IBM Enterprise COBOL V6R4+ - Compilation directive to inform the compiler of the end of sequential code execution (call to exit / abend routine)

Hi,

We have observed that compiler optimization, particularly PERFORM inlining, can be disrupted by certain constructs in the COBOL source code:

• EXEC CICS RETURN

• EXEC CICS HANDLE ABEND LABEL

• CALL to subprogram without expected return, (abend subprogram)

In fact, CICS commands are technically translated as CALLs, and the general rule is that you can return to the program after a CALL.

The case of EXEC CICS RETURN illustrates this: you're not supposed to return to the program, however, for some reason (which I can't explain), the EXEC CICS RETURN command might fail, and in that case, the program can continue to execute sequentially.

The case of a subroutine called to trigger an ABEND, in addition to other processing, is probably common in many customer's platforms; moreover, the Language Environment also handles ABENDs by calling such a routine.

While the COBOL compiler can recognize LE routines, it cannot recognize the routines implemented by clients.

Today the workaround to achieve inlining of PERFORM is to code GOBACKs after a "no-return CALL", which is logically incorrect and inelegant.

For these reasons, we propose implementing a new compilation directive in the COBOL compiler to indicate the end of sequential execution, often placed after a CALL or a CICS command, but other cases must exist.

This compilation directive would help the compiler better manage PERFORM inlining by taking sequence breaks (no-return CALL) into account.

Implementing the compilation directive could trigger a deliberate abend, for example, in the form of an abend S0C1 (illegal instruction), or any other solution.


See COBOL Comminity discussion I start:
https://community.ibm.com/community/user/discussion/ibm-enterprise-cobol-v6-disabling-optimizations-when-the-cics-option-is-active


Thanks.