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/MappedHash.h"
14 #include "lldb/Core/Module.h"
15 #include "lldb/Core/PluginManager.h"
16 #include "lldb/Core/ValueObject.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/ABI.h"
23 #include "lldb/Target/Target.h"
24 #include "lldb/Utility/LLDBLog.h"
25 #include "lldb/Utility/Log.h"
26 #include "lldb/Utility/Timer.h"
27 
28 #include "llvm/ADT/StringRef.h"
29 #include "llvm/Support/DJB.h"
30 
31 using namespace lldb;
32 using namespace lldb_private;
33 
34 char ObjCLanguageRuntime::ID = 0;
35 
36 // Destructor
37 ObjCLanguageRuntime::~ObjCLanguageRuntime() = default;
38 
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 
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 
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 
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 
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 
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 
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
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     const bool exact_match = true;
143     const uint32_t max_matches = UINT32_MAX;
144     TypeList types;
145 
146     llvm::DenseSet<SymbolFile *> searched_symbol_files;
147     module_sp->FindTypes(name, exact_match, max_matches, searched_symbol_files,
148                          types);
149 
150     for (uint32_t i = 0; i < types.GetSize(); ++i) {
151       TypeSP type_sp(types.GetTypeAtIndex(i));
152 
153       if (TypeSystemClang::IsObjCObjectOrInterfaceType(
154               type_sp->GetForwardCompilerType())) {
155         if (TypePayloadClang(type_sp->GetPayload()).IsCompleteObjCClass()) {
156           m_complete_class_cache[name] = type_sp;
157           return type_sp;
158         }
159       }
160     }
161   }
162   m_negative_complete_class_cache.insert(name);
163   return TypeSP();
164 }
165 
166 size_t ObjCLanguageRuntime::GetByteOffsetForIvar(CompilerType &parent_qual_type,
167                                                  const char *ivar_name) {
168   return LLDB_INVALID_IVAR_OFFSET;
169 }
170 
171 bool ObjCLanguageRuntime::ClassDescriptor::IsPointerValid(
172     lldb::addr_t value, uint32_t ptr_size, bool allow_NULLs, bool allow_tagged,
173     bool check_version_specific) const {
174   if (!value)
175     return allow_NULLs;
176   if ((value % 2) == 1 && allow_tagged)
177     return true;
178   if ((value % ptr_size) == 0)
179     return (check_version_specific ? CheckPointer(value, ptr_size) : true);
180   else
181     return false;
182 }
183 
184 ObjCLanguageRuntime::ObjCISA
185 ObjCLanguageRuntime::GetISA(ConstString name) {
186   ISAToDescriptorIterator pos = GetDescriptorIterator(name);
187   if (pos != m_isa_to_descriptor.end())
188     return pos->first;
189   return 0;
190 }
191 
192 ObjCLanguageRuntime::ISAToDescriptorIterator
193 ObjCLanguageRuntime::GetDescriptorIterator(ConstString name) {
194   ISAToDescriptorIterator end = m_isa_to_descriptor.end();
195 
196   if (name) {
197     UpdateISAToDescriptorMap();
198     if (m_hash_to_isa_map.empty()) {
199       // No name hashes were provided, we need to just linearly power through
200       // the names and find a match
201       for (ISAToDescriptorIterator pos = m_isa_to_descriptor.begin();
202            pos != end; ++pos) {
203         if (pos->second->GetClassName() == name)
204           return pos;
205       }
206     } else {
207       // Name hashes were provided, so use them to efficiently lookup name to
208       // isa/descriptor
209       const uint32_t name_hash = llvm::djbHash(name.GetStringRef());
210       std::pair<HashToISAIterator, HashToISAIterator> range =
211           m_hash_to_isa_map.equal_range(name_hash);
212       for (HashToISAIterator range_pos = range.first; range_pos != range.second;
213            ++range_pos) {
214         ISAToDescriptorIterator pos =
215             m_isa_to_descriptor.find(range_pos->second);
216         if (pos != m_isa_to_descriptor.end()) {
217           if (pos->second->GetClassName() == name)
218             return pos;
219         }
220       }
221     }
222   }
223   return end;
224 }
225 
226 std::pair<ObjCLanguageRuntime::ISAToDescriptorIterator,
227           ObjCLanguageRuntime::ISAToDescriptorIterator>
228 ObjCLanguageRuntime::GetDescriptorIteratorPair(bool update_if_needed) {
229   if (update_if_needed)
230     UpdateISAToDescriptorMapIfNeeded();
231 
232   return std::pair<ObjCLanguageRuntime::ISAToDescriptorIterator,
233                    ObjCLanguageRuntime::ISAToDescriptorIterator>(
234       m_isa_to_descriptor.begin(), m_isa_to_descriptor.end());
235 }
236 
237 ObjCLanguageRuntime::ObjCISA
238 ObjCLanguageRuntime::GetParentClass(ObjCLanguageRuntime::ObjCISA isa) {
239   ClassDescriptorSP objc_class_sp(GetClassDescriptorFromISA(isa));
240   if (objc_class_sp) {
241     ClassDescriptorSP objc_super_class_sp(objc_class_sp->GetSuperclass());
242     if (objc_super_class_sp)
243       return objc_super_class_sp->GetISA();
244   }
245   return 0;
246 }
247 
248 ObjCLanguageRuntime::ClassDescriptorSP
249 ObjCLanguageRuntime::GetClassDescriptorFromClassName(
250     ConstString class_name) {
251   ISAToDescriptorIterator pos = GetDescriptorIterator(class_name);
252   if (pos != m_isa_to_descriptor.end())
253     return pos->second;
254   return ClassDescriptorSP();
255 }
256 
257 ObjCLanguageRuntime::ClassDescriptorSP
258 ObjCLanguageRuntime::GetClassDescriptor(ValueObject &valobj) {
259   ClassDescriptorSP objc_class_sp;
260   // if we get an invalid VO (which might still happen when playing around with
261   // pointers returned by the expression parser, don't consider this a valid
262   // ObjC object)
263   if (valobj.GetCompilerType().IsValid()) {
264     addr_t isa_pointer = valobj.GetPointerValue();
265     if (isa_pointer != LLDB_INVALID_ADDRESS) {
266       ExecutionContext exe_ctx(valobj.GetExecutionContextRef());
267 
268       Process *process = exe_ctx.GetProcessPtr();
269       if (process) {
270         Status error;
271         ObjCISA isa = process->ReadPointerFromMemory(isa_pointer, error);
272         if (isa != LLDB_INVALID_ADDRESS)
273           objc_class_sp = GetClassDescriptorFromISA(isa);
274       }
275     }
276   }
277   return objc_class_sp;
278 }
279 
280 ObjCLanguageRuntime::ClassDescriptorSP
281 ObjCLanguageRuntime::GetNonKVOClassDescriptor(ValueObject &valobj) {
282   ObjCLanguageRuntime::ClassDescriptorSP objc_class_sp(
283       GetClassDescriptor(valobj));
284   if (objc_class_sp) {
285     if (!objc_class_sp->IsKVO())
286       return objc_class_sp;
287 
288     ClassDescriptorSP non_kvo_objc_class_sp(objc_class_sp->GetSuperclass());
289     if (non_kvo_objc_class_sp && non_kvo_objc_class_sp->IsValid())
290       return non_kvo_objc_class_sp;
291   }
292   return ClassDescriptorSP();
293 }
294 
295 ObjCLanguageRuntime::ClassDescriptorSP
296 ObjCLanguageRuntime::GetClassDescriptorFromISA(ObjCISA isa) {
297   if (isa) {
298     UpdateISAToDescriptorMap();
299 
300     ObjCLanguageRuntime::ISAToDescriptorIterator pos =
301         m_isa_to_descriptor.find(isa);
302     if (pos != m_isa_to_descriptor.end())
303       return pos->second;
304 
305     if (ABISP abi_sp = m_process->GetABI()) {
306       pos = m_isa_to_descriptor.find(abi_sp->FixCodeAddress(isa));
307       if (pos != m_isa_to_descriptor.end())
308         return pos->second;
309     }
310   }
311   return ClassDescriptorSP();
312 }
313 
314 ObjCLanguageRuntime::ClassDescriptorSP
315 ObjCLanguageRuntime::GetNonKVOClassDescriptor(ObjCISA isa) {
316   if (isa) {
317     ClassDescriptorSP objc_class_sp = GetClassDescriptorFromISA(isa);
318     if (objc_class_sp && objc_class_sp->IsValid()) {
319       if (!objc_class_sp->IsKVO())
320         return objc_class_sp;
321 
322       ClassDescriptorSP non_kvo_objc_class_sp(objc_class_sp->GetSuperclass());
323       if (non_kvo_objc_class_sp && non_kvo_objc_class_sp->IsValid())
324         return non_kvo_objc_class_sp;
325     }
326   }
327   return ClassDescriptorSP();
328 }
329 
330 CompilerType
331 ObjCLanguageRuntime::EncodingToType::RealizeType(const char *name,
332                                                  bool for_expression) {
333   if (m_scratch_ast_ctx_up)
334     return RealizeType(*m_scratch_ast_ctx_up, name, for_expression);
335   return CompilerType();
336 }
337 
338 ObjCLanguageRuntime::EncodingToType::~EncodingToType() = default;
339 
340 ObjCLanguageRuntime::EncodingToTypeSP ObjCLanguageRuntime::GetEncodingToType() {
341   return nullptr;
342 }
343 
344 bool ObjCLanguageRuntime::GetTypeBitSize(const CompilerType &compiler_type,
345                                          uint64_t &size) {
346   void *opaque_ptr = compiler_type.GetOpaqueQualType();
347   size = m_type_size_cache.Lookup(opaque_ptr);
348   // an ObjC object will at least have an ISA, so 0 is definitely not OK
349   if (size > 0)
350     return true;
351 
352   ClassDescriptorSP class_descriptor_sp =
353       GetClassDescriptorFromClassName(compiler_type.GetTypeName());
354   if (!class_descriptor_sp)
355     return false;
356 
357   int32_t max_offset = INT32_MIN;
358   uint64_t sizeof_max = 0;
359   bool found = false;
360 
361   for (size_t idx = 0; idx < class_descriptor_sp->GetNumIVars(); idx++) {
362     const auto &ivar = class_descriptor_sp->GetIVarAtIndex(idx);
363     int32_t cur_offset = ivar.m_offset;
364     if (cur_offset > max_offset) {
365       max_offset = cur_offset;
366       sizeof_max = ivar.m_size;
367       found = true;
368     }
369   }
370 
371   size = 8 * (max_offset + sizeof_max);
372   if (found)
373     m_type_size_cache.Insert(opaque_ptr, size);
374 
375   return found;
376 }
377 
378 lldb::BreakpointPreconditionSP
379 ObjCLanguageRuntime::GetBreakpointExceptionPrecondition(LanguageType language,
380                                                         bool throw_bp) {
381   if (language != eLanguageTypeObjC)
382     return lldb::BreakpointPreconditionSP();
383   if (!throw_bp)
384     return lldb::BreakpointPreconditionSP();
385   BreakpointPreconditionSP precondition_sp(
386       new ObjCLanguageRuntime::ObjCExceptionPrecondition());
387   return precondition_sp;
388 }
389 
390 // Exception breakpoint Precondition class for ObjC:
391 void ObjCLanguageRuntime::ObjCExceptionPrecondition::AddClassName(
392     const char *class_name) {
393   m_class_names.insert(class_name);
394 }
395 
396 ObjCLanguageRuntime::ObjCExceptionPrecondition::ObjCExceptionPrecondition() =
397     default;
398 
399 bool ObjCLanguageRuntime::ObjCExceptionPrecondition::EvaluatePrecondition(
400     StoppointCallbackContext &context) {
401   return true;
402 }
403 
404 void ObjCLanguageRuntime::ObjCExceptionPrecondition::GetDescription(
405     Stream &stream, lldb::DescriptionLevel level) {}
406 
407 Status ObjCLanguageRuntime::ObjCExceptionPrecondition::ConfigurePrecondition(
408     Args &args) {
409   Status error;
410   if (args.GetArgumentCount() > 0)
411     error.SetErrorString(
412         "The ObjC Exception breakpoint doesn't support extra options.");
413   return error;
414 }
415 
416 llvm::Optional<CompilerType>
417 ObjCLanguageRuntime::GetRuntimeType(CompilerType base_type) {
418   CompilerType class_type;
419   bool is_pointer_type = false;
420 
421   if (TypeSystemClang::IsObjCObjectPointerType(base_type, &class_type))
422     is_pointer_type = true;
423   else if (TypeSystemClang::IsObjCObjectOrInterfaceType(base_type))
424     class_type = base_type;
425   else
426     return llvm::None;
427 
428   if (!class_type)
429     return llvm::None;
430 
431   ConstString class_name(class_type.GetTypeName());
432   if (!class_name)
433     return llvm::None;
434 
435   TypeSP complete_objc_class_type_sp = LookupInCompleteClassCache(class_name);
436   if (!complete_objc_class_type_sp)
437     return llvm::None;
438 
439   CompilerType complete_class(
440       complete_objc_class_type_sp->GetFullCompilerType());
441   if (complete_class.GetCompleteType()) {
442     if (is_pointer_type)
443       return complete_class.GetPointerType();
444     else
445       return complete_class;
446   }
447 
448   return llvm::None;
449 }
450