Source/JavaScriptCore/b3/B3BreakCriticalEdges.cpp

/*
 * Copyright (C) 2016-2018 Apple Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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#include "config.h"
#include "B3BreakCriticalEdges.h"

#if ENABLE(B3_JIT)

#include "B3BasicBlockInlines.h"
#include "B3BlockInsertionSet.h"
#include "B3ValueInlines.h"

namespace JSC { namespace B3 {

void breakCriticalEdges(Procedure& proc)
{
    BlockInsertionSet insertionSet(proc);
    
    for (BasicBlock* block : proc) {
        // Non-void terminals that are the moral equivalent of jumps trigger critical edge breaking
        // because of fixSSA's demoteValues.
        if (block->numSuccessors() <= 1
            && block->last()->type() == Void)
            continue;

        for (BasicBlock*& successor : block->successorBlocks()) {
            if (successor->numPredecessors() <= 1)
                continue;

            BasicBlock* pad =
                insertionSet.insertBefore(successor, successor->frequency());
            pad->appendNew<Value>(proc, Jump, successor->at(0)->origin());
            pad->setSuccessors(FrequentedBlock(successor));
            pad->addPredecessor(block);
            successor->replacePredecessor(block, pad);
            successor = pad;
        }
    }

    if (insertionSet.execute())
        proc.invalidateCFG();
}

} } // namespace JSC::B3

#endif // ENABLE(B3_JIT)