C++ JumpList::append方法代码示例

void JIT::compileLoadVarargs(Instruction* instruction)
{
    int thisValue = instruction[3].u.operand;
    int arguments = instruction[4].u.operand;
    int firstFreeRegister = instruction[5].u.operand;

    JumpList slowCase;
    JumpList end;
    bool canOptimize = m_codeBlock->usesArguments()
        && arguments == m_codeBlock->argumentsRegister().offset()
        && !m_codeBlock->symbolTable()->slowArguments();

    if (canOptimize) {
        emitGetVirtualRegister(arguments, regT0);
        slowCase.append(branch64(NotEqual, regT0, TrustedImm64(JSValue::encode(JSValue()))));

        emitGetFromCallFrameHeader32(JSStack::ArgumentCount, regT0);
        slowCase.append(branch32(Above, regT0, TrustedImm32(Arguments::MaxArguments + 1)));
        // regT0: argumentCountIncludingThis

        move(regT0, regT1);
        neg64(regT1);
        add64(TrustedImm32(firstFreeRegister - JSStack::CallFrameHeaderSize), regT1);
        lshift64(TrustedImm32(3), regT1);
        addPtr(callFrameRegister, regT1);
        // regT1: newCallFrame

        slowCase.append(branchPtr(Above, AbsoluteAddress(m_vm->addressOfJSStackLimit()), regT1));

        // Initialize ArgumentCount.
        store32(regT0, Address(regT1, JSStack::ArgumentCount * static_cast<int>(sizeof(Register)) + OBJECT_OFFSETOF(EncodedValueDescriptor, asBits.payload)));

        // Initialize 'this'.
        emitGetVirtualRegister(thisValue, regT2);
        store64(regT2, Address(regT1, CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register))));

        // Copy arguments.
        signExtend32ToPtr(regT0, regT0);
        end.append(branchSub64(Zero, TrustedImm32(1), regT0));
        // regT0: argumentCount

        Label copyLoop = label();
        load64(BaseIndex(callFrameRegister, regT0, TimesEight, CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register))), regT2);
        store64(regT2, BaseIndex(regT1, regT0, TimesEight, CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register))));
        branchSub64(NonZero, TrustedImm32(1), regT0).linkTo(copyLoop, this);

        end.append(jump());
    }

    if (canOptimize)
        slowCase.link(this);

    emitGetVirtualRegister(thisValue, regT0);
    emitGetVirtualRegister(arguments, regT1);
    callOperation(operationLoadVarargs, regT0, regT1, firstFreeRegister);
    move(returnValueGPR, regT1);

    if (canOptimize)
        end.link(this);
}

void JIT::compileLoadVarargs(Instruction* instruction)
{
    int thisValue = instruction[2].u.operand;
    int arguments = instruction[3].u.operand;
    int firstFreeRegister = instruction[4].u.operand;

    JumpList slowCase;
    JumpList end;
    if (m_codeBlock->usesArguments() && arguments == m_codeBlock->argumentsRegister()) {
        emitLoadTag(arguments, regT1);
        slowCase.append(branch32(NotEqual, regT1, TrustedImm32(JSValue::EmptyValueTag)));

        load32(payloadFor(RegisterFile::ArgumentCount), regT2);
        slowCase.append(branch32(Above, regT2, TrustedImm32(Arguments::MaxArguments + 1)));
        // regT2: argumentCountIncludingThis

        move(regT2, regT3);
        add32(TrustedImm32(firstFreeRegister + RegisterFile::CallFrameHeaderSize), regT3);
        lshift32(TrustedImm32(3), regT3);
        addPtr(callFrameRegister, regT3);
        // regT3: newCallFrame

        slowCase.append(branchPtr(Below, AbsoluteAddress(m_globalData->interpreter->registerFile().addressOfEnd()), regT3));

        // Initialize ArgumentCount.
        store32(regT2, payloadFor(RegisterFile::ArgumentCount, regT3));

        // Initialize 'this'.
        emitLoad(thisValue, regT1, regT0);
        store32(regT0, Address(regT3, OBJECT_OFFSETOF(JSValue, u.asBits.payload) + (CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register)))));
        store32(regT1, Address(regT3, OBJECT_OFFSETOF(JSValue, u.asBits.tag) + (CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register)))));

        // Copy arguments.
        neg32(regT2);
        end.append(branchAdd32(Zero, TrustedImm32(1), regT2));
        // regT2: -argumentCount;

        Label copyLoop = label();
        load32(BaseIndex(callFrameRegister, regT2, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.payload) +(CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register)))), regT0);
        load32(BaseIndex(callFrameRegister, regT2, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.tag) +(CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register)))), regT1);
        store32(regT0, BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.payload) +(CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register)))));
        store32(regT1, BaseIndex(regT3, regT2, TimesEight, OBJECT_OFFSETOF(JSValue, u.asBits.tag) +(CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register)))));
        branchAdd32(NonZero, TrustedImm32(1), regT2).linkTo(copyLoop, this);

        end.append(jump());
    }

    if (m_codeBlock->usesArguments() && arguments == m_codeBlock->argumentsRegister())
        slowCase.link(this);

    JITStubCall stubCall(this, cti_op_load_varargs);
    stubCall.addArgument(thisValue);
    stubCall.addArgument(arguments);
    stubCall.addArgument(Imm32(firstFreeRegister));
    stubCall.call(regT3);

    if (m_codeBlock->usesArguments() && arguments == m_codeBlock->argumentsRegister())
        end.link(this);
}

void Generator::generateAssertionEOL(JumpList& failures)
{
    if (m_parser.multiline()) {
        JumpList nextIsNewline;

        generateLoadCharacter(nextIsNewline); // end of input == success
        generateCharacterClassInverted(nextIsNewline, CharacterClass::newline());
        failures.append(jump());
        nextIsNewline.link(this);
    } else {
        failures.append(jne32(length, index));
    }
}

void JIT::compileSetupVarargsFrame(Instruction* instruction, CallLinkInfo* info)
{
    int thisValue = instruction[3].u.operand;
    int arguments = instruction[4].u.operand;
    int firstFreeRegister = instruction[5].u.operand;
    int firstVarArgOffset = instruction[6].u.operand;

    JumpList slowCase;
    JumpList end;
    bool canOptimize = m_codeBlock->usesArguments()
        && arguments == m_codeBlock->argumentsRegister().offset()
        && !m_codeBlock->symbolTable()->slowArguments();

    if (canOptimize) {
        emitGetVirtualRegister(arguments, regT0);
        slowCase.append(branch64(NotEqual, regT0, TrustedImm64(JSValue::encode(JSValue()))));
        
        move(TrustedImm32(-firstFreeRegister), regT1);
        emitSetupVarargsFrameFastCase(*this, regT1, regT0, regT1, regT2, firstVarArgOffset, slowCase);
        end.append(jump());
        slowCase.link(this);
    }

    emitGetVirtualRegister(arguments, regT1);
    callOperation(operationSizeFrameForVarargs, regT1, -firstFreeRegister, firstVarArgOffset);
    move(TrustedImm32(-firstFreeRegister), regT1);
    emitSetVarargsFrame(*this, returnValueGPR, false, regT1, regT1);
    addPtr(TrustedImm32(-(sizeof(CallerFrameAndPC) + WTF::roundUpToMultipleOf(stackAlignmentBytes(), 5 * sizeof(void*)))), regT1, stackPointerRegister);
    emitGetVirtualRegister(arguments, regT2);
    callOperation(operationSetupVarargsFrame, regT1, regT2, firstVarArgOffset, regT0);
    move(returnValueGPR, regT1);

    if (canOptimize)
        end.link(this);
    
    // Profile the argument count.
    load32(Address(regT1, JSStack::ArgumentCount * static_cast<int>(sizeof(Register)) + PayloadOffset), regT2);
    load8(&info->maxNumArguments, regT0);
    Jump notBiggest = branch32(Above, regT0, regT2);
    Jump notSaturated = branch32(BelowOrEqual, regT2, TrustedImm32(255));
    move(TrustedImm32(255), regT2);
    notSaturated.link(this);
    store8(regT2, &info->maxNumArguments);
    notBiggest.link(this);
    
    // Initialize 'this'.
    emitGetVirtualRegister(thisValue, regT0);
    store64(regT0, Address(regT1, CallFrame::thisArgumentOffset() * static_cast<int>(sizeof(Register))));

    addPtr(TrustedImm32(sizeof(CallerFrameAndPC)), regT1, stackPointerRegister);
}

void Generator::generateGreedyQuantifier(JumpList& failures, GenerateAtomFunctor& functor, unsigned min, unsigned max)
{
    if (!max)
        return;

    JumpList doneReadingAtomsList;
    JumpList alternativeFailedList;

    // (0) Setup: Save, then init repeatCount.
    push(repeatCount);
    move(Imm32(0), repeatCount);

    // (1) Greedily read as many copies of the atom as possible, then jump to (2).
    Label readAtom(this);
    functor.generateAtom(this, doneReadingAtomsList);
    add32(Imm32(1), repeatCount);
    if (max == Quantifier::Infinity)
        jump(readAtom);
    else if (max == 1)
        doneReadingAtomsList.append(jump());
    else {
        jne32(repeatCount, Imm32(max), readAtom);
        doneReadingAtomsList.append(jump());
    }

    // (5) Quantifier failed: No more backtracking possible.
    Label quantifierFailed(this);
    pop(repeatCount);
    failures.append(jump()); 

    // (4) Alternative failed: Backtrack, then fall through to (2) to try again.
    Label alternativeFailed(this);
    pop(index);
    functor.backtrack(this);
    sub32(Imm32(1), repeatCount);

    // (2) Verify that we have enough atoms.
    doneReadingAtomsList.link(this);
    jl32(repeatCount, Imm32(min), quantifierFailed);

    // (3) Test the rest of the alternative.
    push(index);
    m_parser.parseAlternative(alternativeFailedList);
    alternativeFailedList.linkTo(alternativeFailed, this);

    pop();
    pop(repeatCount);
}

void Generator::generateAssertionWordBoundary(JumpList& failures, bool invert)
{
    JumpList wordBoundary;
    JumpList notWordBoundary;

    // (1) Check if the previous value was a word char

    // (1.1) check for begin of input
    Jump atBegin = je32(index, Imm32(0));
    // (1.2) load the last char, and chck if is word character
    load16(BaseIndex(input, index, TimesTwo, -2), character);
    JumpList previousIsWord;
    generateCharacterClassInverted(previousIsWord, CharacterClass::wordchar());
    // (1.3) if we get here, previous is not a word char
    atBegin.link(this);

    // (2) Handle situation where previous was NOT a \w

    generateLoadCharacter(notWordBoundary);
    generateCharacterClassInverted(wordBoundary, CharacterClass::wordchar());
    // (2.1) If we get here, neither chars are word chars
    notWordBoundary.append(jump());

    // (3) Handle situation where previous was a \w

    // (3.0) link success in first match to here
    previousIsWord.link(this);
    generateLoadCharacter(wordBoundary);
    generateCharacterClassInverted(notWordBoundary, CharacterClass::wordchar());
    // (3.1) If we get here, this is an end of a word, within the input.
    
    // (4) Link everything up
    
    if (invert) {
        // handle the fall through case
        wordBoundary.append(jump());
    
        // looking for non word boundaries, so link boundary fails to here.
        notWordBoundary.link(this);

        failures.append(wordBoundary);
    } else {
        // looking for word boundaries, so link successes here.
        wordBoundary.link(this);
        
        failures.append(notWordBoundary);
    }
}

void Generator::terminateAlternative(JumpList& successes, JumpList& failures)
{
    successes.append(jump());
    
    failures.link(this);
    peek(index);
}

void Generator::generatePatternCharacter(JumpList& failures, int ch)
{
    generateLoadCharacter(failures);

    // used for unicode case insensitive
    bool hasUpper = false;
    Jump isUpper;
    
    // if case insensitive match
    if (m_parser.ignoreCase()) {
        UChar lower, upper;
        
        // check for ascii case sensitive characters
        if (isASCIIAlpha(ch)) {
            or32(Imm32(32), character);
            ch |= 32;
        } else if (!isASCII(ch) && ((lower = Unicode::toLower(ch)) != (upper = Unicode::toUpper(ch)))) {
            // handle unicode case sentitive characters - branch to success on upper
            isUpper = je32(character, Imm32(upper));
            hasUpper = true;
            ch = lower;
        }
    }
    
    // checks for ch, or lower case version of ch, if insensitive
    failures.append(jne32(character, Imm32((unsigned short)ch)));

    if (m_parser.ignoreCase() && hasUpper) {
        // for unicode case insensitive matches, branch here if upper matches.
        isUpper.link(this);
    }
    
    // on success consume the char
    add32(Imm32(1), index);
}

void Generator::generateCharacterClassInvertedRange(JumpList& failures, JumpList& matchDest, const CharacterRange* ranges, unsigned count, unsigned* matchIndex, const UChar* matches, unsigned matchCount)
{
    do {
        // pick which range we're going to generate
        int which = count >> 1;
        char lo = ranges[which].begin;
        char hi = ranges[which].end;
        
        // check if there are any ranges or matches below lo.  If not, just jl to failure -
        // if there is anything else to check, check that first, if it falls through jmp to failure.
        if ((*matchIndex < matchCount) && (matches[*matchIndex] < lo)) {
            Jump loOrAbove = jge32(character, Imm32((unsigned short)lo));
            
            // generate code for all ranges before this one
            if (which)
                generateCharacterClassInvertedRange(failures, matchDest, ranges, which, matchIndex, matches, matchCount);
            
            do {
                matchDest.append(je32(character, Imm32((unsigned short)matches[*matchIndex])));
                ++*matchIndex;
            } while ((*matchIndex < matchCount) && (matches[*matchIndex] < lo));
            failures.append(jump());

            loOrAbove.link(this);
        } else if (which) {
            Jump loOrAbove = jge32(character, Imm32((unsigned short)lo));

            generateCharacterClassInvertedRange(failures, matchDest, ranges, which, matchIndex, matches, matchCount);
            failures.append(jump());

            loOrAbove.link(this);
        } else
            failures.append(jl32(character, Imm32((unsigned short)lo)));

        while ((*matchIndex < matchCount) && (matches[*matchIndex] <= hi))
            ++*matchIndex;

        matchDest.append(jle32(character, Imm32((unsigned short)hi)));
        // fall through to here, the value is above hi.

        // shuffle along & loop around if there are any more matches to handle.
        unsigned next = which + 1;
        ranges += next;
        count -= next;
    } while (count);
}

bool Generator::generatePatternCharacterPair(JumpList& failures, int ch1, int ch2)
{
    if (m_parser.ignoreCase()) {
        // Non-trivial case folding requires more than one test, so we can't
        // test as a pair with an adjacent character.
        if (!isASCII(ch1) && Unicode::toLower(ch1) != Unicode::toUpper(ch1))
            return false;
        if (!isASCII(ch2) && Unicode::toLower(ch2) != Unicode::toUpper(ch2))
            return false;
    }

    // Optimistically consume 2 characters.
    add32(Imm32(2), index);
    failures.append(jg32(index, length));

    // Load the characters we just consumed, offset -2 characters from index.
    load32(BaseIndex(input, index, TimesTwo, -2 * 2), character);

    if (m_parser.ignoreCase()) {
        // Convert ASCII alphabet characters to upper case before testing for
        // equality. (ASCII non-alphabet characters don't require upper-casing
        // because they have no uppercase equivalents. Unicode characters don't
        // require upper-casing because we only handle Unicode characters whose
        // upper and lower cases are equal.)
        int ch1Mask = 0;
        if (isASCIIAlpha(ch1)) {
            ch1 |= 32;
            ch1Mask = 32;
        }

        int ch2Mask = 0;
        if (isASCIIAlpha(ch2)) {
            ch2 |= 32;
            ch2Mask = 32;
        }

        int mask = ch1Mask | (ch2Mask << 16);
        if (mask)
            or32(Imm32(mask), character);
    }
    int pair = ch1 | (ch2 << 16);

    failures.append(jne32(character, Imm32(pair)));
    return true;
}

void Generator::generateAssertionBOL(JumpList& failures)
{
    if (m_parser.multiline()) {
        JumpList previousIsNewline;

        // begin of input == success
        previousIsNewline.append(je32(index, Imm32(0)));

        // now check prev char against newline characters.
        load16(BaseIndex(input, index, TimesTwo, -2), character);
        generateCharacterClassInverted(previousIsNewline, CharacterClass::newline());

        failures.append(jump());

        previousIsNewline.link(this);
    } else
        failures.append(jne32(index, Imm32(0)));
}

void JIT::emitSlow_op_urshift(Instruction* currentInstruction, Vector<SlowCaseEntry>::iterator& iter)
{
    unsigned dst = currentInstruction[1].u.operand;
    unsigned op1 = currentInstruction[2].u.operand;
    unsigned op2 = currentInstruction[3].u.operand;
    if (isOperandConstantImmediateInt(op2)) {
        int shift = getConstantOperand(op2).asInt32();
        // op1 = regT0
        linkSlowCase(iter); // int32 check
        if (supportsFloatingPointTruncate()) {
            JumpList failures;
            failures.append(emitJumpIfNotImmediateNumber(regT0)); // op1 is not a double
            addPtr(tagTypeNumberRegister, regT0);
            movePtrToDouble(regT0, fpRegT0);
            failures.append(branchTruncateDoubleToInt32(fpRegT0, regT0));
            if (shift)
                urshift32(Imm32(shift & 0x1f), regT0);
            if (shift < 0 || !(shift & 31))
                failures.append(branch32(LessThan, regT0, Imm32(0)));
            emitFastArithReTagImmediate(regT0, regT0);
            emitPutVirtualRegister(dst, regT0);
            emitJumpSlowToHot(jump(), OPCODE_LENGTH(op_rshift));
            failures.link(this);
        }
        if (shift < 0 || !(shift & 31))
            linkSlowCase(iter); // failed to box in hot path
    } else {
        // op1 = regT0
        // op2 = regT1
        if (!isOperandConstantImmediateInt(op1)) {
            linkSlowCase(iter); // int32 check -- op1 is not an int
            if (supportsFloatingPointTruncate()) {
                JumpList failures;
                failures.append(emitJumpIfNotImmediateNumber(regT0)); // op1 is not a double
                addPtr(tagTypeNumberRegister, regT0);
                movePtrToDouble(regT0, fpRegT0);
                failures.append(branchTruncateDoubleToInt32(fpRegT0, regT0));
                failures.append(emitJumpIfNotImmediateInteger(regT1)); // op2 is not an int
                emitFastArithImmToInt(regT1);
                urshift32(regT1, regT0);
                failures.append(branch32(LessThan, regT0, Imm32(0)));
                emitFastArithReTagImmediate(regT0, regT0);
                emitPutVirtualRegister(dst, regT0);
                emitJumpSlowToHot(jump(), OPCODE_LENGTH(op_rshift));
                failures.link(this);
            }
        }
        
        linkSlowCase(iter); // int32 check - op2 is not an int
        linkSlowCase(iter); // Can't represent unsigned result as an immediate
    }
    
    JITStubCall stubCall(this, cti_op_urshift);
    stubCall.addArgument(op1, regT0);
    stubCall.addArgument(op2, regT1);
    stubCall.call(dst);
}

void Generator::generateCharacterClass(JumpList& failures, const CharacterClass& charClass, bool invert)
{
    generateLoadCharacter(failures);

    if (invert)
        generateCharacterClassInverted(failures, charClass);
    else {
        JumpList successes;
        generateCharacterClassInverted(successes, charClass);
        failures.append(jump());
        successes.link(this);
    }
    
    add32(Imm32(1), index);
}

void Generator::generateParenthesesAssertion(JumpList& failures)
{
    JumpList disjunctionFailed;

    push(index);
    m_parser.parseDisjunction(disjunctionFailed);
    Jump success = jump();

    disjunctionFailed.link(this);
    pop(index);
    failures.append(jump());

    success.link(this);
    pop(index);
}

void Generator::generateParenthesesInvertedAssertion(JumpList& failures)
{
    JumpList disjunctionFailed;

    push(index);
    m_parser.parseDisjunction(disjunctionFailed);

    // If the disjunction succeeded, the inverted assertion failed.
    pop(index);
    failures.append(jump());

    // If the disjunction failed, the inverted assertion succeeded.
    disjunctionFailed.link(this);
    pop(index);
}