[Bug other/86161] New: Add insn support for __builtin_isnormal and __builtin_fpclassify

[meissner at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86161

            Bug ID: 86161
           Summary: Add insn support for __builtin_isnormal and
                    __builtin_fpclassify
           Product: gcc
           Version: 9.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: meissner at gcc dot gnu.org
  Target Milestone: ---

I was tracking down a bug in PowerPC with isnormal, and I noticed we don't have
optab support for doing either the isnormal or fpclassify builtins in-line. 
Instead we generate a series of test (isnan, isinfinite, etc.) to calculate the
answer.

The PowerPC has an instruction (xststdcdp) that can simplify this operation. 
There may be other backends that could improve their code if we add the optab
support for these operations.