doc

CompilerDevelopment.md

@@ -12,6 +12,9 @@
 * The same argument applies to `IMemSizer`, and - not entirely sure about that - `IBuiltinFunctions`.
 
 #### Steps to take, in conceptual (!) order:
+
+(note: all these steps have been implemented, rejected or otherwise solved now.)
+
 1. introduce an abstraction `SourceCode` that encapsulates the origin and actual loading of Prog8 source code
    - from the local file system (use case: user programs)
    - from resources (prog8lib)

docs/source/todo.rst

@@ -3,7 +3,9 @@ TODO
 
 For next release
 ^^^^^^^^^^^^^^^^
-...
+- answer the question in zeropage.kt makeAllocation():  numerical variables in zeropage never have an initial value here TODO why not?
+- (for 7.9:) remove support for old @"screencodes" string encoding syntax, parser+code+docs
+- ...
 
 
 Need help with
@@ -21,47 +23,53 @@ Blocked by an official Commander-x16 r39 release
 
 Future Things and Ideas
 ^^^^^^^^^^^^^^^^^^^^^^^
-- remove support for old @"screencodes" string encoding syntax (parser+code+docs)
+Compiler:
+
+- writeAssembly(): make it possible to actually get rid of the VarDecl nodes by fixing the rest of the code mentioned there.
 - allow "xxx" * constexpr  (where constexpr is not a number literal), now gives expression error not same type
 - unify FunctioncallExpression + FunctioncallStatement and PipeExpression + Pipe statement classes, may require moving Expression/Statement into interfaces instead of abstract base classes
 - for the pipe operator: recognise a placeholder (``?`` or ``%`` or ``_``) in a non-unary function call to allow non-unary functions in the chain; ``4 |> mkword(?, $44) |> print_uw``
 - for the pipe operator: make it 100% syntactic sugar so there's no need for asm codegen like translatePipeExpression
 - make it possible to inline non-asmsub routines that just contain a single statement (return, functioncall, assignment)
-  but this requires all identifiers in the inlined expression to be changed to fully scoped names
-- simplifyConditionalExpression() should not split expression if it still results in stack-based evaluation
-- simplifyConditionalExpression() sometimes introduces needless assignment to r9 tempvar
+  but this requires all identifiers in the inlined expression to be changed to fully scoped names.
+  If we can do that why not perhaps also able to inline multi-line subroutines? Why would it be limited to just 1 line? Maybe to protect against code bloat.
+- simplifyConditionalExpression() should not split expression if it still results in stack-based evaluation, but how does it know?
+- simplifyConditionalExpression() sometimes introduces needless assignment to r9 tempvar (scenario sought)
 - consider adding McCarthy evaluation to shortcircuit and and or expressions. First do ifs by splitting them up? Then do expressions that compute a value?
 - use more of Result<> and Either<> to handle errors/ nulls better?
-- rethink the whole "isAugmentable" business.  Because the way this is determined, should always also be exactly mirrorred in the AugmentableAssignmentAsmGen or you'll get a crash at code gen time.
-- can we get rid of pieces of asmgen.AssignmentAsmGen by just reusing the AugmentableAssignment ? generated code should not suffer
 - make it possible to use cpu opcodes such as 'nop' as variable names by prefixing all asm vars with something such as ``p8v_``? Or not worth it (most 3 letter opcodes as variables are nonsensical anyway)
   then we can get rid of the instruction lists in the machinedefinitions as well?
-- c64: make the graphics.BITMAP_ADDRESS configurable (VIC banking)
-- optimize several inner loops in gfx2 even further?
-- add modes 2 and 3 to gfx2 (lowres 4 color and 16 color)?
-- add a flood fill routine to gfx2?
-- add a diskio.f_seek() routine for the Cx16 that uses its seek dos api?
-- make it possible for diskio to read and write from more than one file at the same time (= use multiple io channels)?
-- fix problems in c128 target
-- add (u)word array type (or modifier?) that puts the array into memory as 2 separate byte-arrays 1 for LSB 1 for MSB -> allows for word arrays of length 256
 - [problematic due to 64tass:] add a compiler option to not remove unused subroutines. this allows for building library programs. But this won't work with 64tass's .proc ...
   Perhaps replace all uses of .proc/.pend by .block/.bend will fix that?
   (but we lose the optimizing aspect of the assembler where it strips out unused code.
   There's not really a dynamic switch possible as all assembly lib code is static and uses one or the other)
-- zig 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 this)
-- get rid of all TODO's in the code ;)
+- 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 this)
+- add special (u)word array type (or modifier?) that puts the array into memory as 2 separate byte-arrays 1 for LSB 1 for MSB -> allows for word arrays of length 256
 
+Libraries:
 
-More optimization ideas
-^^^^^^^^^^^^^^^^^^^^^^^
-- VariableAllocator: can we think of a smarter strategy for allocating variables into zeropage, rather than first-come-first-served
-- translateFunctioncall() in BuiltinFunctionsAsmGen: should be able to assign parameters to a builtin function directly from register(s), this will make the use of a builtin function in a pipe expression more efficient without using a temporary variable
-- translateNormalAssignment() -> better code gen for assigning boolean comparison expressions
-- when a for loop's loopvariable isn't referenced in the body, and the iterations are known, replace the loop by a repeatloop
-- automatically convert if statements that test for multiple values (if X==1 or X==2..) to if X in [1,2,..] statements, instead of just a warning.
+- fix the problems in c128 target, and flesh out its libraries.
+- c64: make the graphics.BITMAP_ADDRESS configurable (VIC banking)
+- optimize several inner loops in gfx2 even further?
+- add modes 2 and 3 to gfx2 (lowres 4 color and 16 color)?
+- add a flood fill routine to gfx2?
+- add a diskio.f_seek() routine for the Cx16 that uses its seek dos api? (only if that's stable)
+
+Expressions:
+
+- rethink the whole "isAugmentable" business.  Because the way this is determined, should always also be exactly mirrorred in the AugmentableAssignmentAsmGen or you'll get a crash at code gen time.
+- can we get rid of pieces of asmgen.AssignmentAsmGen by just reusing the AugmentableAssignment ? generated code should not suffer
 - rewrite expression tree evaluation such that it doesn't use an eval stack but flatten the tree into linear code that uses a fixed number of predetermined value 'variables'?
   "Three address code" was mentioned.  https://en.wikipedia.org/wiki/Three-address_code
   these variables have to be unique for each subroutine because they could otherwise be interfered with from irq routines etc.
 - this removes the need for the BinExprSplitter? (which is problematic and very limited now)
   and perhaps as well the assignment splitting in  BeforeAsmAstChanger too
+
+Optimizations:
+
+- VariableAllocator: can we think of a smarter strategy for allocating variables into zeropage, rather than first-come-first-served
+- translateFunctioncall() in BuiltinFunctionsAsmGen: should be able to assign parameters to a builtin function directly from register(s), this will make the use of a builtin function in a pipe expression more efficient without using a temporary variable
+- translateNormalAssignment() -> better code gen for assigning boolean comparison expressions
+- when a for loop's loopvariable isn't referenced in the body, and the iterations are known, replace the loop by a repeatloop
+- automatically convert if statements that test for multiple values (if X==1 or X==2..) to if X in [1,2,..] statements, instead of just a warning.
 - introduce byte-index operator to avoid index multiplications in loops over arrays? see github issue #4