[lldb] Retrieve currently handled Obj-C exception via __cxa_current_exception_type and add GetCurrentExceptionBacktrace SB ABI
This builds on https://reviews.llvm.org/D43884 and https://reviews.llvm.org/D43886 and extends LLDB support of Obj-C exceptions to also look for a "current exception" for a thread in the C++ exception handling runtime metadata (via call to __cxa_current_exception_type). We also construct an actual historical SBThread/ThreadSP that contains frames from the backtrace in the Obj-C exception object.
The high level goal this achieves is that when we're already crashed (because an unhandled exception occurred), we can still access the exception object and retrieve the backtrace from the throw point. In Obj-C, this is particularly useful because a catch+rethrow is very common and in those cases you currently don't have any access to the throw point backtrace.
Differential Revision: https://reviews.llvm.org/D44072
llvm-svn: 349718
diff --git a/lldb/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp b/lldb/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp
index 3f9ae93..8fcf33c 100644
--- a/lldb/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp
+++ b/lldb/source/Plugins/LanguageRuntime/CPlusPlus/ItaniumABI/ItaniumABILanguageRuntime.cpp
@@ -16,6 +16,9 @@
#include "lldb/Core/PluginManager.h"
#include "lldb/Core/ValueObject.h"
#include "lldb/Core/ValueObjectMemory.h"
+#include "lldb/DataFormatters/FormattersHelpers.h"
+#include "lldb/Expression/DiagnosticManager.h"
+#include "lldb/Expression/FunctionCaller.h"
#include "lldb/Interpreter/CommandObject.h"
#include "lldb/Interpreter/CommandObjectMultiword.h"
#include "lldb/Interpreter/CommandReturnObject.h"
@@ -549,6 +552,61 @@
break_site_id, m_cxx_exception_bp_sp->GetID());
}
+ValueObjectSP ItaniumABILanguageRuntime::GetExceptionObjectForThread(
+ ThreadSP thread_sp) {
+ ClangASTContext *clang_ast_context =
+ m_process->GetTarget().GetScratchClangASTContext();
+ CompilerType voidstar =
+ clang_ast_context->GetBasicType(eBasicTypeVoid).GetPointerType();
+
+ DiagnosticManager diagnostics;
+ ExecutionContext exe_ctx;
+ EvaluateExpressionOptions options;
+
+ options.SetUnwindOnError(true);
+ options.SetIgnoreBreakpoints(true);
+ options.SetStopOthers(true);
+ options.SetTimeout(std::chrono::milliseconds(500));
+ options.SetTryAllThreads(false);
+ thread_sp->CalculateExecutionContext(exe_ctx);
+
+ const ModuleList &modules = m_process->GetTarget().GetImages();
+ SymbolContextList contexts;
+ SymbolContext context;
+
+ modules.FindSymbolsWithNameAndType(
+ ConstString("__cxa_current_exception_type"), eSymbolTypeCode, contexts);
+ contexts.GetContextAtIndex(0, context);
+ Address addr = context.symbol->GetAddress();
+
+ Status error;
+ FunctionCaller *function_caller =
+ m_process->GetTarget().GetFunctionCallerForLanguage(
+ eLanguageTypeC, voidstar, addr, ValueList(), "caller", error);
+
+ ExpressionResults func_call_ret;
+ Value results;
+ func_call_ret = function_caller->ExecuteFunction(exe_ctx, nullptr, options,
+ diagnostics, results);
+ if (func_call_ret != eExpressionCompleted || !error.Success()) {
+ return ValueObjectSP();
+ }
+
+ size_t ptr_size = m_process->GetAddressByteSize();
+ addr_t result_ptr = results.GetScalar().ULongLong(LLDB_INVALID_ADDRESS);
+ addr_t exception_addr =
+ m_process->ReadPointerFromMemory(result_ptr - ptr_size, error);
+
+ lldb_private::formatters::InferiorSizedWord exception_isw(exception_addr,
+ *m_process);
+ ValueObjectSP exception = ValueObject::CreateValueObjectFromData(
+ "exception", exception_isw.GetAsData(m_process->GetByteOrder()), exe_ctx,
+ voidstar);
+ exception = exception->GetDynamicValue(eDynamicDontRunTarget);
+
+ return exception;
+}
+
TypeAndOrName ItaniumABILanguageRuntime::GetDynamicTypeInfo(
const lldb_private::Address &vtable_addr) {
std::lock_guard<std::mutex> locker(m_dynamic_type_map_mutex);