proper NOP removal

compiler/src/prog8/ast/base/Extensions.kt

@@ -6,6 +6,7 @@ import prog8.ast.processing.*
 import prog8.ast.statements.Assignment
 import prog8.ast.statements.ForLoop
 import prog8.compiler.CompilationOptions
+import prog8.optimizer.RemoveNops
 
 
 // the name of the subroutine that should be called for every block to initialize its variables
@@ -16,6 +17,12 @@ internal const val initvarsSubName="prog8_init_vars"
 internal const val autoHeapValuePrefix = "auto_heap_value_"
 
 
+internal fun Program.removeNops() {
+    val remover = RemoveNops()
+    remover.visit(this)
+}
+
+
 internal fun Program.checkValid(compilerOptions: CompilationOptions) {
     val checker = AstChecker(this, compilerOptions)
     checker.visit(this)

compiler/src/prog8/compiler/Main.kt

@@ -84,10 +84,11 @@ fun compileProgram(filepath: Path,
                 }
             }
 
+            programAst.removeNops()
             programAst.checkValid(compilerOptions)          // check if final tree is valid
             programAst.checkRecursion()         // check if there are recursive subroutine calls
 
-            printAst(programAst)
+            // printAst(programAst)
             // namespace.debugPrint()
 
             if(generateVmCode) {

compiler/src/prog8/optimizer/StatementOptimizer.kt

@@ -4,6 +4,7 @@ import prog8.ast.*
 import prog8.ast.base.*
 import prog8.ast.expressions.*
 import prog8.ast.processing.IAstModifyingVisitor
+import prog8.ast.processing.IAstVisitor
 import prog8.ast.statements.*
 import prog8.compiler.target.c64.Petscii
 import prog8.functions.BuiltinFunctions
@@ -15,11 +16,11 @@ import kotlin.math.floor
     todo analyse for unreachable code and remove that (f.i. code after goto or return that has no label so can never be jumped to) + print warning about this
 */
 
+
 internal class StatementOptimizer(private val program: Program, private val optimizeInlining: Boolean) : IAstModifyingVisitor {
     var optimizationsDone: Int = 0
         private set
     var scopesToFlatten = mutableListOf<INameScope>()
-    val nopStatements = mutableListOf<NopStatement>()
 
     private val pureBuiltinFunctions = BuiltinFunctions.filter { it.value.pure }
     private val callgraph = CallGraph(program)
@@ -34,11 +35,6 @@ internal class StatementOptimizer(private val program: Program, private val opti
             inlineSubroutines(callgraph)
         }
         super.visit(program)
-
-        // at the end, remove the encountered NOP statements
-        this.nopStatements.forEach {
-            it.definingScope().remove(it)
-        }
     }
 
     private fun inlineSubroutines(callgraph: CallGraph) {
@@ -432,11 +428,6 @@ internal class StatementOptimizer(private val program: Program, private val opti
         return repeatLoop
     }
 
-    override fun visit(nopStatement: NopStatement): IStatement {
-        this.nopStatements.add(nopStatement)
-        return nopStatement
-    }
-
     override fun visit(whenStatement: WhenStatement): IStatement {
         val choices = whenStatement.choices.toList()
         for(choice in choices) {
@@ -654,3 +645,18 @@ internal class StatementOptimizer(private val program: Program, private val opti
 
 
 
+internal class RemoveNops(): IAstVisitor {
+    val nopStatements = mutableListOf<NopStatement>()
+
+    override fun visit(program: Program) {
+        super.visit(program)
+        // at the end, remove the encountered NOP statements
+        this.nopStatements.forEach {
+            it.definingScope().remove(it)
+        }
+    }
+
+    override fun visit(nopStatement: NopStatement) {
+        nopStatements.add(nopStatement)
+    }
+}

examples/cube3d-sprites.p8

@@ -161,7 +161,7 @@
             else
                 c64.SPRPTR[i] = $2000/64        ; small ball
 
-            c64.SPCOL[i] = spritecolors[zc>>13 as byte + 4]      ; further away=darker color  TODO doesn't work anymore?  ">>" seems broken.
+            c64.SPCOL[i] = spritecolors[zc>>13 as byte + 4]      ; further away=darker color
         }
     }
 }