GMP 6.1.2 t-count_zeros failure on ARM with assertions

Torbjörn Granlund tg at
Mon Jan 1 20:37:07 UTC 2018

nisse at (Niels Möller) writes:

  tg at (Torbjörn Granlund) writes:
  > The idea with that was to allow some usages that want to pass 0 to avoid
  > a condition.  Isn't that used?
  The idea makes sense, but I couldn't find any such use. I was thinking
  that any use like that would be accompanied by an #ifdef
  COUNT_LEADING_ZEROS_0, but I found no matches when greping through the
  sources. I could be missing something, of course.
  Or maybe it should be used at some places, but currently isn't.
I assume the hardwired values were there because these expanded to fully
defined instructions.

We might define these directly, at least for arm64, to CLZ and RBIT+CLZ,
respectively, instead of using gcc's builtin semi-defined variants?

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