[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, 55 insertions, 0 deletions

diff --git a/lldb/source/Target/Target.cpp b/lldb/source/Target/Target.cpp
index 3b51e17d1c4e..3f182bc61392 100644
--- a/lldb/source/Target/Target.cpp
+++ b/lldb/source/Target/Target.cpp
@@ -3718,6 +3718,61 @@ Status Target::Attach(ProcessAttachInfo &attach_info, Stream *stream) {
   return error;
 }
 
+llvm::Expected<uint32_t> Target::AddScriptedFrameProviderDescriptor(
+    const ScriptedFrameProviderDescriptor &descriptor) {
+  if (!descriptor.IsValid())
+    return llvm::createStringError("invalid frame provider descriptor");
+
+  llvm::StringRef name = descriptor.GetName();
+  if (name.empty())
+    return llvm::createStringError(
+        "frame provider descriptor has no class name");
+
+  std::lock_guard<std::recursive_mutex> guard(
+      m_frame_provider_descriptors_mutex);
+
+  uint32_t descriptor_id = descriptor.GetID();
+  m_frame_provider_descriptors[descriptor_id] = descriptor;
+
+  // Clear frame providers on existing threads so they reload with new config.
+  if (ProcessSP process_sp = GetProcessSP())
+    for (ThreadSP thread_sp : process_sp->Threads())
+      thread_sp->ClearScriptedFrameProvider();
+
+  return descriptor_id;
+}
+
+bool Target::RemoveScriptedFrameProviderDescriptor(uint32_t id) {
+  std::lock_guard<std::recursive_mutex> guard(
+      m_frame_provider_descriptors_mutex);
+  bool removed = m_frame_provider_descriptors.erase(id);
+
+  if (removed)
+    if (ProcessSP process_sp = GetProcessSP())
+      for (ThreadSP thread_sp : process_sp->Threads())
+        thread_sp->ClearScriptedFrameProvider();
+
+  return removed;
+}
+
+void Target::ClearScriptedFrameProviderDescriptors() {
+  std::lock_guard<std::recursive_mutex> guard(
+      m_frame_provider_descriptors_mutex);
+
+  m_frame_provider_descriptors.clear();
+
+  if (ProcessSP process_sp = GetProcessSP())
+    for (ThreadSP thread_sp : process_sp->Threads())
+      thread_sp->ClearScriptedFrameProvider();
+}
+
+const llvm::DenseMap<uint32_t, ScriptedFrameProviderDescriptor> &
+Target::GetScriptedFrameProviderDescriptors() const {
+  std::lock_guard<std::recursive_mutex> guard(
+      m_frame_provider_descriptors_mutex);
+  return m_frame_provider_descriptors;
+}
+
 void Target::FinalizeFileActions(ProcessLaunchInfo &info) {
   Log *log = GetLog(LLDBLog::Process);