Assembler Optimizer

ah, good point. I just generalized it to this:

pattern: replace ld ?reg2, a; ld ?reg16, ?const1; ld (?reg16), ?reg2 with ld (?const1), a
0: ld ?reg2, a
1: ld ?reg16, ?const1
2: ld (?reg16), ?reg2
replacement:
0: ld (?const1), a
constraints:
regsNotUsedAfter(2, ?reg2)
regsNotUsedAfter(2, ?reg16)
in(?reg16,bc,de,hl,ix,iy)

Thanks santiontanon! With the -po option it finishes in less than two minutes, but the -so is already running for a while. It will probably take an hour or so...

For big projects like this it would be very useful to be able to specify in which files MDL should look for optimizations.

Edit: Ok, -so finished in 25 minutes on an i3-10100, 981 optimization applied, 1289 bytes, 5195 t-states saved. -po found 2344 optimizations, 2438 bytes, 21544 t-states saved.

There are a few issues with generating a bin and using the generated asm.

If I try to generate a bin with the -bin option it ends with an error:
Negative space (-966656) in [insertactualnameofthegame].asm#9855: ds $100000-totallenght

The generated rom is about 3.5MB while it should be 2MB.

When generating an asm file, MDL turns something like this:

slot:
.ram:

into

slot.ram

which makes sjasmplus unable to assemble the code because SLOT is a reserved keyword, resulting in a warning "SLOT only allowed in real device emulation mode (See DEVICE)" and errors like "Label not found: slot.ram".

I didn't know that there's a limit to label lengths in sjasmplus but apparently there is a limit "Labels are case-sensitive and may be of any reasonable length, that is: up to about 70 characters.". It complains about HandleControls.LocationJumpTableCastlesFortressesAndSwitchPalaces (which is less than 70 characters).

If I fix these issues, sjasmplus still ends with a warning "Negative BLOCK?". The generated rom is about 1.92MB so it's too small. I increased the file size to 2MB by appending 0's and compared the result with the original rom, at least the files are the same so that's good

I'll try to see if I can find out where these size issues come from.

I've been looking at this, and I think I know the problem! It seems that even when using the "--longptr" option, sjasmplus clamps all the addresses at "1MB". I've been tracking the addresses in the different parts of the code, and once it passes 1MB, sjasmplus loops back to 0, while MDL keeps counting up. So, the final line of the code, that looks like this is problematic:

    ds $100000 - totallenght ;fill er up to the end

Notice that $100000 is exactly 1MB, but the ROM should be 2MB, so, that line should actually be:

    ds $200000 - totallenght ;fill er up to the end

Since sjasmplus seems to clamp at 1MB, the original code works in sjasmplus, as "totallenght" is incorrect. In MDL, "totallenght" is correct (2015232), and $100000 - 2015232 is a negative number.

I have not tried generating an optimized binary yet, I was just trying to generate a regular binary with -bin. But at least I think this is a clue. (also, I fixed a couple of bugs in MDL, so, it might be worth re-downloading the development release from the link above just in case)

@Ped7g if you read this, could you confirm my suspicion about the 1MB limit in sjasmplus? (or at least the limit with the default "device").

Great!

Yeah when I applied some optimizations I noticed that jerky scrolling too, but I don't remember exactly what caused it...