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Flow analysis: move _unmatched to _FlowAnalysisImpl.

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This will allow me to push additional pattern contexts to represent
subpatterns, while still accumulating the "unmatched" flows for the
pattern as a whole.

Bug: https://github.com/dart-lang/sdk/issues/50419
Change-Id: I8a7b1255abeda1cd07d82828057c81f45954d173
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/274941
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>
This commit is contained in:
Paul Berry 2022-12-12 20:28:29 +00:00 committed by Commit Queue
parent 2d282a65ea
commit a7907254ad
1 changed files with 17 additions and 19 deletions
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36
pkg/_fe_analyzer_shared/lib/src/flow_analysis/flow_analysis.dart
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@ -3266,6 +3266,10 @@ class _FlowAnalysisImpl<Node extends Object, Statement extends Node,
FlowModel<Type> _current = new FlowModel<Type>(Reachability.initial);
/// If a pattern is being analyzed, flow model representing all code paths
/// accumulated so far in which the pattern fails to match. Otherwise `null`.
FlowModel<Type>? _unmatched;
/// The most recently visited expression for which an [ExpressionInfo] object
/// exists, or `null` if no expression has been visited that has a
/// corresponding [ExpressionInfo] object.
@ -3396,8 +3400,7 @@ class _FlowAnalysisImpl<Node extends Object, Statement extends Node,
// This avoids some bogus "unreachable code" warnings in analyzer tests.
// TODO(paulberry): replace this with an implementation that does similar
// promotion to `==` operations.
_PatternContext<Type> context = _stack.last as _PatternContext<Type>;
context._unmatched = _join(context._unmatched, _current);
_unmatched = _join(_unmatched!, _current);
}
@override
@ -3418,10 +3421,10 @@ class _FlowAnalysisImpl<Node extends Object, Statement extends Node,
_current.tryPromoteForTypeCheck(this, scrutineeReference, staticType);
_current = promotionInfo.ifTrue;
if (!coversMatchedType) {
context._unmatched = _join(context._unmatched, promotionInfo.ifFalse);
_unmatched = _join(_unmatched!, promotionInfo.ifFalse);
}
} else if (!coversMatchedType) {
context._unmatched = _join(context._unmatched, _current);
_unmatched = _join(_unmatched!, _current);
}
}
@ -3507,6 +3510,7 @@ class _FlowAnalysisImpl<Node extends Object, Statement extends Node,
void finish() {
assert(_stack.isEmpty);
assert(_current.reachable.parent == null);
assert(_unmatched == null);
}
@override
@ -4357,9 +4361,10 @@ class _FlowAnalysisImpl<Node extends Object, Statement extends Node,
FlowModel.merge(operations, first, second, _current._emptyVariableMap);
FlowModel<Type> _popPattern(Expression? guard) {
_TopPatternContext<Type> context =
_stack.removeLast() as _TopPatternContext<Type>;
FlowModel<Type> unmatched = context._unmatched;
_FlowContext context = _stack.removeLast();
assert(context is _TopPatternContext<Type>);
FlowModel<Type> unmatched = _unmatched!;
_unmatched = null;
if (guard != null) {
ExpressionInfo<Type> guardInfo = _expressionEnd(guard);
_current = guardInfo.ifTrue;
@ -4369,8 +4374,9 @@ class _FlowAnalysisImpl<Node extends Object, Statement extends Node,
}
void _pushPattern(ReferenceWithType<Type>? scrutineeReference) {
_stack.add(new _TopPatternContext<Type>(
scrutineeReference, _current.setUnreachable()));
assert(_unmatched == null);
_unmatched = _current.setUnreachable();
_stack.add(new _TopPatternContext<Type>(scrutineeReference));
}
/// Associates [expression], which should be the most recently visited
@ -5088,10 +5094,6 @@ class _NullInfo<Type extends Object> implements ExpressionInfo<Type> {
/// Base class for [_FlowContext]s representing patterns.
abstract class _PatternContext<Type extends Object> extends _FlowContext {
/// Flow model representing all code paths accumulated so far in which the
/// pattern fails to match.
abstract FlowModel<Type> _unmatched;
/// Reference for the value being matched, if any.
ReferenceWithType<Type>? get _scrutineeReference;
}
@ -5185,15 +5187,11 @@ class _TopPatternContext<Type extends Object> extends _PatternContext<Type> {
@override
final ReferenceWithType<Type>? _scrutineeReference;
@override
FlowModel<Type> _unmatched;
_TopPatternContext(this._scrutineeReference, this._unmatched);
_TopPatternContext(this._scrutineeReference);
@override
String toString() =>
'_TopPatternContext(scrutineeReference: $_scrutineeReference, '
'unmatched: $_unmatched)';
'_TopPatternContext(scrutineeReference: $_scrutineeReference)';
}
/// Specialization of [ExpressionInfo] for the case where the information we