FIX: Incorrect Code Generated If Operand Is [esp][esp] (79159)

The information in this article applies to:

Microsoft Macro Assembler (MASM) 6.0

This article was previously published under Q79159

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

should have been generated by the assembler.

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
main ENDP
CODE32 ENDS

END

Modification Type:	Minor	Last Reviewed:	11/19/2003
Keywords:	kbfix KB79159