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[js_runtime] Use Function.prototype.bind for convertDartClosureToJS

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Change-Id: Ib7142e894959994b296dee7ecc3aaf15feb0af66
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/316100
Reviewed-by: Mayank Patke <fishythefish@google.com>
Commit-Queue: Stephen Adams <sra@google.com>
This commit is contained in:
Stephen Adams 2023-07-26 19:39:28 +00:00 committed by Commit Queue
parent d02097bd1e
commit 0223d07de4
1 changed files with 44 additions and 7 deletions
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51
sdk/lib/_internal/js_runtime/lib/js_helper.dart
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@ -1936,7 +1936,7 @@ int getLength(var array) {
return JS('int', r'#.length', array);
}
invokeClosure(Function closure, int numberOfArguments, var arg1, var arg2,
_invokeClosure(Function closure, int numberOfArguments, var arg1, var arg2,
var arg3, var arg4) {
switch (numberOfArguments) {
case 0:
@ -1955,12 +1955,52 @@ invokeClosure(Function closure, int numberOfArguments, var arg1, var arg2,
/// Called by generated code to convert a Dart closure to a JS
/// closure when the Dart closure is passed to the DOM.
convertDartClosureToJS(closure, int arity) {
convertDartClosureToJS(Object? closure, int arity) {
if (closure == null) return null;
var function = JS('var', r'#.$identity', closure);
if (JS('bool', r'!!#', function)) return function;
function = convertDartClosureToJSUncached(closure, arity);
JS('void', r'#.$identity = #', closure, function);
return function;
}
function = JS(
convertDartClosureToJSUncached(Object closure, int arity) {
// dart2js closures are objects with a separate JavaScript method 'entry
// point' per arity, `call$1`, `call$2` etc. The entry points have no optional
// parameters so additional arguments at the call site will be ignored. This
// lets us simply use `Function.prototype.bind` to pass the closed values that
// are stored in the closure class object.
Object? entry;
switch (arity) {
case 0:
entry = JS('', '#[#]', closure, JS_GET_NAME(JsGetName.CALL_PREFIX0));
case 1:
entry = JS('', '#[#]', closure, JS_GET_NAME(JsGetName.CALL_PREFIX1));
case 2:
entry = JS('', '#[#]', closure, JS_GET_NAME(JsGetName.CALL_PREFIX2));
case 3:
entry = JS('', '#[#]', closure, JS_GET_NAME(JsGetName.CALL_PREFIX3));
case 4:
entry = JS('', '#[#]', closure, JS_GET_NAME(JsGetName.CALL_PREFIX4));
}
if (entry != null) {
return JS('', '#.bind(#)', entry, closure);
}
// The above is an optimization for the following technique.
//
// If the entry is missing (or the above fast path is removed) the wrapped
// closure is a JavaScript function that uses `_invokeClosure` to call the
// Dart closure. In addition to providing a default wrapping implementation,
// the following code causes both `closure` and `_invokeClosure` to
// escape. Escaping both ensures the compiler should connect the escaping
// `closure` with the call sites in `_invokeClosure`, preventing the entry
// points of `closure` from being tree-shaken. (dart2js's current analysis is
// the code enqueuer which is less precise, using only the presence of the
// call sites in `_invokeClosure` to retain the entry points).
return JS(
'var',
r'''
(function(closure, arity, invoke) {
@ -1970,10 +2010,7 @@ convertDartClosureToJS(closure, int arity) {
})(#,#,#)''',
closure,
arity,
DART_CLOSURE_TO_JS(invokeClosure));
JS('void', r'#.$identity = #', closure, function);
return function;
DART_CLOSURE_TO_JS(_invokeClosure));
}
/// Superclass for Dart closures.