Assembler Optimizer

I haven't yet updated the release, but I just pushed a commit where I started adding support for some of sjasm syntax using -dialect sjasm (only the bare minimum I needed for making it work on the Metal Gear disassembly here: https://github.com/GuillianSeed/MetalGear ). 51 patterns matched, saving 52 bytes, only a little bit, but not bad for the first set of patterns (which have not changed for a while!).

It is interesting as each codebase seems to find one corner case or another that I didn't have covered. For example, sjasm uses "#" as a keyword, and I had never thought "#" would be used for anything else than hex constants!

So, still not all of them addressed, but walking down your list TheNestruo ;)

Might dedicate one or two more days to the parser to make it more robust and make sure what is implemented works correctly, and then I will move on to expand the pattern database, to see how far can this first pattern approach be pushed.

I think register allocation algorithms are complex topics, see below paper related to the one from SDCC:
register allocator for Z80 research paper

Finding an improved version seems quite an undertanking.

SDCC peephole optimization for z80 is pretty bad, but is customizable; this is used in Fuzix to improve code generation:

Fuzix peep for z80

"register allocation", the SDCC example that I posted did not run out of registers, but it uses 3 address registers for one pointer variable!
it misses a special feature: "p->x", say p is in HL. now is needed to do some INC HL to get at the x of the struct. and then HL has a different value than the p variable! and for that to be possible the compiler needs a special feature.

to use (iy+offset) is easier because IY stays the same value as the C pointer. but still SDCC doesnt have this (it did INC IY in the example that I posted).

using (iy+offset) could make this simple nice code

;while(1) {
loop:
;p->x += p->dx;
	ld  a,0(iy)
	add 2(iy)
	ld  2(iy),a
	ld  a,1(iy)
	adc 3(iy)
	ld  3(iy),a
	jr  loop
;}
--
139 cycles

I just pushed a new release (alpha v4): https://github.com/santiontanon/mdlz80optimizer/releases/tag...

This release fixes many, many things and adds better support for Glass/asMSX/sjasm syntax (sjasm support is only barebones for now though). For example, I was able to now verify that the symbol tables generated by mdl exactly match those generated by Glass in some more complex projects like "threed".

But the most exciting news is that there is now support for integrating mdl into IDEs/text editors! (thanks to theNestruo for this!). For example, here're a couple of screenshots of it working in VSCode and Sublime Text. This is already being very useful for me, so, I hope it can be useful for others too. If you give it a try and find any issues by all means let me know. We just added support for this yesterday, and I bet there's LOTS of rough edges still!

A nice modern superoptimizer
https://arxiv.org/abs/1711.04422
https://github.com/google/souper

Sadly it works on the intermediate representation (IR) in LLVM
IR is language independent but I do not think it can be translated to z80 asm easily.