fix subroutine calling convention for @Rx parameters: don't pass them via cpu registers

codeGenCpu6502/src/prog8/codegen/cpu6502/FunctionCallAsmGen.kt

@@ -15,12 +15,16 @@ internal class FunctionCallAsmGen(private val program: PtProgram, private val as
         // just ignore any result values from the function call.
     }
 
-    internal fun optimizeIntArgsViaCpuRegisters(params: List<PtSubroutineParameter>) =
-        when(params.size) {
-            1 -> params[0].type.isIntegerOrBool
-            2 -> params[0].type.isByteOrBool && params[1].type.isByteOrBool
+    internal fun optimizeIntArgsViaCpuRegisters(params: List<PtSubroutineParameter>): Boolean {
+        // When the parameter(s) are passed via an explicit register or register pair,
+        // we consider them NOT to be optimized into (possibly different) CPU registers.
+        // Just load them in whatever the register spec says.
+        return when (params.size) {
+            1 -> params[0].type.isIntegerOrBool && params[0].register == null
+            2 -> params[0].type.isByteOrBool && params[1].type.isByteOrBool && params[0].register == null && params[1].register == null
             else -> false
         }
+    }
 
     internal fun translateFunctionCall(call: PtFunctionCall) {
         // Output only the code to set up the parameters and perform the actual call

docs/source/todo.rst

@@ -14,8 +14,9 @@ Future Things and Ideas
 - Kotlin: can we use inline value classes in certain spots?
 - allow multi-value variable initialization (var a,b,c  = 1,2,3)
 - Improve the SublimeText syntax file for prog8, you can also install this for 'bat': https://github.com/sharkdp/bat?tab=readme-ov-file#adding-new-syntaxes--language-definitions
-- Compiling Libraries: improve ability to create library files in prog8; for instance there's still stuff injected into the start of the start() routine AND there is separate setup logic going on before calling it.
-  Make up our mind! Maybe all setup does need to be put into start() ? because the program cannot function correctly when the variables aren't initialized properly bss is not cleared etc. etc.
+- Compiling Libraries: improve ability to create library files in prog8; for instance there's still stuff injected into the start of the start() routine (see translateSubroutine function)
+  AND there is separate setup logic going on before calling it. Make up our mind!
+  Maybe all setup does need to be put into start() ? because the program cannot function correctly when the variables aren't initialized properly bss is not cleared etc. etc.
   Add a -library $xxxx command line option (and/or some directive) to preselect every setting that is required to make a library at $xxxx rather than a normal loadable and runnable program?
   Need to add some way to generate a stable jump table at a given address.
   Need library to not call init_system AND init_system_phase2 not either.

examples/test.p8

@@ -1,34 +1,53 @@
-%import floats
-%import sprites
+%import textio
 %option no_sysinit
 %zeropage basicsafe
 
 
 main {
     sub start() {
+;        uword @shared uw1 = 1001
+;        uword @shared uw2 = 1001
+;        ubyte @shared ub = 42
+;        ubyte @shared index = 2
+;
+;        uword[] array1 = [999,1000,1001]
+;        uword[] @nosplit array2 = [999,1000,1001]
 
-        cx16.mouse_config2(1)
+;        func2(array1[index], ub)      ; args via subroutine variables  (R1, R2)
+;        func2(uw2, ub)                ; args via subroutine variables  (R1, R2)
+;        func1(1001)                   ; arg via AY? or R1?
+;        func1(array1[index])          ; arg via AY? or R1?
+;        func1(array2[index])          ; arg via AY? or R1?
 
-        sprites.init(1, 0, 0, sprites.SIZE_64, sprites.SIZE_64, sprites.COLORS_16, 0)
-
-        sprites.pos(1, 100, 100)
-
-        repeat {
-            word x,y
-            x,y = sprites.getxy(0)
-            sprites.pos(1, x, y)
-        }
-
-        float fz
-        cx16.r0L = single()
-        cx16.r0L, fz = multi()
+        main.func1.arg1 = 9999
+        %asm {{
+            lda  #0
+            ldy  #0
+            jsr  p8s_func1
+        }}
+        cx16.r3 = 8888
+        %asm {{
+            lda  #0
+            ldy  #0
+            jsr  p8s_func1
+        }}
     }
 
-    sub single() -> ubyte {
-        return xx
-    }
+;    sub func2(uword arg1 @R1, ubyte arg2 @R2) {   ; expected args via variables  R1+R2
+;        txt.print_uw(arg1)
+;        txt.chrout('=')
+;        txt.print_uw(cx16.r1)
+;        txt.spc()
+;        txt.print_ub(arg2)
+;        txt.chrout('=')
+;        txt.print_ub(cx16.r2L)
+;        txt.nl()
+;    }
 
-    sub multi() -> ubyte, float {
-        return xx, 3.33
+    sub func1(uword arg1 @R3) {   ; expected arg1 via R3,  not via cpu regs AY
+        txt.print_uw(arg1)
+        txt.chrout('=')
+        txt.print_uw(cx16.r3)
+        txt.nl()
     }
 }

intermediate/src/prog8/intermediate/IRInstructions.kt

@@ -1030,6 +1030,8 @@ data class IRInstruction(
     }
 
     private fun determineReg2Type(): IRDataType? {
+        if(opcode==Opcode.LOADX || opcode==Opcode.LOADIX || opcode==Opcode.STOREX || opcode==Opcode.STOREIX)
+            return IRDataType.BYTE
         if(opcode==Opcode.LOADI || opcode==Opcode.STOREI)
             return IRDataType.WORD
         if(opcode==Opcode.MSIG || opcode==Opcode.LSIG)