[lldb] Introduce ScriptedFrameProvider for real threads (#161870)

This patch extends ScriptedFrame to work with real (non-scripted)
threads,
enabling frame providers to synthesize frames for native processes.

Previously, ScriptedFrame only worked within
ScriptedProcess/ScriptedThread
contexts. This patch decouples ScriptedFrame from ScriptedThread,
allowing
users to augment or replace stack frames in real debugging sessions for
use
cases like custom calling conventions, reconstructing corrupted frames
from
core files, or adding diagnostic frames.

Key changes:

- ScriptedFrame::Create() now accepts ThreadSP instead of requiring
ScriptedThread, extracting architecture from the target triple rather
than ScriptedProcess.arch

- Added SBTarget::RegisterScriptedFrameProvider() and
ClearScriptedFrameProvider() APIs, with Target storing a
SyntheticFrameProviderDescriptor template for new threads

- Added "target frame-provider register/clear" commands for CLI access

- Thread class gains LoadScriptedFrameProvider(),
ClearScriptedFrameProvider(),
and GetFrameProvider() methods for per-thread frame provider management

- New SyntheticStackFrameList overrides FetchFramesUpTo() to lazily
provide
frames from either the frame provider or the real stack

This enables practical use of the SyntheticFrameProvider infrastructure
in
real debugging workflows.

rdar://161834688

Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>

Signed-off-by: Med Ismail Bennani <ismail@bennani.ma>

1 files changed, 57 insertions, 1 deletions

diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/ScriptedFrameProviderPythonInterface.cpp b/lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/ScriptedFrameProviderPythonInterface.cpp
index b866bf332b7b..3dde5036453f 100644
--- a/lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/ScriptedFrameProviderPythonInterface.cpp
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/ScriptedFrameProviderPythonInterface.cpp
@@ -6,6 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "lldb/Core/PluginManager.h"
 #include "lldb/Host/Config.h"
 #include "lldb/Target/Thread.h"
 #include "lldb/Utility/Log.h"
@@ -30,18 +31,45 @@ ScriptedFrameProviderPythonInterface::ScriptedFrameProviderPythonInterface(
     ScriptInterpreterPythonImpl &interpreter)
     : ScriptedFrameProviderInterface(), ScriptedPythonInterface(interpreter) {}
 
+bool ScriptedFrameProviderPythonInterface::AppliesToThread(
+    llvm::StringRef class_name, lldb::ThreadSP thread_sp) {
+  // If there is any issue with this method, we will just assume it also applies
+  // to this thread which is the default behavior.
+  constexpr bool fail_value = true;
+  Status error;
+  StructuredData::ObjectSP obj =
+      CallStaticMethod(class_name, "applies_to_thread", error, thread_sp);
+  if (!ScriptedInterface::CheckStructuredDataObject(LLVM_PRETTY_FUNCTION, obj,
+                                                    error))
+    return fail_value;
+
+  return obj->GetBooleanValue(fail_value);
+}
+
 llvm::Expected<StructuredData::GenericSP>
 ScriptedFrameProviderPythonInterface::CreatePluginObject(
     const llvm::StringRef class_name, lldb::StackFrameListSP input_frames,
     StructuredData::DictionarySP args_sp) {
   if (!input_frames)
-    return llvm::createStringError("Invalid frame list");
+    return llvm::createStringError("invalid frame list");
 
   StructuredDataImpl sd_impl(args_sp);
   return ScriptedPythonInterface::CreatePluginObject(class_name, nullptr,
                                                      input_frames, sd_impl);
 }
 
+std::string ScriptedFrameProviderPythonInterface::GetDescription(
+    llvm::StringRef class_name) {
+  Status error;
+  StructuredData::ObjectSP obj =
+      CallStaticMethod(class_name, "get_description", error);
+  if (!ScriptedInterface::CheckStructuredDataObject(LLVM_PRETTY_FUNCTION, obj,
+                                                    error))
+    return {};
+
+  return obj->GetStringValue().str();
+}
+
 StructuredData::ObjectSP
 ScriptedFrameProviderPythonInterface::GetFrameAtIndex(uint32_t index) {
   Status error;
@@ -54,4 +82,32 @@ ScriptedFrameProviderPythonInterface::GetFrameAtIndex(uint32_t index) {
   return obj;
 }
 
+bool ScriptedFrameProviderPythonInterface::CreateInstance(
+    lldb::ScriptLanguage language, ScriptedInterfaceUsages usages) {
+  if (language != eScriptLanguagePython)
+    return false;
+
+  return true;
+}
+
+void ScriptedFrameProviderPythonInterface::Initialize() {
+  const std::vector<llvm::StringRef> ci_usages = {
+      "target frame-provider register -C <script-name> [-k key -v value ...]",
+      "target frame-provider list",
+      "target frame-provider remove <provider-name>",
+      "target frame-provider clear"};
+  const std::vector<llvm::StringRef> api_usages = {
+      "SBTarget.RegisterScriptedFrameProvider",
+      "SBTarget.RemoveScriptedFrameProvider",
+      "SBTarget.ClearScriptedFrameProvider"};
+  PluginManager::RegisterPlugin(
+      GetPluginNameStatic(),
+      llvm::StringRef("Provide scripted stack frames for threads"),
+      CreateInstance, eScriptLanguagePython, {ci_usages, api_usages});
+}
+
+void ScriptedFrameProviderPythonInterface::Terminate() {
+  PluginManager::UnregisterPlugin(CreateInstance);
+}
+
 #endif