fix asm gen for loops when dealing with registers as loopvar

compiler/src/prog8/compiler/target/c64/AsmPatterns.kt

@@ -2066,7 +2066,20 @@ internal val patterns = listOf<AsmPattern>(
         AsmPattern(listOf(Opcode.PUSH_VAR_BYTE, Opcode.CMP_B), listOf(Opcode.PUSH_VAR_BYTE, Opcode.CMP_UB)) { segment ->
             // this pattern is encountered as part of the loop bound condition in for loops (var + cmp + jz/jnz)
             val cmpval = segment[1].arg!!.integerValue()
-            " lda  ${segment[0].callLabel} |  cmp  #$cmpval "
+            when(segment[0].callLabel) {
+                "A" -> {
+                    " cmp #$cmpval "
+                }
+                "X" -> {
+                    " cpx #$cmpval "
+                }
+                "Y" -> {
+                    " cpy #$cmpval "
+                }
+                else -> {
+                    " lda  ${segment[0].callLabel} |  cmp  #$cmpval "
+                }
+            }
         },
         AsmPattern(listOf(Opcode.PUSH_VAR_WORD, Opcode.CMP_W), listOf(Opcode.PUSH_VAR_WORD, Opcode.CMP_UW)) { segment ->
             // this pattern is encountered as part of the loop bound condition in for loops (var + cmp + jz/jnz)

examples/test.p8

@@ -4,17 +4,13 @@
 ~ main {
 
     sub start() {
-        A=0
-        Y=0
-        ubyte aa =0
-
-        Y=10
-
         for A in 0 to 4 {
             for Y in 0 to 3 {
                 rsave()
                 c64scr.print_ub(A)
                 c64.CHROUT(',')
+                rrestore()
+                rsave()
                 c64scr.print_ub(Y)
                 c64.CHROUT('\n')
                 rrestore()