path: root/src/vm/contractimpl.cpp

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
// File: contractimpl.cpp
//
// Keeps track of contract implementations, used primarily in stub dispatch.
//


//

//
// ============================================================================

#include "common.h"  // Precompiled header

#include "contractimpl.h"
#include "virtualcallstub.h"
#include "decodemd.h"

#ifdef FEATURE_PREJIT 
#include "compile.h"
#endif

#if defined(_DEBUG)
DummyGlobalContract ___contract;
#endif

#ifdef LOGGING 
//----------------------------------------------------------------------------
StubDispatchStats g_sdStats = {0};
#endif // LOGGING

#ifndef DACCESS_COMPILE 

//----------------------------------------------------------------------------
MethodDesc * DispatchSlot::GetMethodDesc()
{
    WRAPPER_NO_CONTRACT;
    if (IsNull())
        return NULL;
    else
        return MethodTable::GetMethodDescForSlotAddress(GetTarget());
}

//------------------------------------------------------------------------
void TypeIDMap::Init(UINT32 idStartValue, UINT32 idIncrementValue, BOOL fUseFatTokensForUniqueness)
{
    STANDARD_VM_CONTRACT;

    LockOwner lock = {&m_lock, IsOwnerOfCrst};
    m_idMap.Init(11, TRUE, &lock);
    m_mtMap.Init(11, TRUE, &lock);
    m_idProvider.Init(idStartValue, idIncrementValue);
    m_entryCount = 0;
    m_fUseFatIdsForUniqueness = fUseFatTokensForUniqueness;
}

#endif // !DACCESS_COMPILE

//------------------------------------------------------------------------
// Returns the ID of the type if found. If not found, returns INVALID_TYPE_ID
UINT32 TypeIDMap::LookupTypeID(PTR_MethodTable pMT)
{
    CONTRACTL {
        NOTHROW;
        SO_TOLERANT;
        PRECONDITION(CheckPointer(GetThread()));
        if (GetThread()->PreemptiveGCDisabled()) { GC_NOTRIGGER; } else { GC_TRIGGERS; }
    } CONTRACTL_END;

    UINT32 id = (UINT32) m_mtMap.LookupValue((UPTR)dac_cast<TADDR>(pMT), 0);
    _ASSERTE(!m_fUseFatIdsForUniqueness || !pMT->RequiresFatDispatchTokens() || (DispatchToken::RequiresDispatchTokenFat(id, 0)));

    return id;
}

//------------------------------------------------------------------------
// Returns the ID of the type if found. If not found, returns INVALID_TYPE_ID
PTR_MethodTable TypeIDMap::LookupType(UINT32 id)
{
    CONTRACTL {
        NOTHROW;
        SO_TOLERANT;
        PRECONDITION(CheckPointer(GetThread()));
        if (GetThread()->PreemptiveGCDisabled()) { GC_NOTRIGGER; } else { GC_TRIGGERS; }
        PRECONDITION(id <= TypeIDProvider::MAX_TYPE_ID);
    } CONTRACTL_END;

    if (!m_idProvider.OwnsID(id))
        return NULL;

    UPTR ret = m_idMap.LookupValue((UPTR)id, 0);
    if (ret == static_cast<UPTR>(INVALIDENTRY))
        return NULL;

    ret <<= 1;

    return PTR_MethodTable(ret);
}

//------------------------------------------------------------------------
// Returns the ID of the type if found. If not found, assigns the ID and
// returns the new ID.
UINT32 TypeIDMap::GetTypeID(PTR_MethodTable pMT)
{
    CONTRACTL {
        THROWS;
        GC_TRIGGERS;
    } CONTRACTL_END;

    // Lookup the value.
    UINT32 id = LookupTypeID(pMT);
#ifndef DACCESS_COMPILE 
    // If the value is not in the table, take the lock, get a new ID, and
    // insert the new pair.
    if (id == TypeIDProvider::INVALID_TYPE_ID)
    {
        // Take the lock
        CrstHolder lh(&m_lock);
        // Check to see if someone beat us to the punch
        id = LookupTypeID(pMT);
        if (id != TypeIDProvider::INVALID_TYPE_ID)
        {
            return id;
        }
        // Get the next ID
        if (m_fUseFatIdsForUniqueness && pMT->RequiresFatDispatchTokens())
        {
            id = GetNextFatID();
        }
        else
        {
            id = GetNextID();
        }

        CONSISTENCY_CHECK(id <= TypeIDProvider::MAX_TYPE_ID);
        // Insert the pair, with lookups in both directions
        CONSISTENCY_CHECK((((UPTR)pMT) & 0x1) == 0);
        m_idMap.InsertValue((UPTR)id, (UPTR)pMT >> 1);
        m_mtMap.InsertValue((UPTR)pMT, (UPTR)id);
        m_entryCount++;
        CONSISTENCY_CHECK(GetThread()->GetDomain()->IsCompilationDomain() || 
                          (LookupType(id) == pMT));
    }
#else // DACCESS_COMPILE
    if (id == TypeIDProvider::INVALID_TYPE_ID)
        DacError(E_FAIL);
#endif // DACCESS_COMPILE
    // Return the ID for this type.
    return id;
} // TypeIDMap::GetTypeID

#ifndef DACCESS_COMPILE 

//------------------------------------------------------------------------
// If TRUE, it points to a matching entry.
// If FALSE, it is at the insertion point.
BOOL 
DispatchMapBuilder::Find(
    DispatchMapTypeID typeID, 
    UINT32            slotNumber, 
    Iterator &        it)
{
    WRAPPER_NO_CONTRACT;
    for (; it.IsValid(); it.Next())
    {
        if (typeID == it.GetTypeID())
        {
            if (slotNumber == it.GetSlotNumber())
            {
                return TRUE;
            }
            if (slotNumber < it.GetSlotNumber())
            {
                return FALSE;
            }
        }
        else if (typeID < it.GetTypeID())
        {
            return FALSE;
        }
    }

    return FALSE;
} // DispatchMapBuilder::Find

//------------------------------------------------------------------------
// If TRUE, contains such an entry.
// If FALSE, no such entry exists.
BOOL DispatchMapBuilder::Contains(DispatchMapTypeID typeID, UINT32 slotNumber)
{
    WRAPPER_NO_CONTRACT;
    Iterator it(this);
    return Find(typeID, slotNumber, it);
}

//------------------------------------------------------------------------
void
DispatchMapBuilder::InsertMDMapping(
    DispatchMapTypeID typeID, 
    UINT32            slotNumber, 
    MethodDesc *      pMDTarget, 
    BOOL              fIsMethodImpl)
{
    CONTRACTL {
        THROWS;
        GC_NOTRIGGER;
    } CONTRACTL_END;

    // Find a matching entry, or move the iterator to insertion point.
    Iterator it(this);
    BOOL fFound = Find(typeID, slotNumber, it);

    // If we find an existing matching entry, fail.
    if (fFound)
    {
        _ASSERTE(false);
        COMPlusThrowHR(COR_E_TYPELOAD);
    }

    // Create and initialize a new entry
    DispatchMapBuilderNode * pNew = NewEntry();
    pNew->Init(typeID, slotNumber, pMDTarget);
    if (fIsMethodImpl)
        pNew->SetIsMethodImpl();

    // Insert at the point of the iterator
    pNew->m_next = NULL;
    if (it.IsValid())
    {
        pNew->m_next = it.EntryNode();
    }
    *(it.EntryNodePtr()) = pNew;
    m_cEntries++;

} // DispatchMapBuilder::InsertMDMapping

//--------------------------------------------------------------------
UINT32 DispatchMapBuilder::Iterator::GetTargetSlot()
{
    WRAPPER_NO_CONTRACT;
    CONSISTENCY_CHECK(IsValid());
    if (GetTargetMD() != NULL)
    {
        return EntryNode()->m_pMDTarget->GetSlot();
    }
    else
    {
        return 0;
    }
}

//------------------------------------------------------------------------
DispatchMapBuilderNode * DispatchMapBuilder::NewEntry()
{
    CONTRACTL {
        THROWS;
        GC_NOTRIGGER;
        INJECT_FAULT(COMPlusThrowOM());
    } CONTRACTL_END;

    return new (m_pAllocator) DispatchMapBuilderNode();
}

//----------------------------------------------------------------------------
DispatchMap::DispatchMap(
    BYTE * pMap, 
    UINT32 cbMap)
{
    LIMITED_METHOD_CONTRACT;
    CONSISTENCY_CHECK(CheckPointer(pMap));
    memcpyNoGCRefs(m_rgMap, pMap, cbMap);
}

//----------------------------------------------------------------------------
// This mapping consists of a list of the following entries.
// <type, [<slot, (index | slot)>]>. This is implemented as
//
// flag:  0 if the map is a part of a JIT'd module
//        1 if the map is a part of an NGEN'd module.
// count: number of types that have entries
// {
//   type:  The ID current type being mapped
//   count: Number of subentries for the current type
//   bool:  Whether or not the target slot/index values can be negative.
//   {
//     slot:       The slot of type that is being mapped
//     index/slot: This is a slot mapping for the current type. The implementation search is 
//                 modified to <this, slot> and the search is restarted from the initial type.
//   }
// }
void 
DispatchMap::CreateEncodedMapping(
    MethodTable *        pMT, 
    DispatchMapBuilder * pMapBuilder, 
    StackingAllocator *  pAllocator, 
    BYTE **              ppbMap, 
    UINT32 *             pcbMap)
{
    CONTRACTL {
        THROWS;
        GC_TRIGGERS;
        INJECT_FAULT(COMPlusThrowOM());
        PRECONDITION(CheckPointer(pMT));
        PRECONDITION(CheckPointer(pMapBuilder));
        PRECONDITION(CheckPointer(pAllocator));
        PRECONDITION(CheckPointer(ppbMap));
        PRECONDITION(CheckPointer(pcbMap));
    } CONTRACTL_END;

    /////////////////////////////////
    // Phase 1 - gather entry counts

    UINT32 cNumTypes = 0;
    UINT32 cNumEntries = 0;

    {
        DispatchMapBuilder::Iterator it(pMapBuilder);
        // We don't want to record overrides or methodImpls in the dispatch map since
        // we have vtables to track this information.
        it.SkipThisTypeEntries();
        if (it.IsValid())
        {
            DispatchMapTypeID curType = DispatchMapTypeID::FromUINT32(INVALIDENTRY);
            do
            {
                cNumEntries++;
                if (curType != it.GetTypeID())
                {
                    cNumTypes++;
                    curType = it.GetTypeID();
                }
            }
            while (it.Next());
        }
    }

    /////////////////////////////////
    // Phase 2 - allocate space

    // Now that we have stats about the overall absolute maximum map size, we can allocate
    // some working space for createing the encoded map in.
    // Sizes: flag==UINT32, typeID==UINT32, slot==UINT32, index/slot==UINT32

    S_UINT32 scbMap = S_UINT32(sizeof(UINT32)) +
                   S_UINT32(cNumTypes) * S_UINT32(sizeof(UINT32)) +
                   S_UINT32(cNumEntries) * S_UINT32((sizeof(UINT32) + sizeof(UINT32)));

    BYTE * pbMap = (BYTE *)pAllocator->Alloc(scbMap);

    /////////////////////////////////
    // Phase 3 - encode the map

    {
        // Create the encoder over the newly allocated memory
        Encoder e(pbMap);
        // Encode the count of type entries
        e.Encode((unsigned)cNumTypes);
        // Start encoding the map
        DispatchMapBuilder::Iterator it(pMapBuilder);
        it.SkipThisTypeEntries();
        
        INT32 curType = -1;
        INT32 prevType;
        INT32 deltaType;
        while (it.IsValid())
        {
            // Encode the type ID
            prevType = curType;
            curType = (INT32)it.GetTypeID().ToUINT32();
            deltaType = curType - prevType - ENCODING_TYPE_DELTA;
            CONSISTENCY_CHECK(0 <= deltaType);
            e.Encode((unsigned)deltaType);
            // Variables for slot delta calculations
            BOOL fHasNegatives = FALSE;
            // Source slot
            INT32 curSlot = -1;
            INT32 prevSlot = -1;
            // Target slot for virtual mappings
            INT32 curTargetSlot = -1;
            INT32 prevTargetSlot = -1;
            // Count and encode the number of sub entries for this type
            UINT32 cSubEntries = 0;
            DispatchMapBuilder::Iterator subIt(it);
            do
            {
                prevTargetSlot = curTargetSlot;
                curTargetSlot = (INT32)subIt.GetTargetSlot();
                INT32 deltaTargetSlot =  curTargetSlot - prevTargetSlot - ENCODING_TARGET_SLOT_DELTA;
                if (deltaTargetSlot < 0)
                {
                    fHasNegatives = TRUE;
                }
                cSubEntries++;
            }
            while (subIt.Next() && (subIt.GetTypeID().ToUINT32() == (UINT32)curType));

            e.Encode((unsigned)cSubEntries);
            e.Encode((unsigned)fHasNegatives);
            e.ContainsNegatives(fHasNegatives);
            // Iterate each subentry and encode it
            curTargetSlot = -1;
            do
            {
                // Only virtual targets can be mapped virtually.
                CONSISTENCY_CHECK((it.GetTargetMD() == NULL) || 
                                  it.GetTargetMD()->IsVirtual());
                // Encode the slot
                prevSlot = curSlot;
                curSlot = it.GetSlotNumber();
                INT32 deltaSlot = curSlot - prevSlot - ENCODING_SLOT_DELTA;
                CONSISTENCY_CHECK(0 <= deltaSlot);
                e.Encode((unsigned)deltaSlot);
                
                // Calculate and encode the target slot delta
                prevTargetSlot = curTargetSlot;
                curTargetSlot = (INT32)it.GetTargetSlot();
                INT32 delta = curTargetSlot - prevTargetSlot - ENCODING_TARGET_SLOT_DELTA;
                
                if (fHasNegatives)
                {
                    e.EncodeSigned((signed)delta);
                }
                else
                {
                    CONSISTENCY_CHECK(0 <= delta);
                    e.Encode((unsigned)delta);
                }
            }
            while (it.Next() && it.GetTypeID().ToUINT32() == (UINT32)curType);
        } // while (it.IsValid())
        
        // Finish and finalize the map, and set the out params.
        e.Done();
        *pcbMap = e.Contents(ppbMap);
    }

#ifdef _DEBUG 
    // Let's verify the mapping
    {
        EncodedMapIterator itMap(*ppbMap);
        DispatchMapBuilder::Iterator itBuilder(pMapBuilder);
        itBuilder.SkipThisTypeEntries();

        while (itMap.IsValid())
        {
            CONSISTENCY_CHECK(itBuilder.IsValid());
            DispatchMapEntry * pEntryMap = itMap.Entry();
            CONSISTENCY_CHECK(pEntryMap->GetTypeID() == itBuilder.GetTypeID());
            CONSISTENCY_CHECK(pEntryMap->GetTargetSlotNumber() == itBuilder.GetTargetSlot());
            itMap.Next();
            itBuilder.Next();
        }

        CONSISTENCY_CHECK(!itBuilder.IsValid());
    }
#endif //_DEBUG
} // DispatchMap::CreateEncodedMapping

#ifdef FEATURE_NATIVE_IMAGE_GENERATION
//------------------------------------------------------------------------
void DispatchMap::Save(DataImage * image)
{
    STANDARD_VM_CONTRACT;

    CONSISTENCY_CHECK(!image->IsStored(this));

    UINT32 cbMap = GetMapSize();
    UINT32 cbObj = GetObjectSize(cbMap);

    image->StoreInternedStructure(
        this, 
        cbObj, 
        DataImage::ITEM_DISPATCH_MAP, 
        sizeof(void *));

#ifdef LOGGING 
    g_sdStats.m_cNGENDispatchMap++;
    g_sdStats.m_cbNGENDispatchMap += cbObj;
#endif //LOGGING
}

//------------------------------------------------------------------------
void DispatchMap::Fixup(DataImage *image)
{
    STANDARD_VM_CONTRACT;
}

#endif //FEATURE_NATIVE_IMAGE_GENERATION

#endif //!DACCESS_COMPILE

//------------------------------------------------------------------------
UINT32 DispatchMap::GetMapSize()
{
    WRAPPER_NO_CONTRACT;
    SUPPORTS_DAC;
    EncodedMapIterator it(this);
    for (; it.IsValid(); it.Next())
    {
    }
    CONSISTENCY_CHECK(dac_cast<TADDR>(it.m_d.End()) > PTR_HOST_MEMBER_TADDR(DispatchMap, this, m_rgMap));
    return (UINT32)(dac_cast<TADDR>(it.m_d.End()) - PTR_HOST_MEMBER_TADDR(DispatchMap, this, m_rgMap));
}

#ifdef DACCESS_COMPILE 

//------------------------------------------------------------------------
void DispatchMap::EnumMemoryRegions(CLRDataEnumMemoryFlags flags)
{
    WRAPPER_NO_CONTRACT;
    SUPPORTS_DAC;

    DAC_ENUM_DTHIS();

    EMEM_OUT(("MEM: %p DispatchMap\n", dac_cast<TADDR>(this)));

    DacEnumMemoryRegion(PTR_HOST_MEMBER_TADDR(DispatchMap,this,m_rgMap), GetMapSize());
}

#endif // DACCESS_COMPILE

//--------------------------------------------------------------------
void DispatchMap::EncodedMapIterator::Invalidate()
{
    LIMITED_METHOD_DAC_CONTRACT;
    m_numTypes = 0;
    m_curType = 0;
    m_numEntries = 0;
    m_curEntry = 0;
}

//--------------------------------------------------------------------
void DispatchMap::EncodedMapIterator::Init(PTR_BYTE pbMap)
{
    CONTRACTL {
        GC_NOTRIGGER;
        NOTHROW;
        INSTANCE_CHECK;
        PRECONDITION(CheckPointer(pbMap, NULL_OK));
        SUPPORTS_DAC;
    } CONTRACTL_END;

    if (pbMap != NULL)
    {
        // Initialize the map decoder
        m_d.Init(pbMap);
        m_numTypes = m_d.Next();
        m_curType = -1;
        m_curTypeId = DispatchMapTypeID::FromUINT32(static_cast<UINT32>(-1));
        m_numEntries = 0;
        m_curEntry = -1;
        m_curTargetSlot = static_cast<UINT32>(-1);
    }
    else
    {
        Invalidate();
    }

    Next();
}

//--------------------------------------------------------------------
DispatchMap::EncodedMapIterator::EncodedMapIterator(MethodTable * pMT)
{
    CONTRACTL {
        GC_NOTRIGGER;
        NOTHROW;
        INSTANCE_CHECK;
        SUPPORTS_DAC;
    } CONTRACTL_END;

    if (pMT->HasDispatchMap())
    {
        DispatchMap * pMap = pMT->GetDispatchMap();        
        Init(PTR_BYTE(PTR_HOST_MEMBER_TADDR(DispatchMap, pMap, m_rgMap)));
    }
    else
    {
        Init(NULL);
    }
}

//--------------------------------------------------------------------
// This should be used only when a dispatch map needs to be used
// separately from its MethodTable.
DispatchMap::EncodedMapIterator::EncodedMapIterator(DispatchMap * pMap)
{
    LIMITED_METHOD_CONTRACT;
    SUPPORTS_DAC;
    PTR_BYTE pBytes = NULL;
    if (pMap != NULL)
    {
        pBytes = PTR_BYTE(PTR_HOST_MEMBER_TADDR(DispatchMap, pMap,m_rgMap));
    }
    Init(pBytes);
}

//--------------------------------------------------------------------
DispatchMap::EncodedMapIterator::EncodedMapIterator(PTR_BYTE pbMap)
{
    LIMITED_METHOD_CONTRACT;

    Init(pbMap);
}

//--------------------------------------------------------------------
BOOL DispatchMap::EncodedMapIterator::Next()
{
    CONTRACTL {
        GC_NOTRIGGER;
        NOTHROW;
        INSTANCE_CHECK;
        SUPPORTS_DAC;
    } CONTRACTL_END;

    if (!IsValid())
    {
        return FALSE;
    }

    m_curEntry++;
    if (m_curEntry == m_numEntries)
    {
        m_curType++;
        if (m_curType == m_numTypes)
        {
            return FALSE;
        }
        m_curTypeId =
            DispatchMapTypeID::FromUINT32(
                (UINT32)((INT32)m_curTypeId.ToUINT32() + 
                         (INT32)m_d.Next() + 
                         ENCODING_TYPE_DELTA));
        _ASSERTE(!m_curTypeId.IsThisClass());
        m_curEntry = 0;
        m_numEntries = m_d.Next();
        m_fCurTypeHasNegativeEntries = (BOOL)m_d.Next();
        m_curSlot = static_cast<UINT32>(-1);
        m_curTargetSlot = static_cast<UINT32>(-1);
        CONSISTENCY_CHECK(m_numEntries != 0);
    }

    // Now gather enough info to initialize the dispatch entry

    // Get the source slot
    m_curSlot = (UINT32)((INT32)m_curSlot + (INT32)m_d.Next() + ENCODING_SLOT_DELTA);

    // If virtual, get the target virtual slot number
    m_curTargetSlot = 
        (UINT32)((INT32)m_curTargetSlot + 
                 ENCODING_TARGET_SLOT_DELTA + 
                 (INT32)(m_fCurTypeHasNegativeEntries ? m_d.NextSigned() : m_d.Next()));
    m_e.InitVirtualMapping(m_curTypeId, m_curSlot, m_curTargetSlot);

    CONSISTENCY_CHECK(IsValid());
    return TRUE;
} // DispatchMap::EncodedMapIterator::Next

//--------------------------------------------------------------------
DispatchMap::Iterator::Iterator(MethodTable * pMT)
    : m_mapIt(pMT)
{
    CONTRACTL {
        THROWS;
        GC_TRIGGERS;
    } CONTRACTL_END;
}

//--------------------------------------------------------------------
BOOL DispatchMap::Iterator::IsValid()
{
    WRAPPER_NO_CONTRACT;
    return m_mapIt.IsValid();
}

//--------------------------------------------------------------------
BOOL DispatchMap::Iterator::Next()
{
    WRAPPER_NO_CONTRACT;
    CONSISTENCY_CHECK(!m_mapIt.Entry()->GetTypeID().IsThisClass());
    if (m_mapIt.IsValid())
    {
        m_mapIt.Next();
        CONSISTENCY_CHECK(!m_mapIt.IsValid() || !m_mapIt.Entry()->GetTypeID().IsThisClass());
    }
    return IsValid();
}

//--------------------------------------------------------------------
DispatchMapEntry * DispatchMap::Iterator::Entry()
{
/*
    CONTRACTL {
        INSTANCE_CHECK;
        MODE_ANY;
        if (FORBIDGC_LOADER_USE_ENABLED()) NOTHROW; else THROWS;
        if (FORBIDGC_LOADER_USE_ENABLED()) GC_NOTRIGGER; else GC_TRIGGERS;
        if (FORBIDGC_LOADER_USE_ENABLED()) FORBID_FAULT; else { INJECT_FAULT(COMPlusThrowOM()); }
        PRECONDITION(IsValid());
    } CONTRACTL_END;
*/
    WRAPPER_NO_CONTRACT;
    CONSISTENCY_CHECK(IsValid());

    DispatchMapEntry * pEntry = NULL;
    if (m_mapIt.IsValid())
    {
        pEntry = m_mapIt.Entry();
    }
    CONSISTENCY_CHECK(CheckPointer(pEntry));
    return pEntry;
}