This change turns the previously used XOR-based type checks for external
pointers into AND-based type checks. With those, the type tag is ORed
into the top bits of an external pointer when it is written, and the
type check performed on every load is done by ANDing the value with the
inverted tag. This will later allow type checking and masking off the GC
marking bits of external pointers in a single operation.
Bug: v8:10391
Change-Id: I89f2b22588b3f7467c79c7916c11f25cd9bcc82d
Cq-Include-Trybots: luci.v8.try:v8_linux64_heap_sandbox_dbg_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2850639
Commit-Queue: Samuel Groß <saelo@google.com>
Reviewed-by: Georg Neis <neis@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74464}
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