https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106643
Bug ID: 106643
Summary: [gfortran + OpenACC] Allocate in module causes
refcount error
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libgomp
Assignee: unassigned at gcc dot gnu.org
Reporter: hberre3 at gatech dot edu
CC: jakub at gcc dot gnu.org
Target Milestone: ---
I built GCC 13 from the default branch with offloading support for the new AMD
MI 210 GPUs by following the documented instructions. I ran into the following
runtime error when running our offloaded code written in Fortran leveraging
OpenACC:
```
/nethome/hberre3/USERSCRATCH/build-gcc-amdgpu//gcc/libgomp/oacc-mem.c:1153:
goacc_enter_data_internal: Assertion `n->refcount != REFCOUNT_INFINITY &&
n->refcount != REFCOUNT_LINK' failed.
```
I was able to create a minimal reproducible example for it:
p_main.f90
```
program p_main
use m_macron
!
==========================================================================
implicit none
call s_vars_init()
call s_vars_read()
call s_macron_init()
end program p_main
```
m_macron.f90
```
module m_macron
use m_vars
implicit none
real(kind(0d0)), allocatable, dimension(:) :: valls
!$acc declare create(valls)
contains
subroutine s_macron_init()
integer :: i
print*, "size=", size
print*, "allocate(valls(1:size))"
allocate(valls(1:size))
print*, "acc enter data create(valls(1:size))"
!$acc enter data create(valls(1:size))
print*, "!$acc update device(valls(1:size))"
valls(size) = size - 2
!$acc update device(valls(1:size))
print*, valls(1:size)
print*, "acc exit data delete(valls)"
!$acc exit data delete(valls)
end subroutine s_macron_init
end module m_macron
```
m_vars.f90
```
module m_vars
integer :: size
contains
subroutine s_vars_init()
size = -100
end subroutine s_vars_init
subroutine s_vars_read()
! Namelist of the global parameters which may be specified by user
namelist /user_inputs/ size
open (1, FILE=trim("in.inp"), FORM='formatted', ACTION='read',
STATUS='old')
read (1, NML=user_inputs); close (1)
end subroutine s_vars_read
end module m_vars
```
in.inp
```
&user_inputs
size = 10
&end/
```
In order to generate this error, I had to create and dynamically allocate the
array in another module. I initially wrote this in a single F90 file but the
executable ran as expected. The error gets produced when running:
```
!$acc enter data create(valls(1:size))
```
Here is the full output when running the executable with the `GOMP_DEBUG`
environment variable set:
```
GOACC_data_start: mapnum=3, hostaddrs=0x7fff23d2efd0, size=0x7fff23d2efb0,
kinds=0x603102
GOACC_data_start: prepare mappings
GOACC_data_start: mappings prepared
size= 10
allocate(valls(1:size))
acc enter data create(valls(1:size))
main:
/nethome/hberre3/USERSCRATCH/build-gcc-amdgpu//gcc/libgomp/oacc-mem.c:1153:
goacc_enter_data_internal: Assertion `n->refcount != REFCOUNT_INFINITY &&
n->refcount != REFCOUNT_LINK' failed.
Program received signal SIGABRT: Process abort signal.
Backtrace for this error:
#0 0x7f4aa4fcdb1f in ???
#1 0x7f4aa4fcda9f in ???
#2 0x7f4aa4fa0e04 in ???
#3 0x7f4aa4fa0cd8 in ???
#4 0x7f4aa4fc63f5 in ???
#5 0x7f4aa57b79e5 in goacc_enter_data_internal
at
/nethome/hberre3/USERSCRATCH/build-gcc-amdgpu//gcc/libgomp/oacc-mem.c:1153
#6 0x7f4aa57b79e5 in goacc_enter_exit_data_internal
at
/nethome/hberre3/USERSCRATCH/build-gcc-amdgpu//gcc/libgomp/oacc-mem.c:1405
#7 0x7f4aa57b8aab in GOACC_enter_data
at
/nethome/hberre3/USERSCRATCH/build-gcc-amdgpu//gcc/libgomp/oacc-mem.c:1478
#8 0x4013b7 in __m_macron_MOD_s_macron_init
at /nethome/hberre3/bug/m_macron.f90:22
#9 0x40182a in p_main
at /nethome/hberre3/bug/p_main.f90:11
#10 0x401866 in main
at /nethome/hberre3/bug/p_main.f90:3
run.sh: line 17: 3052573 Aborted (core dumped) ./main
```
I am not sure if this error is from libgomp or another part of the GCC
codebase. I assume it is related to an issue with the scoping of the array, as
it should be available throughout the entire program, per my reading of the
OpenACC spec:
```
The associated region is the implicit region associated with the function,
subroutine, or program in which the directive appears. If the directive appears
in the declaration section of a Fortran module subprogram or in a C or C++
global scope, the associated region is the implicit region for the whole
program.
```
Our main code currently doesn't call `!$acc enter data create` for dynamically
allocated arrays since it relies on NVIDIA (/PGI) hooking into the `allocate`
call on the CPU. I ran into the above error when converting our
allocation/deallocation routines.
Here is the output of `gfortran -v`:
```
[hberre3@8:instinct]:~ $ ~/tools/gcc/13/bin/gfortran -v
Using built-in specs.
COLLECT_GCC=/nethome/hberre3/tools/gcc/13/bin/gfortran
COLLECT_LTO_WRAPPER=/nethome/hberre3/tools/gcc/13/libexec/gcc/x86_64-pc-linux-gnu/13.0.0/lto-wrapper
OFFLOAD_TARGET_NAMES=amdgcn-amdhsa
Target: x86_64-pc-linux-gnu
Configured with: /nethome/hberre3/USERSCRATCH/build-gcc-amdgpu//gcc/configure
--build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu
--target=x86_64-pc-linux-gnu
--enable-offload-targets=amdgcn-amdhsa=/nethome/hberre3/tools/gcc/13/amdgcn-amdhsa
--enable-languages=c,c++,fortran,lto --disable-multilib
--prefix=/nethome/hberre3/tools/gcc/13
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 13.0.0 20220811 (experimental) (GCC)
```
The code is compiled with `/nethome/hberre3/tools/gcc/13/bin/gfortran -O0 -g
-fopenacc '-foffload-options=-lgfortran -lm'
-foffload-options=amdgcn-amdhsa=-march=gfx90a -fno-exceptions`.
This example runs with NVFortran on NVIDIA GPUs. Thank you for taking a look!
