DFGNonSpeculativeJIT.h   [plain text]

/*
 * Copyright (C) 2011 Apple Inc. All rights reserved.
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#ifndef DFGNonSpeculativeJIT_h
#define DFGNonSpeculativeJIT_h

#if ENABLE(DFG_JIT)

#include <dfg/DFGJITCodeGenerator.h>

namespace JSC { namespace DFG {

class SpeculationCheckIndexIterator;

// === EntryLocation ===
//
// This structure describes an entry point into the non-speculative
// code path. This is used in linking bail-outs from the speculative path.
struct EntryLocation {
    EntryLocation(MacroAssembler::Label, NonSpeculativeJIT*);

    // The node this entry point corresponds to, and the label
    // marking the start of code for the given node.
    MacroAssembler::Label m_entry;
    NodeIndex m_nodeIndex;

    // For every entry point we record a map recording for every
    // machine register which, if any, values it contains. For
    // GPR registers we must also record the format of the value.
    struct RegisterInfo {
        NodeIndex nodeIndex;
        DataFormat format;
        bool isSpilled;
    };
    RegisterInfo m_gprInfo[GPRInfo::numberOfRegisters];
    RegisterInfo m_fprInfo[FPRInfo::numberOfRegisters];
};

// === NonSpeculativeJIT ===
//
// This class is used to generate code for the non-speculative path.
// Code generation will take advantage of static information available
// in the dataflow to perform safe optimizations - for example, avoiding
// boxing numeric values between arithmetic operations, but will not
// perform any unsafe optimizations that would render the code unable
// to produce the correct results for any possible input.
class NonSpeculativeJIT : public JITCodeGenerator {
    friend struct EntryLocation;
public:
    NonSpeculativeJIT(JITCompiler& jit)
        : JITCodeGenerator(jit, false)
    {
    }

    void compile(SpeculationCheckIndexIterator&);

    typedef SegmentedVector<EntryLocation, 16> EntryLocationVector;
    EntryLocationVector& entryLocations() { return m_entryLocations; }

private:
    void compile(SpeculationCheckIndexIterator&, Node&);
    void compile(SpeculationCheckIndexIterator&, BasicBlock&);

    // These methods are used to plant calls out to C++
    // helper routines to convert between types.
    void valueToNumber(JSValueOperand&, GPRReg result);
    void valueToInt32(JSValueOperand&, GPRReg result);
    void numberToInt32(FPRReg, GPRReg result);

    // Record an entry location into the non-speculative code path;
    // for every bail-out on the speculative path we record information
    // to be able to re-enter into the non-speculative one.
    void trackEntry(MacroAssembler::Label entry)
    {
        m_entryLocations.append(EntryLocation(entry, this));
    }
    
    // internal helpers for add/sub/mul operations
    void knownConstantArithOp(NodeType op, NodeIndex regChild, NodeIndex immChild, bool commute);
    void basicArithOp(NodeType op, Node&);

    EntryLocationVector m_entryLocations;
};

} } // namespace JSC::DFG

#endif
#endif