path: root/Source/JavaScriptCore/b3/air/AirCode.h

/*
 * Copyright (C) 2015-2016 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. 
 */

#pragma once

#if ENABLE(B3_JIT)

#include "AirArg.h"
#include "AirBasicBlock.h"
#include "AirSpecial.h"
#include "AirStackSlot.h"
#include "AirTmp.h"
#include "B3SparseCollection.h"
#include "CCallHelpers.h"
#include "RegisterAtOffsetList.h"
#include "StackAlignment.h"
#include <wtf/IndexMap.h>

namespace JSC { namespace B3 {

class Procedure;

#if COMPILER(GCC) && ASSERT_DISABLED
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wreturn-type"
#endif // COMPILER(GCC) && ASSERT_DISABLED

namespace Air {

class BlockInsertionSet;
class CCallSpecial;

typedef void WasmBoundsCheckGeneratorFunction(CCallHelpers&, GPRReg, unsigned);
typedef SharedTask<WasmBoundsCheckGeneratorFunction> WasmBoundsCheckGenerator;

// This is an IR that is very close to the bare metal. It requires about 40x more bytes than the
// generated machine code - for example if you're generating 1MB of machine code, you need about
// 40MB of Air.

class Code {
    WTF_MAKE_NONCOPYABLE(Code);
    WTF_MAKE_FAST_ALLOCATED;
public:
    ~Code();

    Procedure& proc() { return m_proc; }
    
    const Vector<Reg>& regsInPriorityOrder(Arg::Type type) const
    {
        switch (type) {
        case Arg::GP:
            return m_gpRegsInPriorityOrder;
        case Arg::FP:
            return m_fpRegsInPriorityOrder;
        }
        ASSERT_NOT_REACHED();
    }
    
    void setRegsInPriorityOrder(Arg::Type, const Vector<Reg>&);
    
    // This is the set of registers that Air is allowed to emit code to mutate. It's derived from
    // regsInPriorityOrder. Any registers not in this set are said to be "pinned".
    const RegisterSet& mutableRegs() const { return m_mutableRegs; }
    
    bool isPinned(Reg reg) const { return !mutableRegs().get(reg); }
    
    void pinRegister(Reg);

    JS_EXPORT_PRIVATE BasicBlock* addBlock(double frequency = 1);

    // Note that you can rely on stack slots always getting indices that are larger than the index
    // of any prior stack slot. In fact, all stack slots you create in the future will have an index
    // that is >= stackSlots().size().
    JS_EXPORT_PRIVATE StackSlot* addStackSlot(
        unsigned byteSize, StackSlotKind, B3::StackSlot* = nullptr);
    StackSlot* addStackSlot(B3::StackSlot*);

    Special* addSpecial(std::unique_ptr<Special>);

    // This is the special you need to make a C call!
    CCallSpecial* cCallSpecial();

    Tmp newTmp(Arg::Type type)
    {
        switch (type) {
        case Arg::GP:
            return Tmp::gpTmpForIndex(m_numGPTmps++);
        case Arg::FP:
            return Tmp::fpTmpForIndex(m_numFPTmps++);
        }
        ASSERT_NOT_REACHED();
    }

    unsigned numTmps(Arg::Type type)
    {
        switch (type) {
        case Arg::GP:
            return m_numGPTmps;
        case Arg::FP:
            return m_numFPTmps;
        }
        ASSERT_NOT_REACHED();
    }

    unsigned callArgAreaSizeInBytes() const { return m_callArgAreaSize; }

    // You can call this before code generation to force a minimum call arg area size.
    void requestCallArgAreaSizeInBytes(unsigned size)
    {
        m_callArgAreaSize = std::max(
            m_callArgAreaSize,
            static_cast<unsigned>(WTF::roundUpToMultipleOf(stackAlignmentBytes(), size)));
    }

    unsigned frameSize() const { return m_frameSize; }

    // Only phases that do stack allocation are allowed to set this. Currently, only
    // Air::allocateStack() does this.
    void setFrameSize(unsigned frameSize)
    {
        m_frameSize = frameSize;
    }

    // Note that this is not the same thing as proc().numEntrypoints(). This value here may be zero
    // until we lower EntrySwitch.
    unsigned numEntrypoints() const { return m_entrypoints.size(); }
    const Vector<FrequentedBlock>& entrypoints() const { return m_entrypoints; }
    const FrequentedBlock& entrypoint(unsigned index) const { return m_entrypoints[index]; }
    bool isEntrypoint(BasicBlock*) const;
    
    // This is used by lowerEntrySwitch().
    template<typename Vector>
    void setEntrypoints(Vector&& vector)
    {
        m_entrypoints = std::forward<Vector>(vector);
    }
    
    CCallHelpers::Label entrypointLabel(unsigned index) const
    {
        return m_entrypointLabels[index];
    }
    
    // This is used by generate().
    template<typename Vector>
    void setEntrypointLabels(Vector&& vector)
    {
        m_entrypointLabels = std::forward<Vector>(vector);
    }

    const RegisterAtOffsetList& calleeSaveRegisters() const { return m_calleeSaveRegisters; }
    RegisterAtOffsetList& calleeSaveRegisters() { return m_calleeSaveRegisters; }

    // Recomputes predecessors and deletes unreachable blocks.
    void resetReachability();

    JS_EXPORT_PRIVATE void dump(PrintStream&) const;

    unsigned size() const { return m_blocks.size(); }
    BasicBlock* at(unsigned index) const { return m_blocks[index].get(); }
    BasicBlock* operator[](unsigned index) const { return at(index); }

    // This is used by phases that optimize the block list. You shouldn't use this unless you really know
    // what you're doing.
    Vector<std::unique_ptr<BasicBlock>>& blockList() { return m_blocks; }

    // Finds the smallest index' such that at(index') != null and index' >= index.
    JS_EXPORT_PRIVATE unsigned findFirstBlockIndex(unsigned index) const;

    // Finds the smallest index' such that at(index') != null and index' > index.
    unsigned findNextBlockIndex(unsigned index) const;

    BasicBlock* findNextBlock(BasicBlock*) const;

    class iterator {
    public:
        iterator()
            : m_code(nullptr)
            , m_index(0)
        {
        }

        iterator(const Code& code, unsigned index)
            : m_code(&code)
            , m_index(m_code->findFirstBlockIndex(index))
        {
        }

        BasicBlock* operator*()
        {
            return m_code->at(m_index);
        }

        iterator& operator++()
        {
            m_index = m_code->findFirstBlockIndex(m_index + 1);
            return *this;
        }

        bool operator==(const iterator& other) const
        {
            return m_index == other.m_index;
        }

        bool operator!=(const iterator& other) const
        {
            return !(*this == other);
        }

    private:
        const Code* m_code;
        unsigned m_index;
    };

    iterator begin() const { return iterator(*this, 0); }
    iterator end() const { return iterator(*this, size()); }

    const SparseCollection<StackSlot>& stackSlots() const { return m_stackSlots; }
    SparseCollection<StackSlot>& stackSlots() { return m_stackSlots; }

    const SparseCollection<Special>& specials() const { return m_specials; }
    SparseCollection<Special>& specials() { return m_specials; }

    template<typename Callback>
    void forAllTmps(const Callback& callback) const
    {
        for (unsigned i = m_numGPTmps; i--;)
            callback(Tmp::gpTmpForIndex(i));
        for (unsigned i = m_numFPTmps; i--;)
            callback(Tmp::fpTmpForIndex(i));
    }

    void addFastTmp(Tmp);
    bool isFastTmp(Tmp tmp) const { return m_fastTmps.contains(tmp); }
    
    void* addDataSection(size_t);
    
    // The name has to be a string literal, since we don't do any memory management for the string.
    void setLastPhaseName(const char* name)
    {
        m_lastPhaseName = name;
    }

    const char* lastPhaseName() const { return m_lastPhaseName; }

    void setWasmBoundsCheckGenerator(RefPtr<WasmBoundsCheckGenerator> generator)
    {
        m_wasmBoundsCheckGenerator = generator;
    }

    RefPtr<WasmBoundsCheckGenerator> wasmBoundsCheckGenerator() const { return m_wasmBoundsCheckGenerator; }

    // This is a hash of the code. You can use this if you want to put code into a hashtable, but
    // it's mainly for validating the results from JSAir.
    unsigned jsHash() const;

private:
    friend class ::JSC::B3::Procedure;
    friend class BlockInsertionSet;
    
    Code(Procedure&);

    Vector<Reg>& regsInPriorityOrderImpl(Arg::Type type)
    {
        switch (type) {
        case Arg::GP:
            return m_gpRegsInPriorityOrder;
        case Arg::FP:
            return m_fpRegsInPriorityOrder;
        }
        ASSERT_NOT_REACHED();
    }

    Procedure& m_proc; // Some meta-data, like byproducts, is stored in the Procedure.
    Vector<Reg> m_gpRegsInPriorityOrder;
    Vector<Reg> m_fpRegsInPriorityOrder;
    RegisterSet m_mutableRegs;
    SparseCollection<StackSlot> m_stackSlots;
    Vector<std::unique_ptr<BasicBlock>> m_blocks;
    SparseCollection<Special> m_specials;
    HashSet<Tmp> m_fastTmps;
    CCallSpecial* m_cCallSpecial { nullptr };
    unsigned m_numGPTmps { 0 };
    unsigned m_numFPTmps { 0 };
    unsigned m_frameSize { 0 };
    unsigned m_callArgAreaSize { 0 };
    RegisterAtOffsetList m_calleeSaveRegisters;
    Vector<FrequentedBlock> m_entrypoints; // This is empty until after lowerEntrySwitch().
    Vector<CCallHelpers::Label> m_entrypointLabels; // This is empty until code generation.
    RefPtr<WasmBoundsCheckGenerator> m_wasmBoundsCheckGenerator;
    const char* m_lastPhaseName;
};

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

#if COMPILER(GCC) && ASSERT_DISABLED
#pragma GCC diagnostic pop
#endif // COMPILER(GCC) && ASSERT_DISABLED

#endif // ENABLE(B3_JIT)