Fix some oddities in Aarch64 TcmallocSlab::Pop(). - #599
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We were prefetching the slab address we just loaded from, whereas what x86-64 does (and what makes sense) is to prefetch the _previous_ slab address. Also use LSL #2 instead of having a separate instruction (from outside the function) to shift the size class by 2. This was done for a brief period of time earlier, rolled back and then seemingly forgotten in the roll-forward. PiperOrigin-RevId: 974325235
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Fix some oddities in Aarch64 TcmallocSlab::Pop().
We were prefetching the slab address we just loaded from,
whereas what x86-64 does (and what makes sense) is to
prefetch the previous slab address.
Also use LSL #2 instead of having a separate instruction
(from outside the function) to shift the size class by 2.
This was done for a brief period of time earlier, rolled
back and then seemingly forgotten in the roll-forward.