topic Re: Warning 406: In call to FUNCTION, an array temporary was created for argument #n in Intel® Fortran Compiler

Warning 406: In call to FUNCTION, an array temporary was created for argument #n

tidges — Thu, 19 May 2022 05:58:12 GMT

I'm getting this warning from my code, and I think I understand generally what it means (a temporary array is created because the one provided is not contiguous in memory), but I'm confused because I thought all of my array slices were already contiguous, as they're of the form (n:m,j).

The function is (approximately) as follows:

function schrodStep(EJ0, EJ1, EJ2, psi, B) !Calculate the 9-level Schrodinger eqn real(RK), intent(in) :: EJ0, EJ1, EJ2 real(RK), dimension(nPhis_overall, 3), intent(in) :: B real(RK), dimension(nPhis_overall) :: Bx, By, Bz complex(RK), dimension(nPhis_overall, nStates), intent(in) :: psi complex(RK), dimension(nPhis_overall, nStates) :: schrodStep complex(RK), dimension(nPhis_overall) :: psiJ0m0, psiJ1mn1, psiJ1m0, psiJ1m1, psiJ2mn2, psiJ2mn1, psiJ2m0, psiJ2m1, psiJ2m2 Bx = B(1:nPhis_overall, 1) By = B(1:nPhis_overall, 2) Bz = B(1:nPhis_overall, 3) psiJ0m0 = psi(1:nPhis_overall, 1) !and so on, until psiJ2m2 = psi(1:nPhis_overall, 9) schrodStep(1:nPhis_overall, 1) = (xi*psiJ1mn1*(Bx-ci*By)/SQRT(3.0_RK) - xi*psiJ1m1*(Bx+ci*By)/SQRT(3.0_RK) & + SQRT(2.0_RK/3.0_RK)*xi*psiJ1m0*Bz + psiJ0m0*EJ0)*-ci/hbar !And similar lines for the other 8 levels end function

I get the warning for both array arguments (psi and B). This is the core function of a numerical integration, so if it's causing any inefficiency it would be a big deal.

Thanks

Re: Warning 406: In call to FUNCTION, an array temporary was created for argument #n

IanH — Thu, 19 May 2022 06:59:52 GMT

Which line (or lines) is the warning specifically reported for?

From what I can tell, there are no non-intrinsic function references within the code that you show.... is the warning being reported against references to schrodStep? If so, please show the declarations for the actual arguments in the function reference and the source of the reference itself.

Re: Warning 406: In call to FUNCTION, an array temporary was created for argument #n

Steve_Lionel — Thu, 19 May 2022 16:18:00 GMT

The excerpt you provided is not compilable. If you can provide (ideally as an attachment rather than inline) a source that compiles on its own, we can check to see where this warning may be coming from.

Re: Warning 406: In call to FUNCTION, an array temporary was created for argument #n

tidges — Thu, 19 May 2022 16:59:40 GMT

Sure, there's a "resultsStem" parameter which will need to be changed to a writeable directory in order to run but I think that's the only change needed. The calls to my function are lines 192-195, and that is where the warning points to.

Re: Warning 406: In call to FUNCTION, an array temporary was created for argument #n

tidges — Thu, 19 May 2022 17:38:37 GMT

I attached the full code in my reply to Steve, but I've tried to keep only the relevant lines here to make it easier to parse (though obviously it's not longer working code):

program hello use iso_fortran_env, only: int16, int32, real64 use ifport implicit none integer, parameter :: RK=real64, Ishort=int16, Ilong=int32 integer(Ilong) :: nFreqs, nPhis, nPhis_overall, expNum, parLoopInd, folStat integer(Ishort) :: init_i, nStates=9 real(RK), dimension(:), allocatable :: phis, phis_loop, phis_overall, freqs_loop, loopArr, chirpScales real(RK) :: t_max, h, t, tT, tD complex(RK), parameter :: ci=(0.0_RK,1.0_RK), c0=(0.0_RK,0.0_RK), c1=(1.0_RK,0.0_RK) complex(RK), dimension(:,:), allocatable :: psi, psi_new, k, k1, k2, k3, k4 real(RK), dimension(:,:), allocatable :: B, B_Step, B_halfStep, B_background complex(RK), dimension(:), allocatable :: psi_vec allocate(psi_vec(nStates)) psi_vec = SQRT([c0, c0, c1, c0, c0, c0, c0, c0, c0]) allocate(B_background(nPhis_overall,3)) B_background(1:nPhis_overall, 1) = 0.0_RK !Residual background B field (x,y,z) B_background(1:nPhis_overall, 2) = 0.0_RK B_background(1:nPhis_overall, 3) = 0.0_RK do parLoopInd=1,SIZE(loopArr) !Whole run loop for changing parameters allocate(psi_new(nPhis_overall,nStates), psi(nPhis_overall,nStates)) allocate(B(nPhis_overall,3), B_Step(nPhis_overall,3), B_halfStep(nPhis_overall,3)) do expNum=1,size(expTypes) !A/B experiment loop do j=1,nPhis !Phis pulse loop do i=1,nFreqs !Freqs loop !Runge-Kutta initialising t = 0.0_RK do init_i=1,nPhis_overall psi_new(init_i, 1:nStates) = psi_vec end do B_step(1:nPhis_overall, 1) = 0.0_RK B_step(1:nPhis_overall, 2) = 0.0_RK B_step(1:nPhis_overall, 3) = Bz0 do while (t.LT.t_max) !Runge-Kutta loop !z-polarised microwaves with some y component, and z-aligned DC B field. Use previous stepped value to save on calculations psi = psi_new B = B_step B_halfStep(1:nPhis_overall, 1) = 0.0_RK B_halfStep(1:nPhis_overall, 2) = getB_mw(t+h/2.0_RK)*SIND(theta_MW) B_halfStep(1:nPhis_overall, 3) = Bz0 + getB_mw(t+h/2.0_RK)*COSD(theta_MW) B_step(1:nPhis_overall, 1) = 0.0_RK B_step(1:nPhis_overall, 2) = getB_mw(t+h)*SIND(theta_MW) B_step(1:nPhis_overall, 3) = Bz0 + getB_mw(t+h)*COSD(theta_MW) k1 = schrodStep(EJ0, EJ1, EJ2, psi, B+B_background) k2 = schrodStep(EJ0, EJ1, EJ2, psi+h*k1/2.0_RK, B_halfStep+B_background) k3 = schrodStep(EJ0, EJ1, EJ2, psi+h*k2/2.0_RK, B_halfStep+B_background) k4 = schrodStep(EJ0, EJ1, EJ2, psi+h*k3, B_step+B_background) k = (k1 + 2.0_RK*k2 + 2.0_RK*k3 + k4)/6.0_RK psi_new = psi + h*k t = t+h end do !Runge-Kutta time loop end do !Freqs loop end do !Phis pulse loop deallocate(phis) end do !A/B experiment loop deallocate(B, B_halfStep, B_Step, psi, psi_new) end do !Whole run loop for changing parameters end program

and getB_mw() looks like this (nothing interesting, just returns a vector of dimension nPhis_overall because that's the dimension of the 'phis' variable in the argument of the sine at the end)

function getB_mw(t) !Gives two-pulse profile, scaled real(RK), intent(in) :: t real(RK), dimension(nPhis_overall) :: getB_mw if (expType .EQ. 'A') then amp = (TANH(t-10.0_RK)-TANH(t-tD-10.0_RK)+TANH(t-tT-10.0_RK)-TANH(t-tT-tD-10.0_RK))/2 + & 0.008_RK*powerLvl*(EXP(-(t-9.0_RK)**2.0_RK/2.0_RK))!+EXP(-(t-309.0_RK)**2.0_RK/2.0_RK)) else if (expType .EQ. 'B') then amp = (TANH(t-10.0_RK)-TANH(t-tD-10.0_RK)+TANH(t-tT-10.0_RK)-TANH(t-tT-tD-10.0_RK))/2 + & 0.008_RK*powerLvl*EXP(-(t-309.0_RK)**2.0_RK/2.0_RK) end if getB_mw = amp*SIN(2*pi*freqRF*t+phis) end function

The warning points to the Runge-Kutta lines, 49-52 in the first excerpt here.

Re: Warning 406: In call to FUNCTION, an array temporary was created for argument #n

Steve_Lionel — Thu, 19 May 2022 19:09:36 GMT

Thanks - I can reproduce this ~~and it's a bug~~. ~~The compiler is improperly calculating the shape for expressions such as B+B_Background for the purpose of the contiguity check.~~ A workaround is to declare an additional allocatable array, I called it BX and then do something like this:

BX = B+B_background; k1 = schrodStep(EJ0, EJ1, EJ2, psi, BX)

You don't have to explicitly allocate BX.

Let me see if I can come up with a minimal test case.

Re: Warning 406: In call to FUNCTION, an array temporary was created for argument #n

tidges — Thu, 19 May 2022 19:00:12 GMT

Ah I see, I made that change for both psi and B and it did indeed get rid of the warning. Thanks

Re: Warning 406: In call to FUNCTION, an array temporary was created for argument #n

Steve_Lionel — Thu, 19 May 2022 19:07:55 GMT

I have a small reproducer, but I'm uncertain that it's a bug. In reality, the compiler IS creating an array temporary to hold the expression B+B_background, and is not incorrectly calculating the shape. I might argue that this warning ought not to be issued for expressions, but maybe the programmer would like to know if any temporary copy is made. I know there are cases in I/O statements where this warning can inexplicably be generated.

Of course, this warning is only generated if you explicitly ask for /check:arg_temp_created, as that's not the default. Maybe you could just turn this off.