Revert "optimized repeat loop for word counts"

This reverts commit 51e6bf0d

compiler/src/prog8/compiler/target/cpu6502/codegen/AsmGen.kt

@@ -1008,30 +1008,28 @@ internal class AsmGen(private val program: Program,
     }
 
     private fun repeatWordCountInAY(constIterations: Int?, repeatLabel: String, endLabel: String, body: AnonymousScope) {
-        // note: A/Y must have been loaded with the number of iterations!
         if(constIterations==0)
             return
-        if(constIterations==null) {
+        // note: A/Y must have been loaded with the number of iterations already!
-            out( """
-                cmp  #0
-                bne  +
-                cpy  #0
-                beq  $endLabel      ; skip if 0 iterations
-+""")
-        }
         val counterVar = makeLabel("repeatcounter")
         out("""
-            sta  $counterVar
+            cmp  #0
-            iny
+            bne  +
+            cpy  #0
+            beq  $endLabel      ; skip if 0 iterations
++           sta  $counterVar
             sty  $counterVar+1
-$repeatLabel""")
+$repeatLabel
-        translate(body)
+            lda  $counterVar
-        out("""
+            bne  +
-            dec  $counterVar
+            lda  $counterVar+1
-            bne  $repeatLabel
+            beq  $endLabel
++           lda  $counterVar
+            bne  +
             dec  $counterVar+1
-            bne  $repeatLabel
++           dec  $counterVar""")
-            beq  $endLabel""")
+        translate(body)
+        jmp(repeatLabel)
 
         if(constIterations!=null && constIterations>=16 && zeropage.available() > 1) {
             // allocate count var on ZP

examples/test.p8

@@ -3,51 +3,25 @@
 
 main {
 
-    sub iter(uword iterations) -> uword {
-        uword total = 0
-        repeat iterations {
-            repeat iterations {
-                total++
-            }
-        }
-
-        return total
-
-    }
-
     sub start() {
         uword xx1
         uword xx2
         uword xx3
         uword iterations
 
-        xx1 = iter(0)
-        txt.print_uw(xx1)   ; 0
-        txt.nl()
-        xx1 = iter(10)
-        txt.print_uw(xx1)   ; 100
-        txt.nl()
-        xx1 = iter(16)
-        txt.print_uw(xx1)   ; 256
-        txt.nl()
-        xx1 = iter(20)
-        txt.print_uw(xx1)   ; 400
-        txt.nl()
-        xx1 = iter(200)
-        txt.print_uw(xx1)   ; 4000
-        txt.nl()
-        xx1 = iter(600)
-        txt.print_uw(xx1)   ; 32320
-        txt.nl()
-
-
         c64.SETTIM(0,0,0)
 
-        xx1=0
+        iterations = 0
-        xx2=0
+        repeat iterations {
-        xx3=0
+            repeat iterations {
+                xx1++
+                xx2++
+                xx3++
+            }
+        }
+
         iterations = 600
-        repeat 600 {
+        repeat iterations {
             repeat iterations {
                 xx1++
                 xx2++