}
-bool Expression::IsUndefinedLiteral() {
- return AsLiteral() != NULL && AsLiteral()->value()->IsUndefined();
+bool Expression::IsUndefinedLiteral(Isolate* isolate) {
+ VariableProxy* var_proxy = AsVariableProxy();
+ if (var_proxy == NULL) return false;
+ Variable* var = var_proxy->var();
+ // The global identifier "undefined" is immutable. Everything
+ // else could be reassigned.
+ return var != NULL && var->location() == Variable::UNALLOCATED &&
+ var_proxy->name()->Equals(isolate->heap()->undefined_string());
}
static bool MatchLiteralCompareUndefined(Expression* left,
Token::Value op,
Expression* right,
- Expression** expr) {
+ Expression** expr,
+ Isolate* isolate) {
if (IsVoidOfLiteral(left) && Token::IsEqualityOp(op)) {
*expr = right;
return true;
}
- if (left->IsUndefinedLiteral() && Token::IsEqualityOp(op)) {
+ if (left->IsUndefinedLiteral(isolate) && Token::IsEqualityOp(op)) {
*expr = right;
return true;
}
}
-bool CompareOperation::IsLiteralCompareUndefined(Expression** expr) {
- return MatchLiteralCompareUndefined(left_, op_, right_, expr) ||
- MatchLiteralCompareUndefined(right_, op_, left_, expr);
+bool CompareOperation::IsLiteralCompareUndefined(
+ Expression** expr, Isolate* isolate) {
+ return MatchLiteralCompareUndefined(left_, op_, right_, expr, isolate) ||
+ MatchLiteralCompareUndefined(right_, op_, left_, expr, isolate);
}
// True iff the expression is the null literal.
bool IsNullLiteral();
- // True iff the expression is the undefined literal.
- bool IsUndefinedLiteral();
+ // True if we can prove that the expression is the undefined literal.
+ bool IsUndefinedLiteral(Isolate* isolate);
// Expression type bounds
Bounds bounds() { return bounds_; }
// Match special cases.
bool IsLiteralCompareTypeof(Expression** expr, Handle<String>* check);
- bool IsLiteralCompareUndefined(Expression** expr);
+ bool IsLiteralCompareUndefined(Expression** expr, Isolate* isolate);
bool IsLiteralCompareNull(Expression** expr);
protected:
if (expr->IsLiteralCompareTypeof(&sub_expr, &check)) {
return HandleLiteralCompareTypeof(expr, sub_expr, check);
}
- if (expr->IsLiteralCompareUndefined(&sub_expr)) {
+ if (expr->IsLiteralCompareUndefined(&sub_expr, isolate())) {
return HandleLiteralCompareNil(expr, sub_expr, kUndefinedValue);
}
if (expr->IsLiteralCompareNull(&sub_expr)) {