On Sun, 16 Jul 2017, Segher Boessenkool wrote:
> > How? There's no stable sort in libc and switching over to std::stable_sort
> > would be problematic.
> Why?

- you'd need to decide if the build time cost of extra 8000+ lines
  lines brought in by <algorithm> (per each TU) is acceptable;

- you'd need to decide if the code size cost of multiple instantiations
  of template stable_sort is acceptable (or take measures to unify them);

- you'd need to adapt comparators, as STL uses a different interface
  that C qsort;

- you'd need to ensure it doesn't lead to a noticeable slowdown.

(unrelated, but calls to std::stable sort cannot be intercepted by Yuri's
sortcheck, and of course my recent sortcheck-like patch entirely missed it too)

> Sure.  Some of our sorts in fact require stable sort though

At moment only bb-reorder appears to use std::stable_sort, is that what
you meant, or are there more places?


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