Source/JavaScriptCore/dfg/DFGTierUpCheckInjectionPhase.cpp

/*
 * Copyright (C) 2013, 2014 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
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#include "config.h"

#if ENABLE(DFG_JIT)

#include "DFGTierUpCheckInjectionPhase.h"

#include "DFGGraph.h"
#include "DFGInsertionSet.h"
#include "DFGPhase.h"
#include "FTLCapabilities.h"
#include "Operations.h"

namespace JSC { namespace DFG {

class TierUpCheckInjectionPhase : public Phase {
public:
    TierUpCheckInjectionPhase(Graph& graph)
        : Phase(graph, "tier-up check injection")
    {
    }
    
    bool run()
    {
        RELEASE_ASSERT(m_graph.m_plan.mode == DFGMode);
        
        if (!Options::useFTLJIT())
            return false;
        
        if (m_graph.m_profiledBlock->m_didFailFTLCompilation)
            return false;
        
#if ENABLE(FTL_JIT)
        FTL::CapabilityLevel level = FTL::canCompile(m_graph);
        if (level == FTL::CannotCompile)
            return false;
        
        if (!Options::enableOSREntryToFTL())
            level = FTL::CanCompile;
        
        InsertionSet insertionSet(m_graph);
        for (BlockIndex blockIndex = m_graph.numBlocks(); blockIndex--;) {
            BasicBlock* block = m_graph.block(blockIndex);
            if (!block)
                continue;
            
            for (unsigned nodeIndex = 0; nodeIndex < block->size(); ++nodeIndex) {
                Node* node = block->at(nodeIndex);
                if (node->op() != LoopHint)
                    continue;
                
                // We only put OSR checks for the first LoopHint in the block. Note that
                // more than one LoopHint could happen in cases where we did a lot of CFG
                // simplification in the bytecode parser, but it should be very rare.
                
                CodeOrigin codeOrigin = node->codeOrigin;
                
                if (level != FTL::CanCompileAndOSREnter || codeOrigin.inlineCallFrame) {
                    insertionSet.insertNode(
                        nodeIndex + 1, SpecNone, CheckTierUpInLoop, codeOrigin);
                    break;
                }
                
                bool isAtTop = true;
                for (unsigned subNodeIndex = nodeIndex; subNodeIndex--;) {
                    if (!block->at(subNodeIndex)->isSemanticallySkippable()) {
                        isAtTop = false;
                        break;
                    }
                }
                
                if (!isAtTop) {
                    insertionSet.insertNode(
                        nodeIndex + 1, SpecNone, CheckTierUpInLoop, codeOrigin);
                    break;
                }
                
                insertionSet.insertNode(
                    nodeIndex + 1, SpecNone, CheckTierUpAndOSREnter, codeOrigin);
                break;
            }
            
            if (block->last()->op() == Return) {
                insertionSet.insertNode(
                    block->size() - 1, SpecNone, CheckTierUpAtReturn, block->last()->codeOrigin);
            }
            
            insertionSet.execute(block);
        }
        
        m_graph.m_plan.willTryToTierUp = true;
        return true;
#else // ENABLE(FTL_JIT)
        RELEASE_ASSERT_NOT_REACHED();
        return false;
#endif // ENABLE(FTL_JIT)
    }
};

bool performTierUpCheckInjection(Graph& graph)
{
    SamplingRegion samplingRegion("DFG Tier-up Check Injection");
    return runPhase<TierUpCheckInjectionPhase>(graph);
}

} } // namespace JSC::DFG

#endif // ENABLE(DFG_JIT)