[Bug target/99434] std::bit_cast generates more instructions than __builtin_bit_cast and memcpy with -march=native

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99434

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
             Target|                            |x86_64
           Keywords|                            |missed-optimization, ra
          Component|tree-optimization           |target

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This is just a register allocation issue dealing with mulx and TImode.

If mulq was used instead (that is without -march=native), all of the functions
are done correctly.