FIX: Incorrect Code Generated If Operand Is [esp][esp]

The information in this article applies to:

• Microsoft Macro Assembler for MS-DOS, version 6.0
• Microsoft Macro Assembler for OS/2, version 6.0

SYMPTOMS

In the Microsoft Macro Assembler (MASM) version 6.0, incorrect code is generated for instructions using operand [esp][esp], such as the following instructions:

   lea esi, [esp][esp]
   mov esi, [esp][esp]

CAUSE

The operand [esp][esp] is not supported in the Intel instruction set. An error such as:

   error A2029 : multiple base registers not allowed

STATUS

Microsoft has confirmed this to be a problem in MASM version 6.0. This problem was corrected in MASM version 6.0a.

MORE INFORMATION

A listing file from the following program will show that the instruction lea esi, [esp][esp] is encoded as 8D 34 24. This is incorrect.

Sample Code

; Assembler options needed: none

.386 .MODEL flat .STACK 4096

CODE32 SEGMENT PUBLIC USE32 main PROC near

    lea esi, [esp][esp]      ; An error A2029 should be generated.
    ret

END