.. and replace it by base::Optional<Code>. It's no longer needed, now
that Code and InstructionStream cases are merged.
This was trickier than it sounds at first, because:
- CodeLookupResult (CLR) was used during the MARK_COMPACT GC phase and
thus had to observe subtle semantics in the presence of
forwarding pointers.
- CLR implicitly contained a Code object for off_heap_trampolines
and an InstructionStream object for everything else. These implicit
behaviors threaded through elsewhere, e.g. in the
inner-pointer-to-code cache which relies on the fact that the
underlying object pointer does not move until GC completes and
the cache is flushed.
- Semantics of the dual-object {Code,InstructionStream} are generally
very subtle during GC.
This CL attempts to make all this more explicit by introducing a
GcSafeCode wrapper type which must be used in code that is affected
by semantics described above. The GcSafeCode type exposes only methods
that are safe to call during MARK_COMPACT.
Drive-by:
- Rename the Heap::GcSafeFoo function family s.t. a 'GcSafe' prefix
means that the function can be used during GC and returns
GcSafeCode objects; and 'TryFind' vs. 'Find' returns a
base::Optional<Foo> vs. just Foo.
Bug: v8:13654
Change-Id: I410b5539ea1b584b823bce2dafd8d1328eedc039
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4203385
Auto-Submit: Jakob Linke <jgruber@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Jakob Linke <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85562}
3ebbb651e2