Fix off-by-one slab prefetch offset in x86-64 TcmallocSlab::Pop. - #672
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Fix off-by-one slab prefetch offset in x86-64 TcmallocSlab::Pop.#672copybara-service[bot] wants to merge 1 commit into
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Because current holds the pre-decrement index C (since cl/974318602 replaced dec %[current] with a memory RMW subl $0xffff0001), -16(%[scratch], %[current], 8) loads C - 2 into next. Prefetching scratch + (current - 2) * sizeof(void*) redundantly prefetches C - 2 instead of C - 3. Update x86-64 to prefetch C - 3 to match AArch64. PiperOrigin-RevId: 977988165
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Fix off-by-one slab prefetch offset in x86-64 TcmallocSlab::Pop.
Because current holds the pre-decrement index C (since cl/974318602 replaced dec %[current] with a memory RMW subl $0xffff0001), -16(%[scratch], %[current], 8) loads C - 2 into next. Prefetching scratch + (current - 2) * sizeof(void*) redundantly prefetches C - 2 instead of C - 3. Update x86-64 to prefetch C - 3 to match AArch64.