[lldb] Add GetCurrentException APIs to SBThread, add frame recognizer for objc_exception_throw for Obj-C runtimes

This adds new APIs and a command to deal with exceptions (mostly Obj-C exceptions): SBThread and Thread get GetCurrentException API, which returns an SBValue/ValueObjectSP with the current exception for a thread. "Current" means an exception that is currently being thrown, caught or otherwise processed. In this patch, we only know about the exception when in objc_exception_throw, but subsequent patches will expand this (and add GetCurrentExceptionBacktrace, which will return an SBThread/ThreadSP containing a historical thread backtrace retrieved from the exception object. Currently unimplemented, subsequent patches will implement this).

Extracting the exception from objc_exception_throw is implemented by adding a frame recognizer.

This also add a new sub-command "thread exception", which prints the current exception.

Differential Revision: https://reviews.llvm.org/D43886

llvm-svn: 347813

4 files changed, 77 insertions, 5 deletions

diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp
index bc574808415..74b17f539d9 100644
--- a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp
+++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp
@@ -455,13 +455,19 @@ lldb::SearchFilterSP AppleObjCRuntime::CreateExceptionSearchFilter() {
 
   if (target.GetArchitecture().GetTriple().getVendor() == llvm::Triple::Apple) {
     FileSpecList filter_modules;
-    filter_modules.Append(FileSpec("libobjc.A.dylib"));
+    filter_modules.Append(std::get<0>(GetExceptionThrowLocation()));
     return target.GetSearchFilterForModuleList(&filter_modules);
   } else {
     return LanguageRuntime::CreateExceptionSearchFilter();
   }
 }
 
+std::tuple<FileSpec, ConstString>
+AppleObjCRuntime::GetExceptionThrowLocation() {
+  return std::make_tuple(
+      FileSpec("libobjc.A.dylib"), ConstString("objc_exception_throw"));
+}
+
 void AppleObjCRuntime::ReadObjCLibraryIfNeeded(const ModuleList &module_list) {
   if (!HasReadObjCLibrary()) {
     std::lock_guard<std::recursive_mutex> guard(module_list.GetMutex());
diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.h b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.h
index 46ab11d0da6..ac2f5c83ca7 100644
--- a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.h
+++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.h
@@ -86,6 +86,8 @@ public:
   bool ExceptionBreakpointsExplainStop(lldb::StopInfoSP stop_reason) override;
 
   lldb::SearchFilterSP CreateExceptionSearchFilter() override;
+  
+  static std::tuple<FileSpec, ConstString> GetExceptionThrowLocation();
 
   uint32_t GetFoundationVersion();
 
diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV1.cpp b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV1.cpp
index dc3955db9a5..aaecfb27e90 100644
--- a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV1.cpp
+++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV1.cpp
@@ -113,8 +113,9 @@ AppleObjCRuntimeV1::CreateExceptionResolver(Breakpoint *bkpt, bool catch_bp,
 
   if (throw_bp)
     resolver_sp.reset(new BreakpointResolverName(
-        bkpt, "objc_exception_throw", eFunctionNameTypeBase,
-        eLanguageTypeUnknown, Breakpoint::Exact, 0, eLazyBoolNo));
+        bkpt, std::get<1>(GetExceptionThrowLocation()).AsCString(),
+        eFunctionNameTypeBase, eLanguageTypeUnknown, Breakpoint::Exact, 0,
+        eLazyBoolNo));
   // FIXME: don't do catch yet.
   return resolver_sp;
 }
diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp
index b644db41dbf..bbe6dd8e8d1 100644
--- a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp
+++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp
@@ -25,6 +25,7 @@
 #include "lldb/Core/Module.h"
 #include "lldb/Core/PluginManager.h"
 #include "lldb/Core/Section.h"
+#include "lldb/Core/ValueObjectConstResult.h"
 #include "lldb/Core/ValueObjectVariable.h"
 #include "lldb/Expression/DiagnosticManager.h"
 #include "lldb/Expression/FunctionCaller.h"
@@ -39,10 +40,12 @@
 #include "lldb/Symbol/Symbol.h"
 #include "lldb/Symbol/TypeList.h"
 #include "lldb/Symbol/VariableList.h"
+#include "lldb/Target/ABI.h"
 #include "lldb/Target/ExecutionContext.h"
 #include "lldb/Target/Platform.h"
 #include "lldb/Target/Process.h"
 #include "lldb/Target/RegisterContext.h"
+#include "lldb/Target/StackFrameRecognizer.h"
 #include "lldb/Target/Target.h"
 #include "lldb/Target/Thread.h"
 #include "lldb/Utility/ConstString.h"
@@ -373,6 +376,8 @@ ExtractRuntimeGlobalSymbol(Process *process, ConstString name,
   }
 }
 
+static void RegisterObjCExceptionRecognizer();
+
 AppleObjCRuntimeV2::AppleObjCRuntimeV2(Process *process,
                                        const ModuleSP &objc_module_sp)
     : AppleObjCRuntime(process), m_get_class_info_code(),
@@ -393,6 +398,7 @@ AppleObjCRuntimeV2::AppleObjCRuntimeV2(Process *process,
   static const ConstString g_gdb_object_getClass("gdb_object_getClass");
   m_has_object_getClass = (objc_module_sp->FindFirstSymbolWithNameAndType(
                                g_gdb_object_getClass, eSymbolTypeCode) != NULL);
+  RegisterObjCExceptionRecognizer();
 }
 
 bool AppleObjCRuntimeV2::GetDynamicTypeAndAddress(
@@ -799,8 +805,9 @@ AppleObjCRuntimeV2::CreateExceptionResolver(Breakpoint *bkpt, bool catch_bp,
 
   if (throw_bp)
     resolver_sp.reset(new BreakpointResolverName(
-        bkpt, "objc_exception_throw", eFunctionNameTypeBase,
-        eLanguageTypeUnknown, Breakpoint::Exact, 0, eLazyBoolNo));
+        bkpt, std::get<1>(GetExceptionThrowLocation()).AsCString(),
+        eFunctionNameTypeBase, eLanguageTypeUnknown, Breakpoint::Exact, 0,
+        eLazyBoolNo));
   // FIXME: We don't do catch breakpoints for ObjC yet.
   // Should there be some way for the runtime to specify what it can do in this
   // regard?
@@ -2592,3 +2599,59 @@ void AppleObjCRuntimeV2::GetValuesForGlobalCFBooleans(lldb::addr_t &cf_true,
   } else
     this->AppleObjCRuntime::GetValuesForGlobalCFBooleans(cf_true, cf_false);
 }
+
+#pragma mark Frame recognizers
+
+class ObjCExceptionRecognizedStackFrame : public RecognizedStackFrame {
+ public:
+  ObjCExceptionRecognizedStackFrame(StackFrameSP frame_sp) {
+    ThreadSP thread_sp = frame_sp->GetThread();
+    ProcessSP process_sp = thread_sp->GetProcess();
+
+    const lldb::ABISP &abi = process_sp->GetABI();
+    if (!abi) return;
+
+    CompilerType voidstar = process_sp->GetTarget()
+                                .GetScratchClangASTContext()
+                                ->GetBasicType(lldb::eBasicTypeVoid)
+                                .GetPointerType();
+
+    ValueList args;
+    Value input_value;
+    input_value.SetCompilerType(voidstar);
+    args.PushValue(input_value);
+
+    if (!abi->GetArgumentValues(*thread_sp, args)) return;
+
+    addr_t exception_addr = args.GetValueAtIndex(0)->GetScalar().ULongLong();
+
+    Value value(exception_addr);
+    value.SetCompilerType(voidstar);
+    exception = ValueObjectConstResult::Create(frame_sp.get(), value,
+                                               ConstString("exception"));
+    exception = exception->GetDynamicValue(eDynamicDontRunTarget);
+  }
+
+  ValueObjectSP exception;
+
+  lldb::ValueObjectSP GetExceptionObject() override { return exception; }
+};
+
+class ObjCExceptionThrowFrameRecognizer : public StackFrameRecognizer {
+  lldb::RecognizedStackFrameSP RecognizeFrame(lldb::StackFrameSP frame) {
+    return lldb::RecognizedStackFrameSP(
+        new ObjCExceptionRecognizedStackFrame(frame));
+  };
+};
+
+static void RegisterObjCExceptionRecognizer() {
+  static llvm::once_flag g_once_flag;
+  llvm::call_once(g_once_flag, []() {
+    FileSpec module;
+    ConstString function;
+    std::tie(module, function) = AppleObjCRuntime::GetExceptionThrowLocation();
+    StackFrameRecognizerManager::AddRecognizer(
+        StackFrameRecognizerSP(new ObjCExceptionThrowFrameRecognizer()),
+        module.GetFilename(), function, /*first_instruction_only*/ true);
+  });
+}