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

//===-- StackID.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/Target/StackID.h"
#include "lldb/Core/Stream.h"
#include "lldb/Symbol/Block.h"
#include "lldb/Symbol/Symbol.h"
#include "lldb/Symbol/SymbolContext.h"

using namespace lldb_private;

void
StackID::Dump (Stream *s)
{
    s->Printf("StackID (pc = 0x%16.16" PRIx64 ", cfa = 0x%16.16" PRIx64 ", symbol_scope = %p",
              m_pc, m_cfa, static_cast<void*>(m_symbol_scope));
    if (m_symbol_scope)
    {
        SymbolContext sc;

        m_symbol_scope->CalculateSymbolContext (&sc);
        if (sc.block)
            s->Printf(" (Block {0x%8.8" PRIx64 "})", sc.block->GetID());
        else if (sc.symbol)
            s->Printf(" (Symbol{0x%8.8x})", sc.symbol->GetID());
    }
    s->PutCString(") ");
}

bool
lldb_private::operator== (const StackID& lhs, const StackID& rhs)
{
    if (lhs.GetCallFrameAddress() != rhs.GetCallFrameAddress())
        return false;

    SymbolContextScope *lhs_scope = lhs.GetSymbolContextScope();
    SymbolContextScope *rhs_scope = rhs.GetSymbolContextScope();

    // Only compare the PC values if both symbol context scopes are nullptr
    if (lhs_scope == nullptr && rhs_scope == nullptr)
        return lhs.GetPC() == rhs.GetPC();
    
    return lhs_scope == rhs_scope;
}

bool
lldb_private::operator!= (const StackID& lhs, const StackID& rhs)
{
    if (lhs.GetCallFrameAddress() != rhs.GetCallFrameAddress())
        return true;

    SymbolContextScope *lhs_scope = lhs.GetSymbolContextScope();
    SymbolContextScope *rhs_scope = rhs.GetSymbolContextScope();

    if (lhs_scope == nullptr && rhs_scope == nullptr)
        return lhs.GetPC() != rhs.GetPC();

    return lhs_scope != rhs_scope;
}

bool
lldb_private::operator< (const StackID& lhs, const StackID& rhs)
{
    const lldb::addr_t lhs_cfa = lhs.GetCallFrameAddress();
    const lldb::addr_t rhs_cfa = rhs.GetCallFrameAddress();
    
    // FIXME: We are assuming that the stacks grow downward in memory.  That's not necessary, but true on
    // all the machines we care about at present.  If this changes, we'll have to deal with that.  The ABI is the
    // agent who knows this ordering, but the StackID has no access to the ABI.  The most straightforward way
    // to handle this is to add a "m_grows_downward" bool to the StackID, and set it in the constructor.  
    // But I'm not going to waste a bool per StackID on this till we need it.
    
    if (lhs_cfa != rhs_cfa)
        return lhs_cfa < rhs_cfa;

    SymbolContextScope *lhs_scope = lhs.GetSymbolContextScope();
    SymbolContextScope *rhs_scope = rhs.GetSymbolContextScope();

    if (lhs_scope != nullptr && rhs_scope != nullptr)
    {
        // Same exact scope, lhs is not less than (younger than rhs)
        if (lhs_scope == rhs_scope)
            return false;
        
        SymbolContext lhs_sc;
        SymbolContext rhs_sc;
        lhs_scope->CalculateSymbolContext (&lhs_sc);
        rhs_scope->CalculateSymbolContext (&rhs_sc);
        
        // Items with the same function can only be compared
        if (lhs_sc.function == rhs_sc.function &&
            lhs_sc.function != nullptr && lhs_sc.block != nullptr &&
            rhs_sc.function != nullptr && rhs_sc.block != nullptr)
        {
            return rhs_sc.block->Contains (lhs_sc.block);
        }
    }
    return false;
}