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Update notes in README.

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Chris Pressey 2018-02-08 12:18:55 +00:00
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@ -56,6 +56,9 @@ But if you add a value ≥ N to it, it becomes invalid.
This should be tracked in the abstract interpretation.
(If only because abstract interpretation is the major point of this project!)
Range-checking buffers might be too difficult. Range checking tables will be easier.
If a value is ANDed with 15, its range must be 0-15, etc.
### Routine-local static memory locations
These would not need to appear in the inputs/outputs/trashes sets of the routines
@ -64,24 +67,31 @@ that call this routine.
These might be forced to specify an initial value so that they can always be
assumed to be meaningful.
### More modes for `copy`
* don't allow `copy foo, a` probably. insist on `ld a, foo` for this.
* have `copy` instruction able to copy a byte to a user-def mem loc, etc.
* `copy x, [ptr] + y`
* Maybe even `copy [ptra] + y, [ptrb] + y`, which can be compiled to indirect LDA then indirect STA!
### Union rule for trashes in `if`
If one branch trashes {`a`} and the other branch trashes {`b`} then the whole
`if` statement trashes {`a`, `b`}.
### Re-order routines and optimize tail-calls to fallthroughs
Not because it saves 3 bytes, but because it's a neat trick. Doing it optimally
is probably NP-complete. But doing it adeuqately is probably not that hard.
### And at some point...
* Check that the buffer being read or written to through pointer, appears in approporiate inputs or outputs set.
* `interrupt` routines -- to indicate that "the supervisor" has stored values on the stack, so we can trash them.
* error messages that include the line number of the source code
* add absolute addressing in shl/shr, absolute-indexed for add, sub, etc.
* check and disallow recursion.
* automatic tail-call optimization (could be tricky, w/constraints?)
* re-order routines and optimize tail-calls to fallthroughs
* `st a, [ptr] + y`, possibly `ld x, [ptr] + y`, possibly `st x, [ptr] + y`
* Maybe even `copy [ptra] + y, [ptrb] + y`, which can be compiled to indirect LDA then indirect STA!
Things it will not do
---------------------
(this will be moved to a FAQ document at some point)
* Check that a vector is initialized before it's called.
* Check for recursive calls, or prevent bad things happening because of recursive calls.
(You can always recursively call yourself through a vector.)