llvm-project/lldb/source/Target/ThreadPlanShouldStopHere.cpp

//===-- ThreadPlanShouldStopHere.cpp ----------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// C Includes
// C++ Includes
// Other libraries and framework includes
// Project includes
#include "lldb/Core/Log.h"
#include "lldb/Symbol/Symbol.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/Thread.h"
#include "lldb/Target/ThreadPlanShouldStopHere.h"

using namespace lldb;
using namespace lldb_private;

//----------------------------------------------------------------------
// ThreadPlanShouldStopHere constructor
//----------------------------------------------------------------------
ThreadPlanShouldStopHere::ThreadPlanShouldStopHere(ThreadPlan *owner) :
    m_callbacks(),
    m_baton(nullptr),
    m_owner(owner),
    m_flags(ThreadPlanShouldStopHere::eNone)
{
    m_callbacks.should_stop_here_callback = ThreadPlanShouldStopHere::DefaultShouldStopHereCallback;
    m_callbacks.step_from_here_callback = ThreadPlanShouldStopHere::DefaultStepFromHereCallback;
}

ThreadPlanShouldStopHere::ThreadPlanShouldStopHere(ThreadPlan *owner, const ThreadPlanShouldStopHereCallbacks *callbacks, void *baton) :
    m_callbacks (),
    m_baton (),
    m_owner (owner),
    m_flags (ThreadPlanShouldStopHere::eNone)
{
    SetShouldStopHereCallbacks(callbacks, baton);
}

ThreadPlanShouldStopHere::~ThreadPlanShouldStopHere() = default;

bool
ThreadPlanShouldStopHere::InvokeShouldStopHereCallback (FrameComparison operation)
{
    bool should_stop_here = true;
    if (m_callbacks.should_stop_here_callback)
    {
        should_stop_here = m_callbacks.should_stop_here_callback (m_owner, m_flags, operation, m_baton);
        Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));
        if (log)
        {
            lldb::addr_t current_addr = m_owner->GetThread().GetRegisterContext()->GetPC(0);

            log->Printf ("ShouldStopHere callback returned %u from 0x%" PRIx64 ".", should_stop_here, current_addr);
        }
    }
    
    return should_stop_here;
}

bool
ThreadPlanShouldStopHere::DefaultShouldStopHereCallback (ThreadPlan *current_plan,
                                                         Flags &flags,
                                                         FrameComparison operation,
                                                         void *baton)
{
    bool should_stop_here = true;
    StackFrame *frame = current_plan->GetThread().GetStackFrameAtIndex(0).get();
    if (!frame)
        return true;
    
    Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));

    if ((operation == eFrameCompareOlder && flags.Test(eStepOutAvoidNoDebug))
        || (operation == eFrameCompareYounger && flags.Test(eStepInAvoidNoDebug))
        || (operation == eFrameCompareSameParent && flags.Test(eStepInAvoidNoDebug)))
    {
        if (!frame->HasDebugInformation())
        {
            if (log)
                log->Printf ("Stepping out of frame with no debug info");

            should_stop_here = false;
        }
    }
    
    // Always avoid code with line number 0.
    // FIXME: At present the ShouldStop and the StepFromHere calculate this independently.  If this ever
    // becomes expensive (this one isn't) we can try to have this set a state that the StepFromHere can use.
    if (frame)
    {
        SymbolContext sc;
        sc = frame->GetSymbolContext (eSymbolContextLineEntry);
        if (sc.line_entry.line == 0)
            should_stop_here = false;
    }
    
    return should_stop_here;
}

ThreadPlanSP
ThreadPlanShouldStopHere::DefaultStepFromHereCallback (ThreadPlan *current_plan,
                                                         Flags &flags,
                                                         FrameComparison operation,
                                                         void *baton)
{
    const bool stop_others = false;
    const size_t frame_index = 0;
    ThreadPlanSP return_plan_sp;
    // If we are stepping through code at line number 0, then we need to step over this range.  Otherwise
    // we will step out.
    Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_STEP));

    StackFrame *frame = current_plan->GetThread().GetStackFrameAtIndex(0).get();
    if (!frame)
        return return_plan_sp;
    SymbolContext sc;
    sc = frame->GetSymbolContext (eSymbolContextLineEntry|eSymbolContextSymbol);

    if (sc.line_entry.line == 0)
    {
        AddressRange range = sc.line_entry.range;

	// If the whole function is marked line 0 just step out, that's easier & faster than continuing
        // to step through it.
	bool just_step_out = false;
	if (sc.symbol && sc.symbol->ValueIsAddress())
        {
	    Address symbol_end = sc.symbol->GetAddress();
	    symbol_end.Slide(sc.symbol->GetByteSize() - 1);
            if (range.ContainsFileAddress(sc.symbol->GetAddress()) && range.ContainsFileAddress(symbol_end))
	    {
	        if (log)
	            log->Printf("Stopped in a function with only line 0 lines, just stepping out.");
                just_step_out = true;
	    }
	}
        if (!just_step_out)
        {
            if (log)
                log->Printf ("ThreadPlanShouldStopHere::DefaultStepFromHereCallback Queueing StepInRange plan to step through line 0 code.");
            
            return_plan_sp = current_plan->GetThread().QueueThreadPlanForStepInRange(false,
                                                                                     range,
                                                                                     sc,
                                                                                     NULL,
                                                                                     eOnlyDuringStepping,
                                                                                     eLazyBoolCalculate,
                                                                                     eLazyBoolNo);
        }
    }
    
    if (!return_plan_sp)
        return_plan_sp = current_plan->GetThread().QueueThreadPlanForStepOutNoShouldStop(false,
                                                                                         nullptr,
                                                                                         true,
                                                                                         stop_others,
                                                                                         eVoteNo,
                                                                                         eVoteNoOpinion,
                                                                                         frame_index,
                                                                                         true);
    return return_plan_sp;
}

ThreadPlanSP
ThreadPlanShouldStopHere::QueueStepOutFromHerePlan(lldb_private::Flags &flags, lldb::FrameComparison operation)
{
    ThreadPlanSP return_plan_sp;
    if (m_callbacks.step_from_here_callback)
    {
         return_plan_sp = m_callbacks.step_from_here_callback (m_owner, flags, operation, m_baton);
    }
    return return_plan_sp;
}

lldb::ThreadPlanSP
ThreadPlanShouldStopHere::CheckShouldStopHereAndQueueStepOut (lldb::FrameComparison operation)
{
    if (!InvokeShouldStopHereCallback(operation))
        return QueueStepOutFromHerePlan(m_flags, operation);
    else
        return ThreadPlanSP();
}