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x86: simplify ceil(log2(x)) function
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Authored by dougm on Jun 4 2024, 5:10 PM.
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Details

Summary

A function called mask_width in one place and log2 in the other calculates its value in a more complex way than necessary. A simpler implementation offered here saves a few bytes in the functions that call it. 128 bytes in add_deterministic_cache, in particular.

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rG FreeBSD src repository
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dougm requested review of this revision.Jun 4 2024, 5:10 PM

Looks good to me.
A bit ashamed that I could not figure that fls(x - 1) does the job if zero is handled as a special case.

This revision is now accepted and ready to land.Jun 4 2024, 5:30 PM
alc added inline comments.
sys/amd64/vmm/x86.c
63–64

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