This change enables automatic generation of Cast<> operators for
classes that are defined in Torque.
* Cast<> macros are generated for all classes that are defined in
Torque code that are neither shapes nor marked with a new
@doNotGenerateCast annotation.
* Implicitly generated Cast macros simply call through to an
internally-defined "DownCastForTorqueClass" macro that implements
the cast using one of three strategies for efficiency. If the class
has subclasses (i.e. a range of instance types including subtypes),
the DownCastForTorqueClass checks for inclusion in the instance type
range. If the class has a single instance type (i.e. no subclasses),
then either 1) a map check is used if the class has a globally-
defined map constant or 2) an equality check for the instance type
is used.
* Added new intrinsics to introspect class information, e.g. fetching
instance type ranges for a class, accessing the globally-defined map
for a class.
* Removed a whole pile of existing explicit Cast<> operators that are
no longer needed because of the implicitly generated Cast<> macros.
* Added tests for the new Cast<> implementations.
Bug: v8:7793
Change-Id: I3aadb0c62b720e9de4e7978b9ec4f05075771b8b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2250239
Commit-Queue: Daniel Clifford <danno@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68478}
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