https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79930
--- Comment #5 from Adam Hirst <adam at aphirst dot karoo.co.uk> ---
Hmm, even with -Ofast, I don't get any noticeable performance increase if I
change, say, TP_LEFT, to be:
type(Vect3D) pure function TP_LEFT(NU, D, NV) result(tensorproduct)
real(dp), intent(in) :: NU(4), NV(4)
type(Vect3D), intent(in) :: D(4,4)
real(dp) :: Dx(4,4), Dy(4,4), Dz(4,4)
Dx = D%x
Dy = D%y
Dz = D%z
tensorproduct%x = dot_product(matmul(NU, Dx),NV)
tensorproduct%y = dot_product(matmul(NU, Dy),NV)
tensorproduct%z = dot_product(matmul(NU, Dz),NV)
end function
Perhaps you meant to introduce the explicit temporaries at a different level,
or there's another flag I need.
It's worth maybe noting, though, that -Ofast makes the "explicit DO"
implementation EVEN faster, so I'll in the meantime definitely investigate
reintroducing -Ofast to my real codebase.
