PH67073: A LOOP WITH A GOTO STATEMENT EXECUTES MORE TIMES THAN EXPECTED AT OPT(2)

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Users of Enterprise COBOL 6.x compiling programs at OPT(2) that
  include a GO TO statement working with a BINARY/COMP/COMP-4 data
  item serving as a loop counter which increments or decrements by
  1 each iteration where the initial value of the loop counter is
  at or outside the bounds for the loop.
  
  The compiler optimizes the loop to count down to 0 and generates
  an instruction that decrements the loop counter, compares it to
  zero, and branches to the top of the loop if non-zero. If the
  initial value of the counter is at or exceeding the loop bounds,
  it will be transformed to be 0 or negative, and decrementing the
  counter means it's definitely negative, so the loop continues to
  execute until the counter wraps around and eventually reaches 1,
  decrementing to 0, allowing the loop to finally terminate.
  

Local fix

• Compile with OPT(0|1)
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of Enterprise COBOL 6.4 compiling      *
  *                 programs at OPT(2) that include a GO TO      *
  *                 statement working with a BINARY/COMP/COMP-4  *
  *                 data item serving as a loop counter which    *
  *                 increments or decrements by 1 each iteration *
  *                 where the initial value of the loop counter  *
  *                 is at or outside the bounds for the loop.    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Loop executes many more times than      *
  *                      expected.                               *
  ****************************************************************
  * RECOMMENDATION: Apply the provided PTF                       *
  ****************************************************************
  The compiler optimizes the loop to count down to 0 and generates
  an instruction that decrements the loop counter, compares it to
  zero, and branches to the top of the loop if non-zero. If the
  initial value of the counter is at or exceeding the loop bounds,
  it will be transformed to be 0 or negative, and decrementing the
  counter means it's definitely negative, so the loop continues to
  execute until the counter wraps around and eventually reaches 1,
  decrementing to 0, allowing the loop to finally terminate.
  

Problem conclusion

• The compiler was fixed to avoid the optimization in cases where
  it can't ensure the initial value of the loop counter is within
  the loop bounds.
  

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:

  PH68254

Modules/Macros

• IGY8RWTU IGYCASMB IGYCCBE  IGYCCCRT IGYCCICS IGYCCSRV IGYCDGEN
  IGYCDIAG IGYCDMAP IGYCEN$0 IGYCEN$1 IGYCEN$2 IGYCEN$3 IGYCEN$4
  IGYCEN$5 IGYCEN$8 IGYCEN$D IGYCEN$R IGYCFGEN IGYCFREE IGYCINIT
  IGYCJA$0 IGYCJA$1 IGYCJA$2 IGYCJA$3 IGYCJA$4 IGYCJA$5 IGYCJA$8
  IGYCJA$D IGYCJA$R IGYCJBLD IGYCJGEN IGYCLIBR IGYCLSTR IGYCLVL0
  IGYCLVL1 IGYCLVL2 IGYCLVL3 IGYCLVL8 IGYCMALL IGYCOB2E IGYCOSCN
  IGYCPGEN IGYCRCTL IGYCRDPR IGYCRDSC IGYCREAL IGYCRWT  IGYCSCAN
  IGYCSIMD IGYCUE$0 IGYCUE$1 IGYCUE$2 IGYCUE$3 IGYCUE$4 IGYCUE$5
  IGYCUE$8 IGYCUE$D IGYCUE$R IGYCXREF IGYDRV   IGYEQCWI IGYMSGE
  IGYMSGK  IGYMSGT  IGYQCBE  IGYQSPLT IGYZQEN6 IGYZQENU IGYZQJP6
  IGYZQJPN
  

Fix information

• Fixed component name

  ENT COBOL FOR Z

• Fixed component ID

  5655EC600

Applicable component levels

• R640 PSY UO04614

     UP25/08/30 P F508

• R641 PSY UO04615

     UP25/08/30 P F508

• R642 PSY UO04616

     UP25/08/30 P F508

• R64H PSY UO04617

     UP25/08/30 P F508

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.