HackStudio: Update variables view based on the selected backtrace frame

DevTools/HackStudio/Debugger/BacktraceModel.cpp

@@ -27,9 +27,9 @@
 #include "BacktraceModel.h"
 #include "Debugger.h"
 
-RefPtr<BacktraceModel> BacktraceModel::create(const PtraceRegisters& regs)
+NonnullRefPtr<BacktraceModel> BacktraceModel::create(const DebugSession& debug_session, const PtraceRegisters& regs)
 {
-    return adopt(*new BacktraceModel(create_backtrace(regs)));
+    return adopt(*new BacktraceModel(create_backtrace(debug_session, regs)));
 }
 
 GUI::Variant BacktraceModel::data(const GUI::ModelIndex& index, Role role) const
@@ -41,20 +41,19 @@ GUI::Variant BacktraceModel::data(const GUI::ModelIndex& index, Role role) const
     return {};
 }
 
-Vector<BacktraceModel::FrameInfo> BacktraceModel::create_backtrace(const PtraceRegisters& regs)
+Vector<BacktraceModel::FrameInfo> BacktraceModel::create_backtrace(const DebugSession& debug_session, const PtraceRegisters& regs)
 {
     u32 current_ebp = regs.ebp;
     u32 current_instruction = regs.eip;
     Vector<BacktraceModel::FrameInfo> frames;
     do {
-        const auto& debug_info = Debugger::the().session()->debug_info();
+        String name = debug_session.debug_info().name_of_containing_function(current_instruction);
-        String name = debug_info.name_of_containing_function(current_instruction);
         if (name.is_null()) {
             dbg() << "BacktraceModel: couldn't find containing function for address: " << (void*)current_instruction;
             break;
         }
 
-        frames.append({ name, current_instruction });
+        frames.append({ name, current_instruction, current_ebp });
         current_instruction = Debugger::the().session()->peek(reinterpret_cast<u32*>(current_ebp + 4)).value();
         current_ebp = Debugger::the().session()->peek(reinterpret_cast<u32*>(current_ebp)).value();
     } while (current_ebp);

DevTools/HackStudio/Debugger/BacktraceModel.h

@@ -30,9 +30,11 @@
 #include <LibGUI/Model.h>
 #include <sys/arch/i386/regs.h>
 
+class DebugSession;
+
 class BacktraceModel final : public GUI::Model {
 public:
-    static RefPtr<BacktraceModel> create(const PtraceRegisters& regs);
+    static NonnullRefPtr<BacktraceModel> create(const DebugSession&, const PtraceRegisters& regs);
 
     virtual int row_count(const GUI::ModelIndex& = GUI::ModelIndex()) const override { return m_frames.size(); }
     virtual int column_count(const GUI::ModelIndex& = GUI::ModelIndex()) const override { return 1; }
@@ -47,18 +49,21 @@ public:
     virtual void update() override {}
     virtual GUI::ModelIndex index(int row, int column = 0, const GUI::ModelIndex& = GUI::ModelIndex()) const override { return create_index(row, column, &m_frames.at(row)); }
 
-private:
     struct FrameInfo {
         String function_name;
-        u32 address_in_frame;
+        u32 instruction_address;
+        u32 frame_base;
     };
 
+    const Vector<FrameInfo>& frames() const { return m_frames; }
+
+private:
     explicit BacktraceModel(Vector<FrameInfo>&& frames)
         : m_frames(move(frames))
     {
     }
 
-    static Vector<FrameInfo> create_backtrace(const PtraceRegisters&);
+    static Vector<FrameInfo> create_backtrace(const DebugSession&, const PtraceRegisters&);
 
     Vector<FrameInfo> m_frames;
 };

DevTools/HackStudio/Debugger/DebugInfoWidget.cpp

@@ -43,10 +43,25 @@ DebugInfoWidget::DebugInfoWidget()
     m_variables_view = splitter.add<GUI::TreeView>();
 }
 
-void DebugInfoWidget::update_state(const PtraceRegisters& regs)
+void DebugInfoWidget::update_state(const DebugSession& debug_session, const PtraceRegisters& regs)
 {
     m_variables_view->set_model(VariablesModel::create(regs));
-    m_backtrace_view->set_model(BacktraceModel::create(regs));
+    m_backtrace_view->set_model(BacktraceModel::create(debug_session, regs));
+    m_backtrace_view->selection().set(m_backtrace_view->model()->index(0));
+
+    m_backtrace_view->on_selection
+        = [this](auto& index) {
+              auto& model = static_cast<BacktraceModel&>(*m_backtrace_view->model());
+
+              // Note: The recontruction of the register set here is obviously incomplete.
+              // We currently only reconstruct eip & ebp. Ideally would also reconstruct the other registers somehow.
+              // (Other registers may be needed to get the values of variables who are not stored on the stack)
+              PtraceRegisters frame_regs {};
+              frame_regs.eip = model.frames()[index.row()].instruction_address;
+              frame_regs.ebp = model.frames()[index.row()].frame_base;
+
+              m_variables_view->set_model(VariablesModel::create(frame_regs));
+          };
 }
 
 void DebugInfoWidget::program_stopped()

DevTools/HackStudio/Debugger/DebugInfoWidget.h

@@ -38,7 +38,7 @@ class DebugInfoWidget final : public GUI::Widget {
 public:
     virtual ~DebugInfoWidget() override {}
 
-    void update_state(const PtraceRegisters&);
+    void update_state(const DebugSession&, const PtraceRegisters&);
     void program_stopped();
 
 private:

DevTools/HackStudio/main.cpp

@@ -608,14 +608,16 @@ int main(int argc, char** argv)
         [&](const PtraceRegisters& regs) {
             dbg() << "Program stopped";
 
-            auto source_position = Debugger::the().session()->debug_info().get_source_position(regs.eip);
+            ASSERT(Debugger::the().session());
+            const auto& debug_session = *Debugger::the().session();
+            auto source_position = debug_session.debug_info().get_source_position(regs.eip);
             if (!source_position.has_value()) {
                 dbg() << "Could not find source position for address: " << (void*)regs.eip;
                 return Debugger::HasControlPassedToUser::No;
             }
             current_editor_in_execution = get_editor_of_file(source_position.value().file_path);
             current_editor_in_execution->editor().set_execution_position(source_position.value().line_number - 1);
-            debug_info_widget.update_state(regs);
+            debug_info_widget.update_state(debug_session, regs);
             continue_action->set_enabled(true);
             single_step_action->set_enabled(true);
             reveal_action_tab(debug_info_widget);