Keep primitive string storage in Utf16String and remove the UTF-8
storage path from PrimitiveString. ASCII strings still use compact
Utf16String ASCII storage, while UTF-16 becomes the only owned
representation.
Enable -Wexit-time-destructors for all in-tree library targets and
update process-lifetime library statics so they no longer register
exit-time destructors. Long-lived caches, lookup tables, singleton
registries, and generated constants now use NeverDestroyed or leaked
references where the data is intended to live until process exit.
Update LibWeb, LibLine, and the binding generators so regenerated
sources follow the same rule instead of reintroducing destructed
statics.
Similar to GC::Root<T>, make GC::RootVector<T> constructible without
explicitly passing a Heap.
This is implemented by having RootVectorBase use GC::Heap::the() for
heap-free construction.
Property lookup cache entries previously used GC::Weak<T> for shape,
prototype, and prototype_chain_validity pointers. Each GC::Weak
requires a ref-counted WeakImpl allocation and an extra indirection
on every access.
Replace these with GC::RawPtr<T> and make Executable a WeakContainer
so the GC can clear stale pointers during sweep via remove_dead_cells.
For static PropertyLookupCache instances (used throughout the runtime
for well-known property lookups), introduce StaticPropertyLookupCache
which registers itself in a global list that also gets swept.
Now that inline cache entries use GC::RawPtr instead of GC::Weak,
we can compare shape/prototype pointers directly without going
through the WeakImpl indirection. This removes one dependent load
from each IC check in GetById, PutById, GetLength, GetGlobal, and
SetGlobal handlers.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
