tune&fat: run-time vs. compile-time constant thresholds

[Torbjorn Granlund]

bodrato at mail.dm.unipi.it writes:

  I pushed a few changes to the MAYBE_ mechanism of lower degree toom
  functions, and to the ABOVE_THRESHOLD macro (only for GCC).
  
  The effect of the change can be measured looking at Hydra's coverage report:
  
   - before the change we had a total of 43613 branches
  http://hydra.nixos.org/build/2517272/download/1/coverage/
  
   - after it, we have 42003; we avoided 1610 branches, most of them in mpn
  http://hydra.nixos.org/build/2524214/download/1/coverage/
  
Eh, that was a very impressive reduction, an order of magnitude or two
larger that I would have anticipated!

(Should really the Hydra coverage report include the test suite?  I feel
that it just adds noise to the summary, since we certainly don't aim to
"cover" the code there.  I hope its error printing code will remain
poorly covered...)

  Let's see if there are other undesired effects. E.g. tuneup should be
  affected, but I hope it will benefit of this changes too.
  
Why would tuneup be affected?

-- 
Torbjörn