Phase Errors May Be Caused By Forward References (24953)

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.

   jmp dword ptr far_label         ;jump to far label

   mov ax, word ptr label