Introduce a helper library to trim components based on what we believe
it is needed for modular bytecode compilation. The script is configured
to accept a set of entry points, so unreachable libraries can be removed
entirely. The contents of the retained libraries is trimmed to remove
method bodies, constructor bodies, and initializers, except for where
they may be needed.
In the near future, this should be expanded to:
* include proper unit testing in the CFE
* review whether additional trimming operations can be made
* consider an explicit representation of trimmed content, to help the
CFE recover when assumptions are not met (e.g. sentinel markers
to establish whether a value has been trimmed)
* CFE produces trimmed data directly if needed, without having to first
produce the full dill.
Tests that specifically stress that we don't over-trim include:
apply_mixin (requires preserving method bodies), const_body (requires
preserving initializers).
TEST=existing and new e2e dynamic module aot tests.
b/394936876
Change-Id: I26db8385bdfe1664b2aea234ec8bb896c7c21230
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/418702
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Sigmund Cherem <sigmund@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Sigmund Cherem
44f8e21c82