base + index register addressing

[meissner@cygnus.com]

| 
|   In message <199710170919.WAA23619@ongaonga.chch.cri.nz>you write:
|   > 
|   > Here's a patch that I've found that improves register allocation
|   > where the memory address is the sum of two registers.
| Don't forgot those ChangeLog entries!
| 
| I've installed this patch into egcs.

I was going to comment that the patch might be even better, if it dealt with
register + scaled register that some machines have (such as the x86, ns32k, 88k
to name the ones I've dealt with).