LI76206: EXTERN TLS VARIABLE CAUSING ASSEMBLER ERROR

June 2011 Update for XL C/C++ for Linux, V10.1
XL C/C++ for Linux Fix Pack 8 (January 2014 Update) for 10.1
January 2012 Update for XL C/C++ for Linux, V10.1
July 2012 Update for XL C/C++ for Linux, V10.1

APAR status

• Closed as program error.

Error description

• The following test case is generating invalid assembly syntax
  which the assembler does not understand.  The issue is related
  to how thread local storage variables are set to 'extern'.
  
  
    ===== TESTCASE =====
  extern __thread int x, *p;
  
  int  mytest(void **fp)
  {
    __asm ("ori %0, 1, 0" : "=r" (*(&fp)));
    p = &x;
  
          return 6;
  }
  
  This generates the following assembly:
  
  --------------------------------------------
    +106          .tc     x[TC],x[UL]
    +115          .extern x[UA]
  --------------------------------------------
  
  Which causes these assembly errors:
  
  --------------------------------------------
  Assembler:
  tls.s: line 106: 1252-023 The symbol x is not defined.
  tls.s: line 106: 1252-040 The specified expression is not valid.
          Make sure that all symbols are defined.
          Check the rules on symbols used in an arithmetic
          expression concerning relocation.
  --------------------------------------------
  
  OR
  
  --------------------------------------------
  Assembler:
  tls.s: line 106: 1252-142 Syntax error.
  --------------------------------------------
  
  The correct syntax should look like:
  
  --------------------------------------------
    +106          .tc     x[TC],x[UL]
    +115          .extern x[UL]
  --------------------------------------------
  

Local fix

• Remove 'extern' from TLS variable.
  

Problem summary

• PROBLEM DESCRIPTION:
  extern thread local variables do not work when inline ASM is
  present.
  
  USERS AFFECTED:
  Users with TLS programs that want to use inline ASM.
  

Problem conclusion

• The issue was corrected.
  

Temporary fix

Comments

APAR Information

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

  IZ93006

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

Fix information

• Fixed component name

  XL C/C++ RHEL52

• Fixed component ID

  5724U8310

Applicable component levels

• RA10 PSN IZ93006

     UP06/09/13