1 //===-- ClangExpressionVariable.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_CLANGEXPRESSIONVARIABLE_H
10 #define LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGEXPRESSIONVARIABLE_H
11 
12 #include <csignal>
13 #include <cstdint>
14 #include <cstring>
15 
16 #include <map>
17 #include <string>
18 #include <vector>
19 
20 #include "llvm/Support/Casting.h"
21 
22 #include "lldb/Core/Value.h"
23 #include "lldb/Expression/ExpressionVariable.h"
24 #include "lldb/Symbol/TaggedASTType.h"
25 #include "lldb/Utility/ConstString.h"
26 #include "lldb/lldb-public.h"
27 
28 namespace llvm {
29 class Value;
30 }
31 
32 namespace clang {
33 class NamedDecl;
34 }
35 
36 namespace lldb_private {
37 
38 class ValueObjectConstResult;
39 
40 /// \class ClangExpressionVariable ClangExpressionVariable.h
41 /// "lldb/Expression/ClangExpressionVariable.h" Encapsulates one variable for
42 /// the expression parser.
43 ///
44 /// The expression parser uses variables in three different contexts:
45 ///
46 /// First, it stores persistent variables along with the process for use in
47 /// expressions.  These persistent variables contain their own data and are
48 /// typed.
49 ///
50 /// Second, in an interpreted expression, it stores the local variables for
51 /// the expression along with the expression.  These variables contain their
52 /// own data and are typed.
53 ///
54 /// Third, in a JIT-compiled expression, it stores the variables that the
55 /// expression needs to have materialized and dematerialized at each
56 /// execution.  These do not contain their own data but are named and typed.
57 ///
58 /// This class supports all of these use cases using simple type polymorphism,
59 /// and provides necessary support methods.  Its interface is RTTI-neutral.
60 class ClangExpressionVariable : public ExpressionVariable {
61 public:
62   ClangExpressionVariable(ExecutionContextScope *exe_scope,
63                           lldb::ByteOrder byte_order, uint32_t addr_byte_size);
64 
65   ClangExpressionVariable(ExecutionContextScope *exe_scope, Value &value,
66                           ConstString name, uint16_t flags = EVNone);
67 
68   ClangExpressionVariable(const lldb::ValueObjectSP &valobj_sp);
69 
70   ClangExpressionVariable(ExecutionContextScope *exe_scope,
71                           ConstString name,
72                           const TypeFromUser &user_type,
73                           lldb::ByteOrder byte_order, uint32_t addr_byte_size);
74 
75   /// Utility functions for dealing with ExpressionVariableLists in Clang-
76   /// specific ways
77 
78   /// Finds a variable by NamedDecl in the list.
79   ///
80   /// \return
81   ///     The variable requested, or NULL if that variable is not in the list.
82   static ClangExpressionVariable *
83   FindVariableInList(ExpressionVariableList &list, const clang::NamedDecl *decl,
84                      uint64_t parser_id) {
85     lldb::ExpressionVariableSP var_sp;
86     for (size_t index = 0, size = list.GetSize(); index < size; ++index) {
87       var_sp = list.GetVariableAtIndex(index);
88 
89       if (ClangExpressionVariable *clang_var =
90               llvm::dyn_cast<ClangExpressionVariable>(var_sp.get())) {
91         ClangExpressionVariable::ParserVars *parser_vars =
92             clang_var->GetParserVars(parser_id);
93 
94         if (parser_vars && parser_vars->m_named_decl == decl)
95           return clang_var;
96       }
97     }
98     return nullptr;
99   }
100 
101   /// If the variable contains its own data, make a Value point at it. If \a
102   /// exe_ctx in not NULL, the value will be resolved in with that execution
103   /// context.
104   ///
105   /// \param[in] value
106   ///     The value to point at the data.
107   ///
108   /// \param[in] exe_ctx
109   ///     The execution context to use to resolve \a value.
110   ///
111   /// \return
112   ///     True on success; false otherwise (in particular, if this variable
113   ///     does not contain its own data).
114   bool PointValueAtData(Value &value, ExecutionContext *exe_ctx);
115 
116   /// The following values should not live beyond parsing
117   class ParserVars {
118   public:
119     ParserVars() = default;
120 
121     const clang::NamedDecl *m_named_decl =
122         nullptr; ///< The Decl corresponding to this variable
123     llvm::Value *m_llvm_value =
124         nullptr; ///< The IR value corresponding to this variable;
125                  /// usually a GlobalValue
126     lldb_private::Value
127         m_lldb_value;            ///< The value found in LLDB for this variable
128     lldb::VariableSP m_lldb_var; ///< The original variable for this variable
129     const lldb_private::Symbol *m_lldb_sym =
130         nullptr; ///< The original symbol for this
131                  /// variable, if it was a symbol
132 
133     /// Callback that provides a ValueObject for the
134     /// specified frame. Used by the materializer for
135     /// re-fetching ValueObjects when materializing
136     /// ivars.
137     ValueObjectProviderTy m_lldb_valobj_provider;
138   };
139 
140 private:
141   typedef std::map<uint64_t, ParserVars> ParserVarMap;
142   ParserVarMap m_parser_vars;
143 
144 public:
145   /// Make this variable usable by the parser by allocating space for parser-
146   /// specific variables
147   void EnableParserVars(uint64_t parser_id) {
148     m_parser_vars.insert(std::make_pair(parser_id, ParserVars()));
149   }
150 
151   /// Deallocate parser-specific variables
152   void DisableParserVars(uint64_t parser_id) { m_parser_vars.erase(parser_id); }
153 
154   /// Access parser-specific variables
155   ParserVars *GetParserVars(uint64_t parser_id) {
156     ParserVarMap::iterator i = m_parser_vars.find(parser_id);
157 
158     if (i == m_parser_vars.end())
159       return nullptr;
160     else
161       return &i->second;
162   }
163 
164   /// The following values are valid if the variable is used by JIT code
165   struct JITVars {
166     JITVars() = default;
167 
168     lldb::offset_t m_alignment =
169         0;             ///< The required alignment of the variable, in bytes
170     size_t m_size = 0; ///< The space required for the variable, in bytes
171     lldb::offset_t m_offset =
172         0; ///< The offset of the variable in the struct, in bytes
173   };
174 
175 private:
176   typedef std::map<uint64_t, JITVars> JITVarMap;
177   JITVarMap m_jit_vars;
178 
179 public:
180   /// Make this variable usable for materializing for the JIT by allocating
181   /// space for JIT-specific variables
182   void EnableJITVars(uint64_t parser_id) {
183     m_jit_vars.insert(std::make_pair(parser_id, JITVars()));
184   }
185 
186   /// Deallocate JIT-specific variables
187   void DisableJITVars(uint64_t parser_id) { m_jit_vars.erase(parser_id); }
188 
189   JITVars *GetJITVars(uint64_t parser_id) {
190     JITVarMap::iterator i = m_jit_vars.find(parser_id);
191 
192     if (i == m_jit_vars.end())
193       return nullptr;
194     else
195       return &i->second;
196   }
197 
198   TypeFromUser GetTypeFromUser();
199 
200   // llvm casting support
201   static bool classof(const ExpressionVariable *ev) {
202     return ev->getKind() == ExpressionVariable::eKindClang;
203   }
204 
205   /// Members
206   ClangExpressionVariable(const ClangExpressionVariable &) = delete;
207   const ClangExpressionVariable &
208   operator=(const ClangExpressionVariable &) = delete;
209 };
210 
211 } // namespace lldb_private
212 
213 #endif // LLDB_SOURCE_PLUGINS_EXPRESSIONPARSER_CLANG_CLANGEXPRESSIONVARIABLE_H
214