C++ FrameEntry::getKnownType方法代码示例

void
FrameState::pushCopyOf(uint32 index)
{
    FrameEntry *backing = entryFor(index);
    FrameEntry *fe = rawPush();
    fe->resetUnsynced();
    if (backing->isConstant()) {
        fe->setConstant(Jsvalify(backing->getValue()));
    } else {
        if (backing->isTypeKnown())
            fe->setType(backing->getKnownType());
        else
            fe->type.invalidate();
        fe->isNumber = backing->isNumber;
        fe->data.invalidate();
        if (backing->isCopy()) {
            backing = backing->copyOf();
            fe->setCopyOf(backing);
        } else {
            fe->setCopyOf(backing);
            backing->setCopied();
        }

        /* Maintain tracker ordering guarantees for copies. */
        JS_ASSERT(backing->isCopied());
        if (fe->trackerIndex() < backing->trackerIndex())
            swapInTracker(fe, backing);
    }
}

CompileStatus
mjit::Compiler::inlineNativeFunction(uint32_t argc, bool callingNew)
{
    if (!cx->typeInferenceEnabled())
        return Compile_InlineAbort;

    if (applyTricks == LazyArgsObj)
        return Compile_InlineAbort;

    FrameEntry *origCallee = frame.peek(-((int)argc + 2));
    FrameEntry *thisValue = frame.peek(-((int)argc + 1));
    types::TypeSet *thisTypes = analysis->poppedTypes(PC, argc);

    if (!origCallee->isConstant() || !origCallee->isType(JSVAL_TYPE_OBJECT))
        return Compile_InlineAbort;

    JSObject *callee = &origCallee->getValue().toObject();
    if (!callee->isFunction())
        return Compile_InlineAbort;

    /*
     * The callee must have the same parent as the script's global, otherwise
     * inference may not have accounted for any side effects correctly.
     */
    if (!globalObj || globalObj != &callee->global())
        return Compile_InlineAbort;

    Native native = callee->toFunction()->maybeNative();

    if (!native)
        return Compile_InlineAbort;

    JSValueType type = knownPushedType(0);
    JSValueType thisType = thisValue->isTypeKnown()
                           ? thisValue->getKnownType()
                           : JSVAL_TYPE_UNKNOWN;

    /*
     * Note: when adding new natives which operate on properties, add relevant
     * constraint generation to the behavior of TypeConstraintCall.
     */

    /* Handle natives that can be called either with or without 'new'. */

    if (native == js_Array && type == JSVAL_TYPE_OBJECT && globalObj) {
        if (argc == 0 || argc == 1)
            return compileArrayWithLength(argc);
        return compileArrayWithArgs(argc);
    }

    /* Remaining natives must not be called with 'new'. */
    if (callingNew)
        return Compile_InlineAbort;

    if (native == js::num_parseInt && argc >= 1) {
        FrameEntry *arg = frame.peek(-(int32_t)argc);
        JSValueType argType = arg->isTypeKnown() ? arg->getKnownType() : JSVAL_TYPE_UNKNOWN;

        if ((argType == JSVAL_TYPE_DOUBLE || argType == JSVAL_TYPE_INT32) &&
            type == JSVAL_TYPE_INT32) {
            return compileParseInt(argType, argc);
        }
    }

    if (argc == 0) {
        if ((native == js::array_pop || native == js::array_shift) && thisType == JSVAL_TYPE_OBJECT) {
            /*
             * Only handle pop/shift on dense arrays which have never been used
             * in an iterator --- when popping elements we don't account for
             * suppressing deleted properties in active iterators.
             *
             * Constraints propagating properties directly into the result
             * type set are generated by TypeConstraintCall during inference.
             */
            if (!thisTypes->hasObjectFlags(cx, types::OBJECT_FLAG_NON_DENSE_ARRAY |
                                           types::OBJECT_FLAG_ITERATED) &&
                !types::ArrayPrototypeHasIndexedProperty(cx, outerScript)) {
                bool packed = !thisTypes->hasObjectFlags(cx, types::OBJECT_FLAG_NON_PACKED_ARRAY);
                return compileArrayPopShift(thisValue, packed, native == js::array_pop);
            }
        }
    } else if (argc == 1) {
        FrameEntry *arg = frame.peek(-1);
        types::TypeSet *argTypes = frame.extra(arg).types;
        if (!argTypes)
            return Compile_InlineAbort;
        JSValueType argType = arg->isTypeKnown() ? arg->getKnownType() : JSVAL_TYPE_UNKNOWN;

        if (native == js_math_abs) {
            if (argType == JSVAL_TYPE_INT32 && type == JSVAL_TYPE_INT32)
                return compileMathAbsInt(arg);

            if (argType == JSVAL_TYPE_DOUBLE && type == JSVAL_TYPE_DOUBLE)
                return compileMathAbsDouble(arg);
        }
        if (native == js_math_floor && argType == JSVAL_TYPE_DOUBLE &&
            type == JSVAL_TYPE_INT32) {
            return compileRound(arg, Floor);
        }
        if (native == js_math_round && argType == JSVAL_TYPE_DOUBLE &&
//.........这里部分代码省略.........

CompileStatus
mjit::Compiler::compileParseInt(JSValueType argType, uint32_t argc)
{
    bool needStubCall = false;

    if (argc > 1) {
        FrameEntry *arg = frame.peek(-(int32_t)argc + 1);

        if (!arg->isTypeKnown() || arg->getKnownType() != JSVAL_TYPE_INT32)
            return Compile_InlineAbort;

        if (arg->isConstant()) {
            int32_t base = arg->getValue().toInt32();
            if (base != 0 && base != 10)
                return Compile_InlineAbort;
        } else {
            RegisterID baseReg = frame.tempRegForData(arg);
            needStubCall = true;

            Jump isTen = masm.branch32(Assembler::Equal, baseReg, Imm32(10));
            Jump isNotZero = masm.branch32(Assembler::NotEqual, baseReg, Imm32(0));
            stubcc.linkExit(isNotZero, Uses(2 + argc));

            isTen.linkTo(masm.label(), &masm);
        }
    }

    if (argType == JSVAL_TYPE_INT32) {
        if (needStubCall) {
            stubcc.leave();
            stubcc.masm.move(Imm32(argc), Registers::ArgReg1);
            OOL_STUBCALL(stubs::SlowCall, REJOIN_FALLTHROUGH);
        }

        /* 
         * Stack looks like callee, this, arg1, arg2, argN.
         * First pop all args other than arg1.
         */
        frame.popn(argc - 1);
        /* "Shimmy" arg1 to the callee slot and pop this + arg1. */
        frame.shimmy(2);

        if (needStubCall) {
            stubcc.rejoin(Changes(1));
        }        
    } else {
        FrameEntry *arg = frame.peek(-(int32_t)argc);
        FPRegisterID fpScratchReg = frame.allocFPReg();
        FPRegisterID fpReg;
        bool allocate;

        DebugOnly<MaybeJump> notNumber = loadDouble(arg, &fpReg, &allocate);
        JS_ASSERT(!((MaybeJump)notNumber).isSet());

        masm.slowLoadConstantDouble(1, fpScratchReg);

        /* Slow path for NaN and numbers < 1. */
        Jump lessThanOneOrNan = masm.branchDouble(Assembler::DoubleLessThanOrUnordered, 
                                                  fpReg, fpScratchReg);
        stubcc.linkExit(lessThanOneOrNan, Uses(2 + argc));

        frame.freeReg(fpScratchReg);

        /* Truncate to integer, slow path if this overflows. */
        RegisterID reg = frame.allocReg();
        Jump overflow = masm.branchTruncateDoubleToInt32(fpReg, reg);
        stubcc.linkExit(overflow, Uses(2 + argc));

        if (allocate)
            frame.freeReg(fpReg);

        stubcc.leave();
        stubcc.masm.move(Imm32(argc), Registers::ArgReg1);
        OOL_STUBCALL(stubs::SlowCall, REJOIN_FALLTHROUGH);

        frame.popn(2 + argc);
        frame.pushTypedPayload(JSVAL_TYPE_INT32, reg);

        stubcc.rejoin(Changes(1));
    }

    return Compile_Okay;   
}

void
FrameState::storeLocal(uint32 n, bool popGuaranteed, bool typeChange)
{
    FrameEntry *localFe = getLocal(n);
    bool cacheable = !eval && !escaping[n];

    if (!popGuaranteed && !cacheable) {
        JS_ASSERT_IF(base[localIndex(n)] && (!eval || n < script->nfixed),
                     entries[localIndex(n)].type.inMemory() &&
                     entries[localIndex(n)].data.inMemory());
        Address local(JSFrameReg, sizeof(JSStackFrame) + n * sizeof(Value));
        storeTo(peek(-1), local, false);
        forgetAllRegs(getLocal(n));
        localFe->resetSynced();
        return;
    }

    bool wasSynced = localFe->type.synced();

    /* Detect something like (x = x) which is a no-op. */
    FrameEntry *top = peek(-1);
    if (top->isCopy() && top->copyOf() == localFe) {
        JS_ASSERT(localFe->isCopied());
        return;
    }

    /* Completely invalidate the local variable. */
    if (localFe->isCopied()) {
        uncopy(localFe);
        if (!localFe->isCopied())
            forgetAllRegs(localFe);
    } else {
        forgetAllRegs(localFe);
    }

    localFe->resetUnsynced();

    /* Constants are easy to propagate. */
    if (top->isConstant()) {
        localFe->setCopyOf(NULL);
        localFe->setNotCopied();
        localFe->setConstant(Jsvalify(top->getValue()));
        return;
    }

    /*
     * When dealing with copies, there are two important invariants:
     *
     * 1) The backing store precedes all copies in the tracker.
     * 2) The backing store of a local is never a stack slot, UNLESS the local
     *    variable itself is a stack slot (blocks) that precedes the stack
     *    slot.
     *
     * If the top is a copy, and the second condition holds true, the local
     * can be rewritten as a copy of the original backing slot. If the first
     * condition does not hold, force it to hold by swapping in-place.
     */
    FrameEntry *backing = top;
    if (top->isCopy()) {
        backing = top->copyOf();
        JS_ASSERT(backing->trackerIndex() < top->trackerIndex());

        uint32 backingIndex = indexOfFe(backing);
        uint32 tol = uint32(spBase - base);
        if (backingIndex < tol || backingIndex < localIndex(n)) {
            /* local.idx < backing.idx means local cannot be a copy yet */
            if (localFe->trackerIndex() < backing->trackerIndex())
                swapInTracker(backing, localFe);
            localFe->setNotCopied();
            localFe->setCopyOf(backing);
            if (backing->isTypeKnown())
                localFe->setType(backing->getKnownType());
            else
                localFe->type.invalidate();
            localFe->data.invalidate();
            localFe->isNumber = backing->isNumber;
            return;
        }

        /*
         * If control flow lands here, then there was a bytecode sequence like
         *
         *  ENTERBLOCK 2
         *  GETLOCAL 1
         *  SETLOCAL 0
         *
         * The problem is slot N can't be backed by M if M could be popped
         * before N. We want a guarantee that when we pop M, even if it was
         * copied, it has no outstanding copies.
         * 
         * Because of |let| expressions, it's kind of hard to really know
         * whether a region on the stack will be popped all at once. Bleh!
         *
         * This should be rare except in browser code (and maybe even then),
         * but even so there's a quick workaround. We take all copies of the
         * backing fe, and redirect them to be copies of the destination.
         */
        FrameEntry *tos = tosFe();
        for (uint32 i = backing->trackerIndex() + 1; i < tracker.nentries; i++) {
            FrameEntry *fe = tracker[i];
//.........这里部分代码省略.........

//.........这里部分代码省略.........
     * the "lowest" copy in the frame up-front.
     *
     * For example, if the stack is:
     *    [A, B, C, D]
     * And the tracker has:
     *    [A, D, C, B]
     *
     * If B, C, and D are copies of A - we will walk the tracker to the end
     * and select D, not B (see bug 583684).
     */
    uint32 firstCopy = InvalidIndex;
    FrameEntry *tos = tosFe();
    FrameEntry *bestFe = NULL;
    uint32 ncopies = 0;
    for (uint32 i = 0; i < tracker.nentries; i++) {
        FrameEntry *fe = tracker[i];
        if (fe >= tos)
            continue;
        if (fe->isCopy() && fe->copyOf() == original) {
            if (firstCopy == InvalidIndex) {
                firstCopy = i;
                bestFe = fe;
            } else if (fe < bestFe) {
                bestFe = fe;
            }
            ncopies++;
        }
    }

    if (!ncopies) {
        JS_ASSERT(firstCopy == InvalidIndex);
        JS_ASSERT(!bestFe);
        original->copied = false;
        return NULL;
    }

    JS_ASSERT(firstCopy != InvalidIndex);
    JS_ASSERT(bestFe);

    /* Mark all extra copies as copies of the new backing index. */
    bestFe->setCopyOf(NULL);
    if (ncopies > 1) {
        bestFe->setCopied();
        for (uint32 i = firstCopy; i < tracker.nentries; i++) {
            FrameEntry *other = tracker[i];
            if (other >= tos || other == bestFe)
                continue;

            /* The original must be tracked before copies. */
            JS_ASSERT(other != original);

            if (!other->isCopy() || other->copyOf() != original)
                continue;

            other->setCopyOf(bestFe);

            /*
             * This is safe even though we're mutating during iteration. There
             * are two cases. The first is that both indexes are <= i, and :.
             * will never be observed. The other case is we're placing the
             * other FE such that it will be observed later. Luckily, copyOf()
             * will return != original, so nothing will happen.
             */
            if (other->trackerIndex() < bestFe->trackerIndex())
                swapInTracker(bestFe, other);
        }
    } else {
        bestFe->setNotCopied();
    }

    FrameEntry *fe = bestFe;

    /*
     * Switch the new backing store to the old backing store. During
     * this process we also necessarily make sure the copy can be
     * synced.
     */
    if (!original->isTypeKnown()) {
        /*
         * If the copy is unsynced, and the original is in memory,
         * give the original a register. We do this below too; it's
         * okay if it's spilled.
         */
        if (original->type.inMemory() && !fe->type.synced())
            tempRegForType(original);
        fe->type.inherit(original->type);
        if (fe->type.inRegister())
            moveOwnership(fe->type.reg(), fe);
    } else {
        JS_ASSERT(fe->isTypeKnown());
        JS_ASSERT(fe->getKnownType() == original->getKnownType());
    }
    if (original->data.inMemory() && !fe->data.synced())
        tempRegForData(original);
    fe->data.inherit(original->data);
    if (fe->data.inRegister())
        moveOwnership(fe->data.reg(), fe);

    return fe;
}

void
FrameState::sync(Assembler &masm, Uses uses) const
{
    /*
     * Keep track of free registers using a bitmask. If we have to drop into
     * syncFancy(), then this mask will help avoid eviction.
     */
    Registers avail(freeRegs);
    Registers temp(Registers::TempRegs);

    FrameEntry *tos = tosFe();
    FrameEntry *bottom = tos - uses.nuses;

    if (inTryBlock)
        bottom = NULL;

    for (uint32 i = tracker.nentries - 1; i < tracker.nentries; i--) {
        FrameEntry *fe = tracker[i];
        if (fe >= tos)
            continue;

        Address address = addressOf(fe);

        if (!fe->isCopy()) {
            /* Keep track of registers that can be clobbered. */
            if (fe->data.inRegister())
                avail.putReg(fe->data.reg());
            if (fe->type.inRegister())
                avail.putReg(fe->type.reg());

            /* Sync. */
            if (!fe->data.synced() && (fe->data.inRegister() || fe >= bottom)) {
                syncData(fe, address, masm);
                if (fe->isConstant())
                    continue;
            }
            if (!fe->type.synced() && (fe->type.inRegister() || fe >= bottom))
                syncType(fe, addressOf(fe), masm);
        } else if (fe >= bottom) {
            FrameEntry *backing = fe->copyOf();
            JS_ASSERT(backing != fe);
            JS_ASSERT(!backing->isConstant() && !fe->isConstant());

            /*
             * If the copy is backed by something not in a register, fall back
             * to a slower sync algorithm.
             */
            if ((!fe->type.synced() && !backing->type.inRegister()) ||
                (!fe->data.synced() && !backing->data.inRegister())) {
                syncFancy(masm, avail, i, bottom);
                return;
            }

            if (!fe->type.synced()) {
                /* :TODO: we can do better, the type is learned for all copies. */
                if (fe->isTypeKnown()) {
                    //JS_ASSERT(fe->getTypeTag() == backing->getTypeTag());
                    masm.storeTypeTag(ImmType(fe->getKnownType()), address);
                } else {
                    masm.storeTypeTag(backing->type.reg(), address);
                }
            }

            if (!fe->data.synced())
                masm.storePayload(backing->data.reg(), address);
        }
    }
}