LI76851: OMP PARALLEL ERROR FROM C99 VARIABLE USAGE

November 2012 Update for XL C/C++ for Blue Gene/Q, V12.1
February 2013 Update for XL C/C++ for Blue Gene/Q, V12.1

APAR status

• Closed as program error.

Error description

• When compiling an OMP for loop with mismatched loop counter
  datatypes, the OMP syntax check is being too strict and
  outputing an error.
  
  
      ===== TEST CASE =====
  
  int main()
  {
          long var=0;
          #pragma omp parallel for schedule(static)
          for(int i1=0; i1<var; i1++) {}
  }
  
  $ xlc_r reduce.c -qsmp=omp -q64
  "reduce.c", line 5.23: 1506-818 (S) Controlling expression of
  the for loop is not in the canonical form.
  

Local fix

• Move the loop counter variable declaration outside of the for
  loop.  This will change the variable promotion rules and work
  around the issue.
  

Problem summary

• PROBLEM DESCRIPTION:
  The compiler is issuing a severe error for a 'for' loop not in
  OMP canonical form when using -q64, but the C standard allows
  it.
  
  USERS AFFECTED:
  Users using different integral types and sign with loop
  variable in a 'for' loop at 64bit.
  

Problem conclusion

• Confirmed that the OMP form should not be more restrictive than
  the C standard.  The check was relaxed, and mixed integral
  types are now allowed.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  IV23063 LI76852 LI76975 IV31753

Fix information

• Fixed component name

  XL C/C++ FOR BG

• Fixed component ID

  5799AG100

Applicable component levels

• RC10 PSY

     UP