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   const size_t matching_symbols =
107       modules.FindSymbolsWithNameAndType(name, eSymbolTypeObjCClass, sc_list);
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     const uint32_t num_types = module_sp->FindTypes(
125         name, exact_match, max_matches, searched_symbol_files, types);
126 
127     if (num_types) {
128       uint32_t i;
129       for (i = 0; i < num_types; ++i) {
130         TypeSP type_sp(types.GetTypeAtIndex(i));
131 
132         if (ClangASTContext::IsObjCObjectOrInterfaceType(
133                 type_sp->GetForwardCompilerType())) {
134           if (type_sp->IsCompleteObjCClass()) {
135             m_complete_class_cache[name] = type_sp;
136             return type_sp;
137           }
138         }
139       }
140     }
141   }
142   m_negative_complete_class_cache.insert(name);
143   return TypeSP();
144 }
145 
146 size_t ObjCLanguageRuntime::GetByteOffsetForIvar(CompilerType &parent_qual_type,
147                                                  const char *ivar_name) {
148   return LLDB_INVALID_IVAR_OFFSET;
149 }
150 
151 bool ObjCLanguageRuntime::ClassDescriptor::IsPointerValid(
152     lldb::addr_t value, uint32_t ptr_size, bool allow_NULLs, bool allow_tagged,
153     bool check_version_specific) const {
154   if (!value)
155     return allow_NULLs;
156   if ((value % 2) == 1 && allow_tagged)
157     return true;
158   if ((value % ptr_size) == 0)
159     return (check_version_specific ? CheckPointer(value, ptr_size) : true);
160   else
161     return false;
162 }
163 
164 ObjCLanguageRuntime::ObjCISA
165 ObjCLanguageRuntime::GetISA(ConstString name) {
166   ISAToDescriptorIterator pos = GetDescriptorIterator(name);
167   if (pos != m_isa_to_descriptor.end())
168     return pos->first;
169   return 0;
170 }
171 
172 ObjCLanguageRuntime::ISAToDescriptorIterator
173 ObjCLanguageRuntime::GetDescriptorIterator(ConstString name) {
174   ISAToDescriptorIterator end = m_isa_to_descriptor.end();
175 
176   if (name) {
177     UpdateISAToDescriptorMap();
178     if (m_hash_to_isa_map.empty()) {
179       // No name hashes were provided, we need to just linearly power through
180       // the names and find a match
181       for (ISAToDescriptorIterator pos = m_isa_to_descriptor.begin();
182            pos != end; ++pos) {
183         if (pos->second->GetClassName() == name)
184           return pos;
185       }
186     } else {
187       // Name hashes were provided, so use them to efficiently lookup name to
188       // isa/descriptor
189       const uint32_t name_hash = llvm::djbHash(name.GetStringRef());
190       std::pair<HashToISAIterator, HashToISAIterator> range =
191           m_hash_to_isa_map.equal_range(name_hash);
192       for (HashToISAIterator range_pos = range.first; range_pos != range.second;
193            ++range_pos) {
194         ISAToDescriptorIterator pos =
195             m_isa_to_descriptor.find(range_pos->second);
196         if (pos != m_isa_to_descriptor.end()) {
197           if (pos->second->GetClassName() == name)
198             return pos;
199         }
200       }
201     }
202   }
203   return end;
204 }
205 
206 std::pair<ObjCLanguageRuntime::ISAToDescriptorIterator,
207           ObjCLanguageRuntime::ISAToDescriptorIterator>
208 ObjCLanguageRuntime::GetDescriptorIteratorPair(bool update_if_needed) {
209   if (update_if_needed)
210     UpdateISAToDescriptorMapIfNeeded();
211 
212   return std::pair<ObjCLanguageRuntime::ISAToDescriptorIterator,
213                    ObjCLanguageRuntime::ISAToDescriptorIterator>(
214       m_isa_to_descriptor.begin(), m_isa_to_descriptor.end());
215 }
216 
217 ObjCLanguageRuntime::ObjCISA
218 ObjCLanguageRuntime::GetParentClass(ObjCLanguageRuntime::ObjCISA isa) {
219   ClassDescriptorSP objc_class_sp(GetClassDescriptorFromISA(isa));
220   if (objc_class_sp) {
221     ClassDescriptorSP objc_super_class_sp(objc_class_sp->GetSuperclass());
222     if (objc_super_class_sp)
223       return objc_super_class_sp->GetISA();
224   }
225   return 0;
226 }
227 
228 ConstString
229 ObjCLanguageRuntime::GetActualTypeName(ObjCLanguageRuntime::ObjCISA isa) {
230   ClassDescriptorSP objc_class_sp(GetNonKVOClassDescriptor(isa));
231   if (objc_class_sp)
232     return objc_class_sp->GetClassName();
233   return ConstString();
234 }
235 
236 ObjCLanguageRuntime::ClassDescriptorSP
237 ObjCLanguageRuntime::GetClassDescriptorFromClassName(
238     ConstString class_name) {
239   ISAToDescriptorIterator pos = GetDescriptorIterator(class_name);
240   if (pos != m_isa_to_descriptor.end())
241     return pos->second;
242   return ClassDescriptorSP();
243 }
244 
245 ObjCLanguageRuntime::ClassDescriptorSP
246 ObjCLanguageRuntime::GetClassDescriptor(ValueObject &valobj) {
247   ClassDescriptorSP objc_class_sp;
248   // if we get an invalid VO (which might still happen when playing around with
249   // pointers returned by the expression parser, don't consider this a valid
250   // ObjC object)
251   if (valobj.GetCompilerType().IsValid()) {
252     addr_t isa_pointer = valobj.GetPointerValue();
253     if (isa_pointer != LLDB_INVALID_ADDRESS) {
254       ExecutionContext exe_ctx(valobj.GetExecutionContextRef());
255 
256       Process *process = exe_ctx.GetProcessPtr();
257       if (process) {
258         Status error;
259         ObjCISA isa = process->ReadPointerFromMemory(isa_pointer, error);
260         if (isa != LLDB_INVALID_ADDRESS)
261           objc_class_sp = GetClassDescriptorFromISA(isa);
262       }
263     }
264   }
265   return objc_class_sp;
266 }
267 
268 ObjCLanguageRuntime::ClassDescriptorSP
269 ObjCLanguageRuntime::GetNonKVOClassDescriptor(ValueObject &valobj) {
270   ObjCLanguageRuntime::ClassDescriptorSP objc_class_sp(
271       GetClassDescriptor(valobj));
272   if (objc_class_sp) {
273     if (!objc_class_sp->IsKVO())
274       return objc_class_sp;
275 
276     ClassDescriptorSP non_kvo_objc_class_sp(objc_class_sp->GetSuperclass());
277     if (non_kvo_objc_class_sp && non_kvo_objc_class_sp->IsValid())
278       return non_kvo_objc_class_sp;
279   }
280   return ClassDescriptorSP();
281 }
282 
283 ObjCLanguageRuntime::ClassDescriptorSP
284 ObjCLanguageRuntime::GetClassDescriptorFromISA(ObjCISA isa) {
285   if (isa) {
286     UpdateISAToDescriptorMap();
287     ObjCLanguageRuntime::ISAToDescriptorIterator pos =
288         m_isa_to_descriptor.find(isa);
289     if (pos != m_isa_to_descriptor.end())
290       return pos->second;
291   }
292   return ClassDescriptorSP();
293 }
294 
295 ObjCLanguageRuntime::ClassDescriptorSP
296 ObjCLanguageRuntime::GetNonKVOClassDescriptor(ObjCISA isa) {
297   if (isa) {
298     ClassDescriptorSP objc_class_sp = GetClassDescriptorFromISA(isa);
299     if (objc_class_sp && objc_class_sp->IsValid()) {
300       if (!objc_class_sp->IsKVO())
301         return objc_class_sp;
302 
303       ClassDescriptorSP non_kvo_objc_class_sp(objc_class_sp->GetSuperclass());
304       if (non_kvo_objc_class_sp && non_kvo_objc_class_sp->IsValid())
305         return non_kvo_objc_class_sp;
306     }
307   }
308   return ClassDescriptorSP();
309 }
310 
311 CompilerType
312 ObjCLanguageRuntime::EncodingToType::RealizeType(const char *name,
313                                                  bool for_expression) {
314   if (m_scratch_ast_ctx_up)
315     return RealizeType(*m_scratch_ast_ctx_up, name, for_expression);
316   return CompilerType();
317 }
318 
319 CompilerType ObjCLanguageRuntime::EncodingToType::RealizeType(
320     ClangASTContext &ast_ctx, const char *name, bool for_expression) {
321   clang::ASTContext *clang_ast = ast_ctx.getASTContext();
322   if (!clang_ast)
323     return CompilerType();
324   return RealizeType(*clang_ast, name, for_expression);
325 }
326 
327 ObjCLanguageRuntime::EncodingToType::~EncodingToType() {}
328 
329 ObjCLanguageRuntime::EncodingToTypeSP ObjCLanguageRuntime::GetEncodingToType() {
330   return nullptr;
331 }
332 
333 bool ObjCLanguageRuntime::GetTypeBitSize(const CompilerType &compiler_type,
334                                          uint64_t &size) {
335   void *opaque_ptr = compiler_type.GetOpaqueQualType();
336   size = m_type_size_cache.Lookup(opaque_ptr);
337   // an ObjC object will at least have an ISA, so 0 is definitely not OK
338   if (size > 0)
339     return true;
340 
341   ClassDescriptorSP class_descriptor_sp =
342       GetClassDescriptorFromClassName(compiler_type.GetTypeName());
343   if (!class_descriptor_sp)
344     return false;
345 
346   int32_t max_offset = INT32_MIN;
347   uint64_t sizeof_max = 0;
348   bool found = false;
349 
350   for (size_t idx = 0; idx < class_descriptor_sp->GetNumIVars(); idx++) {
351     const auto &ivar = class_descriptor_sp->GetIVarAtIndex(idx);
352     int32_t cur_offset = ivar.m_offset;
353     if (cur_offset > max_offset) {
354       max_offset = cur_offset;
355       sizeof_max = ivar.m_size;
356       found = true;
357     }
358   }
359 
360   size = 8 * (max_offset + sizeof_max);
361   if (found)
362     m_type_size_cache.Insert(opaque_ptr, size);
363 
364   return found;
365 }
366 
367 lldb::BreakpointPreconditionSP
368 ObjCLanguageRuntime::GetBreakpointExceptionPrecondition(LanguageType language,
369                                                         bool throw_bp) {
370   if (language != eLanguageTypeObjC)
371     return lldb::BreakpointPreconditionSP();
372   if (!throw_bp)
373     return lldb::BreakpointPreconditionSP();
374   BreakpointPreconditionSP precondition_sp(
375       new ObjCLanguageRuntime::ObjCExceptionPrecondition());
376   return precondition_sp;
377 }
378 
379 // Exception breakpoint Precondition class for ObjC:
380 void ObjCLanguageRuntime::ObjCExceptionPrecondition::AddClassName(
381     const char *class_name) {
382   m_class_names.insert(class_name);
383 }
384 
385 ObjCLanguageRuntime::ObjCExceptionPrecondition::ObjCExceptionPrecondition() {}
386 
387 bool ObjCLanguageRuntime::ObjCExceptionPrecondition::EvaluatePrecondition(
388     StoppointCallbackContext &context) {
389   return true;
390 }
391 
392 void ObjCLanguageRuntime::ObjCExceptionPrecondition::GetDescription(
393     Stream &stream, lldb::DescriptionLevel level) {}
394 
395 Status ObjCLanguageRuntime::ObjCExceptionPrecondition::ConfigurePrecondition(
396     Args &args) {
397   Status error;
398   if (args.GetArgumentCount() > 0)
399     error.SetErrorString(
400         "The ObjC Exception breakpoint doesn't support extra options.");
401   return error;
402 }
403 
404 llvm::Optional<CompilerType>
405 ObjCLanguageRuntime::GetRuntimeType(CompilerType base_type) {
406   CompilerType class_type;
407   bool is_pointer_type = false;
408 
409   if (ClangASTContext::IsObjCObjectPointerType(base_type, &class_type))
410     is_pointer_type = true;
411   else if (ClangASTContext::IsObjCObjectOrInterfaceType(base_type))
412     class_type = base_type;
413   else
414     return llvm::None;
415 
416   if (!class_type)
417     return llvm::None;
418 
419   ConstString class_name(class_type.GetConstTypeName());
420   if (!class_name)
421     return llvm::None;
422 
423   TypeSP complete_objc_class_type_sp = LookupInCompleteClassCache(class_name);
424   if (!complete_objc_class_type_sp)
425     return llvm::None;
426 
427   CompilerType complete_class(
428       complete_objc_class_type_sp->GetFullCompilerType());
429   if (complete_class.GetCompleteType()) {
430     if (is_pointer_type)
431       return complete_class.GetPointerType();
432     else
433       return complete_class;
434   }
435 
436   return llvm::None;
437 }
438