[lldb/Plugin] Add artificial stackframe loading in ScriptedThread

This patch adds the ability for ScriptedThread to load artificial stack
frames. To do so, the interpreter instance can create a list that will
contain the frame index and its pc address.

Then, when the Scripted Process plugin stops, it will refresh its
Scripted Threads state by invalidating their register context and load
to list from the interpreter object and reconstruct each frame.

This patch also removes all of the default implementation for
`get_stackframes` from the derived ScriptedThread classes, and add the
interface code for the Scripted Thread Interface.

rdar://88721095

Differential Revision: https://reviews.llvm.org/D119388

Signed-off-by: Med Ismail Bennani <medismail.bennani@gmail.com>

lldb/examples/python/scripted_process/scripted_process.py

@@ -306,9 +306,9 @@ def __init__(idx, cfa, pc, symbol_ctx):
                 containing for each entry, the frame index, the canonical
                 frame address, the program counter value for that frame
                 and a symbol context.
-                None if the list is empty.
+                The list can be empty.
         """
-        return 0
+        return self.frames
 
     def get_register_info(self):
         if self.register_info is None:

lldb/include/lldb/Target/StackFrameList.h

@@ -17,6 +17,8 @@
 
 namespace lldb_private {
 
+class ScriptedThread;
+
 class StackFrameList {
 public:
   // Constructors and Destructors
@@ -86,6 +88,7 @@ class StackFrameList {
 
 protected:
   friend class Thread;
+  friend class ScriptedThread;
 
   bool SetFrameAtIndex(uint32_t idx, lldb::StackFrameSP &frame_sp);
 

lldb/source/Plugins/Process/scripted/ScriptedProcess.cpp

@@ -359,6 +359,7 @@ bool ScriptedProcess::DoUpdateThreadList(ThreadList &old_thread_list,
 void ScriptedProcess::RefreshStateAfterStop() {
   // Let all threads recover from stopping and do any clean up based on the
   // previous thread state (if any).
+  m_thread_list.RefreshStateAfterStop();
 }
 
 bool ScriptedProcess::GetProcessInfo(ProcessInstanceInfo &info) {

lldb/source/Plugins/Process/scripted/ScriptedThread.cpp

@@ -147,6 +147,73 @@ ScriptedThread::CreateRegisterContextForFrame(StackFrame *frame) {
   return m_reg_context_sp;
 }
 
+bool ScriptedThread::LoadArtificialStackFrames() {
+  StructuredData::ArraySP arr_sp = GetInterface()->GetStackFrames();
+
+  Status error;
+  if (!arr_sp)
+    return GetInterface()->ErrorWithMessage<bool>(
+        LLVM_PRETTY_FUNCTION, "Failed to get scripted thread stackframes.",
+        error, LLDBLog::Thread);
+
+  size_t arr_size = arr_sp->GetSize();
+  if (arr_size > std::numeric_limits<uint32_t>::max())
+    return GetInterface()->ErrorWithMessage<bool>(
+        LLVM_PRETTY_FUNCTION,
+        llvm::Twine(
+            "StackFrame array size (" + llvm::Twine(arr_size) +
+            llvm::Twine(
+                ") is greater than maximum autorized for a StackFrameList."))
+            .str(),
+        error, LLDBLog::Thread);
+
+  StackFrameListSP frames = GetStackFrameList();
+
+  for (size_t idx = 0; idx < arr_size; idx++) {
+
+    StructuredData::Dictionary *dict;
+
+    if (!arr_sp->GetItemAtIndexAsDictionary(idx, dict) || !dict)
+      return GetInterface()->ErrorWithMessage<bool>(
+          LLVM_PRETTY_FUNCTION,
+          llvm::Twine(
+              "Couldn't get artificial stackframe dictionary at index (" +
+              llvm::Twine(idx) + llvm::Twine(") from stackframe array."))
+              .str(),
+          error, LLDBLog::Thread);
+
+    lldb::addr_t pc;
+    if (!dict->GetValueForKeyAsInteger("pc", pc))
+      return ScriptedInterface::ErrorWithMessage<bool>(
+          LLVM_PRETTY_FUNCTION,
+          "Couldn't find value for key 'pc' in stackframe dictionary.", error,
+          LLDBLog::Thread);
+
+    Address symbol_addr;
+    symbol_addr.SetLoadAddress(pc, &this->GetProcess()->GetTarget());
+
+    lldb::addr_t cfa = LLDB_INVALID_ADDRESS;
+    bool cfa_is_valid = false;
+    const bool behaves_like_zeroth_frame = false;
+    SymbolContext sc;
+    symbol_addr.CalculateSymbolContext(&sc);
+
+    StackFrameSP synth_frame_sp = std::make_shared<StackFrame>(
+        this->shared_from_this(), idx, idx, cfa, cfa_is_valid, pc,
+        StackFrame::Kind::Artificial, behaves_like_zeroth_frame, &sc);
+
+    if (!frames->SetFrameAtIndex(static_cast<uint32_t>(idx), synth_frame_sp))
+      return GetInterface()->ErrorWithMessage<bool>(
+          LLVM_PRETTY_FUNCTION,
+          llvm::Twine("Couldn't add frame (" + llvm::Twine(idx) +
+                      llvm::Twine(") to ScriptedThread StackFrameList."))
+              .str(),
+          error, LLDBLog::Thread);
+  }
+
+  return true;
+}
+
 bool ScriptedThread::CalculateStopInfo() {
   StructuredData::DictionarySP dict_sp = GetInterface()->GetStopReason();
 
@@ -216,6 +283,7 @@ bool ScriptedThread::CalculateStopInfo() {
 
 void ScriptedThread::RefreshStateAfterStop() {
   GetRegisterContext()->InvalidateIfNeeded(/*force=*/false);
+  LoadArtificialStackFrames();
 }
 
 lldb::ScriptedThreadInterfaceSP ScriptedThread::GetInterface() const {

lldb/source/Plugins/Process/scripted/ScriptedThread.h

@@ -42,6 +42,8 @@ class ScriptedThread : public lldb_private::Thread {
   lldb::RegisterContextSP
   CreateRegisterContextForFrame(lldb_private::StackFrame *frame) override;
 
+  bool LoadArtificialStackFrames();
+
   bool CalculateStopInfo() override;
 
   const char *GetInfo() override { return nullptr; }

lldb/source/Plugins/ScriptInterpreter/Python/ScriptedPythonInterface.cpp

@@ -34,6 +34,14 @@ ScriptedPythonInterface::GetStatusFromMethod(llvm::StringRef method_name) {
   return error;
 }
 
+template <>
+StructuredData::ArraySP
+ScriptedPythonInterface::ExtractValueFromPythonObject<StructuredData::ArraySP>(
+    python::PythonObject &p, Status &error) {
+  python::PythonList result_list(python::PyRefType::Borrowed, p.get());
+  return result_list.CreateStructuredArray();
+}
+
 template <>
 StructuredData::DictionarySP
 ScriptedPythonInterface::ExtractValueFromPythonObject<

lldb/source/Plugins/ScriptInterpreter/Python/ScriptedPythonInterface.h

@@ -126,6 +126,11 @@ class ScriptedPythonInterface : virtual public ScriptedInterface {
   ScriptInterpreterPythonImpl &m_interpreter;
 };
 
+template <>
+StructuredData::ArraySP
+ScriptedPythonInterface::ExtractValueFromPythonObject<StructuredData::ArraySP>(
+    python::PythonObject &p, Status &error);
+
 template <>
 StructuredData::DictionarySP
 ScriptedPythonInterface::ExtractValueFromPythonObject<

lldb/source/Plugins/ScriptInterpreter/Python/ScriptedThreadPythonInterface.cpp

@@ -112,7 +112,14 @@ StructuredData::DictionarySP ScriptedThreadPythonInterface::GetStopReason() {
 }
 
 StructuredData::ArraySP ScriptedThreadPythonInterface::GetStackFrames() {
-  return nullptr;
+  Status error;
+  StructuredData::ArraySP arr =
+      Dispatch<StructuredData::ArraySP>("get_stackframes", error);
+
+  if (!CheckStructuredDataObject(LLVM_PRETTY_FUNCTION, arr, error))
+    return {};
+
+  return arr;
 }
 
 StructuredData::DictionarySP ScriptedThreadPythonInterface::GetRegisterInfo() {

lldb/test/API/functionalities/scripted_process/TestScriptedProcess.py

@@ -133,3 +133,6 @@ def cleanup():
                 break
             self.assertEqual(idx, int(reg.value, 16))
 
+        self.assertTrue(frame.IsArtificial(), "Frame is not artificial")
+        pc = frame.GetPCAddress().GetLoadAddress(target)
+        self.assertEqual(pc, 0x0100001b00)

lldb/test/API/functionalities/scripted_process/dummy_scripted_process.py

@@ -46,6 +46,7 @@ def get_scripted_thread_plugin(self):
 class DummyScriptedThread(ScriptedThread):
     def __init__(self, process, args):
         super().__init__(process, args)
+        self.frames.append({"pc": 0x0100001b00 })
 
     def get_thread_id(self) -> int:
         return 0x19
@@ -61,21 +62,6 @@ def get_stop_reason(self) -> Dict[str, Any]:
             "signal": signal.SIGINT
         } }
 
-    def get_stackframes(self):
-        class ScriptedStackFrame:
-            def __init__(idx, cfa, pc, symbol_ctx):
-                self.idx = idx
-                self.cfa = cfa
-                self.pc = pc
-                self.symbol_ctx = symbol_ctx
-
-
-        symbol_ctx = lldb.SBSymbolContext()
-        frame_zero = ScriptedStackFrame(0, 0x42424242, 0x5000000, symbol_ctx)
-        self.frames.append(frame_zero)
-
-        return self.frame_zero[0:0]
-
     def get_register_context(self) -> str:
         return struct.pack(
                 '21Q', 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
@@ -88,4 +74,4 @@ def __lldb_init_module(debugger, dict):
                                      DummyScriptedProcess.__name__))
     else:
         print("Name of the class that will manage the scripted process: '%s.%s'"
-                % (__name__, DummyScriptedProcess.__name__))
+                % (__name__, DummyScriptedProcess.__name__))

lldb/test/API/functionalities/scripted_process/invalid_scripted_process.py

@@ -57,21 +57,6 @@ def get_stop_reason(self) -> Dict[str, Any]:
             "signal": signal.SIGTRAP
         } }
 
-    def get_stackframes(self):
-        class ScriptedStackFrame:
-            def __init__(idx, cfa, pc, symbol_ctx):
-                self.idx = idx
-                self.cfa = cfa
-                self.pc = pc
-                self.symbol_ctx = symbol_ctx
-
-
-        symbol_ctx = lldb.SBSymbolContext()
-        frame_zero = ScriptedStackFrame(0, 0x42424242, 0x5000000, symbol_ctx)
-        self.frames.append(frame_zero)
-
-        return self.frame_zero[0:0]
-
     def get_register_context(self) -> str:
         return None
 

lldb/test/API/functionalities/scripted_process/stack_core_scripted_process.py

@@ -139,21 +139,6 @@ def get_stop_reason(self) -> Dict[str, Any]:
 
         return stop_reason
 
-    def get_stackframes(self):
-        class ScriptedStackFrame:
-            def __init__(idx, cfa, pc, symbol_ctx):
-                self.idx = idx
-                self.cfa = cfa
-                self.pc = pc
-                self.symbol_ctx = symbol_ctx
-
-
-        symbol_ctx = lldb.SBSymbolContext()
-        frame_zero = ScriptedStackFrame(0, 0x42424242, 0x5000000, symbol_ctx)
-        self.frames.append(frame_zero)
-
-        return self.frame_zero[0:0]
-
     def get_register_context(self) -> str:
         if not self.corefile_thread or self.corefile_thread.GetNumFrames() == 0:
             return None