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100 lines
7.3 KiB
ReStructuredText
100 lines
7.3 KiB
ReStructuredText
TODO
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====
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Can we move the asm init code that is injected into the start() subroutine, to init_system_phase2 instead?
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Doc improvements: some short overview for people coming from other programming languages like C:
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tell something about prog8 not having function overloading, max 16 bit (u)word integer as native type (and floats sometimes),
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static variable allocations, no dynamic memory allocation in the language itself (although possible via user written libraries),
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etc ...
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Improve register load order in subroutine call args assignments:
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in certain situations, the "wrong" order of evaluation of function call arguments is done which results
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in overwriting registers that already got their value, which requires a lot of stack juggling (especially on plain 6502 cpu!)
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Maybe this routine can be made more intelligent. See usesOtherRegistersWhileEvaluating() and argumentsViaRegisters().
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Future Things and Ideas
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^^^^^^^^^^^^^^^^^^^^^^^
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Compiler:
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- Can we support signed % (remainder) somehow?
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- Don't add "random" rts to %asm blocks but instead give a warning about it? (but this breaks existing behavior that others already depend on... command line switch? block directive?)
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- IR: implement missing operators in AssignmentGen (array shifts etc)
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- IR: CMPI+BSTEQ --> new BEQ reg,value,label instruction (like BGT etc)
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- instead of copy-pasting inline asmsubs, make them into a 64tass macro and use that instead.
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that will allow them to be reused from custom user written assembly code as well.
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- Multidimensional arrays and chained indexing, purely as syntactic sugar over regular arrays.
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- make a form of "manual generics" possible like: varsub routine(T arg)->T where T is expanded to a specific type
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(this is already done hardcoded for several of the builtin functions)
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- [much work:] more support for (64tass) SEGMENTS ?
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- (What, how, isn't current BSS support enough?)
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- Add a mechanism to allocate variables into golden ram (or segments really) (see GoldenRam class)
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- maybe treat block "golden" in a special way: can only contain vars, every var will be allocated in the Golden ram area?
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- maybe or may not needed: the variables can NOT have initialization values, they will all be set to zero on startup (simple memset)
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just initialize them yourself in start() if you need a non-zero value .
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- OR.... do all this automatically if 'golden' is enabled as a compiler option? So compiler allocates in ZP first, then Golden Ram, then regular ram
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- OR.... make all this more generic and use some %segment option to create real segments for 64tass?
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- (need separate step in codegen and IR to write the "golden" variables)
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- do we need (array)variable alignment tag instead of block alignment tag? You want to align the data, not the code in the block?
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- ir: related to the one above: block alignment doesn't translate well to variables in the block (the actual stuff that needs to be aligned in memory) but: need variable alignment tag instead of block alignment tag, really
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- ir: fix call() return value handling
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- ir: proper code gen for the CALLI instruction and that it (optionally) returns a word value that needs to be assigned to a reg
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- ir: idea: (but LLVM IR simply keeps the variables, so not a good idea then?...): replace all scalar variables by an allocated register. Keep a table of the variable to register mapping (including the datatype)
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global initialization values are simply a list of LOAD instructions.
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Variables replaced include all subroutine parameters! So the only variables that remain as variables are arrays and strings.
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- ir: add more optimizations in IRPeepholeOptimizer
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- ir: the @split arrays are currently also split in _lsb/_msb arrays in the IR, and operations take multiple (byte) instructions that may lead to verbose and slow operation and machine code generation down the line.
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maybe another representation is needed once actual codegeneration is done from the IR...?
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- ir: getting it in shape for code generation...
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- ir: make sure that a 6502 codegen based off the IR, still generates BIT instructions when testing bit 7 or 6 of a byte var.
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- [problematic due to using 64tass:] better support for building library programs, where unused .proc are NOT deleted from the assembly.
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Perhaps replace all uses of .proc/.pend/.endproc by .block/.bend will fix that with a compiler flag?
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But all library code written in asm uses .proc already..... (textual search/replace when writing the actual asm?)
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Once new codegen is written that is based on the IR, this point is mostly moot anyway as that will have its own dead code removal on the IR level.
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- Zig-like try-based error handling where the V flag could indicate error condition? and/or BRK to jump into monitor on failure? (has to set BRK vector for that) But the V flag is also set on certain normal instructions
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Libraries:
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- gfx2: add EOR mode support like in monogfx and see PAINT for inspiration. Self modifying code to keep it optimized?
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- fix the problems in atari target, and flesh out its libraries.
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- c128 target: make syslib more complete (missing kernal routines)?
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- pet32 target: make syslib more complete (missing kernal routines)?
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- VM: implement more diskio support
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Optimizations:
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- VariableAllocator: can we think of a smarter strategy for allocating variables into zeropage, rather than first-come-first-served?
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for instance, vars used inside loops first, then loopvars, then uwords used as pointers (or these first??), then the rest
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- various optimizers skip stuff if compTarget.name==VMTarget.NAME. Once 6502-codegen is done from IR code,
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those checks should probably be removed, or be made permanent
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STRUCTS?
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--------
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- declare struct *type*, or directly declare the variable itself? Problem with the latter is: you cannot easily define multiple variables of the same struct type.
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- can contain only numeric types (byte,word,float) - no nested structs, no reference types (strings, arrays) inside structs
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- only as a reference type (uword pointer). This removes a lot of the problems related to introducing a variable length value type.
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- arrays of struct is just an array of uword pointers. Can even be @split?
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- need to introduce typed pointer datatype in prog8
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- STR remains the type for a string literal (so we can keep doing register-indexed addressing directly on it)
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- ARRAY remains the type for an array literal (so we can keep doing register-indexed addressing directly on it)
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- we probably need to have a STRBYREF and ARRAYBYREF if we deal with a pointer to a string / array (such as when passing it to a function)
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the subtype of those should include the declared element type and the declared length of the string / array
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Other language/syntax features to think about
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---------------------------------------------
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- add (rom/ram)bank support to romsub. A call will then automatically switch banks, use callfar and something else when in banked ram.
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challenges: how to not make this too X16 specific? How does the compiler know what bank to switch (ram/rom)?
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How to make it performant when we want to (i.e. NOT have it use callfar/auto bank switching) ?
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Maybe by having a %option rombank=4 rambank=22 to set that as fixed rombank/rambank for that subroutine/block (and pray the user doesn't change it themselves)
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and then only do bank switching if the bank of the routine is different from the configured rombank/rambank.
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