Q30385

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Q30385: MOV with Type Operator Generates Incorrect Opcodes

Article: Q30385
Version(s): 5.10
Operating System: MS-DOS
Flags: ENDUSER | buglist5.10
Last Modified: 23-MAY-1988

The MOV instruction, using indirect addressing, and the Type
operator generate incorrect opcodes.

   The first MOV instruction generates the opcode "B8FFF4", which is a
move-immediate instruction. The assembler should generate the opcode
"8B44F4".  This opcode is generated on the second move instruction.
   MASM Version 5.00 generates the correct code for both MOV
instructions. The following code demonstrates the problem:

seg_1  segment  para  public  'code'
       assume cs:seg_1
test_str struc
test_f1  dw  ?
test_f2  dw  ?
test_f3  db  8 dup (?)
test_str ends
main_entry proc
       mov  ax,word ptr [si] - type test_str
;
;      This alternate generation works
;
       mov  ax,word ptr { si - type test_str]
main_entry endp
seg_1  ends
       end

   Microsoft is researching this problem and will post new information
as it becomes available.