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[lldb][nfc] Split the constructor of ThreadPlanStepOut #136160

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Apr 17, 2025
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4 changes: 4 additions & 0 deletions lldb/include/lldb/Target/ThreadPlanStepOut.h
Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,10 @@ class ThreadPlanStepOut : public ThreadPlan, public ThreadPlanShouldStopHere {
LazyBool step_out_avoids_code_without_debug_info);

void SetupAvoidNoDebug(LazyBool step_out_avoids_code_without_debug_info);

void SetupReturnAddress(lldb::StackFrameSP return_frame_sp,
lldb::StackFrameSP immediate_return_from_sp,
uint32_t frame_idx, bool continue_to_next_branch);
// Need an appropriate marker for the current stack so we can tell step out
// from step in.

Expand Down
58 changes: 38 additions & 20 deletions lldb/source/Target/ThreadPlanStepOut.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,32 @@ using namespace lldb_private;

uint32_t ThreadPlanStepOut::s_default_flag_values = 0;

/// Computes the target frame this plan should step out to.
static StackFrameSP
ComputeTargetFrame(Thread &thread, uint32_t start_frame_idx,
std::vector<StackFrameSP> &skipped_frames) {
uint32_t frame_idx = start_frame_idx + 1;
StackFrameSP return_frame_sp = thread.GetStackFrameAtIndex(frame_idx);
if (!return_frame_sp)
return nullptr;

while (return_frame_sp->IsArtificial() || return_frame_sp->IsHidden()) {
skipped_frames.push_back(return_frame_sp);

frame_idx++;
return_frame_sp = thread.GetStackFrameAtIndex(frame_idx);

// We never expect to see an artificial frame without a regular ancestor.
// Defensively refuse to step out.
if (!return_frame_sp) {
LLDB_LOG(GetLog(LLDBLog::Step),
"Can't step out of frame with artificial ancestors");
return nullptr;
}
}
return return_frame_sp;
}

// ThreadPlanStepOut: Step out of the current frame
ThreadPlanStepOut::ThreadPlanStepOut(
Thread &thread, SymbolContext *context, bool first_insn, bool stop_others,
Expand All @@ -44,34 +70,25 @@ ThreadPlanStepOut::ThreadPlanStepOut(
m_return_addr(LLDB_INVALID_ADDRESS), m_stop_others(stop_others),
m_immediate_step_from_function(nullptr),
m_calculate_return_value(gather_return_value) {
Log *log = GetLog(LLDBLog::Step);
SetFlagsToDefault();
SetupAvoidNoDebug(step_out_avoids_code_without_debug_info);

m_step_from_insn = thread.GetRegisterContext()->GetPC(0);

uint32_t return_frame_index = frame_idx + 1;
StackFrameSP return_frame_sp(thread.GetStackFrameAtIndex(return_frame_index));
StackFrameSP return_frame_sp =
ComputeTargetFrame(thread, frame_idx, m_stepped_past_frames);
StackFrameSP immediate_return_from_sp(thread.GetStackFrameAtIndex(frame_idx));

SetupReturnAddress(return_frame_sp, immediate_return_from_sp, frame_idx,
continue_to_next_branch);
}

void ThreadPlanStepOut::SetupReturnAddress(
StackFrameSP return_frame_sp, StackFrameSP immediate_return_from_sp,
uint32_t frame_idx, bool continue_to_next_branch) {
if (!return_frame_sp || !immediate_return_from_sp)
return; // we can't do anything here. ValidatePlan() will return false.

// While stepping out, behave as-if artificial frames are not present.
while (return_frame_sp->IsArtificial() || return_frame_sp->IsHidden()) {
m_stepped_past_frames.push_back(return_frame_sp);

++return_frame_index;
return_frame_sp = thread.GetStackFrameAtIndex(return_frame_index);

// We never expect to see an artificial frame without a regular ancestor.
// If this happens, log the issue and defensively refuse to step out.
if (!return_frame_sp) {
LLDB_LOG(log, "Can't step out of frame with artificial ancestors");
return;
}
}

m_step_out_to_id = return_frame_sp->GetStackID();
m_immediate_step_from_id = immediate_return_from_sp->GetStackID();

Expand All @@ -84,8 +101,8 @@ ThreadPlanStepOut::ThreadPlanStepOut(
// First queue a plan that gets us to this inlined frame, and when we get
// there we'll queue a second plan that walks us out of this frame.
m_step_out_to_inline_plan_sp = std::make_shared<ThreadPlanStepOut>(
thread, nullptr, false, stop_others, eVoteNoOpinion, eVoteNoOpinion,
frame_idx - 1, eLazyBoolNo, continue_to_next_branch);
GetThread(), nullptr, false, m_stop_others, eVoteNoOpinion,
eVoteNoOpinion, frame_idx - 1, eLazyBoolNo, continue_to_next_branch);
static_cast<ThreadPlanStepOut *>(m_step_out_to_inline_plan_sp.get())
->SetShouldStopHereCallbacks(nullptr, nullptr);
m_step_out_to_inline_plan_sp->SetPrivate(true);
Expand Down Expand Up @@ -125,6 +142,7 @@ ThreadPlanStepOut::ThreadPlanStepOut(

// Perform some additional validation on the return address.
uint32_t permissions = 0;
Log *log = GetLog(LLDBLog::Step);
if (!m_process.GetLoadAddressPermissions(m_return_addr, permissions)) {
LLDB_LOGF(log, "ThreadPlanStepOut(%p): Return address (0x%" PRIx64
") permissions not found.", static_cast<void *>(this),
Expand Down
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