commit 27f26e51899d07beddf18ed828f1989709f32155
author Martin Kustermann <kustermann@google.com> Mon Dec 15 06:25:41 2025 -0800
committer Commit Queue <dart-scoped@luci-project-accounts.iam.gserviceaccount.com> Mon Dec 15 06:25:41 2025 -0800
tree 34727db38043f81249b794e084127bc0f6e7aa32
parent 4cd737824cf0d023881606a89927d5fce5bbde8a

[dart2wasm] Optimize initialization of dispatch table

This reduces essentials main module by 8.3% (-730 KB)

The dispatch table contains displaced selector rows. Each selector row
contains an entry for each class that provides the selector.

This can lead to very large dispatch tables with repeated elements:
Especially common is a base class with selectors that get inherited
by many subclasses where few subclasses override the selector.

This is common e.g. for `Object.{hashCode,operator==,noSuchMethod}` but
also for user defined base classes that have many subclasses.

This led to the element section being very large: It often contains
large consecutive sub-ranges which refer to the same target function.

To shrink the element size we instead move the initialization of those
large regions homogenious regions to the module init function: We can
utilize the `table.fill` instruction which can initialize a large range
of the table with the same value.

Change-Id: I9fc308969264f4855a514e7d36c761891bb0cb52
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/467843
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Ömer Ağacan <omersa@google.com>