remove unused variables from IR output

codeGenIntermediate/src/prog8/codegen/intermediate/IRCodeGen.kt

@@ -58,7 +58,7 @@ class IRCodeGen(
             val optimizer = IRPeepholeOptimizer(irProg)
             optimizer.optimize()
 
-            val remover = IRUnusedCodeRemover(irProg, errors)
+            val remover = IRUnusedCodeRemover(irProg, irSymbolTable, errors)
             do {
                 val numRemoved = remover.optimize()
             } while(numRemoved>0 && errors.noErrors())
@@ -115,10 +115,10 @@ class IRCodeGen(
             block.children.firstOrNull { it is IRInlineAsmChunk }?.let { first->
                 first as IRInlineAsmChunk
                 if(first.label==null) {
-                    val replacement = IRInlineAsmChunk(block.name, first.assembly, first.isIR, first.next)
+                    val replacement = IRInlineAsmChunk(block.label, first.assembly, first.isIR, first.next)
                     block.children.removeAt(0)
                     block.children.add(0, replacement)
-                } else if(first.label != block.name) {
+                } else if(first.label != block.label) {
                     throw AssemblyError("first chunk in block has label that differs from block name")
                 }
             }

codeGenIntermediate/src/prog8/codegen/intermediate/IRUnusedCodeRemover.kt

@@ -5,7 +5,11 @@ import prog8.code.core.SourceCode.Companion.libraryFilePrefix
 import prog8.intermediate.*
 
 
-internal class IRUnusedCodeRemover(private val irprog: IRProgram, private val errors: IErrorReporter) {
+internal class IRUnusedCodeRemover(
+    private val irprog: IRProgram,
+    private val symbolTable: IRSymbolTable,
+    private val errors: IErrorReporter
+) {
     fun optimize(): Int {
         val allLabeledChunks = mutableMapOf<String, IRCodeChunkBase>()
 
@@ -25,6 +29,7 @@ internal class IRUnusedCodeRemover(private val irprog: IRProgram, private val er
                         errors.warn("unused subroutine ${sub.label}", sub.position)
                     }
                     block.children.remove(sub)
+                    symbolTable.removeTree(sub.label)
                     numRemoved++
                 }
             }
@@ -34,6 +39,7 @@ internal class IRUnusedCodeRemover(private val irprog: IRProgram, private val er
         irprog.blocks.reversed().forEach { block ->
             if(block.isEmpty()) {
                 irprog.blocks.remove(block)
+                symbolTable.removeTree(block.label)
                 numRemoved++
             }
         }
@@ -42,7 +48,7 @@ internal class IRUnusedCodeRemover(private val irprog: IRProgram, private val er
     }
 
     private fun removeUnreachable(allLabeledChunks: MutableMap<String, IRCodeChunkBase>): Int {
-        val entrypointSub = irprog.blocks.single { it.name=="main" }.children.single { it is IRSubroutine && it.label=="main.start" }
+        val entrypointSub = irprog.blocks.single { it.label=="main" }.children.single { it is IRSubroutine && it.label=="main.start" }
         val reachable = mutableSetOf((entrypointSub as IRSubroutine).chunks.first())
 
         fun grow() {

docs/source/todo.rst

@@ -3,7 +3,7 @@ TODO
 
 For next minor release
 ^^^^^^^^^^^^^^^^^^^^^^
-remove unused variables from IR output, such as sys.wait.jiffies when never calling sys.wait
+
 ...
 
 

intermediate/src/prog8/intermediate/IRFileWriter.kt

@@ -55,7 +55,7 @@ class IRFileWriter(private val irProgram: IRProgram, outfileOverride: Path?) {
     private fun writeBlocks() {
         irProgram.blocks.forEach { block ->
             xml.writeStartElement("BLOCK")
-            xml.writeAttribute("NAME", block.name)
+            xml.writeAttribute("NAME", block.label)
             xml.writeAttribute("ADDRESS", block.address?.toHex() ?: "")
             xml.writeAttribute("ALIGN", block.alignment.toString())
             xml.writeAttribute("POS", block.position.toString())

intermediate/src/prog8/intermediate/IRProgram.kt

@@ -60,7 +60,7 @@ class IRProgram(val name: String,
     }
 
     fun addBlock(block: IRBlock) {
-        require(blocks.all { it.name != block.name}) { "duplicate block ${block.name} ${block.position}" }
+        require(blocks.all { it.label != block.label}) { "duplicate block ${block.label} ${block.position}" }
         blocks.add(block)
     }
 
@@ -238,7 +238,7 @@ class IRProgram(val name: String,
 }
 
 class IRBlock(
-    val name: String,
+    val label: String,
     val address: UInt?,
     val alignment: BlockAlignment,
     val position: Position

intermediate/src/prog8/intermediate/IRSymbolTable.kt

@@ -4,6 +4,7 @@ import prog8.code.*
 import prog8.code.ast.PtVariable
 import prog8.code.core.DataType
 import prog8.code.core.ZeropageWish
+import prog8.code.core.internedStringsModuleName
 
 
 // In the Intermediate Representation, all nesting has been removed.
@@ -120,4 +121,15 @@ class IRSymbolTable(sourceSt: SymbolTable?) {
     }
 
     fun getAsmSymbols(): Map<String, String> = asmSymbols
+
+    fun removeTree(label: String) {
+        val prefix = "$label."
+        val vars = table.filter { it.key.startsWith(prefix) }
+        vars.forEach {
+            // check if attempt is made to delete interned strings, if so, refuse that.
+            if(!it.key.startsWith(internedStringsModuleName)) {
+                table.remove(it.key)
+            }
+        }
+    }
 }

virtualmachine/src/prog8/vm/VmProgramLoader.kt

@@ -36,7 +36,7 @@ class VmProgramLoader {
         val chunkReplacements = mutableListOf<Pair<IRCodeChunkBase, IRCodeChunk>>()
         irProgram.blocks.forEach { block ->
             if(block.address!=null)
-                throw IRParseException("blocks cannot have a load address for vm: ${block.name}")
+                throw IRParseException("blocks cannot have a load address for vm: ${block.label}")
 
             block.children.forEach { child ->
                 when(child) {