Source/JavaScriptCore/debugger/DebuggerCallFrame.cpp

/*
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
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#include "config.h"
#include "DebuggerCallFrame.h"

#include "CatchScope.h"
#include "CodeBlock.h"
#include "DebuggerEvalEnabler.h"
#include "DebuggerScope.h"
#include "Interpreter.h"
#include "JSCInlines.h"
#include "JSFunction.h"
#include "JSLexicalEnvironment.h"
#include "JSWithScope.h"
#include "Parser.h"
#include "ShadowChickenInlines.h"
#include "StackVisitor.h"
#include "StrongInlines.h"

namespace JSC {

class LineAndColumnFunctor {
public:
    StackVisitor::Status operator()(StackVisitor& visitor) const
    {
        visitor->computeLineAndColumn(m_line, m_column);
        return StackVisitor::Done;
    }

    unsigned line() const { return m_line; }
    unsigned column() const { return m_column; }

private:
    mutable unsigned m_line { 0 };
    mutable unsigned m_column { 0 };
};

Ref<DebuggerCallFrame> DebuggerCallFrame::create(VM& vm, CallFrame* callFrame)
{
    if (UNLIKELY(callFrame == callFrame->wasmAwareLexicalGlobalObject(vm)->globalExec())) {
        ShadowChicken::Frame emptyFrame;
        RELEASE_ASSERT(!emptyFrame.isTailDeleted);
        return adoptRef(*new DebuggerCallFrame(vm, callFrame, emptyFrame));
    }

    Vector<ShadowChicken::Frame> frames;
    vm.ensureShadowChicken();
    vm.shadowChicken()->iterate(vm, callFrame, [&] (const ShadowChicken::Frame& frame) -> bool {
        frames.append(frame);
        return true;
    });

    RELEASE_ASSERT(frames.size());
    ASSERT(!frames[0].isTailDeleted); // The top frame should never be tail deleted.

    RefPtr<DebuggerCallFrame> currentParent = nullptr;
    ExecState* exec = callFrame->wasmAwareLexicalGlobalObject(vm)->globalExec();
    // This walks the stack from the entry stack frame to the top of the stack.
    for (unsigned i = frames.size(); i--; ) {
        const ShadowChicken::Frame& frame = frames[i];
        if (!frame.isTailDeleted)
            exec = frame.frame;
        Ref<DebuggerCallFrame> currentFrame = adoptRef(*new DebuggerCallFrame(vm, exec, frame));
        currentFrame->m_caller = currentParent;
        currentParent = WTFMove(currentFrame);
    }
    return *currentParent;
}

DebuggerCallFrame::DebuggerCallFrame(VM& vm, CallFrame* callFrame, const ShadowChicken::Frame& frame)
    : m_validMachineFrame(callFrame)
    , m_shadowChickenFrame(frame)
{
    m_position = currentPosition(vm);
}

RefPtr<DebuggerCallFrame> DebuggerCallFrame::callerFrame()
{
    ASSERT(isValid());
    if (!isValid())
        return nullptr;

    return m_caller;
}

ExecState* DebuggerCallFrame::globalExec()
{
    return scope()->globalObject()->globalExec();
}

JSC::JSGlobalObject* DebuggerCallFrame::vmEntryGlobalObject() const
{
    ASSERT(isValid());
    if (!isValid())
        return nullptr;
    VM& vm = m_validMachineFrame->vm();
    return vm.vmEntryGlobalObject(m_validMachineFrame);
}

SourceID DebuggerCallFrame::sourceID() const
{
    ASSERT(isValid());
    if (!isValid())
        return noSourceID;
    if (isTailDeleted())
        return m_shadowChickenFrame.codeBlock->ownerScriptExecutable()->sourceID();
    return sourceIDForCallFrame(m_validMachineFrame);
}

String DebuggerCallFrame::functionName() const
{
    ASSERT(isValid());
    if (!isValid())
        return String();

    VM& vm = m_validMachineFrame->vm();
    if (isTailDeleted()) {
        if (JSFunction* func = jsDynamicCast<JSFunction*>(vm, m_shadowChickenFrame.callee))
            return func->calculatedDisplayName(vm);
        return m_shadowChickenFrame.codeBlock->inferredName().data();
    }

    return m_validMachineFrame->friendlyFunctionName();
}

DebuggerScope* DebuggerCallFrame::scope()
{
    ASSERT(isValid());
    if (!isValid())
        return nullptr;

    if (!m_scope) {
        VM& vm = m_validMachineFrame->vm();
        JSScope* scope;
        CodeBlock* codeBlock = m_validMachineFrame->codeBlock();
        if (isTailDeleted())
            scope = m_shadowChickenFrame.scope;
        else if (codeBlock && codeBlock->scopeRegister().isValid())
            scope = m_validMachineFrame->scope(codeBlock->scopeRegister().offset());
        else if (JSCallee* callee = jsDynamicCast<JSCallee*>(vm, m_validMachineFrame->jsCallee()))
            scope = callee->scope();
        else
            scope = m_validMachineFrame->lexicalGlobalObject()->globalLexicalEnvironment();

        m_scope.set(vm, DebuggerScope::create(vm, scope));
    }
    return m_scope.get();
}

DebuggerCallFrame::Type DebuggerCallFrame::type() const
{
    ASSERT(isValid());
    if (!isValid())
        return ProgramType;

    if (isTailDeleted())
        return FunctionType;

    if (jsDynamicCast<JSFunction*>(m_validMachineFrame->vm(), m_validMachineFrame->jsCallee()))
        return FunctionType;

    return ProgramType;
}

JSValue DebuggerCallFrame::thisValue() const
{
    ASSERT(isValid());
    if (!isValid())
        return jsUndefined();

    CodeBlock* codeBlock = nullptr;
    JSValue thisValue;
    if (isTailDeleted()) {
        thisValue = m_shadowChickenFrame.thisValue;
        codeBlock = m_shadowChickenFrame.codeBlock;
    } else {
        thisValue = m_validMachineFrame->thisValue();
        codeBlock = m_validMachineFrame->codeBlock();
    }

    if (!thisValue)
        return jsUndefined();

    ECMAMode ecmaMode = NotStrictMode;
    if (codeBlock && codeBlock->isStrictMode())
        ecmaMode = StrictMode;
    return thisValue.toThis(m_validMachineFrame, ecmaMode);
}

// Evaluate some JavaScript code in the scope of this frame.
JSValue DebuggerCallFrame::evaluateWithScopeExtension(const String& script, JSObject* scopeExtensionObject, NakedPtr<Exception>& exception)
{
    ASSERT(isValid());
    CallFrame* callFrame = m_validMachineFrame;
    if (!callFrame)
        return jsUndefined();

    VM& vm = callFrame->vm();
    JSLockHolder lock(vm);
    auto catchScope = DECLARE_CATCH_SCOPE(vm);

    CodeBlock* codeBlock = nullptr;
    if (isTailDeleted())
        codeBlock = m_shadowChickenFrame.codeBlock;
    else
        codeBlock = callFrame->codeBlock();
    if (!codeBlock)
        return jsUndefined();
    
    DebuggerEvalEnabler evalEnabler(callFrame, DebuggerEvalEnabler::Mode::EvalOnCallFrameAtDebuggerEntry);

    EvalContextType evalContextType;
    
    if (isFunctionParseMode(codeBlock->unlinkedCodeBlock()->parseMode()))
        evalContextType = EvalContextType::FunctionEvalContext;
    else if (codeBlock->unlinkedCodeBlock()->codeType() == EvalCode)
        evalContextType = codeBlock->unlinkedCodeBlock()->evalContextType();
    else 
        evalContextType = EvalContextType::None;

    VariableEnvironment variablesUnderTDZ;
    JSScope::collectClosureVariablesUnderTDZ(scope()->jsScope(), variablesUnderTDZ);

    auto* eval = DirectEvalExecutable::create(callFrame, makeSource(script, callFrame->callerSourceOrigin()), codeBlock->isStrictMode(), codeBlock->unlinkedCodeBlock()->derivedContextType(), codeBlock->unlinkedCodeBlock()->isArrowFunction(), evalContextType, &variablesUnderTDZ);
    if (UNLIKELY(catchScope.exception())) {
        exception = catchScope.exception();
        catchScope.clearException();
        return jsUndefined();
    }

    JSGlobalObject* globalObject = vm.vmEntryGlobalObject(callFrame);
    if (scopeExtensionObject) {
        JSScope* ignoredPreviousScope = globalObject->globalScope();
        globalObject->setGlobalScopeExtension(JSWithScope::create(vm, globalObject, ignoredPreviousScope, scopeExtensionObject));
    }

    JSValue thisValue = this->thisValue();
    JSValue result = vm.interpreter->execute(eval, callFrame, thisValue, scope()->jsScope());
    if (UNLIKELY(catchScope.exception())) {
        exception = catchScope.exception();
        catchScope.clearException();
    }

    if (scopeExtensionObject)
        globalObject->clearGlobalScopeExtension();

    ASSERT(result);
    return result;
}

void DebuggerCallFrame::invalidate()
{
    RefPtr<DebuggerCallFrame> frame = this;
    while (frame) {
        frame->m_validMachineFrame = nullptr;
        if (frame->m_scope) {
            frame->m_scope->invalidateChain();
            frame->m_scope.clear();
        }
        frame = WTFMove(frame->m_caller);
    }
}

TextPosition DebuggerCallFrame::currentPosition(VM& vm)
{
    if (!m_validMachineFrame)
        return TextPosition();

    if (isTailDeleted()) {
        CodeBlock* codeBlock = m_shadowChickenFrame.codeBlock;
        if (Optional<unsigned> bytecodeOffset = codeBlock->bytecodeOffsetFromCallSiteIndex(m_shadowChickenFrame.callSiteIndex)) {
            return TextPosition(OrdinalNumber::fromOneBasedInt(codeBlock->lineNumberForBytecodeOffset(*bytecodeOffset)),
                OrdinalNumber::fromOneBasedInt(codeBlock->columnNumberForBytecodeOffset(*bytecodeOffset)));
        }
    }

    return positionForCallFrame(vm, m_validMachineFrame);
}

TextPosition DebuggerCallFrame::positionForCallFrame(VM& vm, CallFrame* callFrame)
{
    LineAndColumnFunctor functor;
    StackVisitor::visit(callFrame, &vm, functor);
    return TextPosition(OrdinalNumber::fromOneBasedInt(functor.line()), OrdinalNumber::fromOneBasedInt(functor.column()));
}

SourceID DebuggerCallFrame::sourceIDForCallFrame(CallFrame* callFrame)
{
    ASSERT(callFrame);
    CodeBlock* codeBlock = callFrame->codeBlock();
    if (!codeBlock)
        return noSourceID;
    return codeBlock->ownerScriptExecutable()->sourceID();
}

} // namespace JSC