System clock and the new Fortran 2023 standard

Fortran10 — Fri, 24 Nov 2023 07:27:15 GMT

Fortran 2023 standard talks about the issue with system_clock routine. The user was previously free to use integer of any kind for the actual argument for system_clock.

I have the following code.

I use the same integer kind for system_clock actual arguments

integer ( 8 ) :: start_count
integer ( 8 ) :: rate, stop_count

program system_clock_test implicit none integer ( 4 ), parameter :: x = 100 , y = 100, dx = 1, dy = 1 integer ( 4 ) :: steps = 100000 , step, i, j, ip, jp, im, jm integer ( 8 ) :: start_count integer ( 8 ) :: rate, stop_count real ( 8 ) :: dt = 0.01 , m = 1.0 , k = 0.5 real ( 8 ), dimension ( :, : ), allocatable :: r, c, f, cc, dc, md allocate ( r(x,y) , c(x,y), f(x,y), cc(x,y), dc(x,y), md(x,y) ) !==== call system_clock(count=start_count , count_rate=rate) !==== call random_number ( r ) c = 0.4 + 0.02*( 0.5 - r ) do step = 1, steps do concurrent ( integer :: i=1:x, j=1:y ) f(i,j) = 24.0*c(i,j)*( 1.50 - c(i,j) )**2 - & &c(i,j)**3*( 1.03 - c(i,j) ) jp = j + 1 jm = j - 1 ip = i + 1 im = i - 1 if ( im == 0 ) im = x if ( ip == ( x + 1) ) ip = 1 if ( jm == 0 ) jm = y if ( jp == ( y + 1) ) jp = 1 cc(i,j) = ( c(ip,j) + c(im,j) + c(i,jm) + c(i,jp) - & 4.0*c(i,j) ) /( dx*dy ) dc(i,j) = f(i,j) - k*cc(i,j) md(i,j) = ( dc(ip,j) + dc(im,j) + dc(i,jm) & + dc(i,jp) - 4.0*dc(i,j) ) / ( dx*dy ) c(i,j) = c(i,j) + dt*m*md(i,j) end do end do !===== call system_clock(count=stop_count) !===== print*, ' system clock time : ', real(max(stop_count - start_count , 1_8 )) /real(rate),' seconds' print*, ' kind type start_count : ', kind(start_count) print*, ' kind type stop_count : ', kind(stop_count) end program system_clock_test

and run with

C:\Users\owner\Desktop>ifx test.f90 /O1 Intel(R) Fortran Compiler for applications running on Intel(R) 64, Version 2024.0.0 Build 20231017 Copyright (C) 1985-2023 Intel Corporation. All rights reserved. Microsoft (R) Incremental Linker Version 14.32.31332.0 Copyright (C) Microsoft Corporation. All rights reserved. -out:test.exe -subsystem:console test.obj C:\Users\owner\Desktop>test system clock time : 10.40300 seconds kind type start_count : 8 kind type stop_count : 8

Next I change the integer kind for system_clock actual arguments

integer ( 8 ) :: start_count
integer ( 4 ) :: rate, stop_count

and run with

C:\Users\owner\Desktop>ifx test.f90 /O1 Intel(R) Fortran Compiler for applications running on Intel(R) 64, Version 2024.0.0 Build 20231017 Copyright (C) 1985-2023 Intel Corporation. All rights reserved. Microsoft (R) Incremental Linker Version 14.32.31332.0 Copyright (C) Microsoft Corporation. All rights reserved. -out:test.exe -subsystem:console test.obj C:\Users\owner\Desktop>test system clock time : 1.0000000E-06 seconds kind type start_count : 8 kind type stop_count : 4

As expected, there is an error.

So my question is, should not the latest Intel compiler throw the warning or error message of using different integer kinds ? Or this warning message is expected to be in the next version ?

Re:System clock and the new Fortran 2023 standard

Shiquan_Su — Mon, 04 Dec 2023 18:59:11 GMT

Hi,

I learned from the following post:

https://fortran-lang.discourse.group/t/fortran-2023-standard-and-system-clock/6861

that the Fortran 2023 does not allow mixed type in this function call (cite: "https://j3-fortran.org/doc/year/21/21-117r3.txt"). I also test the case with all variables in integer(4), and it works as everything in integer(8).

$ ifx -what test.f90

Intel(R) Fortran 23.0-1769.01

$ ./a.out

system clock time : 13.75390 seconds

kind type start_count : 4

kind type stop_count : 4

topic System clock and the new Fortran 2023 standard in Intel® Fortran Compiler

System clock and the new Fortran 2023 standard

Re:System clock and the new Fortran 2023 standard