What is the best way of creating peep hole rules that recurse from the
bottom to the top?
I mark them with comments, but that results in other rules not being
able to detect them.
Is there a better way of doing this?
Is this a sign such things should be rather done in the code generator?
Currently I'm doing it like this:
```
// especially needed by HIDE_BKG etc
replace {
ldh a, (%1)
and a, #%2
ldh (%1), a
ldh a, (%1)
and a, #%3
ldh (%1), a
} by {
; switched to ldh (c)
ld c, #<(%1)
ldh a, (c)
and a, #%2
ldh (c), a
ldh a, (c)
and a, #%3
ldh (c), a ; c is #<(%1)
} if notUsed('c'), notSame(%1 'c')
replace {
ldh (c), a ; c is #<(%1)
ldh a, (%1)
and a, #%2
ldh (%1), a
} by {
; switched to ldh (c)
ldh (c), a
ldh a, (c)
and a, #%2
ldh (c), a ; c is #<(%1)
} if notSame(%1 'c')
```
Background: `ldh (c), a` is one, `ldh (#0xffXX), a` is 2 bytes and `ld
(#0xffXX), a` is 3 bytes.
`ldh (c), a` is ultimately a faster version of `ldh (hl), a`.
--
Freundliche Grüße / Yours sincerely
Sebastian Riedel
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