PrefixExpression doesn't cause clobber risk

codeGeneration/src/prog8/compiler/target/cpu6502/codegen/AsmsubHelpers.kt

@@ -44,9 +44,6 @@ internal fun asmsub6502ArgsHaveRegisterClobberRisk(args: List<Expression>,
                     it.registerOrPair in listOf(RegisterOrPair.Y, RegisterOrPair.AY, RegisterOrPair.XY)
                 }
             }
-            is PrefixExpression -> {
-                return true         // TODO really, is prefixexpression problematic for register clobbering?
-            }
             is FunctionCall -> {
                 if (expr.target.nameInSource == listOf("lsb") || expr.target.nameInSource == listOf("msb"))
                     return isClobberRisk(expr.args[0])

docs/source/todo.rst

@@ -3,9 +3,6 @@ TODO
 
 For next compiler release (7.4)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Figure out in asmsub6502ArgsHaveRegisterClobberRisk  if prefixexpression is clobbering or not
-
-
 Use GoSub to call subroutines (statements):
     - [DONE] allow separate assigns to subroutine's parameter variables / registers
     - [DONE] turn a regular subroutine call into assignments to the parameters + GoSub (take code from gosub branch)

examples/test.p8

@@ -5,6 +5,32 @@
 main {
 
     sub start() {
-        ubyte[] array = 100 to 50 step -2
+        ubyte @shared dummy
+        word b1 = 1111
+        byte b2 = 22
+        word b3 = 3333
+        dummy++
+        func(-b1,-b2,-b3)
+    }
+
+    sub printz(word a1, byte a2, word a3) {
+        txt.print_w(a1)
+        txt.spc()
+        txt.print_b(a2)
+        txt.spc()
+        txt.print_w(a3)
+        txt.nl()
+    }
+    asmsub func(word a1 @XY, byte a2 @A, word a3 @R0) {
+        %asm {{
+            stx  printz.a1
+            sty  printz.a1+1
+            sta  printz.a2
+            lda  cx16.r0
+            sta  printz.a3
+            lda  cx16.r0+1
+            sta  printz.a3+1
+            jmp  printz
+        }}
     }
 }