Source/JavaScriptCore/b3/B3BlockInsertionSet.cpp

/*
 * Copyright (C) 2015-2017 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#include "config.h"
#include "B3BlockInsertionSet.h"

#if ENABLE(B3_JIT)

#include "B3BasicBlockInlines.h"
#include "B3InsertionSet.h"
#include "B3ProcedureInlines.h"
#include <wtf/BubbleSort.h>

namespace JSC { namespace B3 {

BlockInsertionSet::BlockInsertionSet(Procedure &proc)
    : GenericBlockInsertionSet(proc.m_blocks)
    , m_proc(proc)
{
}

BlockInsertionSet::~BlockInsertionSet() { }

BasicBlock* BlockInsertionSet::splitForward(
    BasicBlock* block, unsigned& valueIndex, InsertionSet* insertionSet, double frequency)
{
    Value* value = block->at(valueIndex);

    // Create a new block that will go just before 'block', and make it contain everything prior
    // to 'valueIndex'.
    BasicBlock* result = insertBefore(block, frequency);
    result->m_values.resize(valueIndex + 1);
    for (unsigned i = valueIndex; i--;)
        result->m_values[i] = block->m_values[i];

    // Make the new block jump to 'block'.
    result->m_values[valueIndex] = m_proc.add<Value>(Jump, value->origin());
    result->setSuccessors(FrequentedBlock(block));

    // If we had inserted things into 'block' before this, execute those insertions now.
    if (insertionSet)
        insertionSet->execute(result);

    // Remove everything prior to 'valueIndex' from 'block', since those things are now in the
    // new block.
    block->m_values.remove(0, valueIndex);

    // This is being used in a forward loop over 'block'. Update the index of the loop so that
    // it can continue to the next block.
    valueIndex = 0;

    // Fixup the predecessors of 'block'. They now must jump to the new block.
    result->predecessors() = WTFMove(block->predecessors());
    block->addPredecessor(result);
    for (BasicBlock* predecessor : result->predecessors())
        predecessor->replaceSuccessor(block, result);

    return result;
}

} } // namespace JSC::B3

#endif // ENABLE(B3_JIT)