  /// function name, recursing as necessary through LinkageSpecDecls, and
109  /// calling ExtractFromFunctionDecl on anything that was found
110  ///
111  /// \param[in] D
112  /// The Decl to hunt.
113  void ExtractFromTopLevelDecl(clang::Decl *D);
114 
115  clang::ASTContext
116  *m_ast_context; ///< The AST context to use for identifiers and types.
117  clang::ASTConsumer *m_passthrough; ///< The ASTConsumer down the chain, for
118  ///passthrough. NULL if it's a
119  ///SemaConsumer.
120  clang::SemaConsumer *m_passthrough_sema; ///< The SemaConsumer down the chain,
121  ///for passthrough. NULL if it's an
122  ///ASTConsumer.
123  clang::Sema *m_sema; ///< The Sema to use.
124  clang::Action
125  *m_action; ///< The Sema to use, cast to an Action so it's usable.
126 
127  ClangFunctionCaller &m_function; ///< The function to populate with
128  ///information about the argument structure.
129  std::string m_struct_name; ///< The name of the structure to extract.
130 };
131 
132 } // namespace lldb_private
133 
134 #endif // liblldb_ASTStructExtractor_h_
Enumerations for broadcasting.
Definition: SBLaunchInfo.h:14
void PrintStats() override
Passthrough stub.
void HandleTagDeclDefinition(clang::TagDecl *D) override
Passthrough stub.
void Initialize(clang::ASTContext &Context) override
Link this consumer with a particular AST context.
"lldb/Expression/ASTStructExtractor.h" Extracts and describes the argument structure for a wrapped fu...
bool HandleTopLevelDecl(clang::DeclGroupRef D) override
Examine a list of Decls to find the function $__lldb_expr and transform its code. ...
ASTStructExtractor(clang::ASTConsumer *passthrough, const char *struct_name, ClangFunctionCaller &function)
Constructor.
~ASTStructExtractor() override
Destructor.
void HandleTranslationUnit(clang::ASTContext &Ctx) override
Passthrough stub.
"lldb/Expression/ClangFunctionCaller.h" Encapsulates a function that can be called.
void ForgetSema() override
Reset the Sema to NULL now that transformations are done.
void CompleteTentativeDefinition(clang::VarDecl *D) override
Passthrough stub.
void InitializeSema(clang::Sema &S) override
Set the Sema object to use when performing transforms, and pass it on.
void HandleVTable(clang::CXXRecordDecl *RD) override
Passthrough stub.