MAME debugger not handling mirrored addresses correctly?

[alamone]

I actually talked to trap15 about this, and he said that basically an entire rewrite of how MAME works would be required to get this functionality in.
I know some MAME devs check out this forum so maybe they could chime in.

Basically, my problem is that the MAME debugger does not catch accesses to mirrored addresses. The game I'm working on is Gradius IV.
If I recall, it mirrors the first half of the address space (0 to 0x7FFFFFFF) to the second half (0x8000000 onwards). However, the breakpoint, watchpoint, etc.
only catch accesses to the first half. I can't even set breakpoints to the upper half of the memory. But most of the activity seems to occur in the upper
mirrored addresses. Because of this, I've been having to do traces and dump huge ASM dumps and pore over them painstakingly to find the routines I want to modify,
which is a real pain in the arse. Am I missing something here?