[clang] [llvm] [ADT][NFC] Simplify SmallSet (PR #109412)

[Nikita Popov via cfe-commits]

nikic wrote:

Okay, I tried a few things, and can reproduce the regression just by using std::find inside vfind: https://github.com/llvm/llvm-project/commit/21f98691f6e7d8664c094bd4218a508432ab2d23

My best guess at the cause would be the forced unroll in: https://github.com/gcc-mirror/gcc/blob/819098dc71f2079aedc15a904ab5f17f0788d991/libstdc%2B%2B-v3/include/bits/stl_algobase.h#L2107 These finds works on small numbers of iterations (often just up to 4), so probably that forced unroll is not profitable.

It may make sense to restore vfind with a comment on why it's there.

https://github.com/llvm/llvm-project/pull/109412