1 //===-- ObjCLanguageRuntime.cpp -------------------------------------------===//
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 "Plugins/TypeSystem/Clang/TypeSystemClang.h"
13 #include "lldb/Core/Module.h"
14 #include "lldb/Core/PluginManager.h"
15 #include "lldb/Core/ValueObject.h"
16 #include "lldb/Symbol/SymbolContext.h"
17 #include "lldb/Symbol/SymbolFile.h"
18 #include "lldb/Symbol/Type.h"
19 #include "lldb/Symbol/TypeList.h"
20 #include "lldb/Symbol/Variable.h"
21 #include "lldb/Target/ABI.h"
22 #include "lldb/Target/Target.h"
23 #include "lldb/Utility/LLDBLog.h"
24 #include "lldb/Utility/Log.h"
25 #include "lldb/Utility/Timer.h"
26 
27 #include "llvm/ADT/StringRef.h"
28 #include "llvm/Support/DJB.h"
29 #include <optional>
30 
31 using namespace lldb;
32 using namespace lldb_private;
33 
34 char ObjCLanguageRuntime::ID = 0;
35 
36 // Destructor
37 ObjCLanguageRuntime::~ObjCLanguageRuntime() = default;
38 
ObjCLanguageRuntime(Process * process)39 ObjCLanguageRuntime::ObjCLanguageRuntime(Process *process)
40     : LanguageRuntime(process), m_impl_cache(), m_impl_str_cache(),
41       m_has_new_literals_and_indexing(eLazyBoolCalculate),
42       m_isa_to_descriptor(), m_hash_to_isa_map(), m_type_size_cache(),
43       m_isa_to_descriptor_stop_id(UINT32_MAX), m_complete_class_cache(),
44       m_negative_complete_class_cache() {}
45 
IsAllowedRuntimeValue(ConstString name)46 bool ObjCLanguageRuntime::IsAllowedRuntimeValue(ConstString name) {
47   static ConstString g_self = ConstString("self");
48   static ConstString g_cmd = ConstString("_cmd");
49   return name == g_self || name == g_cmd;
50 }
51 
AddClass(ObjCISA isa,const ClassDescriptorSP & descriptor_sp,const char * class_name)52 bool ObjCLanguageRuntime::AddClass(ObjCISA isa,
53                                    const ClassDescriptorSP &descriptor_sp,
54                                    const char *class_name) {
55   if (isa != 0) {
56     m_isa_to_descriptor[isa] = descriptor_sp;
57     // class_name is assumed to be valid
58     m_hash_to_isa_map.insert(std::make_pair(llvm::djbHash(class_name), isa));
59     return true;
60   }
61   return false;
62 }
63 
AddToMethodCache(lldb::addr_t class_addr,lldb::addr_t selector,lldb::addr_t impl_addr)64 void ObjCLanguageRuntime::AddToMethodCache(lldb::addr_t class_addr,
65                                            lldb::addr_t selector,
66                                            lldb::addr_t impl_addr) {
67   Log *log = GetLog(LLDBLog::Step);
68   if (log) {
69     LLDB_LOGF(log,
70               "Caching: class 0x%" PRIx64 " selector 0x%" PRIx64
71               " implementation 0x%" PRIx64 ".",
72               class_addr, selector, impl_addr);
73   }
74   m_impl_cache.insert(std::pair<ClassAndSel, lldb::addr_t>(
75       ClassAndSel(class_addr, selector), impl_addr));
76 }
77 
AddToMethodCache(lldb::addr_t class_addr,llvm::StringRef sel_str,lldb::addr_t impl_addr)78 void ObjCLanguageRuntime::AddToMethodCache(lldb::addr_t class_addr,
79                                            llvm::StringRef sel_str,
80                                            lldb::addr_t impl_addr) {
81   Log *log = GetLog(LLDBLog::Step);
82 
83   LLDB_LOG(log, "Caching: class {0} selector {1} implementation {2}.",
84            class_addr, sel_str, impl_addr);
85 
86   m_impl_str_cache.insert(std::pair<ClassAndSelStr, lldb::addr_t>(
87       ClassAndSelStr(class_addr, sel_str), impl_addr));
88 }
89 
LookupInMethodCache(lldb::addr_t class_addr,lldb::addr_t selector)90 lldb::addr_t ObjCLanguageRuntime::LookupInMethodCache(lldb::addr_t class_addr,
91                                                       lldb::addr_t selector) {
92   MsgImplMap::iterator pos, end = m_impl_cache.end();
93   pos = m_impl_cache.find(ClassAndSel(class_addr, selector));
94   if (pos != end)
95     return (*pos).second;
96   return LLDB_INVALID_ADDRESS;
97 }
98 
LookupInMethodCache(lldb::addr_t class_addr,llvm::StringRef sel_str)99 lldb::addr_t ObjCLanguageRuntime::LookupInMethodCache(lldb::addr_t class_addr,
100                                                       llvm::StringRef sel_str) {
101   MsgImplStrMap::iterator pos, end = m_impl_str_cache.end();
102   pos = m_impl_str_cache.find(ClassAndSelStr(class_addr, sel_str));
103   if (pos != end)
104     return (*pos).second;
105   return LLDB_INVALID_ADDRESS;
106 }
107 
108 lldb::TypeSP
LookupInCompleteClassCache(ConstString & name)109 ObjCLanguageRuntime::LookupInCompleteClassCache(ConstString &name) {
110   CompleteClassMap::iterator complete_class_iter =
111       m_complete_class_cache.find(name);
112 
113   if (complete_class_iter != m_complete_class_cache.end()) {
114     // Check the weak pointer to make sure the type hasn't been unloaded
115     TypeSP complete_type_sp(complete_class_iter->second.lock());
116 
117     if (complete_type_sp)
118       return complete_type_sp;
119     else
120       m_complete_class_cache.erase(name);
121   }
122 
123   if (m_negative_complete_class_cache.count(name) > 0)
124     return TypeSP();
125 
126   const ModuleList &modules = m_process->GetTarget().GetImages();
127 
128   SymbolContextList sc_list;
129   modules.FindSymbolsWithNameAndType(name, eSymbolTypeObjCClass, sc_list);
130   const size_t matching_symbols = sc_list.GetSize();
131 
132   if (matching_symbols) {
133     SymbolContext sc;
134 
135     sc_list.GetContextAtIndex(0, sc);
136 
137     ModuleSP module_sp(sc.module_sp);
138 
139     if (!module_sp)
140       return TypeSP();
141 
142     TypeQuery query(name.GetStringRef(), TypeQueryOptions::e_exact_match);
143     TypeResults results;
144     module_sp->FindTypes(query, results);
145     for (const TypeSP &type_sp : results.GetTypeMap().Types()) {
146       if (TypeSystemClang::IsObjCObjectOrInterfaceType(
147               type_sp->GetForwardCompilerType())) {
148         if (TypePayloadClang(type_sp->GetPayload()).IsCompleteObjCClass()) {
149           m_complete_class_cache[name] = type_sp;
150           return type_sp;
151         }
152       }
153     }
154   }
155   m_negative_complete_class_cache.insert(name);
156   return TypeSP();
157 }
158 
GetByteOffsetForIvar(CompilerType & parent_qual_type,const char * ivar_name)159 size_t ObjCLanguageRuntime::GetByteOffsetForIvar(CompilerType &parent_qual_type,
160                                                  const char *ivar_name) {
161   return LLDB_INVALID_IVAR_OFFSET;
162 }
163 
IsPointerValid(lldb::addr_t value,uint32_t ptr_size,bool allow_NULLs,bool allow_tagged,bool check_version_specific) const164 bool ObjCLanguageRuntime::ClassDescriptor::IsPointerValid(
165     lldb::addr_t value, uint32_t ptr_size, bool allow_NULLs, bool allow_tagged,
166     bool check_version_specific) const {
167   if (!value)
168     return allow_NULLs;
169   if ((value % 2) == 1 && allow_tagged)
170     return true;
171   if ((value % ptr_size) == 0)
172     return (check_version_specific ? CheckPointer(value, ptr_size) : true);
173   else
174     return false;
175 }
176 
177 ObjCLanguageRuntime::ObjCISA
GetISA(ConstString name)178 ObjCLanguageRuntime::GetISA(ConstString name) {
179   ISAToDescriptorIterator pos = GetDescriptorIterator(name);
180   if (pos != m_isa_to_descriptor.end())
181     return pos->first;
182   return 0;
183 }
184 
185 ObjCLanguageRuntime::ISAToDescriptorIterator
GetDescriptorIterator(ConstString name)186 ObjCLanguageRuntime::GetDescriptorIterator(ConstString name) {
187   ISAToDescriptorIterator end = m_isa_to_descriptor.end();
188 
189   if (name) {
190     UpdateISAToDescriptorMap();
191     if (m_hash_to_isa_map.empty()) {
192       // No name hashes were provided, we need to just linearly power through
193       // the names and find a match
194       for (ISAToDescriptorIterator pos = m_isa_to_descriptor.begin();
195            pos != end; ++pos) {
196         if (pos->second->GetClassName() == name)
197           return pos;
198       }
199     } else {
200       // Name hashes were provided, so use them to efficiently lookup name to
201       // isa/descriptor
202       const uint32_t name_hash = llvm::djbHash(name.GetStringRef());
203       std::pair<HashToISAIterator, HashToISAIterator> range =
204           m_hash_to_isa_map.equal_range(name_hash);
205       for (HashToISAIterator range_pos = range.first; range_pos != range.second;
206            ++range_pos) {
207         ISAToDescriptorIterator pos =
208             m_isa_to_descriptor.find(range_pos->second);
209         if (pos != m_isa_to_descriptor.end()) {
210           if (pos->second->GetClassName() == name)
211             return pos;
212         }
213       }
214     }
215   }
216   return end;
217 }
218 
219 std::pair<ObjCLanguageRuntime::ISAToDescriptorIterator,
220           ObjCLanguageRuntime::ISAToDescriptorIterator>
GetDescriptorIteratorPair(bool update_if_needed)221 ObjCLanguageRuntime::GetDescriptorIteratorPair(bool update_if_needed) {
222   if (update_if_needed)
223     UpdateISAToDescriptorMapIfNeeded();
224 
225   return std::pair<ObjCLanguageRuntime::ISAToDescriptorIterator,
226                    ObjCLanguageRuntime::ISAToDescriptorIterator>(
227       m_isa_to_descriptor.begin(), m_isa_to_descriptor.end());
228 }
229 
ReadObjCLibraryIfNeeded(const ModuleList & module_list)230 void ObjCLanguageRuntime::ReadObjCLibraryIfNeeded(
231     const ModuleList &module_list) {
232   if (!HasReadObjCLibrary()) {
233     std::lock_guard<std::recursive_mutex> guard(module_list.GetMutex());
234 
235     size_t num_modules = module_list.GetSize();
236     for (size_t i = 0; i < num_modules; i++) {
237       auto mod = module_list.GetModuleAtIndex(i);
238       if (IsModuleObjCLibrary(mod)) {
239         ReadObjCLibrary(mod);
240         break;
241       }
242     }
243   }
244 }
245 
246 ObjCLanguageRuntime::ObjCISA
GetParentClass(ObjCLanguageRuntime::ObjCISA isa)247 ObjCLanguageRuntime::GetParentClass(ObjCLanguageRuntime::ObjCISA isa) {
248   ClassDescriptorSP objc_class_sp(GetClassDescriptorFromISA(isa));
249   if (objc_class_sp) {
250     ClassDescriptorSP objc_super_class_sp(objc_class_sp->GetSuperclass());
251     if (objc_super_class_sp)
252       return objc_super_class_sp->GetISA();
253   }
254   return 0;
255 }
256 
257 ObjCLanguageRuntime::ClassDescriptorSP
GetClassDescriptorFromClassName(ConstString class_name)258 ObjCLanguageRuntime::GetClassDescriptorFromClassName(
259     ConstString class_name) {
260   ISAToDescriptorIterator pos = GetDescriptorIterator(class_name);
261   if (pos != m_isa_to_descriptor.end())
262     return pos->second;
263   return ClassDescriptorSP();
264 }
265 
266 ObjCLanguageRuntime::ClassDescriptorSP
GetClassDescriptor(ValueObject & valobj)267 ObjCLanguageRuntime::GetClassDescriptor(ValueObject &valobj) {
268   ClassDescriptorSP objc_class_sp;
269   // if we get an invalid VO (which might still happen when playing around with
270   // pointers returned by the expression parser, don't consider this a valid
271   // ObjC object)
272   if (valobj.GetCompilerType().IsValid()) {
273     addr_t isa_pointer = valobj.GetPointerValue();
274     if (isa_pointer != LLDB_INVALID_ADDRESS) {
275       ExecutionContext exe_ctx(valobj.GetExecutionContextRef());
276 
277       Process *process = exe_ctx.GetProcessPtr();
278       if (process) {
279         Status error;
280         ObjCISA isa = process->ReadPointerFromMemory(isa_pointer, error);
281         if (isa != LLDB_INVALID_ADDRESS)
282           objc_class_sp = GetClassDescriptorFromISA(isa);
283       }
284     }
285   }
286   return objc_class_sp;
287 }
288 
289 ObjCLanguageRuntime::ClassDescriptorSP
GetNonKVOClassDescriptor(ValueObject & valobj)290 ObjCLanguageRuntime::GetNonKVOClassDescriptor(ValueObject &valobj) {
291   ObjCLanguageRuntime::ClassDescriptorSP objc_class_sp(
292       GetClassDescriptor(valobj));
293   if (objc_class_sp) {
294     if (!objc_class_sp->IsKVO())
295       return objc_class_sp;
296 
297     ClassDescriptorSP non_kvo_objc_class_sp(objc_class_sp->GetSuperclass());
298     if (non_kvo_objc_class_sp && non_kvo_objc_class_sp->IsValid())
299       return non_kvo_objc_class_sp;
300   }
301   return ClassDescriptorSP();
302 }
303 
304 ObjCLanguageRuntime::ClassDescriptorSP
GetClassDescriptorFromISA(ObjCISA isa)305 ObjCLanguageRuntime::GetClassDescriptorFromISA(ObjCISA isa) {
306   if (isa) {
307     UpdateISAToDescriptorMap();
308 
309     ObjCLanguageRuntime::ISAToDescriptorIterator pos =
310         m_isa_to_descriptor.find(isa);
311     if (pos != m_isa_to_descriptor.end())
312       return pos->second;
313 
314     if (ABISP abi_sp = m_process->GetABI()) {
315       pos = m_isa_to_descriptor.find(abi_sp->FixCodeAddress(isa));
316       if (pos != m_isa_to_descriptor.end())
317         return pos->second;
318     }
319   }
320   return ClassDescriptorSP();
321 }
322 
323 ObjCLanguageRuntime::ClassDescriptorSP
GetNonKVOClassDescriptor(ObjCISA isa)324 ObjCLanguageRuntime::GetNonKVOClassDescriptor(ObjCISA isa) {
325   if (isa) {
326     ClassDescriptorSP objc_class_sp = GetClassDescriptorFromISA(isa);
327     if (objc_class_sp && objc_class_sp->IsValid()) {
328       if (!objc_class_sp->IsKVO())
329         return objc_class_sp;
330 
331       ClassDescriptorSP non_kvo_objc_class_sp(objc_class_sp->GetSuperclass());
332       if (non_kvo_objc_class_sp && non_kvo_objc_class_sp->IsValid())
333         return non_kvo_objc_class_sp;
334     }
335   }
336   return ClassDescriptorSP();
337 }
338 
339 CompilerType
RealizeType(const char * name,bool for_expression)340 ObjCLanguageRuntime::EncodingToType::RealizeType(const char *name,
341                                                  bool for_expression) {
342   if (m_scratch_ast_ctx_sp)
343     return RealizeType(*m_scratch_ast_ctx_sp, name, for_expression);
344   return CompilerType();
345 }
346 
347 ObjCLanguageRuntime::EncodingToType::~EncodingToType() = default;
348 
GetEncodingToType()349 ObjCLanguageRuntime::EncodingToTypeSP ObjCLanguageRuntime::GetEncodingToType() {
350   return nullptr;
351 }
352 
GetTypeBitSize(const CompilerType & compiler_type,uint64_t & size)353 bool ObjCLanguageRuntime::GetTypeBitSize(const CompilerType &compiler_type,
354                                          uint64_t &size) {
355   void *opaque_ptr = compiler_type.GetOpaqueQualType();
356   size = m_type_size_cache.Lookup(opaque_ptr);
357   // an ObjC object will at least have an ISA, so 0 is definitely not OK
358   if (size > 0)
359     return true;
360 
361   ClassDescriptorSP class_descriptor_sp =
362       GetClassDescriptorFromClassName(compiler_type.GetTypeName());
363   if (!class_descriptor_sp)
364     return false;
365 
366   int32_t max_offset = INT32_MIN;
367   uint64_t sizeof_max = 0;
368   bool found = false;
369 
370   for (size_t idx = 0; idx < class_descriptor_sp->GetNumIVars(); idx++) {
371     const auto &ivar = class_descriptor_sp->GetIVarAtIndex(idx);
372     int32_t cur_offset = ivar.m_offset;
373     if (cur_offset > max_offset) {
374       max_offset = cur_offset;
375       sizeof_max = ivar.m_size;
376       found = true;
377     }
378   }
379 
380   size = 8 * (max_offset + sizeof_max);
381   if (found)
382     m_type_size_cache.Insert(opaque_ptr, size);
383 
384   return found;
385 }
386 
387 lldb::BreakpointPreconditionSP
GetBreakpointExceptionPrecondition(LanguageType language,bool throw_bp)388 ObjCLanguageRuntime::GetBreakpointExceptionPrecondition(LanguageType language,
389                                                         bool throw_bp) {
390   if (language != eLanguageTypeObjC)
391     return lldb::BreakpointPreconditionSP();
392   if (!throw_bp)
393     return lldb::BreakpointPreconditionSP();
394   BreakpointPreconditionSP precondition_sp(
395       new ObjCLanguageRuntime::ObjCExceptionPrecondition());
396   return precondition_sp;
397 }
398 
399 // Exception breakpoint Precondition class for ObjC:
AddClassName(const char * class_name)400 void ObjCLanguageRuntime::ObjCExceptionPrecondition::AddClassName(
401     const char *class_name) {
402   m_class_names.insert(class_name);
403 }
404 
405 ObjCLanguageRuntime::ObjCExceptionPrecondition::ObjCExceptionPrecondition() =
406     default;
407 
EvaluatePrecondition(StoppointCallbackContext & context)408 bool ObjCLanguageRuntime::ObjCExceptionPrecondition::EvaluatePrecondition(
409     StoppointCallbackContext &context) {
410   return true;
411 }
412 
GetDescription(Stream & stream,lldb::DescriptionLevel level)413 void ObjCLanguageRuntime::ObjCExceptionPrecondition::GetDescription(
414     Stream &stream, lldb::DescriptionLevel level) {}
415 
ConfigurePrecondition(Args & args)416 Status ObjCLanguageRuntime::ObjCExceptionPrecondition::ConfigurePrecondition(
417     Args &args) {
418   Status error;
419   if (args.GetArgumentCount() > 0)
420     error.SetErrorString(
421         "The ObjC Exception breakpoint doesn't support extra options.");
422   return error;
423 }
424 
425 std::optional<CompilerType>
GetRuntimeType(CompilerType base_type)426 ObjCLanguageRuntime::GetRuntimeType(CompilerType base_type) {
427   CompilerType class_type;
428   bool is_pointer_type = false;
429 
430   if (TypeSystemClang::IsObjCObjectPointerType(base_type, &class_type))
431     is_pointer_type = true;
432   else if (TypeSystemClang::IsObjCObjectOrInterfaceType(base_type))
433     class_type = base_type;
434   else
435     return std::nullopt;
436 
437   if (!class_type)
438     return std::nullopt;
439 
440   ConstString class_name(class_type.GetTypeName());
441   if (!class_name)
442     return std::nullopt;
443 
444   TypeSP complete_objc_class_type_sp = LookupInCompleteClassCache(class_name);
445   if (!complete_objc_class_type_sp)
446     return std::nullopt;
447 
448   CompilerType complete_class(
449       complete_objc_class_type_sp->GetFullCompilerType());
450   if (complete_class.GetCompleteType()) {
451     if (is_pointer_type)
452       return complete_class.GetPointerType();
453     else
454       return complete_class;
455   }
456 
457   return std::nullopt;
458 }
459