topic Re: Thread Sanitizer link error in Intel® Fortran Compiler

Thread Sanitizer link error

vikramb — Wed, 14 Jan 2026 22:17:12 GMT

Hello,

I am using Intel IFX 2024.2 compiler on Linux. I am trying to build my executable and dynamic libraries (on Linux) with thread sanitizer instrumented to detect data races. I am using '-fsanitize=thread' flags for both compiling as well as linking. However when I attempt to build any shared library I get linking errors like this:

" ... libclang_rt.tsan.a(tsan_interceptors_posix.cpp.o): relocation R_X86_64_TPOFF32 against `_ZL10pglob_copy' can not be used when making a shared object; recompile with -fPIC"

" ... libclang_rt.tsan.a(tsan_rtl.cpp.o): relocation R_X86_64_TPOFF32 against hidden symbol `_ZN6__tsan22cur_thread_placeholderE' can not be used when making a shared object"

" ... libclang_rt.tsan.a(tsan_preinit.cpp.o): .preinit_array section is not allowed in DSO"

"ld: failed to set dynamic section sizes: Nonrepresentable section on output"

All my libraries have the '-fPIC' compile flag. So I think the issue is with the TSAN runtime library included with the compiler. How can can I avoid these errors?

Re: Thread Sanitizer link error

vikramb — Wed, 14 Jan 2026 22:18:39 GMT

If there is a way to link against the shared version of the library (libclang_rt.tsan.so) will this problem go away?

Re: Thread Sanitizer link error

vikramb — Thu, 15 Jan 2026 03:32:21 GMT

Here's a minimal example (a translation of C++ example from Intel) to reproduce the error. When attempting to compile into library using the following command

ifx -shared -fPIC -fsanitize=thread -o libmergesort.so mergeSortMod.f90

I get the following errors:

" ... libclang_rt.tsan.a(tsan_interceptors_posix.cpp.o): relocation R_X86_64_TPOFF32 against `_ZL10pglob_copy' can not be used when making a shared object; recompile with -fPIC"
" ... libclang_rt.tsan.a(tsan_rtl.cpp.o): relocation R_X86_64_TPOFF32 against hidden symbol `_ZN6__tsan22cur_thread_placeholderE' can not be used when making a shared object"
"... libclang_rt.tsan.a(tsan_preinit.cpp.o): .preinit_array section is not allowed in DSO"
"ld: failed to set dynamic section sizes: Nonrepresentable section on output"

! Fortran Implementation of Intel C++ Code Example module MergeSortModule use omp_lib implicit none integer, parameter :: task_threshold = 5000 ! Threshold for creating OpenMP tasks integer :: my_counter = 0 ! Counter to track function calls contains ! Description: Initializes the array and shuffles the elements. subroutine InitializeArray(a, n) integer, intent(inout) :: a(:) integer, intent(in) :: n integer :: i, tmp, j ! Initialize the array do i = 1, n a(i) = i - 1 end do print *, "Shuffling the array" ! Shuffle the array (Fisher-Yates Shuffle Algorithm) call random_seed() do i = n, 2, -1 call random_number(tmp) j = floor(tmp * real(i)) + 1 tmp = a(i) a(i) = a(j) a(j) = tmp end do end subroutine InitializeArray ! Description: Checks if the array is correctly sorted function CheckArray(a, n) result(error_flag) integer, intent(in) :: a(:) integer, intent(in) :: n integer :: i, error_flag error_flag = 0 ! Assume no errors do i = 1, n - 1 if (a(i) >= a(i + 1) .or. a(i) /= (i - 1)) then print *, "Sort failed at location", i, ", a(i)=", a(i), " a(i+1)=", a(i + 1) error_flag = 1 return end if end do end function CheckArray ! Description: Merges two sublists of the array subroutine Merge(a, tmp_a, first, middle, last) integer, intent(inout) :: a(:), tmp_a(:) integer, intent(in) :: first, middle, last integer :: p1, p2, p, i p1 = first p2 = middle p = first ! Merge two portions of the array into the temporary array do while (p <= last) if (p1 < middle .and. (p2 > last .or. a(p1) < a(p2))) then tmp_a(p) = a(p1) p1 = p1 + 1 else tmp_a(p) = a(p2) p2 = p2 + 1 end if p = p + 1 end do ! Copy the sorted portion back to the original array do i = first, last a(i) = tmp_a(i) end do end subroutine Merge ! Description: Recursive MergeSort algorithm recursive subroutine MergeSort(a, tmp_a, first, last) integer, intent(inout) :: a(:), tmp_a(:) integer, intent(in) :: first, last integer :: middle if (first < last) then middle = (first + last + 1) / 2 call MergeSort(a, tmp_a, first, middle - 1) call MergeSort(a, tmp_a, middle, last) call Merge(a, tmp_a, first, middle, last) end if end subroutine MergeSort ! Description: OpenMP Task-based version of MergeSort recursive subroutine MergeSortOpenMP(a, tmp_a, first, last) integer, intent(inout) :: a(:), tmp_a(:) integer, intent(in) :: first, last integer :: middle if (first < last) then middle = (first + last + 1) / 2 if (last - first < task_threshold) then call MergeSort(a, tmp_a, first, middle - 1) call MergeSort(a, tmp_a, middle, last) else !$omp task call MergeSortOpenMP(a, tmp_a, first, middle - 1) !$omp task call MergeSortOpenMP(a, tmp_a, middle, last) !$omp taskwait end if call Merge(a, tmp_a, first, middle, last) my_counter = my_counter + 1 end if end subroutine MergeSortOpenMP end module MergeSortModule

Re: Thread Sanitizer link error

vikramb — Thu, 15 Jan 2026 03:36:21 GMT

There is small error in the call to random_number subroutine in the code snippet above. It needs a real argument 'rtmp' instead of integer 'tmp'. This needs to be declared as well.

Re: Thread Sanitizer link error

vikramb — Thu, 15 Jan 2026 03:39:26 GMT

The code snippet to reproduce the errors is below.

The command I tried is

ifx -shared -fPIC -fsanitize=thread -o libmergesort.so mergeSortMod.f90

! Modern Fortran Implementation of the Given C++ Code module MergeSortModule use omp_lib implicit none integer, parameter :: task_threshold = 5000 ! Threshold for creating OpenMP tasks integer :: my_counter = 0 ! Counter to track function calls contains ! Description: Initializes the array and shuffles the elements. subroutine InitializeArray(a, n) integer, intent(inout) :: a(:) integer, intent(in) :: n integer :: i, tmp, j real :: rtmp ! Initialize the array do i = 1, n a(i) = i - 1 end do print *, "Shuffling the array" ! Shuffle the array (Fisher-Yates Shuffle Algorithm) call random_seed() do i = n, 2, -1 call random_number(rtmp) j = floor(rtmp * real(i)) + 1 tmp = a(i) a(i) = a(j) a(j) = tmp end do end subroutine InitializeArray ! Description: Checks if the array is correctly sorted function CheckArray(a, n) result(error_flag) integer, intent(in) :: a(:) integer, intent(in) :: n integer :: i, error_flag error_flag = 0 ! Assume no errors do i = 1, n - 1 if (a(i) >= a(i + 1) .or. a(i) /= (i - 1)) then print *, "Sort failed at location", i, ", a(i)=", a(i), " a(i+1)=", a(i + 1) error_flag = 1 return end if end do end function CheckArray ! Description: Merges two sublists of the array subroutine Merge(a, tmp_a, first, middle, last) integer, intent(inout) :: a(:), tmp_a(:) integer, intent(in) :: first, middle, last integer :: p1, p2, p, i p1 = first p2 = middle p = first ! Merge two portions of the array into the temporary array do while (p <= last) if (p1 < middle .and. (p2 > last .or. a(p1) < a(p2))) then tmp_a(p) = a(p1) p1 = p1 + 1 else tmp_a(p) = a(p2) p2 = p2 + 1 end if p = p + 1 end do ! Copy the sorted portion back to the original array do i = first, last a(i) = tmp_a(i) end do end subroutine Merge ! Description: Recursive MergeSort algorithm recursive subroutine MergeSort(a, tmp_a, first, last) integer, intent(inout) :: a(:), tmp_a(:) integer, intent(in) :: first, last integer :: middle if (first < last) then middle = (first + last + 1) / 2 call MergeSort(a, tmp_a, first, middle - 1) call MergeSort(a, tmp_a, middle, last) call Merge(a, tmp_a, first, middle, last) end if end subroutine MergeSort ! Description: OpenMP Task-based version of MergeSort recursive subroutine MergeSortOpenMP(a, tmp_a, first, last) integer, intent(inout) :: a(:), tmp_a(:) integer, intent(in) :: first, last integer :: middle if (first < last) then middle = (first + last + 1) / 2 if (last - first < task_threshold) then call MergeSort(a, tmp_a, first, middle - 1) call MergeSort(a, tmp_a, middle, last) else !$omp task call MergeSortOpenMP(a, tmp_a, first, middle - 1) !$omp task call MergeSortOpenMP(a, tmp_a, middle, last) !$omp taskwait end if call Merge(a, tmp_a, first, middle, last) my_counter = my_counter + 1 end if end subroutine MergeSortOpenMP end module MergeSortModule

Re: Thread Sanitizer link error

vikramb — Thu, 15 Jan 2026 14:12:48 GMT

Somehow all previous attempts to include code inside have not worked. A minimal example source file is attached. The command I used is 'ifx -shared -fPIC -fsanitize=thread -o libmergesort.so MergeSortModule.f90'.