https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99171
Bug ID: 99171 Summary: [10 Regression] Optional procedure call inside Open MP parallel loop produces Segmentation Fault Product: gcc Version: 10.2.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: fortran Assignee: unassigned at gcc dot gnu.org Reporter: am41119 at hotmail dot com Target Milestone: --- Created attachment 50226 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50226&action=edit Output of using -save-temps during compilation When calling a passed optional procedure inside an Open MP parallel loop (even with OMP_NUM_THREADS=1) the address of the optional procedure is no longer set to the actual passed procedure. Because the address of the optional procedure is no longer correct we get a Segmentation Fault when calling it. The below program works on GCC9 and below. main.f90: ----------------------------------------------- program gcc10_omp_optional_bug implicit none call function_calling_optionals(print_something) call function_calling_optionals_in_omp(print_something) contains subroutine optional_function_template() implicit none end subroutine subroutine print_something() implicit none print *, "Printing Something" end subroutine print_something subroutine function_calling_optionals(optional_function) implicit none procedure(optional_function_template), optional :: optional_function print *, "When optional function is called without Open MP directive:" if (present(optional_function)) then call optional_function() end if end subroutine function_calling_optionals subroutine function_calling_optionals_in_omp(optional_function) implicit none procedure(optional_function_template), optional :: optional_function print *, "When optional function is called inside Open MP directive:" !$omp parallel if (present(optional_function)) then call optional_function() end if !$omp end parallel end subroutine function_calling_optionals_in_omp end program gcc10_omp_optional_bug --------------------------------------------- gfortran -v Using built-in specs. COLLECT_GCC=gfortran COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/10/lto-wrapper OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa:hsa OFFLOAD_TARGET_DEFAULT=1 Target: x86_64-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 10.2.0-5ubuntu1~20.04' --with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs --enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-10 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-10-WJNXnb/gcc-10-10.2.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-10-WJNXnb/gcc-10-10.2.0/debian/tmp-gcn/usr,hsa --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 10.2.0 (Ubuntu 10.2.0-5ubuntu1~20.04) Compile Command: gfortran main.f90 -fopenmp -o main Execution output: When optional function is called without Open MP directive: Printing Something When optional function is called inside Open MP directive: Program received signal SIGILL: Illegal instruction. Program received signal SIGILL: Illegal instruction. Program received signal SIGILL: Illegal instruction. Backtrace for this error: Program received signal SIGILL: Illegal instruction. Backtrace for this error: Backtrace for this error: Backtrace for this error: Program received signal SIGILL: Illegal instruction. Backtrace for this error: Program received signal SIGSEGV: Segmentation fault - invalid memory reference. Backtrace for this error: Program received signal SIGILL: Illegal instruction. Backtrace for this error: Program received signal SIGILL: Illegal instruction. Backtrace for this error: #0 0x7f9e60dd1d01 in ??? #0 0x7f9e60dd1d01 in ??? #0 0x7f9e60dd1d01 in ??? #1 0x7f9e60dd0ed5 in ??? #2 0x7f9e60bc320f in ??? #3 0x7f9e5e993e27 in ??? Illegal instruction (core dumped)