diff --git a/lldb/source/Plugins/Language/CPlusPlus/Coroutines.cpp b/lldb/source/Plugins/Language/CPlusPlus/Coroutines.cpp --- a/lldb/source/Plugins/Language/CPlusPlus/Coroutines.cpp +++ b/lldb/source/Plugins/Language/CPlusPlus/Coroutines.cpp @@ -9,6 +9,8 @@ #include "Coroutines.h" #include "Plugins/TypeSystem/Clang/TypeSystemClang.h" +#include "lldb/Symbol/Function.h" +#include "lldb/Symbol/VariableList.h" using namespace lldb; using namespace lldb_private; @@ -32,6 +34,57 @@ return ptr_sp; } +static Function *ExtractDestroyFunction(ValueObjectSP &frame_ptr_sp) { + lldb::TargetSP target_sp = frame_ptr_sp->GetTargetSP(); + lldb::ProcessSP process_sp = frame_ptr_sp->GetProcessSP(); + auto ptr_size = process_sp->GetAddressByteSize(); + + AddressType addr_type; + lldb::addr_t frame_ptr_addr = frame_ptr_sp->GetPointerValue(&addr_type); + if (!frame_ptr_addr || frame_ptr_addr == LLDB_INVALID_ADDRESS) + return nullptr; + lldbassert(addr_type == AddressType::eAddressTypeLoad); + + Status error; + // The destroy pointer is the 2nd pointer inside the compiler-generated + // `pair`. It + auto destroy_func_ptr_addr = frame_ptr_addr + ptr_size; + lldb::addr_t destroy_func_addr = + process_sp->ReadPointerFromMemory(destroy_func_ptr_addr, error); + if (error.Fail()) + return nullptr; + + Address destroy_func_address; + if (!target_sp->ResolveLoadAddress(destroy_func_addr, destroy_func_address)) + return nullptr; + + Function *destroy_func = + destroy_func_address.CalculateSymbolContextFunction(); + if (!destroy_func) + return nullptr; + + return destroy_func; +} + +static CompilerType InferPromiseType(Function &destroy_func) { + SymbolContext sc; + Block &block = destroy_func.GetBlock(true); + auto variable_list = block.GetBlockVariableList(true); + + // clang generates an artificial `__promise` variable inside the + // `destroy` function. Look for it. + auto promise_var = variable_list->FindVariable(ConstString("__promise")); + if (!promise_var) + return {}; + if (!promise_var->IsArtificial()) + return {}; + + Type *promise_type = promise_var->GetType(); + if (!promise_type) + return {}; + return promise_type->GetForwardCompilerType(); +} + static CompilerType GetCoroutineFrameType(TypeSystemClang &ast_ctx, CompilerType promise_type) { CompilerType void_type = ast_ctx.GetBasicType(lldb::eBasicTypeVoid); @@ -58,7 +111,11 @@ if (!ptr_sp) return false; - stream.Printf("coro frame = 0x%" PRIx64, ptr_sp->GetValueAsUnsigned(0)); + if (!ptr_sp->GetValueAsUnsigned(0)) { + stream << "nullptr"; + } else { + stream.Printf("coro frame = 0x%" PRIx64, ptr_sp->GetValueAsUnsigned(0)); + } return true; } @@ -100,15 +157,26 @@ if (!ptr_sp) return false; - TypeSystemClang *ast_ctx = llvm::dyn_cast_or_null( - valobj_sp->GetCompilerType().GetTypeSystem()); - if (!ast_ctx) - return false; - + // Get the `promise_type` from the template argument CompilerType promise_type( valobj_sp->GetCompilerType().GetTypeTemplateArgument(0)); if (!promise_type) return false; + + // Try to infer the promise_type if it was type-erased + if (promise_type.IsVoidType()) { + if (Function *destroy_func = ExtractDestroyFunction(ptr_sp)) { + if (CompilerType inferred_type = InferPromiseType(*destroy_func)) { + promise_type = inferred_type; + } + } + } + + // Build the coroutine frame type + TypeSystemClang *ast_ctx = llvm::dyn_cast_or_null( + ptr_sp->GetCompilerType().GetTypeSystem()); + if (!ast_ctx) + return {}; CompilerType coro_frame_type = GetCoroutineFrameType(*ast_ctx, promise_type); m_frame_ptr_sp = ptr_sp->Cast(coro_frame_type.GetPointerType()); diff --git a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/TestCoroutineHandle.py b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/TestCoroutineHandle.py --- a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/TestCoroutineHandle.py +++ b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/TestCoroutineHandle.py @@ -33,13 +33,29 @@ ValueCheck(name="current_value", value = "-1"), ]) ]) - # For type-erased `coroutine_handle<>` we are missing the `promise` - # but still show `resume` and `destroy`. + # For a type-erased `coroutine_handle<>`, we can still devirtualize + # the promise call and display the correctly typed promise. self.expect_expr("type_erased_hdl", result_summary=re.compile("^coro frame = 0x[0-9a-f]*$"), result_children=[ ValueCheck(name="resume", summary = test_generator_func_ptr_re), ValueCheck(name="destroy", summary = test_generator_func_ptr_re), + ValueCheck(name="promise", children=[ + ValueCheck(name="current_value", value = "-1"), + ]) + ]) + # For an incorrectly typed `coroutine_handle`, we use the user-supplide + # incorrect type instead of inferring the correct type. Strictly speaking. + # incorrectly typed coroutine handles are undefined behavior. However, + # it provides probably a better debugging experience if we display the + # promise as seen by the program instead of fixing this bug based on + # the available debug info. + self.expect_expr("incorrectly_typed_hdl", + result_summary=re.compile("^coro frame = 0x[0-9a-f]*$"), + result_children=[ + ValueCheck(name="resume", summary = test_generator_func_ptr_re), + ValueCheck(name="destroy", summary = test_generator_func_ptr_re), + ValueCheck(name="promise", value="-1") ]) # Run until after the `co_yield` @@ -69,6 +85,17 @@ ValueCheck(name="current_value", value = "42"), ]) ]) + # Devirtualization still works, also at the final suspension point, despite + # the `resume` pointer being reset to a nullptr + self.expect_expr("type_erased_hdl", + result_summary=re.compile("^coro frame = 0x[0-9a-f]*$"), + result_children=[ + ValueCheck(name="resume", value = "0x0000000000000000"), + ValueCheck(name="destroy", summary = test_generator_func_ptr_re), + ValueCheck(name="promise", children=[ + ValueCheck(name="current_value", value = "42"), + ]) + ]) @add_test_categories(["libstdcxx"]) def test_libstdcpp(self): diff --git a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/main.cpp b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/main.cpp --- a/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/main.cpp +++ b/lldb/test/API/functionalities/data-formatter/data-formatter-stl/generic/coroutine_handle/main.cpp @@ -34,6 +34,8 @@ int main() { int_generator gen = my_generator_func(); std::coroutine_handle<> type_erased_hdl = gen.hdl; + std::coroutine_handle incorrectly_typed_hdl = + std::coroutine_handle::from_address(gen.hdl.address()); gen.hdl.resume(); // Break at initial_suspend gen.hdl.resume(); // Break after co_yield empty_function_so_we_can_set_a_breakpoint(); // Break at final_suspend