The current tracer does a separate visit of the entire JS AST using metadata from the JS printer in order to generate source maps. This new strategy uses a shadow tree tracking position info to generate source map metadata while the JS AST is bring printed. This saves us an entire tree walk and the memory overhead of storing metadata to pass to the separate source map tracer.
In local invocations of Dart2JS I see a memory improvement of >100MB in the emitter phase and a small time improvement of ~4%.
Change-Id: I622e7015e2eddc7835551f970386e13019394a79
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/336760
Commit-Queue: Nate Biggs <natebiggs@google.com>
Reviewed-by: Stephen Adams <sra@google.com>
Nate Biggs
c447f0007e