PH38969: NEW CHECKING OPTIONS FLAG(RENT) AND TYPECHECK(SIGNED)

Obtain the fix for this APAR.

APAR status

• Closed as new function.

Error description

• New options are required to provide more flexibility in
  reentrancy checks and in checking immediate value ranges.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of HLASM for z/OS, z/VM, z/VSE and     *
  *                 Linux                                        *
  ****************************************************************
  * PROBLEM DESCRIPTION: New checking options FLAG(RENT) and     *
  *                      TYPECHECK(SIGNED)                       *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  1. It could sometimes be useful to write code which modifies a
     data area which is normally read-only, or even a copy of that
     area, but there is no way to selectively disable the
     reentrant code check which produces message "ASMA036W
     Reentrant check failed" except by turning it off completely
     for the whole assembly, either by using the NORENT option (if
     the reference is within a CSECT) or by suppressing the
     warning using SUPRWARN(36).
  
  2. Range checking for immediate operand values is inconsistent
     and does not allow the convenience of specifying a signed
     value for an unsigned field, and vice versa.  For a signed
     field, it is possible to get round this using the option
     TYPECHECK(NOMAGNITUDE), but that completely disables all
     range checking.
  
  3. Error messages for immediate values do not show the value in
     error, which can be confusing for instructions which support
     multiple immediate or mask operands.
  
  4. The OPTIONS report showed the ILMA option after the INFO
     option, out of correct alphabetical sequence.
  

Problem conclusion

Temporary fix

Comments

• 1. The new option FLAG(RENT|NORENT) can now be used to enable or
     disable the reentrant code check warning message ASMA036W.
     The default is FLAG(RENT) for compatibility.  ACONTROL
     FLAG(NORENT) may be used to temporarily disable the warning,
     and PUSH and POP ACONTROL may be used as usual to save and
     restore the existing settings around the affected code.
  
  2. The new option TYPECHECK(SIGNED|NOSIGNED) controls whether
     range validation requested via TYPECHECK(MAGNITUDE) for an
     immediate operand value takes into account whether the field
     is signed or not.  The default is TYPECHECK(SIGNED), which
     means that a signed field will only accept the correct range
     of signed values and an unsigned field will only accept the
     correct range of unsigned values.  If TYPECHECK(NOSIGNED) is
     specified, values are accepted from either range, provided
     that they still fit within the size of the field.
  
     The option TYPECHECK(MAGNITUDE|NOMAGNITUDE) now applies to
     both signed and unsigned immediate values occupying one to
     three bytes.  When TYPECHECK(NOMAGNITUDE) is in effect, no
     range or sign check is applied to these values, and the value
     used is simply the required number of low-order bits.  This
     option has sometimes been used to allow an unsigned value to
     be used for a signed immediate field, but the new option
     TYPECHECK(NOSIGNED) can now be used instead to provide
     equivalent function while still validating that the value
     fits within the field.
  
     Immediate and mask fields which are less than one byte or
     have special range constraints are still checked as before,
     giving message ASMA031E if the value is invalid.
  
     Here are some examples of instructions where the immediate
     operand is not in the correct unsigned or signed range
     according to the instruction definition but which are
     accepted without warnings when TYPECHECK(NOSIGNED) is
     specified:
  
       MVI  0(1),-1   is accepted as   MVI  0(1),X'FF'
       TMLL 0,-1      is accepted as   TMLL 0,X'FFFF'
       LHI  0,X'FFFF' is accepted as   LHI  0,-1
  
     Note that sign propagation for signed immediate fields may
     cause confusion when unsigned values outside the signed range
     are used.  In the LHI example, the register will be set to
     the value X'FFFFFFFF', equal to -1, not the specified value
     X'0000FFFF', equal to 65535.  Signed immediate operands
     should normally be entered as the actual value to be used,
     regardless of the form in which the operand appears within
     the generated instruction.
  
  3. Messages ASMA031E and ASMA320W, which are produced when
     immediate values are invalid or out of range, have now been
     modified to show the relevant value.
  
  4. The ILMA option has been moved before the INFO option in
     the OPTIONS report to correct the alphabetical sequence.
  
  Note that this APAR replaces the installation default options
  module ASMADOPT and the macro ASMAOPT used to generate it, so
  any modified local installation defaults (normally defined as
  USERMOD ML00001 based on the sample ASMAOPTS job) must be
  reapplied after installing the PTF.
  
  DOCUMENTATION UPDATES:
  
  The HLASM Programmer's Guide, SC26-4941-08 is updated for the
  new options.
  
  In the section "Assembler options", the FLAG option is updated
  to include the RENT/NORENT options.
  
  In the FLAG syntax diagram, the option RENT/NORENT is added
  after RECORD/NORECORD.  The default is RENT, so that is above
  the line.
  
  In the FLAG defaults, RENT is added after RECORD.  There is no
  abbreviation for this option.
  
  In the FLAG options list, RENT and NORENT are added after
  NORECORD:
  
    RENT
      Instructs the assembler to issue diagnostic warning message
      ASMA036W if reentrant checks as specified by the RENT option
      detect a potential error.
  
    NORENT
      Instructs the assembler not to issue diagnostic warning
      message ASMA036W.
  
  In the section "Assembler options", the TYPECHECK option is
  updated to include the SIGNED/NOSIGNED options.
  
  The default in the syntax diagram and under the "Default"
  heading is changed to:
    TYPECHECK(MAGNITUDE,REGISTER,SIGNED)
  
  The SIGNED/NOSIGNED option is added to the syntax diagram below
  the REGISTER/NOREGISTER option.
  
  The abbreviations list is updated to include the corresponding
  abbreviations SI and NOSI.
  
  The descriptions for MAGNITUDE and NOMAGNITUDE are updated
  as follows:
  
    MAGNITUDE
      Specifies that the assembler performs magnitude validation
      of signed or unsigned immediate-data machine instruction
      operands occupying 1 to 3 bytes, ensuring that the specified
      value fits within the operand field.
  
    NOMAGNITUDE
      Specifies that the assembler does not perform magnitude
      validation of signed or unsigned immediate-data machine
      instruction operands occupying 1 to 3 bytes.  The value
      stored is simply the appropriate number of low-order bits of
      the specified value.
  
  Descriptions for SIGNED and NOSIGNED are added as follows:
  
    SIGNED
      Specifies that the validation for TYPECHECK(MAGNITUDE) takes
      into account whether the field is signed or not, and only
      allows the relevant signed or unsigned range of values.
      This has no effect when TYPECHECK(NOMAGNITUDE) is in effect.
  
    NOSIGNED
      Specifies that the validation for TYPECHECK(MAGNITUDE) does
      not take into account whether the field is signed or not,
      allowing values to be within the valid range of either
      signed or unsigned values for the size of the field.
  
  Similar updates are applied to the HLASM Language Reference,
  SC26-4940-09, where the ACONTROL section on the FLAG option is
  updated to include RENT/NORENT and the section on the TYPECHECK
  option is updated to include SIGNED/NOSIGNED.
  
  In the HLASM Installation and Customization Guide, SC26-3494-05,
  there are new ASMAOPT options to set the default values for
  the new options, and the description of TYPECHECK(MAGNITUDE) is
  changed.
  
    RENTWARN=YES|NO
  
      YES
        Instructs the assembler to perform reentrancy checks as
        specified by the RENT option and issue diagnostic warning
        message ASMA036W for reentrant check failures.
  
      NO
        Instructs the assembler not to issue diagnostic warning
        message ASMA036W.
  
      Default
        RENTWARN=YES
  
      Note: This option can be specified as an assembler
      invocation parameter by specifying the FLAG(RENT|NORENT)
      option.
  
    TYPECHECK=(MAGNITUDE,REGISTER,SIGNED)
  
      MAGNITUDE | NOMAGNITUDE
        Specifies whether the assembler performs magnitude
        validation of signed or unsigned immediate-data machine
        instruction operands occupying 1 to 3 bytes, ensuring that
        the specified value fits within the operand field.
  
      ...
  
      SIGNED | NOSIGNED
        Specifies whether magnitude validation of immediate-data
        operand values should take into account whether the field
        is signed, or should allow both signed and unsigned values
        regardless.
  
  In Appendix F of the Programmer's Guide, the documentation of
  messages ASMA031E and ASMA320W is updated to append a message
  insert "- xxxxxxxx" which identifies the immediate operand value
  that caused the problem.
  
  END OF DOCUMENTATION UPDATES
  

APAR Information

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

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

  UI76369 UI76370 UI76371

Modules/Macros

•    ASMADOPT ASMAINFO ASMAOPT  ASMA00   ASMA01
  ASMA03   ASMA2I   ASMA7DE  ASMA7EN  ASMA7ES  ASMA7JP  ASMA7UE
  ASMA9Z
  

Fix information

• Fixed component name

  HLASM MVS, VM &

• Fixed component ID

  569623400

Applicable component levels

• R160 PSY UI76370

     UP21/07/22 P F107

• R360 PSY UI76369

     UP21/07/21 P 2107

• R689 PSY UI76371

     UP21/07/21 I 1000

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.