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[dart2js] Chain null-field initializers

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Change-Id: I1fff4143ee5698dd1c8c1c833fcb99828d1f8223
Reviewed-on: https://dart-review.googlesource.com/59860
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Stephen Adams <sra@google.com>
This commit is contained in:
Stephen Adams 2018-06-12 17:51:40 +00:00 committed by commit-bot@chromium.org
parent 83142f08c6
commit 14dfd82d69
1 changed files with 25 additions and 2 deletions
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27
pkg/compiler/lib/src/js_emitter/startup_emitter/fragment_emitter.dart
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@ -825,17 +825,40 @@ class FragmentEmitter {
thisRef = js.js('this');
}
// Chain assignments of the same value, e.g. `this.b = this.a = null`.
// Limit chain length so that the JavaScript parser has bounded recursion.
const int maxChainLength = 30;
js.Expression assignment = null;
int chainLength = 0;
bool previousIsNull = false;
void flushAssignment() {
if (assignment != null) {
statements.add(js.js.statement('#;', assignment));
assignment = null;
chainLength = 0;
previousIsNull = false;
}
}
for (Field field in cls.fields) {
if (field.nullInitializerInAllocator) {
// TODO(sra): Chain initializations, e.g. `this.b = this.a = null;`.
statements.add(js.js.statement('#.# = null', [thisRef, field.name]));
if (previousIsNull && chainLength < maxChainLength) {
assignment = js.js('#.# = #', [thisRef, field.name, assignment]);
} else {
flushAssignment();
assignment = js.js('#.# = null', [thisRef, field.name]);
}
++chainLength;
previousIsNull = true;
} else {
flushAssignment();
js.Parameter parameter = new js.Parameter('t${parameters.length}');
parameters.add(parameter);
statements.add(
js.js.statement('#.# = #', [thisRef, field.name, parameter.name]));
}
}
flushAssignment();
if (cls.hasRtiField) {
js.Parameter parameter = new js.Parameter('t${parameters.length}');