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-rw-r--r--js/src/frontend/NameFunctions.cpp485
1 files changed, 485 insertions, 0 deletions
diff --git a/js/src/frontend/NameFunctions.cpp b/js/src/frontend/NameFunctions.cpp
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "frontend/NameFunctions.h"
+
+#include "mozilla/MemoryChecking.h"
+#include "mozilla/ScopeExit.h"
+#include "mozilla/Sprintf.h"
+
+#include "frontend/BytecodeCompiler.h"
+#include "frontend/ParseNode.h"
+#include "frontend/ParseNodeVisitor.h"
+#include "frontend/ParserAtom.h"
+#include "frontend/SharedContext.h"
+#include "util/Poison.h"
+#include "util/StringBuffer.h"
+#include "vm/JSFunction.h"
+
+using namespace js;
+using namespace js::frontend;
+
+namespace {
+
+class NameResolver : public ParseNodeVisitor<NameResolver> {
+ using Base = ParseNodeVisitor;
+
+ static const size_t MaxParents = 100;
+
+ ParserAtomsTable& parserAtoms_;
+ const ParserAtom* prefix_;
+
+ // Number of nodes in the parents array.
+ size_t nparents_;
+
+ // Stack of ParseNodes from the root to the current node.
+ // Only elements 0..nparents_ are initialized.
+ MOZ_INIT_OUTSIDE_CTOR
+ ParseNode* parents_[MaxParents];
+
+ // When naming a function, the buffer where the name is built.
+ // When we are not under resolveFun, buf_ is empty.
+ StringBuffer buf_;
+
+ /* Test whether a ParseNode represents a function invocation */
+ bool isCall(ParseNode* pn) {
+ return pn && pn->isKind(ParseNodeKind::CallExpr);
+ }
+
+ /*
+ * Append a reference to a property named |name| to |buf_|. If |name| is
+ * a proper identifier name, then we append '.name'; otherwise, we
+ * append '["name"]'.
+ *
+ * Note that we need the IsIdentifier check for atoms from both
+ * ParseNodeKind::Name nodes and ParseNodeKind::String nodes:
+ * given code like a["b c"], the front end will produce a ParseNodeKind::Dot
+ * with a ParseNodeKind::Name child whose name contains spaces.
+ */
+ bool appendPropertyReference(const ParserAtom* name) {
+ if (IsIdentifier(name)) {
+ return buf_.append('.') && buf_.append(name);
+ }
+
+ /* Quote the string as needed. */
+ UniqueChars source = QuoteString(cx_, name, '"');
+ return source && buf_.append('[') &&
+ buf_.append(source.get(), strlen(source.get())) && buf_.append(']');
+ }
+
+ /* Append a number to buf_. */
+ bool appendNumber(double n) {
+ char number[30];
+ int digits = SprintfLiteral(number, "%g", n);
+ return buf_.append(number, digits);
+ }
+
+ // Append "[<n>]" to buf_, referencing a property named by a numeric literal.
+ bool appendNumericPropertyReference(double n) {
+ return buf_.append("[") && appendNumber(n) && buf_.append(']');
+ }
+
+ /*
+ * Walk over the given ParseNode, attempting to convert it to a stringified
+ * name that respresents where the function is being assigned to.
+ *
+ * |*foundName| is set to true if a name is found for the expression.
+ */
+ bool nameExpression(ParseNode* n, bool* foundName) {
+ switch (n->getKind()) {
+ case ParseNodeKind::DotExpr: {
+ PropertyAccess* prop = &n->as<PropertyAccess>();
+ if (!nameExpression(&prop->expression(), foundName)) {
+ return false;
+ }
+ if (!*foundName) {
+ return true;
+ }
+ return appendPropertyReference(prop->right()->as<NameNode>().atom());
+ }
+
+ case ParseNodeKind::Name:
+ case ParseNodeKind::PrivateName:
+ *foundName = true;
+ return buf_.append(n->as<NameNode>().atom());
+
+ case ParseNodeKind::ThisExpr:
+ *foundName = true;
+ return buf_.append("this");
+
+ case ParseNodeKind::ElemExpr: {
+ PropertyByValue* elem = &n->as<PropertyByValue>();
+ if (!nameExpression(&elem->expression(), foundName)) {
+ return false;
+ }
+ if (!*foundName) {
+ return true;
+ }
+ if (!buf_.append('[') || !nameExpression(elem->right(), foundName)) {
+ return false;
+ }
+ if (!*foundName) {
+ return true;
+ }
+ return buf_.append(']');
+ }
+
+ case ParseNodeKind::NumberExpr:
+ *foundName = true;
+ return appendNumber(n->as<NumericLiteral>().value());
+
+ default:
+ // We're confused as to what to call this function.
+ *foundName = false;
+ return true;
+ }
+ }
+
+ /*
+ * When naming an anonymous function, the process works loosely by walking
+ * up the AST and then translating that to a string. The stringification
+ * happens from some far-up assignment and then going back down the parse
+ * tree to the function definition point.
+ *
+ * This function will walk up the parse tree, gathering relevant nodes used
+ * for naming, and return the assignment node if there is one. The provided
+ * array and size will be filled in, and the returned node could be nullptr
+ * if no assignment is found. The first element of the array will be the
+ * innermost node relevant to naming, and the last element will be the
+ * outermost node.
+ */
+ ParseNode* gatherNameable(ParseNode** nameable, size_t* size) {
+ MOZ_ASSERT(nparents_ > 0);
+ MOZ_ASSERT(parents_[nparents_ - 1]->is<FunctionNode>());
+
+ *size = 0;
+
+ for (int pos = nparents_ - 2; pos >= 0; pos--) {
+ ParseNode* cur = parents_[pos];
+ if (cur->is<AssignmentNode>()) {
+ return cur;
+ }
+
+ switch (cur->getKind()) {
+ case ParseNodeKind::PrivateName:
+ case ParseNodeKind::Name:
+ return cur; // found the initialized declaration
+ case ParseNodeKind::ThisExpr:
+ return cur; // setting a property of 'this'
+ case ParseNodeKind::Function:
+ return nullptr; // won't find an assignment or declaration
+
+ case ParseNodeKind::ReturnStmt:
+ // Normally the relevant parent of a node is its direct parent, but
+ // sometimes with code like:
+ //
+ // var foo = (function() { return function() {}; })();
+ //
+ // the outer function is just a helper to create a scope for the
+ // returned function. Hence the name of the returned function should
+ // actually be 'foo'. This loop sees if the current node is a
+ // ParseNodeKind::Return, and if there is a direct function
+ // call we skip to that.
+ for (int tmp = pos - 1; tmp > 0; tmp--) {
+ if (isDirectCall(tmp, cur)) {
+ pos = tmp;
+ break;
+ }
+ if (isCall(cur)) {
+ // Don't skip too high in the tree.
+ break;
+ }
+ cur = parents_[tmp];
+ }
+ break;
+
+ case ParseNodeKind::PropertyDefinition:
+ case ParseNodeKind::Shorthand:
+ // Record the ParseNodeKind::PropertyDefinition/Shorthand but skip the
+ // ParseNodeKind::Object so we're not flagged as a contributor.
+ pos--;
+ [[fallthrough]];
+
+ default:
+ // Save any other nodes we encounter on the way up.
+ MOZ_ASSERT(*size < MaxParents);
+ nameable[(*size)++] = cur;
+ break;
+ }
+ }
+
+ return nullptr;
+ }
+
+ /*
+ * Resolve the name of a function. If the function already has a name
+ * listed, then it is skipped. Otherwise an intelligent name is guessed to
+ * assign to the function's displayAtom field.
+ */
+ MOZ_MUST_USE bool resolveFun(FunctionNode* funNode,
+ const ParserAtom** retId) {
+ MOZ_ASSERT(funNode != nullptr);
+
+ FunctionBox* funbox = funNode->funbox();
+
+ MOZ_ASSERT(buf_.empty());
+ auto resetBuf = mozilla::MakeScopeExit([&] { buf_.clear(); });
+
+ *retId = nullptr;
+
+ // If the function already has a name, use that.
+ if (funbox->displayAtom()) {
+ if (!prefix_) {
+ *retId = funbox->displayAtom();
+ return true;
+ }
+ if (!buf_.append(prefix_) || !buf_.append('/') ||
+ !buf_.append(funbox->displayAtom())) {
+ return false;
+ }
+ *retId = buf_.finishParserAtom(parserAtoms_);
+ return !!*retId;
+ }
+
+ // If a prefix is specified, then it is a form of namespace.
+ if (prefix_) {
+ if (!buf_.append(prefix_) || !buf_.append('/')) {
+ return false;
+ }
+ }
+
+ // Gather all nodes relevant to naming.
+ ParseNode* toName[MaxParents];
+ size_t size;
+ ParseNode* assignment = gatherNameable(toName, &size);
+
+ // If the function is assigned to something, then that is very relevant.
+ if (assignment) {
+ if (assignment->is<AssignmentNode>()) {
+ assignment = assignment->as<AssignmentNode>().left();
+ }
+ bool foundName = false;
+ if (!nameExpression(assignment, &foundName)) {
+ return false;
+ }
+ if (!foundName) {
+ return true;
+ }
+ }
+
+ // Other than the actual assignment, other relevant nodes to naming are
+ // those in object initializers and then particular nodes marking a
+ // contribution.
+ for (int pos = size - 1; pos >= 0; pos--) {
+ ParseNode* node = toName[pos];
+
+ if (node->isKind(ParseNodeKind::PropertyDefinition) ||
+ node->isKind(ParseNodeKind::Shorthand)) {
+ ParseNode* left = node->as<BinaryNode>().left();
+ if (left->isKind(ParseNodeKind::ObjectPropertyName) ||
+ left->isKind(ParseNodeKind::StringExpr)) {
+ if (!appendPropertyReference(left->as<NameNode>().atom())) {
+ return false;
+ }
+ } else if (left->isKind(ParseNodeKind::NumberExpr)) {
+ if (!appendNumericPropertyReference(
+ left->as<NumericLiteral>().value())) {
+ return false;
+ }
+ } else {
+ MOZ_ASSERT(left->isKind(ParseNodeKind::ComputedName) ||
+ left->isKind(ParseNodeKind::BigIntExpr));
+ }
+ } else {
+ // Don't have consecutive '<' characters, and also don't start
+ // with a '<' character.
+ if (!buf_.empty() && buf_.getChar(buf_.length() - 1) != '<' &&
+ !buf_.append('<')) {
+ return false;
+ }
+ }
+ }
+
+ // functions which are "genuinely anonymous" but are contained in some
+ // other namespace are rather considered as "contributing" to the outer
+ // function, so give them a contribution symbol here.
+ if (!buf_.empty() && buf_.getChar(buf_.length() - 1) == '/' &&
+ !buf_.append('<')) {
+ return false;
+ }
+
+ if (buf_.empty()) {
+ return true;
+ }
+
+ *retId = buf_.finishParserAtom(parserAtoms_);
+ if (!*retId) {
+ return false;
+ }
+
+ // Skip assigning the guessed name if the function has a (dynamically)
+ // computed inferred name.
+ if (!funNode->isDirectRHSAnonFunction()) {
+ funbox->setGuessedAtom(*retId);
+ }
+ return true;
+ }
+
+ /*
+ * Tests whether parents_[pos] is a function call whose callee is cur.
+ * This is the case for functions which do things like simply create a scope
+ * for new variables and then return an anonymous function using this scope.
+ */
+ bool isDirectCall(int pos, ParseNode* cur) {
+ return pos >= 0 && isCall(parents_[pos]) &&
+ parents_[pos]->as<BinaryNode>().left() == cur;
+ }
+
+ public:
+ MOZ_MUST_USE bool visitFunction(FunctionNode* pn) {
+ const ParserAtom* savedPrefix = prefix_;
+ const ParserAtom* newPrefix = nullptr;
+ if (!resolveFun(pn, &newPrefix)) {
+ return false;
+ }
+
+ // If a function looks like (function(){})() where the parent node
+ // of the definition of the function is a call, then it shouldn't
+ // contribute anything to the namespace, so don't bother updating
+ // the prefix to whatever was returned.
+ if (!isDirectCall(nparents_ - 2, pn)) {
+ prefix_ = newPrefix;
+ }
+
+ bool ok = Base::visitFunction(pn);
+
+ prefix_ = savedPrefix;
+ return ok;
+ }
+
+ // Skip this type of node. It never contains functions.
+ MOZ_MUST_USE bool visitCallSiteObj(CallSiteNode* callSite) {
+ // This node only contains internal strings or undefined and an array -- no
+ // user-controlled expressions.
+ return true;
+ }
+
+ // Skip walking the list of string parts, which never contains functions.
+ MOZ_MUST_USE bool visitTaggedTemplateExpr(BinaryNode* taggedTemplate) {
+ ParseNode* tag = taggedTemplate->left();
+
+ // The leading expression, e.g. |tag| in |tag`foo`|,
+ // that might contain functions.
+ if (!visit(tag)) {
+ return false;
+ }
+
+ // The callsite object node is first. This node only contains
+ // internal strings or undefined and an array -- no user-controlled
+ // expressions.
+ CallSiteNode* element =
+ &taggedTemplate->right()->as<ListNode>().head()->as<CallSiteNode>();
+#ifdef DEBUG
+ {
+ ListNode* rawNodes = &element->head()->as<ListNode>();
+ MOZ_ASSERT(rawNodes->isKind(ParseNodeKind::ArrayExpr));
+ for (ParseNode* raw : rawNodes->contents()) {
+ MOZ_ASSERT(raw->isKind(ParseNodeKind::TemplateStringExpr));
+ }
+ for (ParseNode* cooked : element->contentsFrom(rawNodes->pn_next)) {
+ MOZ_ASSERT(cooked->isKind(ParseNodeKind::TemplateStringExpr) ||
+ cooked->isKind(ParseNodeKind::RawUndefinedExpr));
+ }
+ }
+#endif
+
+ // Next come any interpolated expressions in the tagged template.
+ ParseNode* interpolated = element->pn_next;
+ for (; interpolated; interpolated = interpolated->pn_next) {
+ if (!visit(interpolated)) {
+ return false;
+ }
+ }
+
+ return true;
+ }
+
+ private:
+ // Speed hack: this type of node can't contain functions, so skip walking it.
+ MOZ_MUST_USE bool internalVisitSpecList(ListNode* pn) {
+ // Import/export spec lists contain import/export specs containing
+ // only pairs of names. Alternatively, an export spec list may
+ // contain a single export batch specifier.
+#ifdef DEBUG
+ bool isImport = pn->isKind(ParseNodeKind::ImportSpecList);
+ ParseNode* item = pn->head();
+ if (!isImport && item && item->isKind(ParseNodeKind::ExportBatchSpecStmt)) {
+ MOZ_ASSERT(item->is<NullaryNode>());
+ } else {
+ for (ParseNode* item : pn->contents()) {
+ BinaryNode* spec = &item->as<BinaryNode>();
+ MOZ_ASSERT(spec->isKind(isImport ? ParseNodeKind::ImportSpec
+ : ParseNodeKind::ExportSpec));
+ MOZ_ASSERT(spec->left()->isKind(ParseNodeKind::Name));
+ MOZ_ASSERT(spec->right()->isKind(ParseNodeKind::Name));
+ }
+ }
+#endif
+ return true;
+ }
+
+ public:
+ MOZ_MUST_USE bool visitImportSpecList(ListNode* pn) {
+ return internalVisitSpecList(pn);
+ }
+
+ MOZ_MUST_USE bool visitExportSpecList(ListNode* pn) {
+ return internalVisitSpecList(pn);
+ }
+
+ explicit NameResolver(JSContext* cx, ParserAtomsTable& parserAtoms)
+ : ParseNodeVisitor(cx),
+ parserAtoms_(parserAtoms),
+ prefix_(nullptr),
+ nparents_(0),
+ buf_(cx) {}
+
+ /*
+ * Resolve names for all anonymous functions in the given ParseNode tree.
+ */
+ MOZ_MUST_USE bool visit(ParseNode* pn) {
+ // Push pn to the parse node stack.
+ if (nparents_ >= MaxParents) {
+ // Silently skip very deeply nested functions.
+ return true;
+ }
+ auto initialParents = nparents_;
+ parents_[initialParents] = pn;
+ nparents_++;
+
+ bool ok = Base::visit(pn);
+
+ // Pop pn from the parse node stack.
+ nparents_--;
+ MOZ_ASSERT(initialParents == nparents_, "nparents imbalance detected");
+ MOZ_ASSERT(parents_[initialParents] == pn,
+ "pushed child shouldn't change underneath us");
+ AlwaysPoison(&parents_[initialParents], JS_OOB_PARSE_NODE_PATTERN,
+ sizeof(parents_[initialParents]), MemCheckKind::MakeUndefined);
+
+ return ok;
+ }
+};
+
+} /* anonymous namespace */
+
+bool frontend::NameFunctions(JSContext* cx, ParserAtomsTable& parserAtoms,
+ ParseNode* pn) {
+ AutoTraceLog traceLog(TraceLoggerForCurrentThread(cx),
+ TraceLogger_BytecodeNameFunctions);
+ NameResolver nr(cx, parserAtoms);
+ return nr.visit(pn);
+}
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