[Fortran] Incorrect unparsing for omp parallel

[ouankou]

This bug was found while debugging for issue #130.

Given input:

      program main
      include 'omp_lib.h'
      integer i
      integer item(10)
      external process
      do i = 1, 10
        item(i) = 11-i
      enddo  

!$omp parallel
!$omp single
      print *, 'using ', omp_get_num_threads(), ' threads' 
      do i = 1, 10
!$omp task 
      call process(i,item)
!$omp end task
      enddo  
!$omp end single
!$omp end parallel
      end 

******************************************
      subroutine process(input,item)
      include 'omp_lib.h'
      integer input
      integer item(10)
      print *, 'idx ', input,'-> ', item(input)
      print *, 'by thread ', omp_get_thread_num()
      end

!pragma omp end parallel or !$omp omp end parallel will be inserted right above !$omp end single. Neither should happen.

The output from code above:

      PROGRAM main
      include "omp_lib.h"
      INTEGER :: i
      INTEGER, DIMENSION(10) :: item
      external :: process
      DO i = 1, 10
      item(i) = 11 - i
      END DO
      
!$omp parallel 
      
!$omp single 
      PRINT *, 'using ',omp_get_num_threads(),' threads'
      DO i = 1, 10
      
!$omp task 
      CALL process(i,item)
!$omp end task 
      END DO
      !pragma omp end parallel 
!$omp end single 
******************************************
!$omp end parallel
      END PROGRAM 

      SUBROUTINE process(input,item)
      include "omp_lib.h"
      INTEGER :: input
      INTEGER, DIMENSION(10) :: item
      PRINT *, 'idx ',input,'-> ',item(input)
      PRINT *, 'by thread ',omp_get_thread_num()
      END SUBROUTINE

The extra Fortran comment comes from:

rexompiler/src/backend/unparser/FortranCodeGeneration/unparseFortran_statements.C

Line 4060 in 973614c

AstAttribute* att = stmt->getAttribute("OmpAttributeList"); //TODO: we removed OmpAttribute and this need to be changed

This piece of code above is fine, but it should not be called in this case. I think the bug exists somewhere else.

[yanyh15]

@ouankou I also found some bugs related to Fortran, but I am not sure whether it is related to this bug or not. After lowing and unparsing, the new file generated for the outlined function is empty. I am submitting another issue with details for that.

[ouankou]

It's fixed by the commit cf02a62. We missed or accidentally removed an upstream commit addressing the situation of multiple Fortran comments following the same statement.

@yanyh15 This bug is not related to issue #135. I tested the code in that issue and still got an empty outlined function.