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[parser] Avoid redundant rewriting of arrow params

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This fixed a TODO from cec289ea by marking RewritableExpressions as
rewritten in AddArrowFunctionFormalParameters when decomposing
Assignments into pattern/initializer.

Also added a set_rewritten() helper method to RewritableExpression
to simplify callsites.

Change-Id: Ifa36c9fb6c79193cbbcb168eedf7f782dc73a77b
Reviewed-on: https://chromium-review.googlesource.com/622353
Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47524}
This commit is contained in:
Adam Klein 2017-08-18 18:24:34 -07:00 committed by Commit Bot
parent c652a9eb2d
commit 35e4bcb677
3 changed files with 11 additions and 7 deletions
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5
src/ast/ast.h
View File

@ -2244,13 +2244,16 @@ class RewritableExpression final : public Expression {
public:
Expression* expression() const { return expr_; }
bool is_rewritten() const { return IsRewrittenField::decode(bit_field_); }
void set_rewritten() {
bit_field_ = IsRewrittenField::update(bit_field_, true);
}
void Rewrite(Expression* new_expression) {
DCHECK(!is_rewritten());
DCHECK_NOT_NULL(new_expression);
DCHECK(!new_expression->IsRewritableExpression());
expr_ = new_expression;
bit_field_ = IsRewrittenField::update(bit_field_, true);
set_rewritten();
}
private:

5
src/parsing/parser.cc
View File

@ -2427,6 +2427,11 @@ void Parser::AddArrowFunctionFormalParameters(
Expression* initializer = nullptr;
if (expr->IsAssignment()) {
if (expr->IsRewritableExpression()) {
// This expression was parsed as a possible destructuring assignment.
// Mark it as already-rewritten to avoid an unnecessary visit later.
expr->AsRewritableExpression()->set_rewritten();
}
Assignment* assignment = expr->AsAssignment();
DCHECK(!assignment->IsCompoundAssignment());
initializer = assignment->value();

8
src/parsing/pattern-rewriter.cc
View File

@ -299,14 +299,10 @@ void PatternRewriter::VisitRewritableExpression(RewritableExpression* node) {
DCHECK_EQ(AstNode::kArrayLiteral, node->expression()->node_type());
return Visit(node->expression());
} else if (context() != ASSIGNMENT) {
// TODO(adamk): This early return should be a DCHECK, but in some cases we
// try to rewrite the same assignment twice: https://crbug.com/756332
// DCHECK(!node->is_rewritten());
if (node->is_rewritten()) return;
// This is not a destructuring assignment. Mark the node as rewritten to
// prevent redundant rewriting and visit the underlying expression.
node->Rewrite(node->expression());
DCHECK(!node->is_rewritten());
node->set_rewritten();
return Visit(node->expression());
}