Work around an infinite recursion with deadlock that only exists on

adrian-prantl · adrian-prantl · commit a8339d305273 · 2023-01-20T15:37:00.000-08:00
the swift branch. The function IRExecutionUnit::PopulateSymtab() is only implemented in swift-lldb. One thing it does is resolve any unresolved global symbols in the JIT module. This global search can cause the JIT module to recursively be asked for its symtab. This patch works around the problem by removing the JIT module from the list of modules being searched while in PopulateSymtab. That isn't done in the most elegant fashion, as it does so by changing the state of the IRExecutionUnit object. (lldb) bt * thread swiftlang#2, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP frame #0: 0x00007ff80dc2a0ce libsystem_kernel.dylib`__psynch_cvwait + 10 frame swiftlang#1: 0x00007ff80dc66758 libsystem_pthread.dylib`_pthread_cond_wait + 1242 frame swiftlang#2: 0x00007ff80dba51fd libc++.1.dylib`std::__1::__call_once(unsigned long volatile&, void*, void (*)(void*)) + 70 frame swiftlang#3: 0x000000014ff9235d LLDB`lldb_private::ObjectFile::GetSymtab() at mutex:676:9 [opt] * frame swiftlang#4: 0x000000014ff92334 LLDB`lldb_private::ObjectFile::GetSymtab() [inlined] void llvm::call_once<lldb_private::ObjectFile::GetSymtab()::$_0>(flag=<unavailable>, F=<unavailable>)::$_0&&) at Threading.h:89:5 [opt] frame swiftlang#5: 0x000000014ff92334 LLDB`lldb_private::ObjectFile::GetSymtab(this=0x0000600003d04f18) at ObjectFile.cpp:758:5 [opt] frame swiftlang#6: 0x0000000150531d67 LLDB`SymbolFileSymtab::CalculateAbilities(this=0x0000600003e20600) at SymbolFileSymtab.cpp:60:42 [opt] frame swiftlang#7: 0x000000015053001d LLDB`lldb_private::SymbolFileCommon::GetAbilities(this=0x0000600003e20600) at SymbolFile.h:478:21 [opt] frame swiftlang#8: 0x000000014ff9a8cd LLDB`lldb_private::SymbolFile::FindPlugin(objfile_sp=std::__1::shared_ptr<lldb_private::ObjectFile>::element_type @ 0x0000600003d04f18 strong=7 weak=2) at SymbolFile.cpp:71:62 [opt] frame swiftlang#9: 0x000000014ff9f4bd LLDB`lldb_private::SymbolVendor::AddSymbolFileRepresentation(this=0x00006000002b05a0, objfile_sp=std::__1::shared_ptr<lldb_private::ObjectFile>::element_type @ 0x0000600003d04f18 strong=7 weak=2) at SymbolVendor.cpp:71:27 [opt] frame swiftlang#10: 0x000000014ff9f419 LLDB`lldb_private::SymbolVendor::FindPlugin(module_sp=std::__1::shared_ptr<lldb_private::Module>::element_type @ 0x0000000106589ca0 strong=12 weak=26, feedback_strm=0x0000000000000000) at SymbolVendor.cpp:57:16 [opt] frame swiftlang#11: 0x000000014fe8d2a0 LLDB`lldb_private::Module::GetSymbolFile(this=0x0000000106589ca0, can_create=<unavailable>, feedback_strm=0x0000000000000000) at Module.cpp:1083:13 [opt] frame swiftlang#12: 0x000000014fe8c4c0 LLDB`lldb_private::Module::FindFunctions(lldb_private::ConstString, lldb_private::CompilerDeclContext const&, lldb::FunctionNameType, lldb_private::ModuleFunctionSearchOptions const&, lldb_private::SymbolContextList&) at Module.cpp:857:29 [opt] frame swiftlang#13: 0x000000014fe8c4b0 LLDB`lldb_private::Module::FindFunctions(this=0x0000000106589ca0, name=<unavailable>, parent_decl_ctx=0x00007ff7bfef98d0, name_type_mask=eFunctionNameTypeFull, options=0x00007ff7bfef9990, sc_list=0x00007ff7bfef9960) at Module.cpp:878:3 [opt] frame swiftlang#14: 0x000000014fe92ba1 LLDB`lldb_private::ModuleList::FindFunctions(this=<unavailable>, name=<unavailable>, name_type_mask=<unavailable>, options=0x00007ff7bfef9990, sc_list=0x00007ff7bfef9960) const at ModuleList.cpp:554:18 [opt] frame swiftlang#15: 0x000000014fef36cb LLDB`lldb_private::IRExecutionUnit::FindInSymbols(this=<unavailable>, names=<unavailable>, sc=0x00000001004db950, symbol_was_missing_weak=<unavailable>) at IRExecutionUnit.cpp:843:33 [opt] frame swiftlang#16: 0x000000014fef3c36 LLDB`lldb_private::IRExecutionUnit::FindSymbol(this=0x00000001004db860, name=<unavailable>, missing_weak=0x00007ff7bfef9a97) at IRExecutionUnit.cpp:915:22 [opt] frame swiftlang#17: 0x000000014fef43f3 LLDB`lldb_private::IRExecutionUnit::MemoryManager::GetSymbolAddressAndPresence(this=0x0000000107c71000, Name="_$sBoWV", missing_weak=0x00007ff7bfef9a97) at IRExecutionUnit.cpp:1010:31 [opt] frame swiftlang#18: 0x000000014fef4490 LLDB`non-virtual thunk to lldb_private::IRExecutionUnit::MemoryManager::findSymbol(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) [inlined] lldb_private::IRExecutionUnit::MemoryManager::findSymbol(this=<unavailable>, Name=<unavailable>) at IRExecutionUnit.cpp:988:21 [opt] frame swiftlang#19: 0x000000014fef447d LLDB`non-virtual thunk to lldb_private::IRExecutionUnit::MemoryManager::findSymbol(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) at IRExecutionUnit.cpp:0 [opt] frame swiftlang#20: 0x0000000154ab3a5c LLDB`llvm::LinkingSymbolResolver::findSymbol(this=0x0000000107e0ecc0, Name="_$sBoWV") at MCJIT.cpp:681:26 [opt] frame swiftlang#21: 0x0000000154abd458 LLDB`llvm::LegacyJITSymbolResolver::lookup(this=<unavailable>, Symbols=<unavailable>, OnResolved=<unavailable>)>) at JITSymbol.cpp:125:22 [opt] frame swiftlang#22: 0x0000000154abf6f3 LLDB`llvm::RuntimeDyldImpl::resolveExternalSymbols(this=0x000000013cfeea20) at RuntimeDyld.cpp:1195:16 [opt] frame swiftlang#23: 0x0000000154abecde LLDB`llvm::RuntimeDyldImpl::resolveRelocations(this=0x000000013cfeea20) at RuntimeDyld.cpp:131:18 [opt] frame swiftlang#24: 0x0000000154ab1482 LLDB`llvm::MCJIT::finalizeLoadedModules(this=0x0000000107e0ea00) at MCJIT.cpp:242:8 [opt] frame swiftlang#25: 0x0000000154ab24ec LLDB`llvm::MCJIT::getGlobalValueAddress(this=0x0000000107e0ea00, Name=<unavailable>) at MCJIT.cpp:400:5 [opt] frame swiftlang#26: 0x000000014fef499d LLDB`lldb_private::IRExecutionUnit::PopulateSymtab(this=0x00000001004db860, obj_file=<unavailable>, symtab=0x0000600003342f80) at IRExecutionUnit.cpp:1246:34 [opt] frame swiftlang#27: 0x00000001503e4bf1 LLDB`ObjectFileJIT::ParseSymtab(this=0x0000600003d04f18, symtab=0x0000600003342f80) at ObjectFileJIT.cpp:112:18 [opt] frame swiftlang#28: 0x000000014ff93a14 LLDB`void std::__1::__call_once_proxy<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >(void*) at ObjectFile.cpp:764:9 [opt] frame swiftlang#29: 0x000000014ff93998 LLDB`void std::__1::__call_once_proxy<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >(void*) [inlined] decltype(__f=0x00007ff7bfefa180)::$_0>(fp)()) std::__1::__invoke<lldb_private::ObjectFile::GetSymtab()::$_0>(lldb_private::ObjectFile::GetSymtab()::$_0&&) at type_traits:3918:1 [opt] frame swiftlang#30: 0x000000014ff93998 LLDB`void std::__1::__call_once_proxy<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >(void*) [inlined] void std::__1::__call_once_param<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >::__execute<>(this=<unavailable>, (null)=<unavailable>) at mutex:630:9 [opt] frame swiftlang#31: 0x000000014ff93984 LLDB`void std::__1::__call_once_proxy<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >(void*) [inlined] std::__1::__call_once_param<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >::operator(this=<unavailable>)() at mutex:622:9 [opt] frame swiftlang#32: 0x000000014ff93984 LLDB`void std::__1::__call_once_proxy<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >(__vp=<unavailable>) at mutex:658:5 [opt] frame swiftlang#33: 0x00007ff80dba5242 libc++.1.dylib`std::__1::__call_once(unsigned long volatile&, void*, void (*)(void*)) + 139 frame swiftlang#34: 0x000000014ff9235d LLDB`lldb_private::ObjectFile::GetSymtab() at mutex:676:9 [opt] frame swiftlang#35: 0x000000014ff92334 LLDB`lldb_private::ObjectFile::GetSymtab() [inlined] void llvm::call_once<lldb_private::ObjectFile::GetSymtab()::$_0>(flag=<unavailable>, F=<unavailable>)::$_0&&) at Threading.h:89:5 [opt] frame swiftlang#36: 0x000000014ff92334 LLDB`lldb_private::ObjectFile::GetSymtab(this=0x0000600003d04f18) at ObjectFile.cpp:758:5 [opt] frame swiftlang#37: 0x0000000150531d67 LLDB`SymbolFileSymtab::CalculateAbilities(this=0x0000600003e20100) at SymbolFileSymtab.cpp:60:42 [opt] frame swiftlang#38: 0x000000015053001d LLDB`lldb_private::SymbolFileCommon::GetAbilities(this=0x0000600003e20100) at SymbolFile.h:478:21 [opt] frame swiftlang#39: 0x000000014ff9a8cd LLDB`lldb_private::SymbolFile::FindPlugin(objfile_sp=std::__1::shared_ptr<lldb_private::ObjectFile>::element_type @ 0x0000600003d04f18 strong=7 weak=2) at SymbolFile.cpp:71:62 [opt] frame swiftlang#40: 0x000000014ff9f4bd LLDB`lldb_private::SymbolVendor::AddSymbolFileRepresentation(this=0x00006000002b0560, objfile_sp=std::__1::shared_ptr<lldb_private::ObjectFile>::element_type @ 0x0000600003d04f18 strong=7 weak=2) at SymbolVendor.cpp:71:27 [opt] frame swiftlang#41: 0x000000014ff9f419 LLDB`lldb_private::SymbolVendor::FindPlugin(module_sp=std::__1::shared_ptr<lldb_private::Module>::element_type @ 0x0000000106589ca0 strong=12 weak=26, feedback_strm=0x0000000000000000) at SymbolVendor.cpp:57:16 [opt] frame swiftlang#42: 0x000000014fe8d2a0 LLDB`lldb_private::Module::GetSymbolFile(this=0x0000000106589ca0, can_create=<unavailable>, feedback_strm=0x0000000000000000) at Module.cpp:1083:13 [opt] frame swiftlang#43: 0x000000015041f366 LLDB`lldb_private::PlatformDarwin::LocateExecutableScriptingResources(this=<unavailable>, target=0x000000010309e800, module=0x0000000106589ca0, feedback_stream=0x00007ff7bfefa770) at PlatformDarwin.cpp:212:40 [opt] frame swiftlang#44: 0x000000014fe8f97c LLDB`lldb_private::Module::LoadScriptingResourceInTarget(this=<unavailable>, target=0x000000010309e800, error=0x00007ff7bfefa750, feedback_stream=<unavailable>) at Module.cpp:1588:44 [opt] frame swiftlang#45: 0x0000000150027520 LLDB`lldb_private::Target::ModulesDidLoad(lldb_private::ModuleList&) [inlined] LoadScriptingResourceForModule(module_sp=<unavailable>, target=0x000000010309e800) at Target.cpp:1415:32 [opt] frame swiftlang#46: 0x00000001500274f4 LLDB`lldb_private::Target::ModulesDidLoad(this=0x000000010309e800, module_list=<unavailable>) at Target.cpp:1672:7 [opt] frame swiftlang#47: 0x00000001500284ca LLDB`non-virtual thunk to lldb_private::Target::NotifyModuleAdded(lldb_private::ModuleList const&, std::__1::shared_ptr<lldb_private::Module> const&) at Target.cpp:1637:5 [opt] frame swiftlang#48: 0x00000001500284a7 LLDB`non-virtual thunk to lldb_private::Target::NotifyModuleAdded(lldb_private::ModuleList const&, std::__1::shared_ptr<lldb_private::Module> const&) at Target.cpp:0 [opt] frame swiftlang#49: 0x000000014fe91f8b LLDB`lldb_private::ModuleList::Append(std::__1::shared_ptr<lldb_private::Module> const&, bool) at ModuleList.cpp:334:19 [opt] frame swiftlang#50: 0x000000014fe91f44 LLDB`lldb_private::ModuleList::Append(this=0x000000010309eb48, module_sp=std::__1::shared_ptr<lldb_private::Module>::element_type @ 0x0000000106589ca0 strong=12 weak=26, notify=<unavailable>) at ModuleList.cpp:339:3 [opt] frame swiftlang#51: 0x000000014fef5200 LLDB`lldb_private::IRExecutionUnit::CreateJITModule(this=<unavailable>, name="$__lldb_expr2") at IRExecutionUnit.cpp:1339:27 [opt] frame swiftlang#52: 0x000000015011063b LLDB`lldb_private::SwiftUserExpression::Parse(this=<unavailable>, diagnostic_manager=<unavailable>, exe_ctx=<unavailable>, execution_policy=eExecutionPolicyOnlyWhenNeeded, keep_result_in_memory=<unavailable>, generate_debug_info=<unavailable>) at SwiftUserExpression.cpp:802:28 [opt] frame swiftlang#53: 0x000000014ff0cd05 LLDB`lldb_private::UserExpression::Evaluate(exe_ctx=<unavailable>, options=0x00006000033441e0, expr="", prefix="", result_valobj_sp=nullptr, error=0x00007ff7bfefaf40, fixed_expression=Summary Unavailable, ctx_obj=0x0000000000000000) at UserExpression.cpp:281:27 [opt] frame swiftlang#54: 0x000000015002e124 LLDB`lldb_private::Target::EvaluateExpression(this=0x000000010309e800, expr="", exe_scope=<unavailable>, result_valobj_sp=nullptr, options=<unavailable>, fixed_expression=Summary Unavailable, ctx_obj=0x0000000000000000) at Target.cpp:2960:25 [opt] frame swiftlang#55: 0x000000014fcc3e62 LLDB`lldb::SBFrame::EvaluateExpression(this=<unavailable>, expr=<unavailable>, options=0x0000600000011880) at SBFrame.cpp:1084:17 [opt] frame swiftlang#56: 0x000000014fdaaf70 LLDB`_wrap_SBFrame_EvaluateExpression(_object*, _object*) at LLDBWrapPython.cpp:32887:22 [opt] frame swiftlang#57: 0x000000014fdaaebf LLDB`_wrap_SBFrame_EvaluateExpression(self=<unavailable>, args=<unavailable>) at LLDBWrapPython.cpp:32933:18 [opt] (cherry picked from commit ba81700)
diff --git a/lldb/include/lldb/Expression/IRExecutionUnit.h b/lldb/include/lldb/Expression/IRExecutionUnit.h
@@ -391,6 +391,9 @@ class IRExecutionUnit : public std::enable_shared_from_this<IRExecutionUnit>,
   std::vector<ConstString> m_failed_lookups;
 
   std::atomic<bool> m_did_jit;
+  // BEGIN SWIFT
+  std::atomic<bool> m_in_populate_symtab = false;
+  // END SWIFT
 
   lldb::addr_t m_function_load_addr;
   lldb::addr_t m_function_end_load_addr;
diff --git a/lldb/source/Expression/IRExecutionUnit.cpp b/lldb/source/Expression/IRExecutionUnit.cpp
@@ -840,17 +840,20 @@ IRExecutionUnit::FindInSymbols(const std::vector<ConstString> &names,
     }
 
     if (sc.target_sp) {
+      ModuleList images = sc.target_sp->GetImages();
+      // BEGIN SWIFT
+      if (m_in_populate_symtab)
+        if (lldb::ModuleSP module_sp = m_jit_module_wp.lock())
+        images.Remove(module_sp);
+      // END SWIFT
+
       SymbolContextList sc_list;
-      sc.target_sp->GetImages().FindFunctions(name, lldb::eFunctionNameTypeFull,
-                                              function_options, sc_list);
+      images.FindFunctions(name, lldb::eFunctionNameTypeFull, function_options,
+                           sc_list);
       if (auto load_addr = resolver.Resolve(sc_list))
         return *load_addr;
-    }
 
-    if (sc.target_sp) {
-      SymbolContextList sc_list;
-      sc.target_sp->GetImages().FindSymbolsWithNameAndType(
-          name, lldb::eSymbolTypeAny, sc_list);
+      images.FindSymbolsWithNameAndType(name, lldb::eSymbolTypeAny, sc_list);
       if (auto load_addr = resolver.Resolve(sc_list))
         return *load_addr;
     }
@@ -1195,6 +1198,9 @@ uint32_t IRExecutionUnit::GetAddressByteSize() const {
 
 void IRExecutionUnit::PopulateSymtab(lldb_private::ObjectFile *obj_file,
                                      lldb_private::Symtab &symtab) {
+  // BEGIN SWIFT
+  m_in_populate_symtab = true;
+  auto _ = llvm::make_scope_exit([this]() { m_in_populate_symtab = false; });
   if (m_execution_engine_up) {
     uint32_t symbol_id = 0;
     lldb_private::SectionList *section_list = obj_file->GetSectionList();
@@ -1272,6 +1278,7 @@ void IRExecutionUnit::PopulateSymtab(lldb_private::ObjectFile *obj_file,
       }
     }
   }
+  // END SWIFT
 }
 
 void IRExecutionUnit::PopulateSectionList(
