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

#ifndef lldb_UnwindLLDB_h_
#define lldb_UnwindLLDB_h_

// C Includes
// C++ Includes
#include <vector>

// Other libraries and framework includes
// Project includes
#include "lldb/lldb-public.h"
#include "lldb/Core/ConstString.h"
#include "lldb/Symbol/FuncUnwinders.h"
#include "lldb/Symbol/UnwindPlan.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/Unwind.h"

namespace lldb_private {

class RegisterContextLLDB;

class UnwindLLDB : public lldb_private::Unwind
{
public: 
    UnwindLLDB (lldb_private::Thread &thread);

    ~UnwindLLDB() override = default;

    enum RegisterSearchResult
    {
        eRegisterFound = 0,
        eRegisterNotFound,
        eRegisterIsVolatile
    };

protected:
    friend class lldb_private::RegisterContextLLDB;

    struct RegisterLocation {
        enum RegisterLocationTypes
        {
            eRegisterNotSaved = 0,              // register was not preserved by callee.  If volatile reg, is unavailable
            eRegisterSavedAtMemoryLocation,     // register is saved at a specific word of target mem (target_memory_location)
            eRegisterInRegister,                // register is available in a (possible other) register (register_number)
            eRegisterSavedAtHostMemoryLocation, // register is saved at a word in lldb's address space
            eRegisterValueInferred,             // register val was computed (and is in inferred_value)
            eRegisterInLiveRegisterContext      // register value is in a live (stack frame #0) register
        };
        int type;
        union
        {
            lldb::addr_t target_memory_location;
            uint32_t     register_number;       // in eRegisterKindLLDB register numbering system
            void*        host_memory_location;
            uint64_t     inferred_value;        // eRegisterValueInferred - e.g. stack pointer == cfa + offset
        } location;
    };

    void
    DoClear() override
    {
        m_frames.clear();
        m_candidate_frame.reset();
        m_unwind_complete = false;
    }

    uint32_t
    DoGetFrameCount() override;

    bool
    DoGetFrameInfoAtIndex(uint32_t frame_idx,
                          lldb::addr_t& cfa,
                          lldb::addr_t& start_pc) override;
    
    lldb::RegisterContextSP
    DoCreateRegisterContextForFrame(lldb_private::StackFrame *frame) override;

    typedef std::shared_ptr<RegisterContextLLDB> RegisterContextLLDBSP;

    // Needed to retrieve the "next" frame (e.g. frame 2 needs to retrieve frame 1's RegisterContextLLDB)
    // The RegisterContext for frame_num must already exist or this returns an empty shared pointer.
    RegisterContextLLDBSP
    GetRegisterContextForFrameNum (uint32_t frame_num);

    // Iterate over the RegisterContextLLDB's in our m_frames vector, look for the first one that
    // has a saved location for this reg.
    bool
    SearchForSavedLocationForRegister (uint32_t lldb_regnum, lldb_private::UnwindLLDB::RegisterLocation &regloc, uint32_t starting_frame_num, bool pc_register);


    //------------------------------------------------------------------
    /// Provide the list of user-specified trap handler functions
    ///
    /// The Platform is one source of trap handler function names; that
    /// may be augmented via a setting.  The setting needs to be converted
    /// into an array of ConstStrings before it can be used - we only want
    /// to do that once per thread so it's here in the UnwindLLDB object.
    ///
    /// @return
    ///     Vector of ConstStrings of trap handler function names.  May be
    ///     empty.
    //------------------------------------------------------------------
    const std::vector<ConstString> &
    GetUserSpecifiedTrapHandlerFunctionNames ()
    {
        return m_user_supplied_trap_handler_functions;
    }

private:
    struct Cursor
    {
        lldb::addr_t start_pc;  // The start address of the function/symbol for this frame - current pc if unknown
        lldb::addr_t cfa;       // The canonical frame address for this stack frame
        lldb_private::SymbolContext sctx;  // A symbol context we'll contribute to & provide to the StackFrame creation
        RegisterContextLLDBSP reg_ctx_lldb_sp; // These are all RegisterContextLLDB's

        Cursor () : start_pc (LLDB_INVALID_ADDRESS), cfa (LLDB_INVALID_ADDRESS), sctx(), reg_ctx_lldb_sp() { }
    private:
        DISALLOW_COPY_AND_ASSIGN (Cursor);
    };

    typedef std::shared_ptr<Cursor> CursorSP;
    std::vector<CursorSP> m_frames;
    CursorSP m_candidate_frame;
    bool m_unwind_complete; // If this is true, we've enumerated all the frames in the stack, and m_frames.size() is the 
                            // number of frames, etc.  Otherwise we've only gone as far as directly asked, and m_frames.size()
                            // is how far we've currently gone.
 
    std::vector<ConstString> m_user_supplied_trap_handler_functions;

    //-----------------------------------------------------------------
    // Check if Full UnwindPlan of First frame is valid or not.
    // If not then try Fallback UnwindPlan of the frame. If Fallback
    // UnwindPlan succeeds then update the Full UnwindPlan with the
    // Fallback UnwindPlan.
    //-----------------------------------------------------------------
    void
    UpdateUnwindPlanForFirstFrameIfInvalid (ABI* abi);

    CursorSP
    GetOneMoreFrame (ABI* abi);

    bool
    AddOneMoreFrame (ABI *abi);

    bool
    AddFirstFrame ();

    //------------------------------------------------------------------
    // For UnwindLLDB only
    //------------------------------------------------------------------
    DISALLOW_COPY_AND_ASSIGN (UnwindLLDB);
};

} // namespace lldb_private

#endif // lldb_UnwindLLDB_h_
