Goals of this CL, a followup to 2f63acea22:
* Ensure that X::New() depends on the initialization guarantees of
Object::Allocate<X>(...):
* Ptr fields are guaranteed to be initialized to Object::null().
* Non-Ptr fields are guaranteed to be zero-initialized.
In cases where the only uses of the allocated object before return
was to perform unnecessary field assignments, X::New() just simply
returns the result of Object::Allocate<X>(...).
Otherwise, the old now-unnecessary assignments have been changed
into ASSERTs so that they will be checked in DEBUG mode.
* Ensure that NoSafepointScopes are entered in X::New() only when
necessary (e.g., to ensure fields used to calculate to(...)
are properly set before being seen by pointer visitors as the GC
may run when outside a NoSafepointScope).
In particular, the often occurring pattern:
auto& result = X::Handle();
{
auto raw = Object::Allocate<X>(...);
NoSafepointScope no_safepoint;
result = raw;
}
...
has been replaced with:
const auto& result = X::Handle(Object::Allocate<X>(...));
* If a handle was allocated, the only uses of that handle before
returning must be performed under a NoSafepointScope, and the same
operations can be done directly on the object pointer, then do so
and remove the unnecessary handle allocation.
Notable changes outside the above:
* Swapped ObjectPool::EntryType::{kImmediate,kTaggedObject} so that
kImmediate has value 0, since Object::Allocate<ObjectPool>(len)
zero-initializes the payload and without this change,
ObjectPool::New() must set the entry types manually.
* Removed the old static ArrayPtr cached_array_ field on
SubtypeTestCache as well as SubtypeTestCache::{Init,Cleanup} and
instead added Object::empty_subtype_test_cache_array().
* Removed the no-arg Closure::New() method, which is never used.
* Inlined the no-arg Script::New() method into its only caller,
one of the other Script::New() overloads.
TEST=ci
Issue: https://github.com/dart-lang/sdk/issues/52876
Change-Id: I079b4c9f73c7d2c0146c30cf2cd570b91a1ecf36
Cq-Include-Trybots: luci.dart.try:vm-linux-debug-x64-try,vm-linux-debug-x64c-try,vm-linux-release-x64-try,vm-aot-linux-product-x64-try,vm-aot-linux-release-x64-try,vm-aot-linux-debug-x64-try,vm-ffi-qemu-linux-release-riscv64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/313120
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Tess Strickland <sstrickl@google.com>
Tess Strickland
86d1261dff