1//===-- ASTResultSynthesizer.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_ASTRESULTSYNTHESIZER_H
10#define LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_ASTRESULTSYNTHESIZER_H
11
12#include "lldb/Target/Target.h"
13#include "clang/Sema/SemaConsumer.h"
14
15namespace clang {
16class CompoundStmt;
17class DeclContext;
18class NamedDecl;
19class ObjCMethodDecl;
20class TypeDecl;
21} // namespace clang
22
23namespace lldb_private {
24
25/// \class ASTResultSynthesizer ASTResultSynthesizer.h
26/// "lldb/Expression/ASTResultSynthesizer.h" Adds a result variable
27/// declaration to the ASTs for an expression.
28///
29/// Users expect the expression "i + 3" to return a result, even if a result
30/// variable wasn't specifically declared.  To fulfil this requirement, LLDB
31/// adds a result variable to the expression, transforming it to "int
32/// $__lldb_expr_result = i + 3."  The IR transformers ensure that the
33/// resulting variable is mapped to the right piece of memory.
34/// ASTResultSynthesizer's job is to add the variable and its initialization
35/// to the ASTs for the expression, and it does so by acting as a SemaConsumer
36/// for Clang.
37class ASTResultSynthesizer : public clang::SemaConsumer {
38public:
39  /// Constructor
40  ///
41  /// \param[in] passthrough
42  ///     Since the ASTs must typically go through to the Clang code generator
43  ///     in order to produce LLVM IR, this SemaConsumer must allow them to
44  ///     pass to the next step in the chain after processing.  Passthrough is
45  ///     the next ASTConsumer, or NULL if none is required.
46  ///
47  /// \param[in] top_level
48  ///     If true, register all top-level Decls and don't try to handle the
49  ///     main function.
50  ///
51  /// \param[in] target
52  ///     The target, which contains the persistent variable store and the
53  ///     AST importer.
54  ASTResultSynthesizer(clang::ASTConsumer *passthrough, bool top_level,
55                       Target &target);
56
57  /// Destructor
58  ~ASTResultSynthesizer() override;
59
60  /// Link this consumer with a particular AST context
61  ///
62  /// \param[in] Context
63  ///     This AST context will be used for types and identifiers, and also
64  ///     forwarded to the passthrough consumer, if one exists.
65  void Initialize(clang::ASTContext &Context) override;
66
67  /// Examine a list of Decls to find the function $__lldb_expr and transform
68  /// its code
69  ///
70  /// \param[in] D
71  ///     The list of Decls to search.  These may contain LinkageSpecDecls,
72  ///     which need to be searched recursively.  That job falls to
73  ///     TransformTopLevelDecl.
74  bool HandleTopLevelDecl(clang::DeclGroupRef D) override;
75
76  /// Passthrough stub
77  void HandleTranslationUnit(clang::ASTContext &Ctx) override;
78
79  /// Passthrough stub
80  void HandleTagDeclDefinition(clang::TagDecl *D) override;
81
82  /// Passthrough stub
83  void CompleteTentativeDefinition(clang::VarDecl *D) override;
84
85  /// Passthrough stub
86  void HandleVTable(clang::CXXRecordDecl *RD) override;
87
88  /// Passthrough stub
89  void PrintStats() override;
90
91  /// Set the Sema object to use when performing transforms, and pass it on
92  ///
93  /// \param[in] S
94  ///     The Sema to use.  Because Sema isn't externally visible, this class
95  ///     casts it to an Action for actual use.
96  void InitializeSema(clang::Sema &S) override;
97
98  /// Reset the Sema to NULL now that transformations are done
99  void ForgetSema() override;
100
101  /// The parse has succeeded, so record its persistent decls
102  void CommitPersistentDecls();
103
104private:
105  /// Hunt the given Decl for FunctionDecls named $__lldb_expr, recursing as
106  /// necessary through LinkageSpecDecls, and calling SynthesizeResult on
107  /// anything that was found
108  ///
109  /// \param[in] D
110  ///     The Decl to hunt.
111  void TransformTopLevelDecl(clang::Decl *D);
112
113  /// Process an Objective-C method and produce the result variable and
114  /// initialization
115  ///
116  /// \param[in] MethodDecl
117  ///     The method to process.
118  bool SynthesizeObjCMethodResult(clang::ObjCMethodDecl *MethodDecl);
119
120  /// Process a function and produce the result variable and initialization
121  ///
122  /// \param[in] FunDecl
123  ///     The function to process.
124  bool SynthesizeFunctionResult(clang::FunctionDecl *FunDecl);
125
126  /// Process a function body and produce the result variable and
127  /// initialization
128  ///
129  /// \param[in] Body
130  ///     The body of the function.
131  ///
132  /// \param[in] DC
133  ///     The DeclContext of the function, into which the result variable
134  ///     is inserted.
135  bool SynthesizeBodyResult(clang::CompoundStmt *Body, clang::DeclContext *DC);
136
137  /// Given a DeclContext for a function or method, find all types declared in
138  /// the context and record any persistent types found.
139  ///
140  /// \param[in] FunDeclCtx
141  ///     The context for the function to process.
142  void RecordPersistentTypes(clang::DeclContext *FunDeclCtx);
143
144  /// Given a TypeDecl, if it declares a type whose name starts with a dollar
145  /// sign, register it as a pointer type in the target's scratch AST context.
146  void MaybeRecordPersistentType(clang::TypeDecl *D);
147
148  /// Given a NamedDecl, register it as a pointer type in the target's scratch
149  /// AST context.
150  void RecordPersistentDecl(clang::NamedDecl *D);
151
152  clang::ASTContext
153      *m_ast_context; ///< The AST context to use for identifiers and types.
154  clang::ASTConsumer *m_passthrough; ///< The ASTConsumer down the chain, for
155                                     ///passthrough.  NULL if it's a
156                                     ///SemaConsumer.
157  clang::SemaConsumer *m_passthrough_sema; ///< The SemaConsumer down the chain,
158                                           ///for passthrough.  NULL if it's an
159                                           ///ASTConsumer.
160
161  std::vector<clang::NamedDecl *> m_decls; ///< Persistent declarations to
162                                           ///register assuming the expression
163                                           ///succeeds.
164
165  Target &m_target;    ///< The target, which contains the persistent variable
166                       ///store and the
167  clang::Sema *m_sema; ///< The Sema to use.
168  bool m_top_level;
169};
170
171} // namespace lldb_private
172
173#endif // LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_ASTRESULTSYNTHESIZER_H
174