Late fields start out holding a sentinel value and after they are initialized or assigned, never hold a sentinel value again.
This CL implements some removal of checks and loads based on this monotonic behaviour.
On two large Dart Angular apps, this reduces the number of late-instance-field checks by ~25%.
One app is 0.44% smaller, the other is 0.98% smaller.
The optimization_test.dart no longer forces `--disable-inlining` because that prevents the inlining that exposes the optimization opportunities.
Most tests already use `@pragma('dart2js:noInline')` to prevent inlining where relevant.
Change-Id: I2327a96e69191313ed6c07eabe94aa2962fb2648
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/246881
Reviewed-by: Joshua Litt <joshualitt@google.com>
Commit-Queue: Stephen Adams <sra@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Stephen Adams
6384eceedc