https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115710
Bug ID: 115710
Summary: fortran complex abs does not vectorise
Product: gcc
Version: 14.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: mjr19 at cam dot ac.uk
Target Milestone: ---
subroutine foo(a,b,n)
complex(kind(1d0))::a(*)
real(kind(1d0))::b(*)
integer::i,n
do i=1,n
b(i)=abs(a(i))**2
end do
end subroutine foo
fails to vectorise with "gfortran-14 -mavx2 -mfma -Ofast".
I am very impressed that the **2 simply removes the sqrt, so the above code is
simpler than the code without **2 (which also doesn't vectorise, and should). I
am also impressed that
b(i)=a(i)*conjg(a(i))
and
b(i)=real(a(i))*real(a(i))+aimag(a(i))*aimag(a(i))
produce identical, vectorised, assembler. But the abs example ought to be the
same too.
