[PATCH] D42357: Under limitation of allocated buffer, inplace_merge() does NOT take usage of partial allocated buffer but applies native rotate directly.

[WeiChungChang via Phabricator via cfe-commits]

WeiChungChang added a comment.

Here gives the comparison between GCC & LLVM's std c++ library.

It is shown that libc++ soon suffers from rotate speed under limited allocated buffer and slower than GCC's corresponding version.
Both LLVM & GCC run the same test program.

F5782010: 0124.png <https://reviews.llvm.org/F5782010>

|      | full | 25% | 12.5% | 6.25% | 3.125% |
| LLVM | 0.238614667  | 0.733295778 | 1.137285111   | 1.348671667   | 1.603639556    |
| GCC  | 0.368778444  | 0.351659222 | 0.532976333   | 0.660785778   | 0.832495444    |
|


Repository:
  rCXX libc++

https://reviews.llvm.org/D42357