KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q24953: Phase Errors May Be Caused By Forward References

Article: Q24953
Product(s): Microsoft Macro Assembler
Version(s): 1.25,1.27,3.0x,4.0,5.0,5.1
Operating System(s): 
Keyword(s): 
Last Modified: 06-MAY-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Macro Assembler (MASM), versions 1.25, 1.27, 3.0x, 4.0, 5.0, 5.1 
-------------------------------------------------------------------------------

SUMMARY
=======

Phase errors indicate that a relative address of a label changed between pass 1
and pass 2 of the assembly process. They usually are caused by improper forward
references to labels. During pass 1, the assembler will have to make assumptions
(e.g. it might assume a near jump during pass 1 if the location of a label is
not known). During pass 2, the assembler may have to change those assumptions
(e.g. now it knows that the jump is to a far label). If this involves changing
the size of an instruction, that difference can cause a phase error.

To examine the assumptions made by the assembler on pass 1, use the /D option to
get a pass 1 listing.

MORE INFORMATION
================

Phase errors can usually be prevented by using segment overrides or explicit
type specification, as shown in the following examples:

     jmp dword ptr far_label         ;jump to far label

     mov ax, word ptr label

Additional query words: 1.25 1.27 3.0x 4.00 5.00 5.10

======================================================================
Keywords          :  
Technology        : kbMASMsearch kbAudDeveloper kbMASM510 kbMASM125 kbMASM127 kbMASM30xSearch kbMASM400 kbMASM500
Version           : :1.25,1.27,3.0x,4.0,5.0,5.1

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.