Alexander Markov
51d1c8923a
This is a reland of commit 88496ba1c3
Fixes on top of the original change:
* Closure layout is changed to avoid gap between fixed fields and
variable-length elements on compressed pointers architecture.
This gap was causing crashes in the GC when scanning closure
objects.
* pkg/vm_snapshot_analysis/test/instruction_sizes_test is fixed
on arm64 by decreasing threshold for detecting size changes.
Original change's description:
> [vm,dart2bytecode,modular_aot] Variable-length closure objects
>
> Extend closure objects with variable number of elements to capture.
> This is needed to support capturing multiple independent contexts
> after capturing is computed in the front-end.
>
> The following fixed Closure fields are moved into variable-length
> elements:
> - delayed type arguments;
> - instantiator type arguments;
> - function type arguments;
> - context.
>
> Number of elements and presence/indices of various type arguments
> are encoded into the new length_and_flags field in the Closure.
>
> Most closure objects don't need any of the type arguments so this
> change will reduce average Closure object size.
TEST=ci
Issue: https://github.com/dart-lang/sdk/issues/61572
Issue: https://github.com/dart-lang/sdk/issues/61635
Change-Id: I8685e632e2d0832766ecdc470f3cf9a6b880de48
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/494243
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
Reviewed-by: Slava Egorov <vegorov@google.com>
This package contains Dart bytecode compiler.
Status: experimental
NOTE: This package is currently experimental and not published or included in the SDK.
Do not take dependency on this package unless you are prepared for breaking changes and possibly removal of this code at any point in time.