Possible bug when function used to fill an array

_xl_ — Tue, 13 Dec 2011 15:03:27 GMT

Hi,

We recently noticed a difference of comportement between gfortran and ifort with function filling an array.

Ifort crashes with segmentation fault with big arrays whereas gfortran just work.

I updated to last ifort version :

ifort (IFORT) 12.1.0 20111011

Here is an example reproducing the problem :

program toto

implicit none

real, allocatable :: tata(:)

integer(kind=8) :: length, max

length = 2**10

max = 2**(30)

do while (length .lt. max)

print *, "length", length

allocate(tata(length))

tata = titi(length)

deallocate(tata)

print *, "length", length

length = length * 2

end do

contains

function titi(length)

integer(kind=8) :: length

real, dimension(length) :: titi

titi = 1.0

end function titi

end program toto

GFortran output :

length 1024

length 2048

length 4096

length 8192

length 16384

length 32768

length 65536

length 131072

length 262144

length 524288

length 1048576

length 2097152

length 4194304

length 8388608

length 16777216

length 33554432

length 67108864

length 134217728

length 268435456

length 536870912

ifort output :

length 1024 1073741824

length 1024

length 2048

length 4096

length 8192

length 16384

length 32768

length 65536

length 131072

length 262144

length 524288

length 1048576

length 2097152

zsh: segmentation fault ./a.out

The machine is a Bi quad coreIntel Xeon CPU E5410 @ 2.33GHz running debian squeeze 6.0.3 with kernel2.6.32-5-amd64

Thanks,

XL.

Possible bug when function used to fill an array

Ron_Green — Tue, 13 Dec 2011 15:41:07 GMT

"Useful Links" at the top of this forum has common mistakes/problems such as this:

http://software.intel.com/en-us/articles/determining-root-cause-of-sigsegv-or-sigbus-errors/

ron

Possible bug when function used to fill an array

_xl_ — Wed, 14 Dec 2011 07:50:42 GMT

Ok, thanks,

Does that mean that in my case ifort creates a temporary array to store values inside titi function and then copy it to tata array whereas gfortran directly works into tata array ?

So is it better to use a subroutine with tata in INTENT(OUT) if we want to work directly on tata array ?

Thanks,

XL.

EDIT : OK I found the answer in the attached PDF to your link, i have to use au subroutine.

topic Possible bug when function used to fill an array in Intel® Fortran Compiler

Possible bug when function used to fill an array

Possible bug when function used to fill an array

Possible bug when function used to fill an array