Approximatrix Forums — 32 bit executable fails, 64 bit fine

Re: 32 bit executable fails, 64 bit fine

2016-03-14T02:44:12Z

jeff wrote:

baf1 wrote:
Starting with Fortran 2003, allocate on assign is allowed.

If it is being backported to 5.3, it will be integrated when/if 5.3.1 is released. We have a policy of only shipping release versions of GNU Fortran. Thank you for seeing that the bug is fixed, though!

OK, that likely means waiting until 6.1 is released in a few months.

Re: 32 bit executable fails, 64 bit fine

2016-03-13T13:45:48Z

baf1 wrote:

Starting with Fortran 2003, allocate on assign is allowed.

Ah, I wasn't aware of that addition to the standard. I can't say that I agree with it, though, but the Fortran standards committee always seems to make odd decisions.

If it is being backported to 5.3, it will be integrated when/if 5.3.1 is released. We have a policy of only shipping release versions of GNU Fortran. Thank you for seeing that the bug is fixed, though!

Re: 32 bit executable fails, 64 bit fine

2016-03-13T03:53:36Z

Jeff

The gfortran developers confirm that this is a bug in gfortran which they believe (hope) has been fixed in a very recent set of patches submitted to both the 6.0 branch and backported to the 5-branch. Perhaps you will have a chance in the not-to-distant future to rebuild gfortran from the most recent 5.3.1 sources.

Re: 32 bit executable fails, 64 bit fine

2016-03-13T00:02:48Z

Other programmers and the Intel compiler agree with me that the code is standards conforming. Likely a gfortran bug, although odd that it only occurs with the 32bit executable. I am assuming you build gcc/gfortran all at once from the same source. I filed a gfortran bug report on bugzilla.

Re: 32 bit executable fails, 64 bit fine

2016-03-12T22:08:35Z

Jeff

No, I do not believe you are correct. Starting with Fortran 2003, allocate on assign is allowed. However, I will check further on this.

Re: 32 bit executable fails, 64 bit fine

2016-03-12T21:35:31Z

You're probably seeing the crash because you're assigning values to s, an allocatable array, without first allocating it. If you were to allocate first, it should work on both:

program defer
  implicit none
  character(len=:), dimension(:), allocatable::s

  allocate(character(len=3)::s(3))

  s(1) = "a12"
  s(2) = "ab3"
  s(3) = "abc"
  write(*,*)"shape of s: ",shape(s)
end program defer

The fact that it works on 64-bit is incidental. In reality, you're overwriting an undefined area of memory and luckily getting away with it.

32 bit executable fails, 64 bit fine

2016-03-12T19:33:11Z

This may be a gcc/gfortran library bug, but might be something related to your build of gfortran. The program below crashes with

Program received signal SIGSEGV: Segmentation fault - invalid memory reference.
Backtrace for this error:
#0 ffffffff

when building with 32 bit architecture selected (-m32 flag), but executes correctly without error when 64 bit is selected.

program defer
implicit none
character(len=:), dimension(:), allocatable::s
s=["a12","ab3","abc"]
write(*,*)"shape of s: ",shape(s)
end program defer