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Work around an infinite recursion with deadlock that only exists on
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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 llvm#2, queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
    frame #0: 0x00007ff80dc2a0ce libsystem_kernel.dylib`__psynch_cvwait + 10
    frame llvm#1: 0x00007ff80dc66758 libsystem_pthread.dylib`_pthread_cond_wait + 1242
    frame llvm#2: 0x00007ff80dba51fd libc++.1.dylib`std::__1::__call_once(unsigned long volatile&, void*, void (*)(void*)) + 70
    frame llvm#3: 0x000000014ff9235d LLDB`lldb_private::ObjectFile::GetSymtab() at mutex:676:9 [opt]
  * frame llvm#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 llvm#5: 0x000000014ff92334 LLDB`lldb_private::ObjectFile::GetSymtab(this=0x0000600003d04f18) at ObjectFile.cpp:758:5 [opt]
    frame llvm#6: 0x0000000150531d67 LLDB`SymbolFileSymtab::CalculateAbilities(this=0x0000600003e20600) at SymbolFileSymtab.cpp:60:42 [opt]
    frame llvm#7: 0x000000015053001d LLDB`lldb_private::SymbolFileCommon::GetAbilities(this=0x0000600003e20600) at SymbolFile.h:478:21 [opt]
    frame llvm#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 llvm#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 llvm#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 llvm#11: 0x000000014fe8d2a0 LLDB`lldb_private::Module::GetSymbolFile(this=0x0000000106589ca0, can_create=<unavailable>, feedback_strm=0x0000000000000000) at Module.cpp:1083:13 [opt]
    frame llvm#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 llvm#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 llvm#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 llvm#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 llvm#16: 0x000000014fef3c36 LLDB`lldb_private::IRExecutionUnit::FindSymbol(this=0x00000001004db860, name=<unavailable>, missing_weak=0x00007ff7bfef9a97) at IRExecutionUnit.cpp:915:22 [opt]
    frame llvm#17: 0x000000014fef43f3 LLDB`lldb_private::IRExecutionUnit::MemoryManager::GetSymbolAddressAndPresence(this=0x0000000107c71000, Name="_$sBoWV", missing_weak=0x00007ff7bfef9a97) at IRExecutionUnit.cpp:1010:31 [opt]
    frame llvm#18: 0x000000014fef4490 LLDB`non-virtual thunk to lldb_private::IRExecutionUnit::MemoryManager::findSymbol(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) [inlined] lldb_private::IRExecutionUnit::MemoryManager::findSymbol(this=<unavailable>, Name=<unavailable>) at IRExecutionUnit.cpp:988:21 [opt]
    frame llvm#19: 0x000000014fef447d LLDB`non-virtual thunk to lldb_private::IRExecutionUnit::MemoryManager::findSymbol(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) at IRExecutionUnit.cpp:0 [opt]
    frame llvm#20: 0x0000000154ab3a5c LLDB`llvm::LinkingSymbolResolver::findSymbol(this=0x0000000107e0ecc0, Name="_$sBoWV") at MCJIT.cpp:681:26 [opt]
    frame llvm#21: 0x0000000154abd458 LLDB`llvm::LegacyJITSymbolResolver::lookup(this=<unavailable>, Symbols=<unavailable>, OnResolved=<unavailable>)>) at JITSymbol.cpp:125:22 [opt]
    frame llvm#22: 0x0000000154abf6f3 LLDB`llvm::RuntimeDyldImpl::resolveExternalSymbols(this=0x000000013cfeea20) at RuntimeDyld.cpp:1195:16 [opt]
    frame llvm#23: 0x0000000154abecde LLDB`llvm::RuntimeDyldImpl::resolveRelocations(this=0x000000013cfeea20) at RuntimeDyld.cpp:131:18 [opt]
    frame llvm#24: 0x0000000154ab1482 LLDB`llvm::MCJIT::finalizeLoadedModules(this=0x0000000107e0ea00) at MCJIT.cpp:242:8 [opt]
    frame llvm#25: 0x0000000154ab24ec LLDB`llvm::MCJIT::getGlobalValueAddress(this=0x0000000107e0ea00, Name=<unavailable>) at MCJIT.cpp:400:5 [opt]
    frame llvm#26: 0x000000014fef499d LLDB`lldb_private::IRExecutionUnit::PopulateSymtab(this=0x00000001004db860, obj_file=<unavailable>, symtab=0x0000600003342f80) at IRExecutionUnit.cpp:1246:34 [opt]
    frame llvm#27: 0x00000001503e4bf1 LLDB`ObjectFileJIT::ParseSymtab(this=0x0000600003d04f18, symtab=0x0000600003342f80) at ObjectFileJIT.cpp:112:18 [opt]
    frame llvm#28: 0x000000014ff93a14 LLDB`void std::__1::__call_once_proxy<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >(void*) at ObjectFile.cpp:764:9 [opt]
    frame llvm#29: 0x000000014ff93998 LLDB`void std::__1::__call_once_proxy<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >(void*) [inlined] decltype(__f=0x00007ff7bfefa180)::$_0>(fp)()) std::__1::__invoke<lldb_private::ObjectFile::GetSymtab()::$_0>(lldb_private::ObjectFile::GetSymtab()::$_0&&) at type_traits:3918:1 [opt]
    frame llvm#30: 0x000000014ff93998 LLDB`void std::__1::__call_once_proxy<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >(void*) [inlined] void std::__1::__call_once_param<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >::__execute<>(this=<unavailable>, (null)=<unavailable>) at mutex:630:9 [opt]
    frame llvm#31: 0x000000014ff93984 LLDB`void std::__1::__call_once_proxy<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >(void*) [inlined] std::__1::__call_once_param<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >::operator(this=<unavailable>)() at mutex:622:9 [opt]
    frame llvm#32: 0x000000014ff93984 LLDB`void std::__1::__call_once_proxy<std::__1::tuple<lldb_private::ObjectFile::GetSymtab()::$_0&&> >(__vp=<unavailable>) at mutex:658:5 [opt]
    frame llvm#33: 0x00007ff80dba5242 libc++.1.dylib`std::__1::__call_once(unsigned long volatile&, void*, void (*)(void*)) + 139
    frame llvm#34: 0x000000014ff9235d LLDB`lldb_private::ObjectFile::GetSymtab() at mutex:676:9 [opt]
    frame llvm#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 llvm#36: 0x000000014ff92334 LLDB`lldb_private::ObjectFile::GetSymtab(this=0x0000600003d04f18) at ObjectFile.cpp:758:5 [opt]
    frame llvm#37: 0x0000000150531d67 LLDB`SymbolFileSymtab::CalculateAbilities(this=0x0000600003e20100) at SymbolFileSymtab.cpp:60:42 [opt]
    frame llvm#38: 0x000000015053001d LLDB`lldb_private::SymbolFileCommon::GetAbilities(this=0x0000600003e20100) at SymbolFile.h:478:21 [opt]
    frame llvm#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 llvm#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 llvm#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 llvm#42: 0x000000014fe8d2a0 LLDB`lldb_private::Module::GetSymbolFile(this=0x0000000106589ca0, can_create=<unavailable>, feedback_strm=0x0000000000000000) at Module.cpp:1083:13 [opt]
    frame llvm#43: 0x000000015041f366 LLDB`lldb_private::PlatformDarwin::LocateExecutableScriptingResources(this=<unavailable>, target=0x000000010309e800, module=0x0000000106589ca0, feedback_stream=0x00007ff7bfefa770) at PlatformDarwin.cpp:212:40 [opt]
    frame llvm#44: 0x000000014fe8f97c LLDB`lldb_private::Module::LoadScriptingResourceInTarget(this=<unavailable>, target=0x000000010309e800, error=0x00007ff7bfefa750, feedback_stream=<unavailable>) at Module.cpp:1588:44 [opt]
    frame llvm#45: 0x0000000150027520 LLDB`lldb_private::Target::ModulesDidLoad(lldb_private::ModuleList&) [inlined] LoadScriptingResourceForModule(module_sp=<unavailable>, target=0x000000010309e800) at Target.cpp:1415:32 [opt]
    frame llvm#46: 0x00000001500274f4 LLDB`lldb_private::Target::ModulesDidLoad(this=0x000000010309e800, module_list=<unavailable>) at Target.cpp:1672:7 [opt]
    frame llvm#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 llvm#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 llvm#49: 0x000000014fe91f8b LLDB`lldb_private::ModuleList::Append(std::__1::shared_ptr<lldb_private::Module> const&, bool) at ModuleList.cpp:334:19 [opt]
    frame llvm#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 llvm#51: 0x000000014fef5200 LLDB`lldb_private::IRExecutionUnit::CreateJITModule(this=<unavailable>, name="$__lldb_expr2") at IRExecutionUnit.cpp:1339:27 [opt]
    frame llvm#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 llvm#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 llvm#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 llvm#55: 0x000000014fcc3e62 LLDB`lldb::SBFrame::EvaluateExpression(this=<unavailable>, expr=<unavailable>, options=0x0000600000011880) at SBFrame.cpp:1084:17 [opt]
    frame llvm#56: 0x000000014fdaaf70 LLDB`_wrap_SBFrame_EvaluateExpression(_object*, _object*) at LLDBWrapPython.cpp:32887:22 [opt]
    frame llvm#57: 0x000000014fdaaebf LLDB`_wrap_SBFrame_EvaluateExpression(self=<unavailable>, args=<unavailable>) at LLDBWrapPython.cpp:32933:18 [opt]

(cherry picked from commit ba81700)
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@adrian-prantl
adrian-prantl committed Jan 20, 2023
1 parent ffc35a5 commit a8339d3
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Showing 2 changed files with 17 additions and 7 deletions.
3 changes: 3 additions & 0 deletions lldb/include/lldb/Expression/IRExecutionUnit.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
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21 changes: 14 additions & 7 deletions lldb/source/Expression/IRExecutionUnit.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
}
Expand Down Expand Up @@ -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();
Expand Down Expand Up @@ -1272,6 +1278,7 @@ void IRExecutionUnit::PopulateSymtab(lldb_private::ObjectFile *obj_file,
}
}
}
// END SWIFT
}

void IRExecutionUnit::PopulateSectionList(
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