[Bug tree-optimization/78071] New: -Os -ffast-math generates pow() for 1/(x*x)

[colanderman at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78071

            Bug ID: 78071
           Summary: -Os -ffast-math generates pow() for 1/(x*x)
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: colanderman at gmail dot com
  Target Milestone: ---

Created attachment 39865
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39865&action=edit
source code

The expression 1/(x*x) (where x is a double or float), when compiled with "-Os
-ffast-math" on Intel (e.g. -march=core2), is compiled as a call to pow() or
powf().  "-Os" and "-O3 -ffast-math" work as expected (generate a div + mul).