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[Flang][OpenMP] Execution error of a WRITE statement with an unopened unit in a parallel region #68856

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yus3710-fj opened this issue Oct 12, 2023 · 3 comments · Fixed by #74468
Closed

[Flang][OpenMP] Execution error of a WRITE statement with an unopened unit in a parallel region #68856

yus3710-fj opened this issue Oct 12, 2023 · 3 comments · Fixed by #74468
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flang:runtime openmp

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@yus3710-fj
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This is an issue from Fujitsu testsuite.

The execution of a program compiled by flang-new terminates with a fatal error.
In the program, there is a WRITE statement in a parallel region and the unit specified in that is not opened explicitly.
The execution terminates normally when OpenMP is disabled.

The following are the test program, Flang-new and gfortran execution result.

! test.f90
!$omp parallel
write(1,*) 'OK'
!$omp end parallel
end
$ flang-new -v test.f90 -fopenmp
flang-new version 18.0.0 (https://github.com/llvm/llvm-project.git dae91f5dbc5bee579eac7f4cbb71e86f2934817f)
Target: aarch64-unknown-linux-gnu
Thread model: posix
InstalledDir: /path/to/install/bin
Found candidate GCC installation: /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0
Selected GCC installation: /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0
Candidate multilib: .;@m64
Selected multilib: .;@m64
 "/path/to/install/bin/flang-new" -fc1 -triple aarch64-unknown-linux-gnu -emit-obj -fopenmp -fcolor-diagnostics -mrelocation-model pic -pic-level 2 -pic-is-pie -target-cpu generic -target-feature +neon -target-feature +v8a -o /tmp/test-f33630.o -x f95-cpp-input test.f90
 "/usr/bin/ld" -pie -EL --hash-style=gnu --eh-frame-hdr -m aarch64linux -dynamic-linker /lib/ld-linux-aarch64.so.1 -o a.out /lib/../lib64/Scrt1.o /lib/../lib64/crti.o /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0/crtbeginS.o -L/path/to/install/lib/clang/18/lib/aarch64-unknown-linux-gnu -L/path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0 -L/path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/lib -L/usr/lib /tmp/test-f33630.o -L/path/to/install/lib -lFortran_main -lFortranRuntime -lFortranDecimal -lm -lomp -L/path/to/install/lib -lgcc --as-needed -lgcc_s --no-as-needed -lpthread -lc -lgcc --as-needed -lgcc_s --no-as-needed /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0/crtendS.o /lib/../lib64/crtn.o
$ ./a.out
$ OMP_NUM_THREADS=4 ./a.out

fatal Fortran runtime error(/path/to/test.f90:2): Attempted output to read-only file
Aborted (core dumped)
$ flang-new test.f90
$ ./a.out
$ cat fort.1 
 OK
$ gfortran -v test.f90 -fopenmp
Driving: gfortran -v test.f90 -fopenmp -l gfortran -l m -shared-libgcc
Using built-in specs.
COLLECT_GCC=gfortran
Target: aarch64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl --disable-libmpx --enable-gnu-indirect-function --build=aarch64-redhat-linux
Thread model: posix
gcc version 8.4.1 20200928 (Red Hat 8.4.1-1) (GCC) 
 :
$ OMP_NUM_THREADS=4 ./a.out
$ cat fort.1
 OK
 OK
 OK
 OK
@github-actions github-actions bot added the flang Flang issues not falling into any other category label Oct 12, 2023
@yus3710-fj yus3710-fj added openmp flang:runtime and removed flang Flang issues not falling into any other category labels Oct 12, 2023
@llvmbot
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llvmbot commented Oct 12, 2023

@llvm/issue-subscribers-openmp

Author: Yusuke MINATO (yus3710-fj)

This is an issue from Fujitsu testsuite.

The execution of a program compiled by flang-new terminates with a fatal error.
In the program, there is a WRITE statement in a parallel region and the unit specified in that is not opened explicitly.
The execution terminates normally when OpenMP is disabled.

The following are the test program, Flang-new and gfortran execution result.

! test.f90
!$omp parallel
write(1,*) 'OK'
!$omp end parallel
end
$ flang-new -v test.f90 -fopenmp
flang-new version 18.0.0 (https://github.com/llvm/llvm-project.git dae91f5dbc5bee579eac7f4cbb71e86f2934817f)
Target: aarch64-unknown-linux-gnu
Thread model: posix
InstalledDir: /path/to/install/bin
Found candidate GCC installation: /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0
Selected GCC installation: /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0
Candidate multilib: .;@<!-- -->m64
Selected multilib: .;@<!-- -->m64
 "/path/to/install/bin/flang-new" -fc1 -triple aarch64-unknown-linux-gnu -emit-obj -fopenmp -fcolor-diagnostics -mrelocation-model pic -pic-level 2 -pic-is-pie -target-cpu generic -target-feature +neon -target-feature +v8a -o /tmp/test-f33630.o -x f95-cpp-input test.f90
 "/usr/bin/ld" -pie -EL --hash-style=gnu --eh-frame-hdr -m aarch64linux -dynamic-linker /lib/ld-linux-aarch64.so.1 -o a.out /lib/../lib64/Scrt1.o /lib/../lib64/crti.o /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0/crtbeginS.o -L/path/to/install/lib/clang/18/lib/aarch64-unknown-linux-gnu -L/path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0 -L/path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/lib -L/usr/lib /tmp/test-f33630.o -L/path/to/install/lib -lFortran_main -lFortranRuntime -lFortranDecimal -lm -lomp -L/path/to/install/lib -lgcc --as-needed -lgcc_s --no-as-needed -lpthread -lc -lgcc --as-needed -lgcc_s --no-as-needed /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0/crtendS.o /lib/../lib64/crtn.o
$ ./a.out
$ OMP_NUM_THREADS=4 ./a.out

fatal Fortran runtime error(/path/to/test.f90:2): Attempted output to read-only file
Aborted (core dumped)
$ flang-new test.f90
$ ./a.out
$ cat fort.1 
 OK
$ gfortran -v test.f90 -fopenmp
Driving: gfortran -v test.f90 -fopenmp -l gfortran -l m -shared-libgcc
Using built-in specs.
COLLECT_GCC=gfortran
Target: aarch64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl --disable-libmpx --enable-gnu-indirect-function --build=aarch64-redhat-linux
Thread model: posix
gcc version 8.4.1 20200928 (Red Hat 8.4.1-1) (GCC) 
 :
$ OMP_NUM_THREADS=4 ./a.out
$ cat fort.1
 OK
 OK
 OK
 OK

@llvmbot
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llvmbot commented Oct 12, 2023

@llvm/issue-subscribers-flang-runtime

Author: Yusuke MINATO (yus3710-fj)

This is an issue from Fujitsu testsuite.

The execution of a program compiled by flang-new terminates with a fatal error.
In the program, there is a WRITE statement in a parallel region and the unit specified in that is not opened explicitly.
The execution terminates normally when OpenMP is disabled.

The following are the test program, Flang-new and gfortran execution result.

! test.f90
!$omp parallel
write(1,*) 'OK'
!$omp end parallel
end
$ flang-new -v test.f90 -fopenmp
flang-new version 18.0.0 (https://github.com/llvm/llvm-project.git dae91f5dbc5bee579eac7f4cbb71e86f2934817f)
Target: aarch64-unknown-linux-gnu
Thread model: posix
InstalledDir: /path/to/install/bin
Found candidate GCC installation: /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0
Selected GCC installation: /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0
Candidate multilib: .;@<!-- -->m64
Selected multilib: .;@<!-- -->m64
 "/path/to/install/bin/flang-new" -fc1 -triple aarch64-unknown-linux-gnu -emit-obj -fopenmp -fcolor-diagnostics -mrelocation-model pic -pic-level 2 -pic-is-pie -target-cpu generic -target-feature +neon -target-feature +v8a -o /tmp/test-f33630.o -x f95-cpp-input test.f90
 "/usr/bin/ld" -pie -EL --hash-style=gnu --eh-frame-hdr -m aarch64linux -dynamic-linker /lib/ld-linux-aarch64.so.1 -o a.out /lib/../lib64/Scrt1.o /lib/../lib64/crti.o /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0/crtbeginS.o -L/path/to/install/lib/clang/18/lib/aarch64-unknown-linux-gnu -L/path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0 -L/path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/lib -L/usr/lib /tmp/test-f33630.o -L/path/to/install/lib -lFortran_main -lFortranRuntime -lFortranDecimal -lm -lomp -L/path/to/install/lib -lgcc --as-needed -lgcc_s --no-as-needed -lpthread -lc -lgcc --as-needed -lgcc_s --no-as-needed /path/to/gcc/11.2.0/lib/gcc/aarch64-unknown-linux-gnu/11.2.0/crtendS.o /lib/../lib64/crtn.o
$ ./a.out
$ OMP_NUM_THREADS=4 ./a.out

fatal Fortran runtime error(/path/to/test.f90:2): Attempted output to read-only file
Aborted (core dumped)
$ flang-new test.f90
$ ./a.out
$ cat fort.1 
 OK
$ gfortran -v test.f90 -fopenmp
Driving: gfortran -v test.f90 -fopenmp -l gfortran -l m -shared-libgcc
Using built-in specs.
COLLECT_GCC=gfortran
Target: aarch64-redhat-linux
Configured with: ../configure --enable-bootstrap --enable-languages=c,c++,fortran,lto --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared --enable-threads=posix --enable-checking=release --enable-multilib --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-linker-build-id --with-gcc-major-version-only --with-linker-hash-style=gnu --enable-plugin --enable-initfini-array --with-isl --disable-libmpx --enable-gnu-indirect-function --build=aarch64-redhat-linux
Thread model: posix
gcc version 8.4.1 20200928 (Red Hat 8.4.1-1) (GCC) 
 :
$ OMP_NUM_THREADS=4 ./a.out
$ cat fort.1
 OK
 OK
 OK
 OK

@sihuan
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sihuan commented Nov 1, 2023

It looks like the problem is here.

llvm-project/flang/runtime/unit.cpp

Lines 52 to 66 in 760658c

ExternalFileUnit *ExternalFileUnit::LookUpOrCreateAnonymous(int unit,
Direction dir, std::optional<bool> isUnformatted,
const Terminator &terminator) {
bool exists{false};
ExternalFileUnit *result{
GetUnitMap().LookUpOrCreate(unit, terminator, exists)};
if (result && !exists) {
IoErrorHandler handler{terminator};
result->OpenAnonymousUnit(
dir == Direction::Input ? OpenStatus::Unknown : OpenStatus::Replace,
Action::ReadWrite, Position::Rewind, Convert::Unknown, handler);
result->isUnformatted = isUnformatted;
}
return result;
}

The first thread adds Unit 1 to UnitMap, and then opens/initializes the unit via OpenAnonymousUnit. And the other threads can find Unit 1 in UnitMap, but Unit 1 may not have been initialized, I mean mayWrite_ has not been set.

llvm-project/flang/runtime/file.cpp

Line 139 in b120fe8

mayWrite_ = *action != Action::Read;

Then got the IostatWriteToReadOnly error.

llvm-project/flang/runtime/unit.cpp

Lines 204 to 209 in b120fe8

if (mayWrite()) {
direction_ = Direction::Output;
return IostatOk;
} else {
return IostatWriteToReadOnly;
}

@sihuan sihuan mentioned this issue Dec 5, 2023
Merged
sihuan added a commit that referenced this issue Dec 6, 2023
@sihuan
[flang][runtime] Add a critical section for LookUpOrCreateAnonymous. (#…
62ece9c 
…74468)

In parallel regions `LookUpOrCreateAnonymous` may return an anonymous
unit that has not yet been opened, which may cause a runtime error.
This commit ensures that the returned anonymous unit has been opened.
For details see:
#68856 (comment)

Fixes #68856
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[flang][runtime] Add a critical section for LookUpOrCreateAnonymous. sihuan/llvm-project
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@sihuan @llvmbot @yus3710-fj