Source/JavaScriptCore/b3/air/AirBreakCriticalEdges.cpp

/*
 * Copyright (C) 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
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#include "config.h"
#include "AirBreakCriticalEdges.h"

#if ENABLE(B3_JIT)

#include "AirBlockInsertionSet.h"
#include "AirCode.h"

namespace JSC { namespace B3 { namespace Air {

void breakCriticalEdges(Code& code)
{
    BlockInsertionSet insertionSet(code);
    
    for (BasicBlock* block : code) {
        if (block->numSuccessors() <= 1)
            continue;
        
        for (BasicBlock*& successor : block->successorBlocks()) {
            if (successor->numPredecessors() <= 1)
                continue;
            
            BasicBlock* pad = insertionSet.insertBefore(successor, successor->frequency());
            pad->append(Jump, successor->at(0).origin);
            pad->setSuccessors(successor);
            pad->addPredecessor(block);
            successor->replacePredecessor(block, pad);
            successor = pad;
        }
    }
    
    insertionSet.execute();
}

} } } // namespace JSC::B3::Air

#endif // ENABLE(B3_JIT)