FIX: Incorrect RET Generated for PROC when EPILOGUE:NONE

MS-DOS                      | OS/2

The information in this article applies to:

• Microsoft Macro Assembler for MS-DOS, versions 6.0, 6.0a, 6.0b, 6.1, and 6.1a
• Microsoft Macro Assembler for OS/2, versions 6.0, 6.0a, and 6.0b

SYMPTOMS

When Microsoft Macro Assembler (MASM) processes source code for an application, it may generate the incorrect form for a RET instruction in a PROC. Specifically, the assembler generates a RET 4 instruction instead of a RET instruction when the source code contains a RET instruction.

CAUSE

The source code uses the OPTION EPILOGUE statement multiple times to set the EPILOGUE macro to NONE.

RESOLUTION

Modify the source code to specify RET 0. The assembler translates this expression into a RET instruction.

STATUS

Microsoft has confirmed this to be a problem in MASM versions 6.0, 6.0a, 6.0b, 6.1, and 6.1a. This problem was corrected in MASM for MS-DOS version 6.11.

MORE INFORMATION

The following code example demonstrates this problem:

Sample Code

; Assembler options needed: /c /Fl /Sa

.MODEL small, Pascal

_text SEGMENT

OPTION EPILOGUE:NONE p0 PROC parm1:DWORD

    ret                 ; This correctly generates a RET

OPTION EPILOGUE:EpilogueDef p1 PROC parm1:DWORD

    ret                 ; This correctly generates a RET 4

OPTION EPILOGUE:NONE p2 PROC parm1:DWORD

    ret                 ; This incorrectly generates a RET 4

_text ENDS

END