FIX: Incorrect Code Generated for IRET With PROC USES

MS-DOS     | OS/2

The information in this article applies to:

• Microsoft Macro Assembler for MS-DOS and OS/2, versions 5.1 and 5.1a

SYMPTOMS

A procedure that uses the USES keyword cannot return by using IRET. The USES statement pushes the specified registers on the stack upon entry and pops them before exiting a procedure. If the USES keyword is used with a procedure that ends with an IRET instruction, the pushes will be generated for the procedure, but the pops will not.

STATUS

Microsoft has confirmed this to be a problem in MASM versions 5.1 and 5.1a. This problem has been corrected in MASM version 6.0.

MORE INFORMATION

The following code demonstrates the problem. The di, si, and bp registers will be pushed onto the stack, but not popped.

Source Code:

; Compile options needed: none

         .model large, c

         .code

   first PROC far uses di si bp
         MOV si,3
         MOV di,4
         IRET
   first ENDP

         END first