1 //===-- ObjCLanguageRuntime.cpp ---------------------------------*- 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 #include "clang/AST/Type.h"
9 
10 #include "ObjCLanguageRuntime.h"
11 
12 #include "lldb/Core/MappedHash.h"
13 #include "lldb/Core/Module.h"
14 #include "lldb/Core/PluginManager.h"
15 #include "lldb/Core/ValueObject.h"
16 #include "lldb/Symbol/ClangASTContext.h"
17 #include "lldb/Symbol/SymbolContext.h"
18 #include "lldb/Symbol/SymbolFile.h"
19 #include "lldb/Symbol/Type.h"
20 #include "lldb/Symbol/TypeList.h"
21 #include "lldb/Symbol/Variable.h"
22 #include "lldb/Target/Target.h"
23 #include "lldb/Utility/Log.h"
24 #include "lldb/Utility/Timer.h"
25 
26 #include "llvm/ADT/StringRef.h"
27 #include "llvm/Support/DJB.h"
28 
29 using namespace lldb;
30 using namespace lldb_private;
31 
32 char ObjCLanguageRuntime::ID = 0;
33 
34 // Destructor
35 ObjCLanguageRuntime::~ObjCLanguageRuntime() {}
36 
37 ObjCLanguageRuntime::ObjCLanguageRuntime(Process *process)
38     : LanguageRuntime(process), m_impl_cache(),
39       m_has_new_literals_and_indexing(eLazyBoolCalculate),
40       m_isa_to_descriptor(), m_hash_to_isa_map(), m_type_size_cache(),
41       m_isa_to_descriptor_stop_id(UINT32_MAX), m_complete_class_cache(),
42       m_negative_complete_class_cache() {}
43 
44 bool ObjCLanguageRuntime::IsWhitelistedRuntimeValue(ConstString name) {
45   static ConstString g_self = ConstString("self");
46   static ConstString g_cmd = ConstString("_cmd");
47   return name == g_self || name == g_cmd;
48 }
49 
50 bool ObjCLanguageRuntime::AddClass(ObjCISA isa,
51                                    const ClassDescriptorSP &descriptor_sp,
52                                    const char *class_name) {
53   if (isa != 0) {
54     m_isa_to_descriptor[isa] = descriptor_sp;
55     // class_name is assumed to be valid
56     m_hash_to_isa_map.insert(std::make_pair(llvm::djbHash(class_name), isa));
57     return true;
58   }
59   return false;
60 }
61 
62 void ObjCLanguageRuntime::AddToMethodCache(lldb::addr_t class_addr,
63                                            lldb::addr_t selector,
64                                            lldb::addr_t impl_addr) {
65   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
66   if (log) {
67     LLDB_LOGF(log,
68               "Caching: class 0x%" PRIx64 " selector 0x%" PRIx64
69               " implementation 0x%" PRIx64 ".",
70               class_addr, selector, impl_addr);
71   }
72   m_impl_cache.insert(std::pair<ClassAndSel, lldb::addr_t>(
73       ClassAndSel(class_addr, selector), impl_addr));
74 }
75 
76 lldb::addr_t ObjCLanguageRuntime::LookupInMethodCache(lldb::addr_t class_addr,
77                                                       lldb::addr_t selector) {
78   MsgImplMap::iterator pos, end = m_impl_cache.end();
79   pos = m_impl_cache.find(ClassAndSel(class_addr, selector));
80   if (pos != end)
81     return (*pos).second;
82   return LLDB_INVALID_ADDRESS;
83 }
84 
85 lldb::TypeSP
86 ObjCLanguageRuntime::LookupInCompleteClassCache(ConstString &name) {
87   CompleteClassMap::iterator complete_class_iter =
88       m_complete_class_cache.find(name);
89 
90   if (complete_class_iter != m_complete_class_cache.end()) {
91     // Check the weak pointer to make sure the type hasn't been unloaded
92     TypeSP complete_type_sp(complete_class_iter->second.lock());
93 
94     if (complete_type_sp)
95       return complete_type_sp;
96     else
97       m_complete_class_cache.erase(name);
98   }
99 
100   if (m_negative_complete_class_cache.count(name) > 0)
101     return TypeSP();
102 
103   const ModuleList &modules = m_process->GetTarget().GetImages();
104 
105   SymbolContextList sc_list;
106   modules.FindSymbolsWithNameAndType(name, eSymbolTypeObjCClass, sc_list);
107   const size_t matching_symbols = sc_list.GetSize();
108 
109   if (matching_symbols) {
110     SymbolContext sc;
111 
112     sc_list.GetContextAtIndex(0, sc);
113 
114     ModuleSP module_sp(sc.module_sp);
115 
116     if (!module_sp)
117       return TypeSP();
118 
119     const bool exact_match = true;
120     const uint32_t max_matches = UINT32_MAX;
121     TypeList types;
122 
123     llvm::DenseSet<SymbolFile *> searched_symbol_files;
124     module_sp->FindTypes(name, exact_match, max_matches, searched_symbol_files,
125                          types);
126 
127     for (uint32_t i = 0; i < types.GetSize(); ++i) {
128       TypeSP type_sp(types.GetTypeAtIndex(i));
129 
130       if (ClangASTContext::IsObjCObjectOrInterfaceType(
131               type_sp->GetForwardCompilerType())) {
132         if (type_sp->IsCompleteObjCClass()) {
133           m_complete_class_cache[name] = type_sp;
134           return type_sp;
135         }
136       }
137     }
138   }
139   m_negative_complete_class_cache.insert(name);
140   return TypeSP();
141 }
142 
143 size_t ObjCLanguageRuntime::GetByteOffsetForIvar(CompilerType &parent_qual_type,
144                                                  const char *ivar_name) {
145   return LLDB_INVALID_IVAR_OFFSET;
146 }
147 
148 bool ObjCLanguageRuntime::ClassDescriptor::IsPointerValid(
149     lldb::addr_t value, uint32_t ptr_size, bool allow_NULLs, bool allow_tagged,
150     bool check_version_specific) const {
151   if (!value)
152     return allow_NULLs;
153   if ((value % 2) == 1 && allow_tagged)
154     return true;
155   if ((value % ptr_size) == 0)
156     return (check_version_specific ? CheckPointer(value, ptr_size) : true);
157   else
158     return false;
159 }
160 
161 ObjCLanguageRuntime::ObjCISA
162 ObjCLanguageRuntime::GetISA(ConstString name) {
163   ISAToDescriptorIterator pos = GetDescriptorIterator(name);
164   if (pos != m_isa_to_descriptor.end())
165     return pos->first;
166   return 0;
167 }
168 
169 ObjCLanguageRuntime::ISAToDescriptorIterator
170 ObjCLanguageRuntime::GetDescriptorIterator(ConstString name) {
171   ISAToDescriptorIterator end = m_isa_to_descriptor.end();
172 
173   if (name) {
174     UpdateISAToDescriptorMap();
175     if (m_hash_to_isa_map.empty()) {
176       // No name hashes were provided, we need to just linearly power through
177       // the names and find a match
178       for (ISAToDescriptorIterator pos = m_isa_to_descriptor.begin();
179            pos != end; ++pos) {
180         if (pos->second->GetClassName() == name)
181           return pos;
182       }
183     } else {
184       // Name hashes were provided, so use them to efficiently lookup name to
185       // isa/descriptor
186       const uint32_t name_hash = llvm::djbHash(name.GetStringRef());
187       std::pair<HashToISAIterator, HashToISAIterator> range =
188           m_hash_to_isa_map.equal_range(name_hash);
189       for (HashToISAIterator range_pos = range.first; range_pos != range.second;
190            ++range_pos) {
191         ISAToDescriptorIterator pos =
192             m_isa_to_descriptor.find(range_pos->second);
193         if (pos != m_isa_to_descriptor.end()) {
194           if (pos->second->GetClassName() == name)
195             return pos;
196         }
197       }
198     }
199   }
200   return end;
201 }
202 
203 std::pair<ObjCLanguageRuntime::ISAToDescriptorIterator,
204           ObjCLanguageRuntime::ISAToDescriptorIterator>
205 ObjCLanguageRuntime::GetDescriptorIteratorPair(bool update_if_needed) {
206   if (update_if_needed)
207     UpdateISAToDescriptorMapIfNeeded();
208 
209   return std::pair<ObjCLanguageRuntime::ISAToDescriptorIterator,
210                    ObjCLanguageRuntime::ISAToDescriptorIterator>(
211       m_isa_to_descriptor.begin(), m_isa_to_descriptor.end());
212 }
213 
214 ObjCLanguageRuntime::ObjCISA
215 ObjCLanguageRuntime::GetParentClass(ObjCLanguageRuntime::ObjCISA isa) {
216   ClassDescriptorSP objc_class_sp(GetClassDescriptorFromISA(isa));
217   if (objc_class_sp) {
218     ClassDescriptorSP objc_super_class_sp(objc_class_sp->GetSuperclass());
219     if (objc_super_class_sp)
220       return objc_super_class_sp->GetISA();
221   }
222   return 0;
223 }
224 
225 ConstString
226 ObjCLanguageRuntime::GetActualTypeName(ObjCLanguageRuntime::ObjCISA isa) {
227   ClassDescriptorSP objc_class_sp(GetNonKVOClassDescriptor(isa));
228   if (objc_class_sp)
229     return objc_class_sp->GetClassName();
230   return ConstString();
231 }
232 
233 ObjCLanguageRuntime::ClassDescriptorSP
234 ObjCLanguageRuntime::GetClassDescriptorFromClassName(
235     ConstString class_name) {
236   ISAToDescriptorIterator pos = GetDescriptorIterator(class_name);
237   if (pos != m_isa_to_descriptor.end())
238     return pos->second;
239   return ClassDescriptorSP();
240 }
241 
242 ObjCLanguageRuntime::ClassDescriptorSP
243 ObjCLanguageRuntime::GetClassDescriptor(ValueObject &valobj) {
244   ClassDescriptorSP objc_class_sp;
245   // if we get an invalid VO (which might still happen when playing around with
246   // pointers returned by the expression parser, don't consider this a valid
247   // ObjC object)
248   if (valobj.GetCompilerType().IsValid()) {
249     addr_t isa_pointer = valobj.GetPointerValue();
250     if (isa_pointer != LLDB_INVALID_ADDRESS) {
251       ExecutionContext exe_ctx(valobj.GetExecutionContextRef());
252 
253       Process *process = exe_ctx.GetProcessPtr();
254       if (process) {
255         Status error;
256         ObjCISA isa = process->ReadPointerFromMemory(isa_pointer, error);
257         if (isa != LLDB_INVALID_ADDRESS)
258           objc_class_sp = GetClassDescriptorFromISA(isa);
259       }
260     }
261   }
262   return objc_class_sp;
263 }
264 
265 ObjCLanguageRuntime::ClassDescriptorSP
266 ObjCLanguageRuntime::GetNonKVOClassDescriptor(ValueObject &valobj) {
267   ObjCLanguageRuntime::ClassDescriptorSP objc_class_sp(
268       GetClassDescriptor(valobj));
269   if (objc_class_sp) {
270     if (!objc_class_sp->IsKVO())
271       return objc_class_sp;
272 
273     ClassDescriptorSP non_kvo_objc_class_sp(objc_class_sp->GetSuperclass());
274     if (non_kvo_objc_class_sp && non_kvo_objc_class_sp->IsValid())
275       return non_kvo_objc_class_sp;
276   }
277   return ClassDescriptorSP();
278 }
279 
280 ObjCLanguageRuntime::ClassDescriptorSP
281 ObjCLanguageRuntime::GetClassDescriptorFromISA(ObjCISA isa) {
282   if (isa) {
283     UpdateISAToDescriptorMap();
284     ObjCLanguageRuntime::ISAToDescriptorIterator pos =
285         m_isa_to_descriptor.find(isa);
286     if (pos != m_isa_to_descriptor.end())
287       return pos->second;
288   }
289   return ClassDescriptorSP();
290 }
291 
292 ObjCLanguageRuntime::ClassDescriptorSP
293 ObjCLanguageRuntime::GetNonKVOClassDescriptor(ObjCISA isa) {
294   if (isa) {
295     ClassDescriptorSP objc_class_sp = GetClassDescriptorFromISA(isa);
296     if (objc_class_sp && objc_class_sp->IsValid()) {
297       if (!objc_class_sp->IsKVO())
298         return objc_class_sp;
299 
300       ClassDescriptorSP non_kvo_objc_class_sp(objc_class_sp->GetSuperclass());
301       if (non_kvo_objc_class_sp && non_kvo_objc_class_sp->IsValid())
302         return non_kvo_objc_class_sp;
303     }
304   }
305   return ClassDescriptorSP();
306 }
307 
308 CompilerType
309 ObjCLanguageRuntime::EncodingToType::RealizeType(const char *name,
310                                                  bool for_expression) {
311   if (m_scratch_ast_ctx_up)
312     return RealizeType(*m_scratch_ast_ctx_up, name, for_expression);
313   return CompilerType();
314 }
315 
316 ObjCLanguageRuntime::EncodingToType::~EncodingToType() {}
317 
318 ObjCLanguageRuntime::EncodingToTypeSP ObjCLanguageRuntime::GetEncodingToType() {
319   return nullptr;
320 }
321 
322 bool ObjCLanguageRuntime::GetTypeBitSize(const CompilerType &compiler_type,
323                                          uint64_t &size) {
324   void *opaque_ptr = compiler_type.GetOpaqueQualType();
325   size = m_type_size_cache.Lookup(opaque_ptr);
326   // an ObjC object will at least have an ISA, so 0 is definitely not OK
327   if (size > 0)
328     return true;
329 
330   ClassDescriptorSP class_descriptor_sp =
331       GetClassDescriptorFromClassName(compiler_type.GetTypeName());
332   if (!class_descriptor_sp)
333     return false;
334 
335   int32_t max_offset = INT32_MIN;
336   uint64_t sizeof_max = 0;
337   bool found = false;
338 
339   for (size_t idx = 0; idx < class_descriptor_sp->GetNumIVars(); idx++) {
340     const auto &ivar = class_descriptor_sp->GetIVarAtIndex(idx);
341     int32_t cur_offset = ivar.m_offset;
342     if (cur_offset > max_offset) {
343       max_offset = cur_offset;
344       sizeof_max = ivar.m_size;
345       found = true;
346     }
347   }
348 
349   size = 8 * (max_offset + sizeof_max);
350   if (found)
351     m_type_size_cache.Insert(opaque_ptr, size);
352 
353   return found;
354 }
355 
356 lldb::BreakpointPreconditionSP
357 ObjCLanguageRuntime::GetBreakpointExceptionPrecondition(LanguageType language,
358                                                         bool throw_bp) {
359   if (language != eLanguageTypeObjC)
360     return lldb::BreakpointPreconditionSP();
361   if (!throw_bp)
362     return lldb::BreakpointPreconditionSP();
363   BreakpointPreconditionSP precondition_sp(
364       new ObjCLanguageRuntime::ObjCExceptionPrecondition());
365   return precondition_sp;
366 }
367 
368 // Exception breakpoint Precondition class for ObjC:
369 void ObjCLanguageRuntime::ObjCExceptionPrecondition::AddClassName(
370     const char *class_name) {
371   m_class_names.insert(class_name);
372 }
373 
374 ObjCLanguageRuntime::ObjCExceptionPrecondition::ObjCExceptionPrecondition() {}
375 
376 bool ObjCLanguageRuntime::ObjCExceptionPrecondition::EvaluatePrecondition(
377     StoppointCallbackContext &context) {
378   return true;
379 }
380 
381 void ObjCLanguageRuntime::ObjCExceptionPrecondition::GetDescription(
382     Stream &stream, lldb::DescriptionLevel level) {}
383 
384 Status ObjCLanguageRuntime::ObjCExceptionPrecondition::ConfigurePrecondition(
385     Args &args) {
386   Status error;
387   if (args.GetArgumentCount() > 0)
388     error.SetErrorString(
389         "The ObjC Exception breakpoint doesn't support extra options.");
390   return error;
391 }
392 
393 llvm::Optional<CompilerType>
394 ObjCLanguageRuntime::GetRuntimeType(CompilerType base_type) {
395   CompilerType class_type;
396   bool is_pointer_type = false;
397 
398   if (ClangASTContext::IsObjCObjectPointerType(base_type, &class_type))
399     is_pointer_type = true;
400   else if (ClangASTContext::IsObjCObjectOrInterfaceType(base_type))
401     class_type = base_type;
402   else
403     return llvm::None;
404 
405   if (!class_type)
406     return llvm::None;
407 
408   ConstString class_name(class_type.GetConstTypeName());
409   if (!class_name)
410     return llvm::None;
411 
412   TypeSP complete_objc_class_type_sp = LookupInCompleteClassCache(class_name);
413   if (!complete_objc_class_type_sp)
414     return llvm::None;
415 
416   CompilerType complete_class(
417       complete_objc_class_type_sp->GetFullCompilerType());
418   if (complete_class.GetCompleteType()) {
419     if (is_pointer_type)
420       return complete_class.GetPointerType();
421     else
422       return complete_class;
423   }
424 
425   return llvm::None;
426 }
427