https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101824
Bug ID: 101824
Summary: VOLATILE not honored
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: martin.diehl at kuleuven dot be
Target Milestone: ---
I have a wrapper to C to control a Fortran program with IPC signals:
/* c_interface.c */
#include <signal.h>
void signalterm_c(void (*handler)(int)){
signal(SIGTERM, handler);
}
void signalusr1_c(void (*handler)(int)){
signal(SIGUSR1, handler);
}
! c_interface.f90
module c_interface
implicit none
interface
subroutine signalterm_C(handler) bind(C)
use, intrinsic :: ISO_C_Binding, only: C_FUNPTR
type(C_FUNPTR), intent(in), value :: handler
end subroutine signalterm_C
subroutine signalusr1_C(handler) bind(C)
use, intrinsic :: ISO_C_Binding, only: C_FUNPTR
type(C_FUNPTR), intent(in), value :: handler
end subroutine signalusr1_C
end interface
end module c_interface
! wait_for_SIGTERM.f90
program wait_for_SIGTERM
use, intrinsic :: ISO_C_binding
use c_interface
implicit none
logical, volatile :: &
interface_SIGTERM, & ! termination signal
interface_SIGUSR1 ! 1. user-defined signal
call init
do while( .not. interface_SIGTERM)
enddo
contains
subroutine init()
call signalterm_c(c_funloc(catchSIGTERM))
call signalusr1_c(c_funloc(catchSIGUSR1))
call interface_setSIGTERM(.false.)
call interface_setSIGUSR1(.false.)
end subroutine init
subroutine catchSIGTERM(signal) bind(C)
integer(C_INT), value :: signal
print'(a,i0)', ' received signal ',signal
call interface_setSIGTERM(.not. interface_SIGTERM)
end subroutine catchSIGTERM
subroutine catchSIGUSR1(signal) bind(C)
integer(C_INT), value :: signal
print'(a,i0)', ' received signal ',signal
call interface_setSIGUSR1(.not. interface_SIGUSR1)
end subroutine catchSIGUSR1
subroutine interface_setSIGTERM(state)
logical, intent(in) :: state
interface_SIGTERM = state
print*, 'set SIGTERM to',state
end subroutine interface_setSIGTERM
subroutine interface_setSIGUSR1(state)
logical, intent(in) :: state
interface_SIGUSR1 = state
print*, 'set SIGUSR1 to',state
end subroutine interface_setSIGUSR1
end program
Compile and run (tested on Linux):
gfortran c_interface.c c_interface.f90 wait_for_SIGTERM.f90 -o wait
./wait&
kill -SIGUSR1 XXXX
kill -SIGUSR1 XXXX
kill -SIGTERM XXXX
If compiled without optimization flag, the loop exits on SIGTERM (indented
behavior). If compiled with `-O3`, it runs forever. This behavior is
independent of the VOLATILE attribute.
There is a little discussion on
https://fortran-lang.discourse.group/t/volatile-needed/1648
