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darling-JavaScriptCore/runtime/AbstractModuleRecord.cpp

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/*
* Copyright (C) 2015-2019 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "AbstractModuleRecord.h"
#include "Error.h"
#include "JSCInlines.h"
#include "JSMap.h"
#include "JSModuleEnvironment.h"
#include "JSModuleNamespaceObject.h"
#include "JSModuleRecord.h"
#include "WebAssemblyModuleRecord.h"
#include <wtf/Optional.h>
namespace JSC {
namespace AbstractModuleRecordInternal {
static constexpr bool verbose = false;
} // namespace AbstractModuleRecordInternal
const ClassInfo AbstractModuleRecord::s_info = { "AbstractModuleRecord", &Base::s_info, nullptr, nullptr, CREATE_METHOD_TABLE(AbstractModuleRecord) };
AbstractModuleRecord::AbstractModuleRecord(VM& vm, Structure* structure, const Identifier& moduleKey)
: Base(vm, structure)
, m_moduleKey(moduleKey)
{
}
void AbstractModuleRecord::finishCreation(JSGlobalObject* globalObject, VM& vm)
{
Base::finishCreation(vm);
ASSERT(inherits(vm, info()));
auto scope = DECLARE_THROW_SCOPE(vm);
JSMap* map = JSMap::create(globalObject, vm, globalObject->mapStructure());
scope.releaseAssertNoException();
m_dependenciesMap.set(vm, this, map);
putDirect(vm, Identifier::fromString(vm, "dependenciesMap"_s), m_dependenciesMap.get());
}
void AbstractModuleRecord::visitChildren(JSCell* cell, SlotVisitor& visitor)
{
AbstractModuleRecord* thisObject = jsCast<AbstractModuleRecord*>(cell);
ASSERT_GC_OBJECT_INHERITS(thisObject, info());
Base::visitChildren(thisObject, visitor);
visitor.append(thisObject->m_moduleEnvironment);
visitor.append(thisObject->m_moduleNamespaceObject);
visitor.append(thisObject->m_dependenciesMap);
}
void AbstractModuleRecord::appendRequestedModule(const Identifier& moduleName)
{
m_requestedModules.add(moduleName.impl());
}
void AbstractModuleRecord::addStarExportEntry(const Identifier& moduleName)
{
m_starExportEntries.add(moduleName.impl());
}
void AbstractModuleRecord::addImportEntry(const ImportEntry& entry)
{
bool isNewEntry = m_importEntries.add(entry.localName.impl(), entry).isNewEntry;
ASSERT_UNUSED(isNewEntry, isNewEntry); // This is guaranteed by the parser.
}
void AbstractModuleRecord::addExportEntry(const ExportEntry& entry)
{
bool isNewEntry = m_exportEntries.add(entry.exportName.impl(), entry).isNewEntry;
ASSERT_UNUSED(isNewEntry, isNewEntry); // This is guaranteed by the parser.
}
auto AbstractModuleRecord::tryGetImportEntry(UniquedStringImpl* localName) -> Optional<ImportEntry>
{
const auto iterator = m_importEntries.find(localName);
if (iterator == m_importEntries.end())
return WTF::nullopt;
return Optional<ImportEntry>(iterator->value);
}
auto AbstractModuleRecord::tryGetExportEntry(UniquedStringImpl* exportName) -> Optional<ExportEntry>
{
const auto iterator = m_exportEntries.find(exportName);
if (iterator == m_exportEntries.end())
return WTF::nullopt;
return Optional<ExportEntry>(iterator->value);
}
auto AbstractModuleRecord::ExportEntry::createLocal(const Identifier& exportName, const Identifier& localName) -> ExportEntry
{
return ExportEntry { Type::Local, exportName, Identifier(), Identifier(), localName };
}
auto AbstractModuleRecord::ExportEntry::createIndirect(const Identifier& exportName, const Identifier& importName, const Identifier& moduleName) -> ExportEntry
{
return ExportEntry { Type::Indirect, exportName, moduleName, importName, Identifier() };
}
auto AbstractModuleRecord::ExportEntry::createNamespace(const Identifier& exportName, const Identifier& moduleName) -> ExportEntry
{
return ExportEntry { Type::Namespace, exportName, moduleName, Identifier(), Identifier() };
}
auto AbstractModuleRecord::Resolution::notFound() -> Resolution
{
return Resolution { Type::NotFound, nullptr, Identifier() };
}
auto AbstractModuleRecord::Resolution::error() -> Resolution
{
return Resolution { Type::Error, nullptr, Identifier() };
}
auto AbstractModuleRecord::Resolution::ambiguous() -> Resolution
{
return Resolution { Type::Ambiguous, nullptr, Identifier() };
}
AbstractModuleRecord* AbstractModuleRecord::hostResolveImportedModule(JSGlobalObject* globalObject, const Identifier& moduleName)
{
VM& vm = globalObject->vm();
auto scope = DECLARE_THROW_SCOPE(vm);
JSValue moduleNameValue = identifierToJSValue(vm, moduleName);
JSValue entry = m_dependenciesMap->JSMap::get(globalObject, moduleNameValue);
RETURN_IF_EXCEPTION(scope, nullptr);
RELEASE_AND_RETURN(scope, jsCast<AbstractModuleRecord*>(entry.get(globalObject, Identifier::fromString(vm, "module"))));
}
auto AbstractModuleRecord::resolveImport(JSGlobalObject* globalObject, const Identifier& localName) -> Resolution
{
VM& vm = globalObject->vm();
auto scope = DECLARE_THROW_SCOPE(vm);
Optional<ImportEntry> optionalImportEntry = tryGetImportEntry(localName.impl());
if (!optionalImportEntry)
return Resolution::notFound();
const ImportEntry& importEntry = *optionalImportEntry;
if (importEntry.type == AbstractModuleRecord::ImportEntryType::Namespace)
return Resolution::notFound();
AbstractModuleRecord* importedModule = hostResolveImportedModule(globalObject, importEntry.moduleRequest);
RETURN_IF_EXCEPTION(scope, Resolution::error());
return importedModule->resolveExport(globalObject, importEntry.importName);
}
struct AbstractModuleRecord::ResolveQuery {
struct Hash {
static unsigned hash(const ResolveQuery&);
static bool equal(const ResolveQuery&, const ResolveQuery&);
static constexpr bool safeToCompareToEmptyOrDeleted = true;
};
using HashTraits = WTF::CustomHashTraits<ResolveQuery>;
ResolveQuery(AbstractModuleRecord* moduleRecord, UniquedStringImpl* exportName)
: moduleRecord(moduleRecord)
, exportName(exportName)
{
}
ResolveQuery(AbstractModuleRecord* moduleRecord, const Identifier& exportName)
: ResolveQuery(moduleRecord, exportName.impl())
{
}
enum EmptyValueTag { EmptyValue };
ResolveQuery(EmptyValueTag)
{
}
enum DeletedValueTag { DeletedValue };
ResolveQuery(DeletedValueTag)
: moduleRecord(nullptr)
, exportName(WTF::HashTableDeletedValue)
{
}
bool isEmptyValue() const
{
return !exportName;
}
bool isDeletedValue() const
{
return exportName.isHashTableDeletedValue();
}
void dump(PrintStream& out) const
{
if (!moduleRecord) {
out.print("<empty>");
return;
}
out.print(moduleRecord->moduleKey(), " \"", exportName.get(), "\"");
}
// The module record is not marked from the GC. But these records are reachable from the JSGlobalObject.
// So we don't care the reachability to this record.
AbstractModuleRecord* moduleRecord;
RefPtr<UniquedStringImpl> exportName;
};
inline unsigned AbstractModuleRecord::ResolveQuery::Hash::hash(const ResolveQuery& query)
{
return WTF::PtrHash<AbstractModuleRecord*>::hash(query.moduleRecord) + IdentifierRepHash::hash(query.exportName);
}
inline bool AbstractModuleRecord::ResolveQuery::Hash::equal(const ResolveQuery& lhs, const ResolveQuery& rhs)
{
return lhs.moduleRecord == rhs.moduleRecord && lhs.exportName == rhs.exportName;
}
auto AbstractModuleRecord::tryGetCachedResolution(UniquedStringImpl* exportName) -> Optional<Resolution>
{
const auto iterator = m_resolutionCache.find(exportName);
if (iterator == m_resolutionCache.end())
return WTF::nullopt;
return Optional<Resolution>(iterator->value);
}
void AbstractModuleRecord::cacheResolution(UniquedStringImpl* exportName, const Resolution& resolution)
{
m_resolutionCache.add(exportName, resolution);
}
auto AbstractModuleRecord::resolveExportImpl(JSGlobalObject* globalObject, const ResolveQuery& root) -> Resolution
{
VM& vm = globalObject->vm();
auto scope = DECLARE_THROW_SCOPE(vm);
if (AbstractModuleRecordInternal::verbose)
dataLog("Resolving ", root, "\n");
// https://tc39.github.io/ecma262/#sec-resolveexport
// How to avoid C++ recursion in this function:
// This function avoids C++ recursion of the naive ResolveExport implementation.
// Flatten the recursion to the loop with the task queue and frames.
//
// 1. pendingTasks
// We enqueue the recursive resolveExport call to this queue to avoid recursive calls in C++.
// The task has 3 types. (1) Query, (2) IndirectFallback and (3) GatherStars.
// (1) Query
// Querying the resolution to the current module.
// (2) IndirectFallback
// Examine the result of the indirect export resolution. Only when the indirect export resolution fails,
// we look into the star exports. (step 5-a-vi).
// (3) GatherStars
// Examine the result of the star export resolutions.
//
// 2. frames
// When the spec calls the resolveExport recursively, instead we append the frame
// (that holds the result resolution) to the frames and enqueue the task to the pendingTasks.
// The entry in the frames means the *local* resolution result of the specific recursive resolveExport.
//
// We should maintain the local resolution result instead of holding the global resolution result only.
// For example,
//
// star
// (1) ---> (2) "Resolve"
// |
// |
// +-> (3) "NotFound"
// |
// | star
// +-> (4) ---> (5) "Resolve" [here]
// |
// |
// +-> (6) "Error"
//
// Consider the above graph. The numbers represents the modules. Now we are [here].
// If we only hold the global resolution result during the resolveExport operation, [here],
// we decide the entire result of resolveExport is "Ambiguous", because there are multiple
// "Resolve" (in module (2) and (5)). However, this should become "Error" because (6) will
// propagate "Error" state to the (4), (4) will become "Error" and then, (1) will become
// "Error". We should aggregate the results at the star exports point ((4) and (1)).
//
// Usually, both "Error" and "Ambiguous" states will throw the syntax error. So except for the content of the
// error message, there are no difference. (And if we fix the (6) that raises "Error", next, it will produce
// the "Ambiguous" error due to (5). Anyway, user need to fix the both. So which error should be raised at first
// doesn't matter so much.
//
// However, this may become the problem under the module namespace creation.
// http://www.ecma-international.org/ecma-262/6.0/#sec-getmodulenamespace
// section 15.2.1.18, step 3-d-ii
// Here, we distinguish "Ambiguous" and "Error". When "Error" state is produced, we need to throw the propagated error.
// But if "Ambiguous" state comes, we just ignore the result.
// To follow the requirement strictly, in this implementation, we keep the local resolution result to produce the
// correct result under the above complex cases.
// Caching strategy:
// The resolveExport operation is frequently called. So caching results is important.
// We observe the following aspects and based on them construct the caching strategy.
// Here, we attempt to cache the resolution by constructing the map in module records.
// That means Module -> ExportName -> Maybe<Resolution>.
// Technically, all the AbstractModuleRecords have the Map<ExportName, Resolution> for caching.
//
// The important observations are that,
//
// - *cacheable* means that traversing to this node from a path will produce the same results as starting from this node.
//
// Here, we define the resovling route. We represent [?] as the module that has the local binding.
// And (?) as the module without the local binding.
//
// @ -> (A) -> (B) -> [C]
//
// We list the resolving route for each node.
//
// (A): (A) -> (B) -> [C]
// (B): (B) -> [C]
// [C]: [C]
//
// In this case, if we start the tracing from (B), the resolving route becomes (B) -> [C].
// So this is the same. At that time, we can say (B) is cacheable in the first tracing.
//
// - The cache ability of a node depends on the resolving route from this node.
//
// 1. The starting point is always cacheable.
//
// 2. A module that has resolved a local binding is always cacheable.
//
// @ -> (A) -> [B]
//
// In the above case, we can see the [B] as cacheable.
// This is because when starting from [B] node, we immediately resolve with the local binding.
// So the resolving route from [B] does not depend on the starting point.
//
// 3. If we don't follow any star links during the resolution, we can see all the traced nodes are cacheable.
//
// If there are non star links, it means that there is *no branch* in the module dependency graph.
// This *no branch* feature makes all the modules cachable.
//
// I.e, if we traverse one star link (even if we successfully resolve that star link),
// we must still traverse all other star links. I would also explain we don't run into
// this when resolving a local/indirect link. When resolving a local/indirect link,
// we won't traverse any star links.
// And since the module can hold only one local/indirect link for the specific export name (if there
// are multiple local/indirect links that has the same export name, it should be syntax error in the
// parsing phase.), there is no multiple outgoing links from a module.
//
// @ -> (A) --> (B) -> [C] -> (D) -> (E) -+
// ^ |
// | |
// +------------------------+
//
// When starting from @, [C] will be found as the module resolving the given binding.
// In this case, (B) can cache this resolution. Since the resolving route is the same to the one when
// starting from (B). After caching the above result, we attempt to resolve the same binding from (D).
//
// @
// |
// v
// @ -> (A) --> (B) -> [C] -> (D) -> (E) -+
// ^ |
// | |
// +------------------------+
//
// In this case, we can use the (B)'s cached result. And (E) can be cached.
//
// (E): The resolving route is now (E) -> (B) -> [C]. That is the same when starting from (E).
//
// No branching makes that the problematic *once-visited* node cannot be seen.
// The *once-visited* node makes the resolving route changed since when we see the *once-visited* node,
// we stop tracing this.
//
// If there is no star links and if we look *once-visited* node under no branching graph, *once-visited*
// node cannot resolve the requested binding. If the *once-visited* node can resolve the binding, we
// should have already finished the resolution before reaching this *once-visited* node.
//
// 4. Once we follow star links, we should not retrieve the result from the cache and should not cache.
//
// Star links are only the way to introduce branch.
// Once we follow the star links during the resolution, we cannot cache naively.
// This is because the cacheability depends on the resolving route. And branching produces the problematic *once-visited*
// nodes. Since we don't follow the *once-visited* node, the resolving route from the node becomes different from
// the resolving route when starting from this node.
//
// The following example explains when we should not retrieve the cache and cache the result.
//
// +----> (D) ------+
// | |
// | v
// (A) *----+----> (B) ---> [C]
// ^
// |
// @
//
// When starting from (B), we find [C]. In this resolving route, we don't find any star link.
// And by definition, (B) and [C] are cachable. (B) is the starting point. And [C] has the local binding.
//
// +----> (D) ------+
// | |
// | v
// @-> (A) *----+----> (B) ---> [C]
//
// But when starting from (A), we should not get the value from the cache. Because,
//
// 1. When looking (D), we reach [C] and make both resolved.
// 2. When looking (B), if we retrieved the last cache from (B), (B) becomes resolved.
// 3. But actually, (B) is not-found in this trial because (C) is already *once-visited*.
// 4. If we accidentally make (B) resolved, (A) becomes ambiguous. But the correct answer is resolved.
//
// Why is this problem caused? This is because the *once-visited* node makes the result not-found.
// In the second trial, (B) -> [C] result is changed from resolved to not-found.
//
// When does this become a problem? If the status of the *once-visited* node group is resolved,
// changing the result to not-found makes the result changed.
//
// This problem does not happen when we don't see any star link yet. Now, consider the minimum case.
//
// @-> (A) -> [ some graph ]
// ^ |
// | |
// +------------+
//
// In (A), we don't see any star link yet. So we can say that all the visited nodes does not have any local
// resolution. Because if they had a local/indirect resolution, we should have already finished the tracing.
//
// And even if the some graph will see the *once-visited* node (in this case, (A)), that does not affect the
// result of the resolution. Because even if we follow the link to (A) or not follow the link to (A), the status
// of the link is always not-found since (A) does not have any local resolution.
// In the above case, we can use the result of the [some graph].
//
// 5. Once we see star links, even if we have not yet traversed that star link path, we should disable caching.
//
// Here is the reason why:
//
// +-------------+
// | |
// v |
// (A) -> (B) -> (C) *-> [E]
// * ^
// | |
// v @
// [D]
//
// In the above case, (C) will be resolved with [D].
// (C) will see (A) and (A) gives up in (A) -> (B) -> (C) route. So, (A) will fallback to [D].
//
// +-------------+
// | |
// v |
// @-> (A) -> (B) -> (C) *-> [E]
// *
// |
// v
// [D]
//
// But in this case, (A) will be resolved with [E] (not [D]).
// (C) will attempt to follow the link to (A), but it fails.
// So (C) will fallback to the star link and found [E]. In this senario,
// (C) is now resolved with [E]'s result.
//
// The cause of this problem is also the same to 4.
// In the latter case, when looking (C), we cannot use the cached result in (C).
// Because the cached result of (C) depends on the *once-visited* node (A) and
// (A) has the fallback system with the star link.
// In the latter trial, we now assume that (A)'s status is not-found.
// But, actually, in the former trial, (A)'s status becomes resolved due to the fallback to the [D].
//
// To summarize the observations.
//
// 1. The starting point is always cacheable.
// 2. A module that has resolved a local binding is always cacheable.
// 3. If we don't follow any star links during the resolution, we can see all the traced nodes are cacheable.
// 4. Once we follow star links, we should not retrieve the result from the cache and should not cache the result.
// 5. Once we see star links, even if we have not yet traversed that star link path, we should disable caching.
using ResolveSet = WTF::HashSet<ResolveQuery, ResolveQuery::Hash, ResolveQuery::HashTraits>;
enum class Type { Query, IndirectFallback, GatherStars };
struct Task {
ResolveQuery query;
Type type;
};
auto typeString = [] (Type type) -> const char* {
switch (type) {
case Type::Query:
return "Query";
case Type::IndirectFallback:
return "IndirectFallback";
case Type::GatherStars:
return "GatherStars";
}
RELEASE_ASSERT_NOT_REACHED();
return nullptr;
};
Vector<Task, 8> pendingTasks;
ResolveSet resolveSet;
Vector<Resolution, 8> frames;
bool foundStarLinks = false;
frames.append(Resolution::notFound());
// Call when the query is not resolved in the current module.
// It will enqueue the star resolution requests. Return "false" if the error occurs.
auto resolveNonLocal = [&](const ResolveQuery& query) -> bool {
// https://tc39.github.io/ecma262/#sec-resolveexport
// section 15.2.1.16.3, step 6
// If the "default" name is not resolved in the current module, we need to throw an error and stop resolution immediately,
// Rationale to this error: A default export cannot be provided by an export *.
VM& vm = globalObject->vm();
auto scope = DECLARE_THROW_SCOPE(vm);
if (query.exportName == vm.propertyNames->defaultKeyword.impl())
return false;
// Enqueue the task to gather the results of the stars.
// And append the new Resolution frame to gather the local result of the stars.
pendingTasks.append(Task { query, Type::GatherStars });
foundStarLinks = true;
frames.append(Resolution::notFound());
// Enqueue the tasks in reverse order.
for (auto iterator = query.moduleRecord->starExportEntries().rbegin(), end = query.moduleRecord->starExportEntries().rend(); iterator != end; ++iterator) {
const RefPtr<UniquedStringImpl>& starModuleName = *iterator;
AbstractModuleRecord* importedModuleRecord = query.moduleRecord->hostResolveImportedModule(globalObject, Identifier::fromUid(vm, starModuleName.get()));
RETURN_IF_EXCEPTION(scope, false);
pendingTasks.append(Task { ResolveQuery(importedModuleRecord, query.exportName.get()), Type::Query });
}
return true;
};
// Return the current resolution value of the top frame.
auto currentTop = [&] () -> Resolution& {
ASSERT(!frames.isEmpty());
return frames.last();
};
// Merge the given resolution to the current resolution value of the top frame.
// If there is ambiguity, return "false". When the "false" is returned, we should make the result "ambiguous".
auto mergeToCurrentTop = [&] (const Resolution& resolution) -> bool {
if (resolution.type == Resolution::Type::NotFound)
return true;
if (currentTop().type == Resolution::Type::NotFound) {
currentTop() = resolution;
return true;
}
if (currentTop().moduleRecord != resolution.moduleRecord || currentTop().localName != resolution.localName)
return false;
return true;
};
auto cacheResolutionForQuery = [] (const ResolveQuery& query, const Resolution& resolution) {
ASSERT(resolution.type == Resolution::Type::Resolved);
query.moduleRecord->cacheResolution(query.exportName.get(), resolution);
};
pendingTasks.append(Task { root, Type::Query });
while (!pendingTasks.isEmpty()) {
const Task task = pendingTasks.takeLast();
const ResolveQuery& query = task.query;
if (AbstractModuleRecordInternal::verbose)
dataLog(" ", typeString(task.type), " ", task.query, "\n");
switch (task.type) {
case Type::Query: {
AbstractModuleRecord* moduleRecord = query.moduleRecord;
if (!resolveSet.add(task.query).isNewEntry)
continue;
// 5. Once we see star links, even if we have not yet traversed that star link path, we should disable caching.
if (!moduleRecord->starExportEntries().isEmpty())
foundStarLinks = true;
// 4. Once we follow star links, we should not retrieve the result from the cache and should not cache the result.
if (!foundStarLinks) {
if (Optional<Resolution> cachedResolution = moduleRecord->tryGetCachedResolution(query.exportName.get())) {
if (!mergeToCurrentTop(*cachedResolution))
return Resolution::ambiguous();
continue;
}
}
const Optional<ExportEntry> optionalExportEntry = moduleRecord->tryGetExportEntry(query.exportName.get());
if (!optionalExportEntry) {
// If there is no matched exported binding in the current module,
// we need to look into the stars.
bool success = resolveNonLocal(task.query);
EXCEPTION_ASSERT(!scope.exception() || !success);
if (!success)
return Resolution::error();
continue;
}
const ExportEntry& exportEntry = *optionalExportEntry;
switch (exportEntry.type) {
case ExportEntry::Type::Local: {
ASSERT(!exportEntry.localName.isNull());
Resolution resolution { Resolution::Type::Resolved, moduleRecord, exportEntry.localName };
// 2. A module that has resolved a local binding is always cacheable.
cacheResolutionForQuery(query, resolution);
if (!mergeToCurrentTop(resolution))
return Resolution::ambiguous();
continue;
}
case ExportEntry::Type::Indirect: {
AbstractModuleRecord* importedModuleRecord = moduleRecord->hostResolveImportedModule(globalObject, exportEntry.moduleName);
RETURN_IF_EXCEPTION(scope, Resolution::error());
// When the imported module does not produce any resolved binding, we need to look into the stars in the *current*
// module. To do this, we append the `IndirectFallback` task to the task queue.
pendingTasks.append(Task { query, Type::IndirectFallback });
// And append the new Resolution frame to check the indirect export will be resolved or not.
frames.append(Resolution::notFound());
pendingTasks.append(Task { ResolveQuery(importedModuleRecord, exportEntry.importName), Type::Query });
continue;
}
case ExportEntry::Type::Namespace: {
AbstractModuleRecord* importedModuleRecord = moduleRecord->hostResolveImportedModule(globalObject, exportEntry.moduleName);
RETURN_IF_EXCEPTION(scope, Resolution::error());
Resolution resolution { Resolution::Type::Resolved, importedModuleRecord, vm.propertyNames->starNamespacePrivateName };
// 2. A module that has resolved a module namespace binding is always cacheable.
cacheResolutionForQuery(query, resolution);
if (!mergeToCurrentTop(resolution))
return Resolution::ambiguous();
continue;
}
}
break;
}
case Type::IndirectFallback: {
Resolution resolution = frames.takeLast();
if (resolution.type == Resolution::Type::NotFound) {
// Indirect export entry does not produce any resolved binding.
// So we will investigate the stars.
bool success = resolveNonLocal(task.query);
EXCEPTION_ASSERT(!scope.exception() || !success);
if (!success)
return Resolution::error();
continue;
}
ASSERT_WITH_MESSAGE(resolution.type == Resolution::Type::Resolved, "When we see Error and Ambiguous, we immediately return from this loop. So here, only Resolved comes.");
// 3. If we don't follow any star links during the resolution, we can see all the traced nodes are cacheable.
// 4. Once we follow star links, we should not retrieve the result from the cache and should not cache the result.
if (!foundStarLinks)
cacheResolutionForQuery(query, resolution);
// If indirect export entry produces Resolved, we should merge it to the upper frame.
// And do not investigate the stars of the current module.
if (!mergeToCurrentTop(resolution))
return Resolution::ambiguous();
break;
}
case Type::GatherStars: {
Resolution resolution = frames.takeLast();
ASSERT_WITH_MESSAGE(resolution.type == Resolution::Type::Resolved || resolution.type == Resolution::Type::NotFound, "When we see Error and Ambiguous, we immediately return from this loop. So here, only Resolved and NotFound comes.");
// Merge the star resolution to the upper frame.
if (!mergeToCurrentTop(resolution))
return Resolution::ambiguous();
break;
}
}
}
ASSERT(frames.size() == 1);
// 1. The starting point is always cacheable.
if (frames[0].type == Resolution::Type::Resolved)
cacheResolutionForQuery(root, frames[0]);
return frames[0];
}
auto AbstractModuleRecord::resolveExport(JSGlobalObject* globalObject, const Identifier& exportName) -> Resolution
{
// Look up the cached resolution first before entering the resolving loop, since the loop setup takes some cost.
if (Optional<Resolution> cachedResolution = tryGetCachedResolution(exportName.impl()))
return *cachedResolution;
return resolveExportImpl(globalObject, ResolveQuery(this, exportName.impl()));
}
static void getExportedNames(JSGlobalObject* globalObject, AbstractModuleRecord* root, IdentifierSet& exportedNames)
{
VM& vm = globalObject->vm();
auto scope = DECLARE_THROW_SCOPE(vm);
HashSet<AbstractModuleRecord*> exportStarSet;
Vector<AbstractModuleRecord*, 8> pendingModules;
pendingModules.append(root);
while (!pendingModules.isEmpty()) {
AbstractModuleRecord* moduleRecord = pendingModules.takeLast();
if (exportStarSet.contains(moduleRecord))
continue;
exportStarSet.add(moduleRecord);
for (const auto& pair : moduleRecord->exportEntries()) {
const AbstractModuleRecord::ExportEntry& exportEntry = pair.value;
if (moduleRecord == root || vm.propertyNames->defaultKeyword != exportEntry.exportName)
exportedNames.add(exportEntry.exportName.impl());
}
for (const auto& starModuleName : moduleRecord->starExportEntries()) {
AbstractModuleRecord* requestedModuleRecord = moduleRecord->hostResolveImportedModule(globalObject, Identifier::fromUid(vm, starModuleName.get()));
RETURN_IF_EXCEPTION(scope, void());
pendingModules.append(requestedModuleRecord);
}
}
}
JSModuleNamespaceObject* AbstractModuleRecord::getModuleNamespace(JSGlobalObject* globalObject)
{
VM& vm = globalObject->vm();
auto scope = DECLARE_THROW_SCOPE(vm);
// http://www.ecma-international.org/ecma-262/6.0/#sec-getmodulenamespace
if (m_moduleNamespaceObject)
return m_moduleNamespaceObject.get();
IdentifierSet exportedNames;
getExportedNames(globalObject, this, exportedNames);
RETURN_IF_EXCEPTION(scope, nullptr);
Vector<std::pair<Identifier, Resolution>> resolutions;
for (auto& name : exportedNames) {
Identifier ident = Identifier::fromUid(vm, name.get());
const Resolution resolution = resolveExport(globalObject, ident);
RETURN_IF_EXCEPTION(scope, nullptr);
switch (resolution.type) {
case Resolution::Type::NotFound:
throwSyntaxError(globalObject, scope, makeString("Exported binding name '", String(name.get()), "' is not found."));
return nullptr;
case Resolution::Type::Error:
throwSyntaxError(globalObject, scope, makeString("Exported binding name 'default' cannot be resolved by star export entries."));
return nullptr;
case Resolution::Type::Ambiguous:
break;
case Resolution::Type::Resolved:
resolutions.append({ WTFMove(ident), resolution });
break;
}
}
auto* moduleNamespaceObject = JSModuleNamespaceObject::create(globalObject, globalObject->moduleNamespaceObjectStructure(), this, WTFMove(resolutions));
RETURN_IF_EXCEPTION(scope, nullptr);
// Materialize *namespace* slot with module namespace object unless the module environment is not yet materialized, in which case we'll do it in setModuleEnvironment
if (m_moduleEnvironment) {
bool putResult = false;
constexpr bool shouldThrowReadOnlyError = false;
constexpr bool ignoreReadOnlyErrors = true;
symbolTablePutTouchWatchpointSet(m_moduleEnvironment.get(), globalObject, vm.propertyNames->starNamespacePrivateName, moduleNamespaceObject, shouldThrowReadOnlyError, ignoreReadOnlyErrors, putResult);
RETURN_IF_EXCEPTION(scope, nullptr);
}
m_moduleNamespaceObject.set(vm, this, moduleNamespaceObject);
return moduleNamespaceObject;
}
void AbstractModuleRecord::setModuleEnvironment(JSGlobalObject* globalObject, JSModuleEnvironment* moduleEnvironment)
{
VM& vm = globalObject->vm();
auto scope = DECLARE_THROW_SCOPE(vm);
ASSERT(!m_moduleEnvironment);
// If module namespace object is materialized, we will materialize *namespace* slot too.
if (m_moduleNamespaceObject) {
bool putResult = false;
constexpr bool shouldThrowReadOnlyError = false;
constexpr bool ignoreReadOnlyErrors = true;
symbolTablePutTouchWatchpointSet(moduleEnvironment, globalObject, vm.propertyNames->starNamespacePrivateName, m_moduleNamespaceObject.get(), shouldThrowReadOnlyError, ignoreReadOnlyErrors, putResult);
RETURN_IF_EXCEPTION(scope, void());
}
m_moduleEnvironment.set(vm, this, moduleEnvironment);
}
void AbstractModuleRecord::link(JSGlobalObject* globalObject, JSValue scriptFetcher)
{
VM& vm = globalObject->vm();
if (auto* jsModuleRecord = jsDynamicCast<JSModuleRecord*>(vm, this))
return jsModuleRecord->link(globalObject, scriptFetcher);
#if ENABLE(WEBASSEMBLY)
if (auto* wasmModuleRecord = jsDynamicCast<WebAssemblyModuleRecord*>(vm, this))
return wasmModuleRecord->link(globalObject, scriptFetcher, nullptr, Wasm::CreationMode::FromModuleLoader);
#endif
RELEASE_ASSERT_NOT_REACHED();
}
JS_EXPORT_PRIVATE JSValue AbstractModuleRecord::evaluate(JSGlobalObject* globalObject)
{
VM& vm = globalObject->vm();
if (auto* jsModuleRecord = jsDynamicCast<JSModuleRecord*>(vm, this))
return jsModuleRecord->evaluate(globalObject);
#if ENABLE(WEBASSEMBLY)
if (auto* wasmModuleRecord = jsDynamicCast<WebAssemblyModuleRecord*>(vm, this))
return wasmModuleRecord->evaluate(globalObject);
#endif
RELEASE_ASSERT_NOT_REACHED();
return jsUndefined();
}
static String printableName(const RefPtr<UniquedStringImpl>& uid)
{
if (uid->isSymbol())
return uid.get();
return WTF::makeString("'", String(uid.get()), "'");
}
static String printableName(const Identifier& ident)
{
return printableName(ident.impl());
}
void AbstractModuleRecord::dump()
{
dataLog("\nAnalyzing ModuleRecord key(", printableName(m_moduleKey), ")\n");
dataLog(" Dependencies: ", m_requestedModules.size(), " modules\n");
for (const auto& moduleName : m_requestedModules)
dataLog(" module(", printableName(moduleName), ")\n");
dataLog(" Import: ", m_importEntries.size(), " entries\n");
for (const auto& pair : m_importEntries) {
const ImportEntry& importEntry = pair.value;
dataLog(" import(", printableName(importEntry.importName), "), local(", printableName(importEntry.localName), "), module(", printableName(importEntry.moduleRequest), ")\n");
}
dataLog(" Export: ", m_exportEntries.size(), " entries\n");
for (const auto& pair : m_exportEntries) {
const ExportEntry& exportEntry = pair.value;
switch (exportEntry.type) {
case ExportEntry::Type::Local:
dataLog(" [Local] ", "export(", printableName(exportEntry.exportName), "), local(", printableName(exportEntry.localName), ")\n");
break;
case ExportEntry::Type::Indirect:
dataLog(" [Indirect] ", "export(", printableName(exportEntry.exportName), "), import(", printableName(exportEntry.importName), "), module(", printableName(exportEntry.moduleName), ")\n");
break;
case ExportEntry::Type::Namespace:
dataLog(" [Namespace] ", "export(", printableName(exportEntry.exportName), "), module(", printableName(exportEntry.moduleName), ")\n");
break;
}
}
for (const auto& moduleName : m_starExportEntries)
dataLog(" [Star] module(", printableName(moduleName.get()), ")\n");
}
} // namespace JSC
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