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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef jit_MIRGraph_h
#define jit_MIRGraph_h

// This file declares the data structures used to build a control-flow graph
// containing MIR.

#include "jit/FixedList.h"
#include "jit/IonAllocPolicy.h"
#include "jit/MIR.h"

namespace js {
namespace jit {

class BytecodeAnalysis;
class MBasicBlock;
class MIRGraph;
class MStart;

class MDefinitionIterator;

typedef InlineListIterator<MInstruction> MInstructionIterator;
typedef InlineListReverseIterator<MInstruction> MInstructionReverseIterator;
typedef InlineForwardListIterator<MPhi> MPhiIterator;
typedef InlineForwardListIterator<MResumePoint> MResumePointIterator;

class LBlock;

class MBasicBlock : public TempObject, public InlineListNode<MBasicBlock>
{
  public:
    enum Kind {
        NORMAL,
        PENDING_LOOP_HEADER,
        LOOP_HEADER,
        SPLIT_EDGE,
        DEAD
    };

  private:
    MBasicBlock(MIRGraph& graph, CompileInfo& info, jsbytecode* pc, Kind kind);
    bool init();
    void copySlots(MBasicBlock* from);
    bool inherit(TempAllocator& alloc, BytecodeAnalysis* analysis, MBasicBlock* pred,
                 uint32_t popped, unsigned stackPhiCount = 0);
    bool inheritResumePoint(MBasicBlock* pred);
    void assertUsesAreNotWithin(MUseIterator use, MUseIterator end);

    // This block cannot be reached by any means.
    bool unreachable_;

    // Pushes a copy of a local variable or argument.
    void pushVariable(uint32_t slot);

    // Sets a variable slot to the top of the stack, correctly creating copies
    // as needed.
    void setVariable(uint32_t slot);

  public:
    ///////////////////////////////////////////////////////
    ////////// BEGIN GRAPH BUILDING INSTRUCTIONS //////////
    ///////////////////////////////////////////////////////

    // Creates a new basic block for a MIR generator. If |pred| is not nullptr,
    // its slots and stack depth are initialized from |pred|.
    static MBasicBlock* New(MIRGraph& graph, BytecodeAnalysis* analysis, CompileInfo& info,
                            MBasicBlock* pred, jsbytecode* entryPc, Kind kind);
    static MBasicBlock* NewPopN(MIRGraph& graph, CompileInfo& info,
                                MBasicBlock* pred, jsbytecode* entryPc, Kind kind, uint32_t popn);
    static MBasicBlock* NewWithResumePoint(MIRGraph& graph, CompileInfo& info,
                                           MBasicBlock* pred, jsbytecode* entryPc,
                                           MResumePoint* resumePoint);
    static MBasicBlock* NewPendingLoopHeader(MIRGraph& graph, CompileInfo& info,
                                             MBasicBlock* pred, jsbytecode* entryPc,
                                             unsigned loopStateSlots);
    static MBasicBlock* NewSplitEdge(MIRGraph& graph, CompileInfo& info, MBasicBlock* pred);
    static MBasicBlock* NewAbortPar(MIRGraph& graph, CompileInfo& info,
                                    MBasicBlock* pred, jsbytecode* entryPc,
                                    MResumePoint* resumePoint);
    static MBasicBlock* NewAsmJS(MIRGraph& graph, CompileInfo& info,
                                 MBasicBlock* pred, Kind kind);

    bool dominates(const MBasicBlock* other) const;

    void setId(uint32_t id) {
        id_ = id;
    }

    // Mark the current block and all dominated blocks as unreachable.
    void setUnreachable();
    bool unreachable() const {
        return unreachable_;
    }
    // Move the definition to the top of the stack.
    void pick(int32_t depth);

    // Exchange 2 stack slots at the defined depth
    void swapAt(int32_t depth);

    // Gets the instruction associated with various slot types.
    MDefinition* peek(int32_t depth);

    MDefinition* scopeChain();
    MDefinition* argumentsObject();

    // Increase the number of slots available
    bool increaseSlots(size_t num);
    bool ensureHasSlots(size_t num);

    // Initializes a slot value; must not be called for normal stack
    // operations, as it will not create new SSA names for copies.
    void initSlot(uint32_t index, MDefinition* ins);

    // Discard the slot at the given depth, lowering all slots above.
    void shimmySlots(int discardDepth);

    // In an OSR block, set all MOsrValues to use the MResumePoint attached to
    // the MStart.
    void linkOsrValues(MStart* start);

    // Sets the instruction associated with various slot types. The
    // instruction must lie at the top of the stack.
    void setLocal(uint32_t local);
    void setArg(uint32_t arg);
    void setSlot(uint32_t slot);
    void setSlot(uint32_t slot, MDefinition* ins);

    // Rewrites a slot directly, bypassing the stack transition. This should
    // not be used under most circumstances.
    void rewriteSlot(uint32_t slot, MDefinition* ins);

    // Rewrites a slot based on its depth (same as argument to peek()).
    void rewriteAtDepth(int32_t depth, MDefinition* ins);

    // Tracks an instruction as being pushed onto the operand stack.
    void push(MDefinition* ins);
    void pushArg(uint32_t arg);
    void pushLocal(uint32_t local);
    void pushSlot(uint32_t slot);
    void setScopeChain(MDefinition* ins);
    void setArgumentsObject(MDefinition* ins);

    // Returns the top of the stack, then decrements the virtual stack pointer.
    MDefinition* pop();
    void popn(uint32_t n);

    // Adds an instruction to this block's instruction list. |ins| may be
    // nullptr to simplify OOM checking.
    void add(MInstruction* ins);

    // Marks the last instruction of the block; no further instructions
    // can be added.
    void end(MControlInstruction* ins);

    // Adds a phi instruction, but does not set successorWithPhis.
    void addPhi(MPhi* phi);

    // Adds a resume point to this block.
    void addResumePoint(MResumePoint* resume) {
        resumePoints_.pushFront(resume);
    }

    // Adds a predecessor. Every predecessor must have the same exit stack
    // depth as the entry state to this block. Adding a predecessor
    // automatically creates phi nodes and rewrites uses as needed.
    bool addPredecessor(TempAllocator& alloc, MBasicBlock* pred);
    bool addPredecessorPopN(TempAllocator& alloc, MBasicBlock* pred, uint32_t popped);

    // Stranger utilities used for inlining.
    bool addPredecessorWithoutPhis(MBasicBlock* pred);
    void inheritSlots(MBasicBlock* parent);
    bool initEntrySlots(TempAllocator& alloc);

    // Replaces an edge for a given block with a new block. This is
    // used for critical edge splitting and also for inserting
    // bailouts during ParallelSafetyAnalysis.
    //
    // Note: If successorWithPhis is set, you must not be replacing it.
    void replacePredecessor(MBasicBlock* old, MBasicBlock* split);
    void replaceSuccessor(size_t pos, MBasicBlock* split);

    // Removes `pred` from the predecessor list.  `pred` should not be
    // the final predecessor. If this block defines phis, removes the
    // entry for `pred` and updates the indices of later entries.
    // This may introduce redundant phis if the new block has fewer
    // than two predecessors.
    void removePredecessor(MBasicBlock* pred);

    // Resets all the dominator info so that it can be recomputed.
    void clearDominatorInfo();

    // Sets a back edge. This places phi nodes and rewrites instructions within
    // the current loop as necessary. If the backedge introduces new types for
    // phis at the loop header, returns a disabling abort.
    AbortReason setBackedge(MBasicBlock* block);
    bool setBackedgeAsmJS(MBasicBlock* block);

    // Resets a LOOP_HEADER block to a NORMAL block.  This is needed when
    // optimizations remove the backedge.
    void clearLoopHeader();

    // Propagates phis placed in a loop header down to this successor block.
    void inheritPhis(MBasicBlock* header);

    // Compute the types for phis in this block according to their inputs.
    bool specializePhis();

    void insertBefore(MInstruction* at, MInstruction* ins);
    void insertAfter(MInstruction* at, MInstruction* ins);

    // Add an instruction to this block, from elsewhere in the graph.
    void addFromElsewhere(MInstruction* ins);

    // Move an instruction. Movement may cross block boundaries.
    void moveBefore(MInstruction* at, MInstruction* ins);

    // Removes an instruction with the intention to discard it.
    void discard(MInstruction* ins);
    void discardLastIns();
    MInstructionIterator discardAt(MInstructionIterator& iter);
    MInstructionReverseIterator discardAt(MInstructionReverseIterator& iter);
    MDefinitionIterator discardDefAt(MDefinitionIterator& iter);
    void discardAllInstructions();
    void discardAllPhiOperands();
    void discardAllPhis();
    void discardAllResumePoints(bool discardEntry = true);

    // Discards a phi instruction and updates predecessor successorWithPhis.
    MPhiIterator discardPhiAt(MPhiIterator& at);

    // Mark this block as having been removed from the graph.
    void markAsDead() {
        kind_ = DEAD;
    }

    ///////////////////////////////////////////////////////
    /////////// END GRAPH BUILDING INSTRUCTIONS ///////////
    ///////////////////////////////////////////////////////

    MIRGraph& graph() {
        return graph_;
    }
    CompileInfo& info() const {
        return info_;
    }
    jsbytecode* pc() const {
        return pc_;
    }
    uint32_t nslots() const {
        return slots_.length();
    }
    uint32_t id() const {
        return id_;
    }
    uint32_t numPredecessors() const {
        return predecessors_.length();
    }

    uint32_t domIndex() const {
        JS_ASSERT(!isDead());
        return domIndex_;
    }
    void setDomIndex(uint32_t d) {
        domIndex_ = d;
    }

    MBasicBlock* getPredecessor(uint32_t i) const {
        return predecessors_[i];
    }
    MControlInstruction* lastIns() const {
        return lastIns_;
    }
    MPhiIterator phisBegin() const {
        return phis_.begin();
    }
    MPhiIterator phisEnd() const {
        return phis_.end();
    }
    bool phisEmpty() const {
        return phis_.empty();
    }
    MResumePointIterator resumePointsBegin() const {
        return resumePoints_.begin();
    }
    MResumePointIterator resumePointsEnd() const {
        return resumePoints_.end();
    }
    bool resumePointsEmpty() const {
        return resumePoints_.empty();
    }
    MInstructionIterator begin() {
        return instructions_.begin();
    }
    MInstructionIterator begin(MInstruction* at) {
        JS_ASSERT(at->block() == this);
        return instructions_.begin(at);
    }
    MInstructionIterator end() {
        return instructions_.end();
    }
    MInstructionReverseIterator rbegin() {
        return instructions_.rbegin();
    }
    MInstructionReverseIterator rbegin(MInstruction* at) {
        JS_ASSERT(at->block() == this);
        return instructions_.rbegin(at);
    }
    MInstructionReverseIterator rend() {
        return instructions_.rend();
    }
    bool isLoopHeader() const {
        return kind_ == LOOP_HEADER;
    }
    bool hasUniqueBackedge() const {
        JS_ASSERT(isLoopHeader());
        JS_ASSERT(numPredecessors() >= 2);
        return numPredecessors() == 2;
    }
    MBasicBlock* backedge() const {
        JS_ASSERT(hasUniqueBackedge());
        return getPredecessor(numPredecessors() - 1);
    }
    MBasicBlock* loopHeaderOfBackedge() const {
        JS_ASSERT(isLoopBackedge());
        return getSuccessor(numSuccessors() - 1);
    }
    MBasicBlock* loopPredecessor() const {
        JS_ASSERT(isLoopHeader());
        return getPredecessor(0);
    }
    bool isLoopBackedge() const {
        if (!numSuccessors())
            return false;
        MBasicBlock* lastSuccessor = getSuccessor(numSuccessors() - 1);
        return lastSuccessor->isLoopHeader() &&
               lastSuccessor->hasUniqueBackedge() &&
               lastSuccessor->backedge() == this;
    }
    bool isSplitEdge() const {
        return kind_ == SPLIT_EDGE;
    }
    bool isDead() const {
        return kind_ == DEAD;
    }

    uint32_t stackDepth() const {
        return stackPosition_;
    }
    void setStackDepth(uint32_t depth) {
        stackPosition_ = depth;
    }
    bool isMarked() const {
        return mark_;
    }
    void mark() {
        mark_ = true;
    }
    void unmark() {
        mark_ = false;
    }
    void makeStart(MStart* start) {
        add(start);
        start_ = start;
    }
    MStart* start() const {
        return start_;
    }

    MBasicBlock* immediateDominator() const {
        return immediateDominator_;
    }

    void setImmediateDominator(MBasicBlock* dom) {
        immediateDominator_ = dom;
    }

    MTest* immediateDominatorBranch(BranchDirection* pdirection);

    size_t numImmediatelyDominatedBlocks() const {
        return immediatelyDominated_.length();
    }

    MBasicBlock* getImmediatelyDominatedBlock(size_t i) const {
        return immediatelyDominated_[i];
    }

    MBasicBlock** immediatelyDominatedBlocksBegin() {
        return immediatelyDominated_.begin();
    }

    MBasicBlock** immediatelyDominatedBlocksEnd() {
        return immediatelyDominated_.end();
    }

    size_t numDominated() const {
        return numDominated_;
    }

    void addNumDominated(size_t n) {
        numDominated_ += n;
    }

    bool addImmediatelyDominatedBlock(MBasicBlock* child);

    // This function retrieves the internal instruction associated with a
    // slot, and should not be used for normal stack operations. It is an
    // internal helper that is also used to enhance spew.
    MDefinition* getSlot(uint32_t index);

    MResumePoint* entryResumePoint() const {
        return entryResumePoint_;
    }
    MResumePoint* callerResumePoint() {
        return entryResumePoint()->caller();
    }
    void setCallerResumePoint(MResumePoint* caller) {
        entryResumePoint()->setCaller(caller);
    }
    size_t numEntrySlots() const {
        return entryResumePoint()->numOperands();
    }
    MDefinition* getEntrySlot(size_t i) const {
        JS_ASSERT(i < numEntrySlots());
        return entryResumePoint()->getOperand(i);
    }

    LBlock* lir() const {
        return lir_;
    }
    void assignLir(LBlock* lir) {
        JS_ASSERT(!lir_);
        lir_ = lir;
    }

    MBasicBlock* successorWithPhis() const {
        return successorWithPhis_;
    }
    uint32_t positionInPhiSuccessor() const {
        return positionInPhiSuccessor_;
    }
    void setSuccessorWithPhis(MBasicBlock* successor, uint32_t id) {
        successorWithPhis_ = successor;
        positionInPhiSuccessor_ = id;
    }
    size_t numSuccessors() const;
    MBasicBlock* getSuccessor(size_t index) const;
    size_t getSuccessorIndex(MBasicBlock*) const;

    void setLoopDepth(uint32_t loopDepth) {
        loopDepth_ = loopDepth;
    }
    uint32_t loopDepth() const {
        return loopDepth_;
    }

    bool strict() const {
        return info_.script()->strict();
    }

    void dumpStack(FILE* fp);

    void dump(FILE* fp);
    void dump();

    // Track bailouts by storing the current pc in MIR instruction added at this
    // cycle. This is also used for tracking calls when profiling.
    void updateTrackedPc(jsbytecode* pc) {
        trackedPc_ = pc;
    }

    jsbytecode* trackedPc() {
        return trackedPc_;
    }

  private:
    MIRGraph& graph_;
    CompileInfo& info_; // Each block originates from a particular script.
    InlineList<MInstruction> instructions_;
    Vector<MBasicBlock*, 1, IonAllocPolicy> predecessors_;
    InlineForwardList<MPhi> phis_;
    InlineForwardList<MResumePoint> resumePoints_;
    FixedList<MDefinition*> slots_;
    uint32_t stackPosition_;
    MControlInstruction* lastIns_;
    jsbytecode* pc_;
    uint32_t id_;
    uint32_t domIndex_; // Index in the dominator tree.
    LBlock* lir_;
    MStart* start_;
    MResumePoint* entryResumePoint_;
    MBasicBlock* successorWithPhis_;
    uint32_t positionInPhiSuccessor_;
    Kind kind_;
    uint32_t loopDepth_;

    // Utility mark for traversal algorithms.
    bool mark_;

    Vector<MBasicBlock*, 1, IonAllocPolicy> immediatelyDominated_;
    MBasicBlock* immediateDominator_;
    size_t numDominated_;

    jsbytecode* trackedPc_;

#if defined (JS_ION_PERF)
    unsigned lineno_;
    unsigned columnIndex_;

  public:
    void setLineno(unsigned l) { lineno_ = l; }
    unsigned lineno() const { return lineno_; }
    void setColumnIndex(unsigned c) { columnIndex_ = c; }
    unsigned columnIndex() const { return columnIndex_; }
#endif
};

typedef InlineListIterator<MBasicBlock> MBasicBlockIterator;
typedef InlineListIterator<MBasicBlock> ReversePostorderIterator;
typedef InlineListReverseIterator<MBasicBlock> PostorderIterator;

typedef Vector<MBasicBlock*, 1, IonAllocPolicy> MIRGraphReturns;

class MIRGraph
{
    InlineList<MBasicBlock> blocks_;
    TempAllocator* alloc_;
    MIRGraphReturns* returnAccumulator_;
    uint32_t blockIdGen_;
    uint32_t idGen_;
    MBasicBlock* osrBlock_;
    MStart* osrStart_;

    size_t numBlocks_;
    bool hasTryBlock_;

  public:
    MIRGraph(TempAllocator* alloc)
      : alloc_(alloc),
        returnAccumulator_(nullptr),
        blockIdGen_(0),
        idGen_(1),
        osrBlock_(nullptr),
        osrStart_(nullptr),
        numBlocks_(0),
        hasTryBlock_(false)
    { }

    TempAllocator& alloc() const {
        return *alloc_;
    }

    void addBlock(MBasicBlock* block);
    void insertBlockAfter(MBasicBlock* at, MBasicBlock* block);

    void unmarkBlocks();

    void setReturnAccumulator(MIRGraphReturns* accum) {
        returnAccumulator_ = accum;
    }
    MIRGraphReturns* returnAccumulator() const {
        return returnAccumulator_;
    }

    bool addReturn(MBasicBlock* returnBlock) {
        if (!returnAccumulator_)
            return true;

        return returnAccumulator_->append(returnBlock);
    }

    MBasicBlock* entryBlock() {
        return *blocks_.begin();
    }

    void clearBlockList() {
        blocks_.clear();
        blockIdGen_ = 0;
        numBlocks_ = 0;
    }
    void resetInstructionNumber() {
        // This intentionally starts above 0. The id 0 is in places used to
        // indicate a failure to perform an operation on an instruction.
        idGen_ = 1;
    }
    MBasicBlockIterator begin() {
        return blocks_.begin();
    }
    MBasicBlockIterator begin(MBasicBlock* at) {
        return blocks_.begin(at);
    }
    MBasicBlockIterator end() {
        return blocks_.end();
    }
    PostorderIterator poBegin() {
        return blocks_.rbegin();
    }
    PostorderIterator poEnd() {
        return blocks_.rend();
    }
    ReversePostorderIterator rpoBegin() {
        return blocks_.begin();
    }
    ReversePostorderIterator rpoBegin(MBasicBlock* at) {
        return blocks_.begin(at);
    }
    ReversePostorderIterator rpoEnd() {
        return blocks_.end();
    }
    void removeBlocksAfter(MBasicBlock* block);
    void removeBlock(MBasicBlock* block);
    void moveBlockToEnd(MBasicBlock* block) {
        JS_ASSERT(block->id());
        blocks_.remove(block);
        blocks_.pushBack(block);
    }
    size_t numBlocks() const {
        return numBlocks_;
    }
    uint32_t numBlockIds() const {
        return blockIdGen_;
    }
    void allocDefinitionId(MDefinition* ins) {
        ins->setId(idGen_++);
    }
    uint32_t getNumInstructionIds() {
        return idGen_;
    }
    MResumePoint* entryResumePoint() {
        return blocks_.begin()->entryResumePoint();
    }

    void copyIds(const MIRGraph& other) {
        idGen_ = other.idGen_;
        blockIdGen_ = other.blockIdGen_;
        numBlocks_ = other.numBlocks_;
    }

    void setOsrBlock(MBasicBlock* osrBlock) {
        JS_ASSERT(!osrBlock_);
        osrBlock_ = osrBlock;
    }
    MBasicBlock* osrBlock() {
        return osrBlock_;
    }
    void setOsrStart(MStart* osrStart) {
        osrStart_ = osrStart;
    }
    MStart* osrStart() {
        return osrStart_;
    }

    bool hasTryBlock() const {
        return hasTryBlock_;
    }
    void setHasTryBlock() {
        hasTryBlock_ = true;
    }

    // The per-thread context. So as not to modify the calling convention for
    // parallel code, we obtain the current ForkJoinContext from thread-local
    // storage.  This helper method will lazilly insert an MForkJoinContext
    // instruction in the entry block and return the definition.
    MDefinition* forkJoinContext();

    void dump(FILE* fp);
    void dump();
};

class MDefinitionIterator
{

  friend class MBasicBlock;

  private:
    MBasicBlock* block_;
    MPhiIterator phiIter_;
    MInstructionIterator iter_;

    bool atPhi() const {
        return phiIter_ != block_->phisEnd();
    }

    MDefinition* getIns() {
        if (atPhi())
            return *phiIter_;
        return *iter_;
    }

    void next() {
        if (atPhi())
            phiIter_++;
        else
            iter_++;
    }

    bool more() const {
        return atPhi() || (*iter_) != block_->lastIns();
    }

  public:
    MDefinitionIterator(MBasicBlock* block)
      : block_(block),
        phiIter_(block->phisBegin()),
        iter_(block->begin())
    { }

    MDefinitionIterator operator ++(int) {
        MDefinitionIterator old(*this);
        if (more())
            next();
        return old;
    }

    operator bool() const {
        return more();
    }

    MDefinition* operator*() {
        return getIns();
    }

    MDefinition* operator ->() {
        return getIns();
    }

};

} // namespace jit
} // namespace js

#endif /* jit_MIRGraph_h */