[lldb] Expose QueueThreadPlanForStepSingleInstruction function to SBThreadPlan (#137904)

Expose `QueueThreadPlanForStepSingleInstruction` function to
SBThreadPlan

Author: eronnen

lldb/include/lldb/API/SBThreadPlan.h

@@ -105,6 +105,9 @@ class LLDB_API SBThreadPlan {
   SBThreadPlan QueueThreadPlanForStepOut(uint32_t frame_idx_to_step_to,
                                          bool first_insn, SBError &error);
 
+  SBThreadPlan QueueThreadPlanForStepSingleInstruction(bool step_over,
+                                                       SBError &error);
+
   SBThreadPlan QueueThreadPlanForRunToAddress(SBAddress address);
   SBThreadPlan QueueThreadPlanForRunToAddress(SBAddress address,
                                               SBError &error);

lldb/source/API/SBThreadPlan.cpp

@@ -325,6 +325,29 @@ SBThreadPlan::QueueThreadPlanForStepOut(uint32_t frame_idx_to_step_to,
   return SBThreadPlan();
 }
 
+SBThreadPlan
+SBThreadPlan::QueueThreadPlanForStepSingleInstruction(bool step_over,
+                                                      SBError &error) {
+  LLDB_INSTRUMENT_VA(this, step_over, error);
+
+  ThreadPlanSP thread_plan_sp(GetSP());
+  if (thread_plan_sp) {
+    Status plan_status;
+    SBThreadPlan plan(
+        thread_plan_sp->GetThread().QueueThreadPlanForStepSingleInstruction(
+            step_over, false, false, plan_status));
+
+    if (plan_status.Fail())
+      error.SetErrorString(plan_status.AsCString());
+    else
+      plan.GetSP()->SetPrivate(true);
+
+    return plan;
+  }
+
+  return SBThreadPlan();
+}
+
 SBThreadPlan
 SBThreadPlan::QueueThreadPlanForRunToAddress(SBAddress sb_address) {
   LLDB_INSTRUMENT_VA(this, sb_address);

lldb/test/API/functionalities/step_scripted/Steps.py

@@ -45,6 +45,26 @@ def queue_child_thread_plan(self):
         return self.thread_plan.QueueThreadPlanForStepScripted("Steps.StepOut")
 
 
+class StepSingleInstruction(StepWithChild):
+    def __init__(self, thread_plan, dict):
+        super().__init__(thread_plan)
+
+    def queue_child_thread_plan(self):
+        return self.thread_plan.QueueThreadPlanForStepSingleInstruction(
+            False, lldb.SBError()
+        )
+
+
+class StepSingleInstructionWithStepOver(StepWithChild):
+    def __init__(self, thread_plan, dict):
+        super().__init__(thread_plan)
+
+    def queue_child_thread_plan(self):
+        return self.thread_plan.QueueThreadPlanForStepSingleInstruction(
+            True, lldb.SBError()
+        )
+
+
 # This plan does a step-over until a variable changes value.
 class StepUntil(StepWithChild):
     def __init__(self, thread_plan, args_data):

lldb/test/API/functionalities/step_scripted/TestStepScripted.py

@@ -44,6 +44,48 @@ def step_out_with_scripted_plan(self, name):
         stop_desc = thread.GetStopDescription(1000)
         self.assertIn("Stepping out from", stop_desc, "Got right description")
 
+    def run_until_branch_instruction(self):
+        self.build()
+        (target, process, thread, bkpt) = lldbutil.run_to_source_breakpoint(
+            self, "Break on branch instruction", self.main_source_file
+        )
+
+        # Check that we landed in a call instruction
+        frame = thread.GetFrameAtIndex(0)
+        current_instruction = target.ReadInstructions(frame.GetPCAddress(), 1)[0]
+        self.assertEqual(
+            lldb.eInstructionControlFlowKindCall,
+            current_instruction.GetControlFlowKind(target),
+        )
+        return (target, process, thread, bkpt)
+
+    def test_step_single_instruction(self):
+        (target, process, thread, bkpt) = self.run_until_branch_instruction()
+
+        err = thread.StepUsingScriptedThreadPlan("Steps.StepSingleInstruction")
+        self.assertSuccess(err)
+
+        # Verify that stepping a single instruction after "foo();" steps into `foo`
+        frame = thread.GetFrameAtIndex(0)
+        self.assertEqual("foo", frame.GetFunctionName())
+
+    def test_step_single_instruction_with_step_over(self):
+        (target, process, thread, bkpt) = self.run_until_branch_instruction()
+
+        frame = thread.GetFrameAtIndex(0)
+        next_instruction = target.ReadInstructions(frame.GetPCAddress(), 2)[1]
+        next_instruction_address = next_instruction.GetAddress()
+
+        err = thread.StepUsingScriptedThreadPlan(
+            "Steps.StepSingleInstructionWithStepOver"
+        )
+        self.assertSuccess(err)
+
+        # Verify that stepping over an instruction doesn't step into `foo`
+        frame = thread.GetFrameAtIndex(0)
+        self.assertEqual("main", frame.GetFunctionName())
+        self.assertEqual(next_instruction_address, frame.GetPCAddress())
+
     def test_misspelled_plan_name(self):
         """Test that we get a useful error if we misspell the plan class name"""
         self.build()

lldb/test/API/functionalities/step_scripted/main.c

@@ -8,6 +8,6 @@ void foo() {
 }
 
 int main() {
-  foo();
+  foo(); // Break on branch instruction.
   return 0;
 }