[Bug tree-optimization/83352] Missed optimization in math expression: sqrt(sqrt(a)) == pow(a, 1/4)

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83352

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
             Target|                            |x86_64-*-* i?86-*-*
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2017-12-11
                 CC|                            |rguenth at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
We have it

  /* sqrt(sqrt(x)) -> pow(x,1/4).  */
  (simplify
   (sqrts (sqrts @0))
   (pows @0 { build_real (type, dconst_quarter ()); }))

but only for canonicalization, we then expand that as (sqrt (sqrt @0)) again.
What is it that it can be "compiled in faster way" to?