radix_trie: simplify trimkey functions
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Authored by dougm on Jun 23 2023, 8:34 AM.

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rGa42d8fe001b9: radix_trie: simplify trimkey functions

Summary

Replacing a branch and two shifts with a single masking operation saves 64 bytes the pair of functions lookup_le and lookup_ge.

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rG FreeBSD src repository

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dougm requested review of this revision.Jun 23 2023, 8:34 AM

dougm created this revision.

alc added inline comments.Jun 25 2023, 12:21 AM

sys/vm/vm_radix.c
187–188	I don't see the point of retaining this variable.
188	Can you revise the comment at the top of the function to more clearly explain what is being done here? "Trims the key" is not very clear.

dougm updated this revision to Diff 123735.Jun 25 2023, 3:33 AM

dougm marked 2 inline comments as done.

alc accepted this revision.Jun 25 2023, 5:48 PM

This revision is now accepted and ready to land.Jun 25 2023, 5:48 PM

Closed by commit rGa42d8fe001b9: radix_trie: simplify trimkey functions (authored by dougm). · Explain WhyJun 25 2023, 5:51 PM

This revision was automatically updated to reflect the committed changes.

dougm added a commit: rGa42d8fe001b9: radix_trie: simplify trimkey functions.

Herald added a subscriber: imp. · View Herald TranscriptJun 25 2023, 5:51 PM

I'm surprised this is needed, you'd hope the compiler could do this transformation. Maybe worth filling a LLVM bug report?

Revision Contents
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Size

sys/

kern/

subr_pctrie.c

11 lines

vm/

vm_radix.c

11 lines

Diff 123744

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sys/kern/subr_pctrie.c