[kernel] Short-circut 'computeNonNull' when already nonNullable
When compiling "compile.dart" the type given to computeNonNull
is already non-nullable in ~42% of the cases, meaning it spends
time not doing anything.
Change-Id: I94598efceb3b46f0ac81ec36814c216d01a9e38b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/298823
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Jens Johansen <jensj@google.com>
diff --git a/pkg/front_end/test/spell_checking_list_code.txt b/pkg/front_end/test/spell_checking_list_code.txt
index 77689cf..98a588b 100644
--- a/pkg/front_end/test/spell_checking_list_code.txt
+++ b/pkg/front_end/test/spell_checking_list_code.txt
@@ -211,6 +211,7 @@
chloestefantsova
chunks
ci
+circuit
circuited
ck
cl
@@ -1485,6 +1486,7 @@
subscription
subsection
subsections
+subsequently
subspace
subspaces
subst
diff --git a/pkg/kernel/lib/src/non_null.dart b/pkg/kernel/lib/src/non_null.dart
index f03c436..d59e40e 100644
--- a/pkg/kernel/lib/src/non_null.dart
+++ b/pkg/kernel/lib/src/non_null.dart
@@ -7,6 +7,16 @@
/// Returns the type defined as `NonNull(type)` in the nnbd specification.
DartType computeNonNull(DartType type) {
+ if (type.nullability == Nullability.nonNullable) {
+ // The visitor below always returns null when the input type is already
+ // nullable, subsequently returning the input type.
+ // When compiling "compile.dart" this is exactly what happens ~42% of the
+ // time. Here we short-circuit the visit.
+ // Note that some use [declaredNullability] instead of [nullability], but
+ // that [nullability] is only nonNullable if [declaredNullability] is too.
+ assert(type.accept(const _NonNullVisitor()) == null);
+ return type;
+ }
return type.accept(const _NonNullVisitor()) ?? type;
}
