[libcxx] r275114 - Don't compute modulus of hash if it is smaller than the bucket count.

[Duncan P. N. Exon Smith via cfe-commits]

> On 2016-Jul-17, at 14:09, Eric Fiselier <eric at efcs.ca> wrote:
> 
> What I'm curious about if this performance regression was cause by (1) the removal of this 2 week old optimization or (2) the implementation of "fast mod". I suspect it's because of (1).
> 

BTW, definitely from the 2 week old optimization.  I finally figured out how to look at a larger graph; if you zoom in it makes it pretty clear:
  http://llvm.org/perf/db_default/v4/nts/graph?hide_all_points=yes&moving_window_size=10&plot.0=42.1039.3&submit=Update