[PATCH] D92689: [scudo][standalone] Small changes to the fastpath

[Kostya Kortchinsky via Phabricator via llvm-commits]

cryptoad created this revision.
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There are a few things that I wanted to reorganize for a while:

- the loop that incrementally goes through classes on failure looked horrible in assembly, mostly because of `LIKELY`/`UNLIKELY` within the loop. So remove those, we are already in an unlikely scenario
- hooks are not used by default on Android/Fuchsia/etc so mark the tests for the existence of the weak functions as unlikely
- mark of couple of conditions as likely/unlikely
- in `reallocate`, the old size was computed again while we already have it in a variable. So just use the one we have.
- remove the bitwise AND trick and use a logical AND, that has one less test by using a purposeful underflow when `Size` is 0 (I actually looked at the assembly of the previous code to steal that trick)
- move the read of the options closer to where they are used, mark them as `const`

Overall this makes things a tiny bit faster, but cleaner.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D92689

Files:
  compiler-rt/lib/scudo/standalone/combined.h

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