CCData.cpp

/*******************************************************************************
 * Copyright IBM Corp. and others 2020
 *
 * This program and the accompanying materials are made available under
 * the terms of the Eclipse Public License 2.0 which accompanies this
 * distribution and is available at https://www.eclipse.org/legal/epl-2.0/
 * or the Apache License, Version 2.0 which accompanies this distribution
 * and is available at https://www.apache.org/licenses/LICENSE-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License, v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception [1] and GNU General Public
 * License, version 2 with the OpenJDK Assembly Exception [2].
 *
 * [1] https://www.gnu.org/software/classpath/license.html
 * [2] https://openjdk.org/legal/assembly-exception.html
 *
 * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0-only WITH Classpath-exception-2.0 OR GPL-2.0-only WITH OpenJDK-assembly-exception-1.0
 *******************************************************************************/

#include "omrcomp.h"
#include "OMR/Bytes.hpp"

#include "codegen/CCData.hpp"

#include "infra/Monitor.hpp"
#include "infra/CriticalSection.hpp"

using TR::CCData;

size_t CCData::dataSizeFromBytesSize(size_t sizeBytes)
   {
   return (sizeBytes + sizeof(data_t) - 1) / sizeof(data_t);
   }

size_t CCData::dataAlignmentFromBytesAlignment(size_t alignmentBytes)
   {
   return (alignmentBytes + OMR_ALIGNOF(data_t) - 1) / OMR_ALIGNOF(data_t);
   }

size_t CCData::byteIndexFromDataIndex(size_t dataIndex)
   {
   return dataIndex * sizeof(data_t);
   }

CCData::key_t CCData::key(const void * const data, const size_t sizeBytes)
   {
   return key_t(static_cast<const key_t::value_type *>(data), sizeBytes);
   }

CCData::key_t CCData::key(const char * const str)
   {
   return key_t(static_cast<const key_t::value_type *>(str));
   }

CCData::CCData(void * const storage, const size_t sizeBytes)
: _putIndex(0), _lock(TR::Monitor::create("CCDataMutex"))
   {
   if (sizeBytes > 0)
      {
      void *alignedStorage = storage;
      size_t sizeBytesAfterAlignment = sizeBytes;
      bool success = OMR::align(OMR_ALIGNOF(data_t), sizeof(data_t), alignedStorage, sizeBytesAfterAlignment) != NULL;
      TR_ASSERT_FATAL(success, "Can't align CCData storage to required boundary");
      _data = static_cast<char *>(alignedStorage);
      _capacity = dataSizeFromBytesSize(sizeBytesAfterAlignment);
      }
   else
      {
      _data = NULL;
      _capacity = 0;
      }
   }

bool CCData::put_impl(const void * const value, const size_t sizeBytes, const size_t alignmentBytes, const key_t * const key, index_t &index)
   {
   const OMR::CriticalSection critsec(_lock);

   /**
    * Multiple compilation threads may be attempting to update the same value with
    * the same key.  Once we have the mutex, check if the value already exists and
    * return successfully.
    */
   if (key && find_unsafe(*key, &index))
      {
      return true;
      }

   // The following feels like it could be simplified and calculated more efficiently. If you're reading this, have a go at it.
   size_t putByteIndex = byteIndexFromDataIndex(_putIndex);
   const size_t sizeDataUnits = dataSizeFromBytesSize(sizeBytes);
   const size_t alignmentDataUnits = dataAlignmentFromBytesAlignment(alignmentBytes);
   const size_t alignmentMask = alignmentDataUnits - 1;
   const size_t alignmentPadding = (alignmentDataUnits - ((reinterpret_cast<uintptr_t>(_data + putByteIndex) / OMR_ALIGNOF(data_t)) & alignmentMask)) & alignmentMask;
   const size_t remainingCapacity = _capacity - _putIndex;

   if (sizeDataUnits + alignmentPadding > remainingCapacity)
      return false;

   _putIndex += alignmentPadding;
   index = _putIndex;
   putByteIndex = byteIndexFromDataIndex(_putIndex);

   if (key != NULL)
      _mappings[*key] = _putIndex;

   if (value != NULL)
      {
      std::copy(static_cast<const char *>(value),
                static_cast<const char *>(value) + sizeBytes,
                _data + putByteIndex);
      }

   _putIndex += sizeDataUnits;

   return true;
   }

bool CCData::get(const index_t index, void * const value, const size_t sizeBytes) const
   {
   if (index >= _capacity)
      return false;

   const size_t byteIndex = byteIndexFromDataIndex(index);

   std::copy(_data + byteIndex,
             _data + byteIndex + sizeBytes,
             static_cast<char *>(value));

   return true;
   }

bool CCData::find(const key_t key, index_t * const index) const
   {
   const OMR::CriticalSection critsec(_lock);
   return find_unsafe(key, index);
   }

bool CCData::find_unsafe(const key_t key, index_t * const index) const
   {
   auto e = _mappings.find(key);
   if (e != _mappings.end())
      {
      if (index != NULL)
         *index = e->second;
      return true;
      }

   return false;
   }