regno_reg_rtx and related macros

[Richard Kenner]

    So unrealistic that gcc even has a documented option which is supposed
    to provide such information for a debugger:

    `-gLEVEL'

     ...

     Level 3 includes extra information, such as all the macro
     definitions present in the program.  Some debuggers support macro
     expansion when you use `-g3'.


Right, but my understanding is that this is meant to allow *constants* to
be understood by the debugger.  Full macro expansion is quite another thing.
Certainly, I'm all for it if it can be done, but I'm somewhat dubious.