topic Indeed, the problem should be in Intel® Fortran Compiler

intrinsinc REAL & ifort 16.0.2 - bug?

janusz_andrzejewski — Sat, 20 Feb 2016 15:19:45 GMT

Here is a small code:

PROGRAM test
IMPLICIT NONE
INTEGER, PARAMETER :: wp=KIND(1.0d0)
REAL(wp), ALLOCATABLE, DIMENSION(:) :: rr
COMPLEX(wp), ALLOCATABLE, DIMENSION(:) :: cc
INTEGER :: n

n=1000000 !<= this value is OK
n=1100000 !<= this value causes error

   ALLOCATE(cc(n))
   cc=(1.0_wp, 1.0_wp)
   ALLOCATE(rr(n))
   rr(:)=REAL(cc(:), KIND=wp) !<= here is runtime error
   ! rr(:)=REAL(cc(:))    !<= it's OK

END PROGRAM

When I compile without any switch under ifort 16.0.2 program crashes. It runs well under -O3 optimization level and crushes under the

-O0, -O1 -O2 optimization levels.

It run well if one switch the working precision (wp) from DOUBLE PRECISION to SINGLE PRECISION (i.e. wp=KIND(1.0) )

Under ifort 16.0.1 everything is OK.

I get a stack overflow,

TimP — Sat, 20 Feb 2016 15:47:18 GMT

I get a stack overflow, avoided simply by boosting the stack limit.

No doubt that the update is causing you a slightly increased stack consumption. I see that an extra temporary array and copy is created at the lower optimizations. I don't know whether that would be accepted as a bug.

Thank you.

janusz_andrzejewski — Sat, 20 Feb 2016 16:38:02 GMT

Thank you.

Setting stack unlimited ( ulimit -s unlimited) the problem for intel 16.0.2 has gone.

Regarding ifort 16.0.1. In standard stack size (8192 kB) even if I enlarge n 1000 times, program still runs well.

Indeed, the problem should be

janusz_andrzejewski — Sun, 21 Feb 2016 19:08:58 GMT

Indeed, the problem should be connected to the stack. If I decreased stack size to 5000 kB, then the program also crashed at n=1000 000.

In the case of ifort 16.0.2. The mentioned problem could be solved/avoided by using the -heap-arrays switch. But with the standard stack size (8192 kB) and with the -heap-arrays 100000 (means that temporary array larger then 100MB is allocated on heap memory) the program is running well. For me, there is something wrong or I do not understand the idea of the -heap-arrays switch

The value given on the -heap

Steven_L_Intel1 — Mon, 22 Feb 2016 01:43:55 GMT

The value given on the -heap-arrays switch is not used in any meaningful fashion. You may as well leave it off.

FWIW, you may find https:/

Steven_L_Intel1 — Mon, 22 Feb 2016 18:01:12 GMT

FWIW, you may find https://software.intel.com/en-us/blogs/2008/03/31/doctor-it-hurts-when-i-do-this worth a read.