C++ JSValue::description方法代码示例

void* prepareOSREntry(ExecState* exec, CodeBlock* codeBlock, unsigned bytecodeIndex)
{
#if DFG_ENABLE(OSR_ENTRY)
    ASSERT(codeBlock->getJITType() == JITCode::DFGJIT);
    ASSERT(codeBlock->alternative());
    ASSERT(codeBlock->alternative()->getJITType() == JITCode::BaselineJIT);
    ASSERT(!codeBlock->jitCodeMap());
    ASSERT(codeBlock->numberOfDFGOSREntries());

#if ENABLE(JIT_VERBOSE_OSR)
    dataLog("OSR in %p(%p) from bc#%u\n", codeBlock, codeBlock->alternative(), bytecodeIndex);
#endif
    
    JSGlobalData* globalData = &exec->globalData();
    OSREntryData* entry = codeBlock->dfgOSREntryDataForBytecodeIndex(bytecodeIndex);
    
    ASSERT(entry->m_bytecodeIndex == bytecodeIndex);
    
    // The code below checks if it is safe to perform OSR entry. It may find
    // that it is unsafe to do so, for any number of reasons, which are documented
    // below. If the code decides not to OSR then it returns 0, and it's the caller's
    // responsibility to patch up the state in such a way as to ensure that it's
    // both safe and efficient to continue executing baseline code for now. This
    // should almost certainly include calling either codeBlock->optimizeAfterWarmUp()
    // or codeBlock->dontOptimizeAnytimeSoon().
    
    // 1) Verify predictions. If the predictions are inconsistent with the actual
    //    values, then OSR entry is not possible at this time. It's tempting to
    //    assume that we could somehow avoid this case. We can certainly avoid it
    //    for first-time loop OSR - that is, OSR into a CodeBlock that we have just
    //    compiled. Then we are almost guaranteed that all of the predictions will
    //    check out. It would be pretty easy to make that a hard guarantee. But
    //    then there would still be the case where two call frames with the same
    //    baseline CodeBlock are on the stack at the same time. The top one
    //    triggers compilation and OSR. In that case, we may no longer have
    //    accurate value profiles for the one deeper in the stack. Hence, when we
    //    pop into the CodeBlock that is deeper on the stack, we might OSR and
    //    realize that the predictions are wrong. Probably, in most cases, this is
    //    just an anomaly in the sense that the older CodeBlock simply went off
    //    into a less-likely path. So, the wisest course of action is to simply not
    //    OSR at this time.
    
    for (size_t argument = 0; argument < entry->m_expectedValues.numberOfArguments(); ++argument) {
        if (argument >= exec->argumentCountIncludingThis()) {
#if ENABLE(JIT_VERBOSE_OSR)
            dataLog("    OSR failed because argument %zu was not passed, expected ", argument);
            entry->m_expectedValues.argument(argument).dump(WTF::dataFile());
            dataLog(".\n");
#endif
            return 0;
        }
        
        JSValue value;
        if (!argument)
            value = exec->hostThisValue();
        else
            value = exec->argument(argument - 1);
        
        if (!entry->m_expectedValues.argument(argument).validate(value)) {
#if ENABLE(JIT_VERBOSE_OSR)
            dataLog("    OSR failed because argument %zu is %s, expected ", argument, value.description());
            entry->m_expectedValues.argument(argument).dump(WTF::dataFile());
            dataLog(".\n");
#endif
            return 0;
        }
    }
    
    for (size_t local = 0; local < entry->m_expectedValues.numberOfLocals(); ++local) {
        if (entry->m_localsForcedDouble.get(local)) {
            if (!exec->registers()[local].jsValue().isNumber()) {
#if ENABLE(JIT_VERBOSE_OSR)
                dataLog("    OSR failed because variable %zu is %s, expected number.\n", local, exec->registers()[local].jsValue().description());
#endif
                return 0;
            }
            continue;
        }
        if (!entry->m_expectedValues.local(local).validate(exec->registers()[local].jsValue())) {
#if ENABLE(JIT_VERBOSE_OSR)
            dataLog("    OSR failed because variable %zu is %s, expected ", local, exec->registers()[local].jsValue().description());
            entry->m_expectedValues.local(local).dump(WTF::dataFile());
            dataLog(".\n");
#endif
            return 0;
        }
    }

    // 2) Check the stack height. The DFG JIT may require a taller stack than the
    //    baseline JIT, in some cases. If we can't grow the stack, then don't do
    //    OSR right now. That's the only option we have unless we want basic block
    //    boundaries to start throwing RangeErrors. Although that would be possible,
    //    it seems silly: you'd be diverting the program to error handling when it
    //    would have otherwise just kept running albeit less quickly.
    
    if (!globalData->interpreter->registerFile().grow(&exec->registers()[codeBlock->m_numCalleeRegisters])) {
#if ENABLE(JIT_VERBOSE_OSR)
        dataLog("    OSR failed because stack growth failed.\n");
#endif
        return 0;
//.........这里部分代码省略.........

//.........这里部分代码省略.........

    if (strlen(nodeFlagsAsString(node.flags()))) {
        dataLog("%s%s", hasPrinted ? ", " : "", nodeFlagsAsString(node.flags()));
        hasPrinted = true;
    }
    if (node.hasArrayMode()) {
        dataLog("%s%s", hasPrinted ? ", " : "", modeToString(node.arrayMode()));
        hasPrinted = true;
    }
    if (node.hasVarNumber()) {
        dataLog("%svar%u", hasPrinted ? ", " : "", node.varNumber());
        hasPrinted = true;
    }
    if (node.hasRegisterPointer()) {
        dataLog(
            "%sglobal%u(%p)", hasPrinted ? ", " : "",
            globalObjectFor(node.codeOrigin)->findRegisterIndex(node.registerPointer()),
            node.registerPointer());
        hasPrinted = true;
    }
    if (node.hasIdentifier()) {
        dataLog("%sid%u{%s}", hasPrinted ? ", " : "", node.identifierNumber(), m_codeBlock->identifier(node.identifierNumber()).ustring().utf8().data());
        hasPrinted = true;
    }
    if (node.hasStructureSet()) {
        for (size_t i = 0; i < node.structureSet().size(); ++i) {
            dataLog("%sstruct(%p)", hasPrinted ? ", " : "", node.structureSet()[i]);
            hasPrinted = true;
        }
    }
    if (node.hasStructure()) {
        dataLog("%sstruct(%p)", hasPrinted ? ", " : "", node.structure());
        hasPrinted = true;
    }
    if (node.hasStructureTransitionData()) {
        dataLog("%sstruct(%p -> %p)", hasPrinted ? ", " : "", node.structureTransitionData().previousStructure, node.structureTransitionData().newStructure);
        hasPrinted = true;
    }
    if (node.hasStorageAccessData()) {
        StorageAccessData& storageAccessData = m_storageAccessData[node.storageAccessDataIndex()];
        dataLog("%sid%u{%s}", hasPrinted ? ", " : "", storageAccessData.identifierNumber, m_codeBlock->identifier(storageAccessData.identifierNumber).ustring().utf8().data());
        
        dataLog(", %lu", static_cast<unsigned long>(storageAccessData.offset));
        hasPrinted = true;
    }
    ASSERT(node.hasVariableAccessData() == node.hasLocal());
    if (node.hasVariableAccessData()) {
        VariableAccessData* variableAccessData = node.variableAccessData();
        int operand = variableAccessData->operand();
        if (operandIsArgument(operand))
            dataLog("%sarg%u(%s)", hasPrinted ? ", " : "", operandToArgument(operand), nameOfVariableAccessData(variableAccessData));
        else
            dataLog("%sr%u(%s)", hasPrinted ? ", " : "", operand, nameOfVariableAccessData(variableAccessData));
        hasPrinted = true;
    }
    if (node.hasConstantBuffer()) {
        if (hasPrinted)
            dataLog(", ");
        dataLog("%u:[", node.startConstant());
        for (unsigned i = 0; i < node.numConstants(); ++i) {
            if (i)
                dataLog(", ");
            dataLog("%s", m_codeBlock->constantBuffer(node.startConstant())[i].description());
        }
        dataLog("]");
        hasPrinted = true;
    }
    if (op == JSConstant) {
        dataLog("%s$%u", hasPrinted ? ", " : "", node.constantNumber());
        JSValue value = valueOfJSConstant(nodeIndex);
        dataLog(" = %s", value.description());
        hasPrinted = true;
    }
    if (op == WeakJSConstant) {
        dataLog("%s%p", hasPrinted ? ", " : "", node.weakConstant());
        hasPrinted = true;
    }
    if  (node.isBranch() || node.isJump()) {
        dataLog("%sT:#%u", hasPrinted ? ", " : "", node.takenBlockIndex());
        hasPrinted = true;
    }
    if  (node.isBranch()) {
        dataLog("%sF:#%u", hasPrinted ? ", " : "", node.notTakenBlockIndex());
        hasPrinted = true;
    }
    dataLog("%sbc#%u", hasPrinted ? ", " : "", node.codeOrigin.bytecodeIndex);
    hasPrinted = true;
    (void)hasPrinted;
    
    dataLog(")");

    if (!skipped) {
        if (node.hasVariableAccessData())
            dataLog("  predicting %s%s", speculationToString(node.variableAccessData()->prediction()), node.variableAccessData()->shouldUseDoubleFormat() ? ", forcing double" : "");
        else if (node.hasHeapPrediction())
            dataLog("  predicting %s", speculationToString(node.getHeapPrediction()));
    }
    
    dataLog("\n");
}