Stabilize pi benchmark optimizations for release

examples/pi-bench.lyng

@@ -0,0 +1,72 @@
+import lyng.time
+
+val WORK_SIZE = 200
+val TASK_COUNT = 10
+
+fn piSpigot(iThread: Int, n: Int) {
+    var pi = []
+    val boxes = n * 10 / 3
+    var reminders = List.fill(boxes) { 2 }
+    var heldDigits = 0
+    for (i in 0..n) {
+        var carriedOver = 0
+        var sum = 0
+        for (k in 1..boxes) {
+            val j = boxes - k
+            val denom = j * 2 + 1
+            reminders[j] *= 10
+            sum = reminders[j] + carriedOver
+            val quotient = sum / denom
+            reminders[j] = sum % denom
+            carriedOver = quotient * j
+        }
+        reminders[0] = sum % 10
+        var q = sum / 10
+        if (q == 9) {
+            ++heldDigits
+        } else if (q == 10) {
+            q = 0
+            for (k in 1..heldDigits) {
+                var replaced = pi[i - k]
+                if (replaced == 9) {
+                    replaced = 0
+                } else {
+                    ++replaced
+                }
+                pi[i - k] = replaced
+            }
+            heldDigits = 1
+        } else {
+            heldDigits = 1
+        }
+        pi.add(q)
+    }
+
+    var s = ""
+    for (i in (n - 8)..<n) {
+        s += pi[i]
+    }
+
+    println(iThread, " - done: ", s)
+}
+
+
+var counter = 0
+
+
+for( repeat in 1..30) {
+    val t0 = Instant()
+    (1..TASK_COUNT).map {
+        val counterState = counter
+        val t = launch {
+            piSpigot(counterState, WORK_SIZE)
+        }
+        ++counter
+        t
+    }.forEach { (it as Deferred).await() }
+
+    val dt = Instant() - t0
+
+    println("$repeat: all done, dt = ", dt)
+    delay(1000)
+}

examples/pi-test.lyng

@@ -0,0 +1,49 @@
+fn piSpigot(n) {
+  var pi = []
+  val boxes = n * 10 / 3
+  var reminders = []
+  for (i in 0..<boxes) {
+    reminders.add(2)
+  }
+  var heldDigits = 0
+  for (i in 0..n) {
+    var carriedOver = 0
+    var sum = 0
+    for (k in 1..boxes) {
+      val j = boxes - k
+      val denom = j * 2 + 1
+      reminders[j] *= 10
+      sum = reminders[j] + carriedOver
+      // Keep this integer-only. Real coercion here is much slower in the hot loop.
+      val quotient = sum / denom
+      reminders[j] = sum % denom
+      carriedOver = quotient * j
+    }
+    reminders[0] = sum % 10
+    var q = sum / 10
+    if (q == 9) {
+      ++heldDigits
+    } else if (q == 10) {
+      q = 0
+      for (k in 1..heldDigits) {
+        var replaced = pi[i - k]
+        if (replaced == 9) {
+          replaced = 0
+        } else {
+          ++replaced
+        }
+        pi[i - k] = replaced
+      }
+      heldDigits = 1
+    } else {
+      heldDigits = 1
+    }
+    pi.add(q)
+  }
+
+  var suffix = ""
+  for (i in (n - 8)..<n) {
+    suffix += pi[i]
+  }
+  suffix
+}

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/BytecodeCompiler.kt

@@ -1783,7 +1783,11 @@ class BytecodeCompiler(
         return when (slotTypes[slot]) {
             SlotType.INT -> NumericKind.INT
             SlotType.REAL -> NumericKind.REAL
-            else -> NumericKind.UNKNOWN
+            else -> when (slotObjClass[slot]) {
+                ObjInt.type -> NumericKind.INT
+                ObjReal.type -> NumericKind.REAL
+                else -> NumericKind.UNKNOWN
+            }
         }
     }
 
@@ -1800,7 +1804,21 @@ class BytecodeCompiler(
             is ConstRef -> numericKindFromConst(ref.constValue)
             is LocalVarRef -> resolveDirectNameSlot(ref.name)?.let { numericKindFromSlot(it.slot) } ?: NumericKind.UNKNOWN
             is FastLocalVarRef -> resolveDirectNameSlot(ref.name)?.let { numericKindFromSlot(it.slot) } ?: NumericKind.UNKNOWN
-            is LocalSlotRef -> resolveSlot(ref)?.let { numericKindFromSlot(it) } ?: NumericKind.UNKNOWN
+            is LocalSlotRef -> resolveLocalSlotByRefOrName(ref)?.let { numericKindFromSlot(it) } ?: NumericKind.UNKNOWN
+            is IndexRef -> {
+                val receiver = when (val target = ref.targetRef) {
+                    is LocalSlotRef -> resolveLocalSlotByRefOrName(target)
+                    is LocalVarRef -> resolveDirectNameSlot(target.name)?.slot
+                    is FastLocalVarRef -> resolveDirectNameSlot(target.name)?.slot
+                    else -> null
+                }
+                val elementClass = receiver?.let { listElementClassBySlot[it] } ?: listElementClassFromReceiverRef(ref.targetRef)
+                when (elementClass) {
+                    ObjInt.type -> NumericKind.INT
+                    ObjReal.type -> NumericKind.REAL
+                    else -> NumericKind.UNKNOWN
+                }
+            }
             is UnaryOpRef -> inferNumericKind(ref.a)
             is BinaryOpRef -> {
                 val op = ref.op
@@ -2431,7 +2449,7 @@ class BytecodeCompiler(
                 updateSlotType(slot, SlotType.OBJ)
                 return value
             }
-            val value = compileRef(assignValue(ref)) ?: return null
+            var value = compileRef(assignValue(ref)) ?: return null
             if (isLoopVarRef(localTarget)) {
                 emitLoopVarReassignError(localTarget.name, localTarget.pos())
                 return value
@@ -2473,7 +2491,7 @@ class BytecodeCompiler(
             else -> null
         }
         if (nameTarget != null) {
-            val value = compileRef(assignValue(ref)) ?: return null
+            var value = compileRef(assignValue(ref)) ?: return null
             val resolved = resolveAssignableSlotByName(nameTarget) ?: return null
             val slot = resolved.first
             val isMutable = resolved.second
@@ -2698,6 +2716,7 @@ class BytecodeCompiler(
             if (!target.optionalRef) {
                 val index = compileRefWithFallback(target.indexRef, null, Pos.builtIn) ?: return null
                 builder.emit(Opcode.SET_INDEX, receiver.slot, index.slot, value.slot)
+                noteListElementClassMutation(receiver.slot, value)
             } else {
                 val nullSlot = allocSlot()
                 builder.emit(Opcode.CONST_NULL, nullSlot)
@@ -2710,6 +2729,7 @@ class BytecodeCompiler(
                 )
                 val index = compileRefWithFallback(target.indexRef, null, Pos.builtIn) ?: return null
                 builder.emit(Opcode.SET_INDEX, receiver.slot, index.slot, value.slot)
+                noteListElementClassMutation(receiver.slot, value)
                 builder.mark(endLabel)
             }
             return value
@@ -3026,9 +3046,32 @@ class BytecodeCompiler(
             val receiver = compileRefWithFallback(indexTarget.targetRef, null, Pos.builtIn) ?: return null
             val current = allocSlot()
             val result = allocSlot()
-            val rhs = compileRef(ref.value) ?: return compileEvalRef(ref)
+            var rhs = compileRef(ref.value) ?: return compileEvalRef(ref)
+            val elementClass = listElementClassBySlot[receiver.slot] ?: listElementClassFromReceiverRef(indexTarget.targetRef)
             if (!indexTarget.optionalRef) {
                 val index = compileRefWithFallback(indexTarget.indexRef, null, Pos.builtIn) ?: return null
+                if (elementClass == ObjInt.type) {
+                    builder.emit(Opcode.GET_INDEX, receiver.slot, index.slot, current)
+                    val currentInt = allocSlot()
+                    builder.emit(Opcode.UNBOX_INT_OBJ, current, currentInt)
+                    updateSlotType(currentInt, SlotType.INT)
+                    if (rhs.type != SlotType.INT) {
+                        coerceToArithmeticInt(ref.value, rhs)?.let { rhs = it }
+                    }
+                    val typed = when (ref.op) {
+                        BinOp.PLUS -> compileAssignOpBinary(SlotType.INT, rhs, currentInt, Opcode.ADD_INT, Opcode.ADD_REAL, Opcode.ADD_OBJ)
+                        BinOp.MINUS -> compileAssignOpBinary(SlotType.INT, rhs, currentInt, Opcode.SUB_INT, Opcode.SUB_REAL, Opcode.SUB_OBJ)
+                        BinOp.STAR -> compileAssignOpBinary(SlotType.INT, rhs, currentInt, Opcode.MUL_INT, Opcode.MUL_REAL, Opcode.MUL_OBJ)
+                        BinOp.SLASH -> compileAssignOpBinary(SlotType.INT, rhs, currentInt, Opcode.DIV_INT, Opcode.DIV_REAL, Opcode.DIV_OBJ)
+                        BinOp.PERCENT -> compileAssignOpBinary(SlotType.INT, rhs, currentInt, Opcode.MOD_INT, null, Opcode.MOD_OBJ)
+                        else -> null
+                    }
+                    if (typed != null && typed.type == SlotType.INT) {
+                        builder.emit(Opcode.SET_INDEX, receiver.slot, index.slot, currentInt)
+                        noteListElementClassMutation(receiver.slot, typed)
+                        return CompiledValue(currentInt, SlotType.INT)
+                    }
+                }
                 builder.emit(Opcode.GET_INDEX, receiver.slot, index.slot, current)
                 builder.emit(objOp, current, rhs.slot, result)
                 builder.emit(Opcode.SET_INDEX, receiver.slot, index.slot, result)
@@ -3586,7 +3629,7 @@ class BytecodeCompiler(
         val elementClass = listElementClassBySlot[receiver.slot] ?: listElementClassFromReceiverRef(ref.targetRef)
         if (elementClass != null) {
             slotObjClass[dst] = elementClass
-            if (elementClass == ObjString.type && elementClass.isClosed) {
+            if (elementClass.isClosed) {
                 stableObjSlots.add(dst)
             } else {
                 stableObjSlots.remove(dst)
@@ -4649,6 +4692,9 @@ class BytecodeCompiler(
                 val encodedCount = encodeCallArgCount(args) ?: return null
                 setPos(callPos)
                 builder.emit(Opcode.CALL_MEMBER_SLOT, receiver.slot, encodedMethodId, args.base, encodedCount, dst)
+                if (receiverClass == ObjList.type && ref.name == "add" && ref.args.size == 1 && !ref.args.first().isSplat) {
+                    noteListElementClassMutation(receiver.slot, CompiledValue(args.base, SlotType.OBJ))
+                }
                 return CompiledValue(dst, SlotType.OBJ)
             }
             val nullSlot = allocSlot()
@@ -4815,7 +4861,7 @@ class BytecodeCompiler(
                 " receiver=$kind(${ref.name}) slot=$slot slotClass=$slotCls nameClass=$nameCls"
             }
             is LocalSlotRef -> {
-                val slot = resolveSlot(ref)
+                val slot = resolveLocalSlotByRefOrName(ref)
                 val slotCls = slot?.let { slotObjClass[it]?.className }
                 val nameCls = nameObjClass[ref.name]?.className
                 val scopeId = refScopeId(ref)
@@ -4971,9 +5017,10 @@ class BytecodeCompiler(
         val specs = if (needPlan) ArrayList<BytecodeConst.CallArgSpec>(args.size) else null
         for ((index, arg) in args.withIndex()) {
             val compiled = compileArgValue(arg.value) ?: return null
+            val objValue = ensureObjSlot(compiled)
             val dst = argSlots[index]
-            if (compiled.slot != dst || compiled.type != SlotType.OBJ) {
+            if (objValue.slot != dst) {
-                builder.emit(Opcode.BOX_OBJ, compiled.slot, dst)
+                emitMove(objValue, dst)
             }
             updateSlotType(dst, SlotType.OBJ)
             specs?.add(BytecodeConst.CallArgSpec(arg.name, arg.isSplat))
@@ -5833,7 +5880,8 @@ class BytecodeCompiler(
                 emitMove(value, localSlot)
             }
             updateSlotType(localSlot, value.type)
-            updateSlotObjClass(localSlot, stmt.initializer, stmt.initializerObjClass)
+            slotObjClass[value.slot]?.let { slotObjClass[localSlot] = it }
+                ?: updateSlotObjClass(localSlot, stmt.initializer, stmt.initializerObjClass)
             updateListElementClassFromDecl(localSlot, scopeId, stmt.slotIndex)
             updateListElementClassFromInitializer(localSlot, stmt.initializer)
             updateNameObjClassFromSlot(stmt.name, localSlot)
@@ -5865,7 +5913,8 @@ class BytecodeCompiler(
             }
             updateSlotType(scopeSlot, value.type)
             updateNameObjClassFromSlot(stmt.name, scopeSlot)
-            updateSlotObjClass(scopeSlot, stmt.initializer, stmt.initializerObjClass)
+            slotObjClass[value.slot]?.let { slotObjClass[scopeSlot] = it }
+                ?: updateSlotObjClass(scopeSlot, stmt.initializer, stmt.initializerObjClass)
             updateListElementClassFromDecl(scopeSlot, scopeId, stmt.slotIndex)
             updateListElementClassFromInitializer(scopeSlot, stmt.initializer)
             val declId = builder.addConst(
@@ -5901,7 +5950,9 @@ class BytecodeCompiler(
             updateSlotTypeByName(stmt.name, value.type)
         }
         updateNameObjClassFromSlot(stmt.name, value.slot)
-        updateSlotObjClass(value.slot, stmt.initializer, stmt.initializerObjClass)
+        if (slotObjClass[value.slot] == null) {
+            updateSlotObjClass(value.slot, stmt.initializer, stmt.initializerObjClass)
+        }
         updateListElementClassFromDecl(value.slot, scopeId, stmt.slotIndex)
         updateListElementClassFromInitializer(value.slot, stmt.initializer)
         return value
@@ -5991,6 +6042,16 @@ class BytecodeCompiler(
         listElementClassBySlot[slot] = elementClass
     }
 
+    private fun noteListElementClassMutation(receiverSlot: Int, value: CompiledValue) {
+        val newClass = elementClassFromValue(value) ?: return
+        val current = listElementClassBySlot[receiverSlot]
+        if (current == null || current == newClass) {
+            listElementClassBySlot[receiverSlot] = newClass
+        } else {
+            listElementClassBySlot.remove(receiverSlot)
+        }
+    }
+
     private fun updateNameObjClassFromSlot(name: String, slot: Int) {
         val cls = slotObjClass[slot] ?: return
         nameObjClass[name] = cls
@@ -6086,9 +6147,6 @@ class BytecodeCompiler(
         if (range == null && rangeRef == null) {
             rangeRef = extractRangeFromLocal(stmt.source)
         }
-        if (rangeRef != null && !isConstIntRange(rangeRef)) {
-            rangeRef = null
-        }
         val typedRangeLocal = if (range == null && rangeRef == null) extractTypedRangeLocal(stmt.source) else null
         val loopSlotPlan = stmt.loopSlotPlan
         val loopSlotIndex = stmt.loopSlotPlan[stmt.loopVarName]
@@ -6129,120 +6187,16 @@ class BytecodeCompiler(
         val breakFlagSlot = allocSlot()
         if (range == null && rangeRef == null && typedRangeLocal == null) {
             val sourceValue = compileStatementValueOrFallback(stmt.source) ?: return null
-            val sourceObj = ensureObjSlot(sourceValue)
+            return emitIterableForIn(
-            val typeId = builder.addConst(BytecodeConst.ObjRef(ObjIterable))
+                stmt = stmt,
-            val typeSlot = allocSlot()
+                sourceValue = sourceValue,
-            builder.emit(Opcode.CONST_OBJ, typeId, typeSlot)
+                wantResult = wantResult,
-            builder.emit(Opcode.ASSERT_IS, sourceObj.slot, typeSlot)
+                loopSlotId = loopSlotId,
-
+                breakFlagSlot = breakFlagSlot,
-            val iterableMethods = ObjIterable.instanceMethodIdMap(includeAbstract = true)
+                needsBreakFlag = needsBreakFlag,
-            val iteratorMethodId = iterableMethods["iterator"]
+                hasRealWiden = hasRealWiden,
-            if (iteratorMethodId == null) {
+                realWidenSlots = realWidenSlots,
-                throw BytecodeCompileException("Missing member id for Iterable.iterator", stmt.pos)
-            }
-            val iteratorMethods = ObjIterator.instanceMethodIdMap(includeAbstract = true)
-            val hasNextMethodId = iteratorMethods["hasNext"]
-            if (hasNextMethodId == null) {
-                throw BytecodeCompileException("Missing member id for Iterator.hasNext", stmt.pos)
-            }
-            val nextMethodId = iteratorMethods["next"]
-            if (nextMethodId == null) {
-                throw BytecodeCompileException("Missing member id for Iterator.next", stmt.pos)
-            }
-
-            val iterSlot = allocSlot()
-            builder.emit(Opcode.CALL_MEMBER_SLOT, sourceObj.slot, iteratorMethodId, 0, 0, iterSlot)
-            builder.emit(Opcode.ITER_PUSH, iterSlot)
-
-            if (needsBreakFlag) {
-                val falseId = builder.addConst(BytecodeConst.Bool(false))
-                builder.emit(Opcode.CONST_BOOL, falseId, breakFlagSlot)
-            }
-            val resultSlot = if (wantResult) {
-                val slot = allocSlot()
-                val voidId = builder.addConst(BytecodeConst.ObjRef(ObjVoid))
-                builder.emit(Opcode.CONST_OBJ, voidId, slot)
-                slot
-            } else {
-                null
-            }
-
-            val loopLabel = builder.label()
-            val continueLabel = builder.label()
-            val endLabel = builder.label()
-            builder.mark(loopLabel)
-
-            val hasNextSlot = allocSlot()
-            builder.emit(Opcode.CALL_MEMBER_SLOT, iterSlot, hasNextMethodId, 0, 0, hasNextSlot)
-            val condSlot = allocSlot()
-            builder.emit(Opcode.OBJ_TO_BOOL, hasNextSlot, condSlot)
-            builder.emit(
-                Opcode.JMP_IF_FALSE,
-                listOf(CmdBuilder.Operand.IntVal(condSlot), CmdBuilder.Operand.LabelRef(endLabel))
             )
-
-            val nextSlot = allocSlot()
-            builder.emit(Opcode.CALL_MEMBER_SLOT, iterSlot, nextMethodId, 0, 0, nextSlot)
-            val nextObj = ensureObjSlot(CompiledValue(nextSlot, SlotType.UNKNOWN))
-            emitMove(CompiledValue(nextObj.slot, SlotType.OBJ), loopSlotId)
-            updateSlotType(loopSlotId, SlotType.OBJ)
-            updateSlotTypeByName(stmt.loopVarName, SlotType.OBJ)
-
-            loopStack.addLast(
-                LoopContext(
-                    stmt.label,
-                    endLabel,
-                    continueLabel,
-                    breakFlagSlot,
-                    resultSlot,
-                    hasIterator = true
-                )
-            )
-            val bodyValue = compileLoopBody(stmt.body, wantResult) ?: return null
-            if (hasRealWiden) {
-                applySlotTypes(realWidenSlots, SlotType.UNKNOWN)
-            }
-            loopStack.removeLast()
-            if (wantResult) {
-                val bodyObj = ensureObjSlot(bodyValue)
-                builder.emit(Opcode.MOVE_OBJ, bodyObj.slot, resultSlot!!)
-            }
-            builder.mark(continueLabel)
-            if (hasRealWiden) {
-                emitLoopRealCoercions(realWidenSlots)
-            }
-            builder.emit(Opcode.JMP, listOf(CmdBuilder.Operand.LabelRef(loopLabel)))
-
-            builder.mark(endLabel)
-            if (needsBreakFlag) {
-                val afterPop = builder.label()
-                builder.emit(
-                    Opcode.JMP_IF_TRUE,
-                    listOf(CmdBuilder.Operand.IntVal(breakFlagSlot), CmdBuilder.Operand.LabelRef(afterPop))
-                )
-                builder.emit(Opcode.ITER_POP)
-                builder.mark(afterPop)
-            } else {
-                builder.emit(Opcode.ITER_POP)
-            }
-            if (stmt.elseStatement != null) {
-                val afterElse = if (needsBreakFlag) builder.label() else null
-                if (needsBreakFlag) {
-                    builder.emit(
-                        Opcode.JMP_IF_TRUE,
-                        listOf(CmdBuilder.Operand.IntVal(breakFlagSlot), CmdBuilder.Operand.LabelRef(afterElse!!))
-                    )
-                }
-                val elseValue = compileStatementValueOrFallback(stmt.elseStatement, wantResult) ?: return null
-                if (wantResult) {
-                    val elseObj = ensureObjSlot(elseValue)
-                    builder.emit(Opcode.MOVE_OBJ, elseObj.slot, resultSlot!!)
-                }
-                if (needsBreakFlag) {
-                    builder.mark(afterElse!!)
-                }
-            }
-            return resultSlot ?: breakFlagSlot
         }
 
         val iSlot = loopSlotId
@@ -6261,9 +6215,23 @@ class BytecodeCompiler(
             if (rangeRef != null) {
                 val left = rangeRef.left ?: return null
                 val right = rangeRef.right ?: return null
-                val startValue = compileRef(left) ?: return null
+                val startCompiled = compileRef(left) ?: return null
-                val endValue = compileRef(right) ?: return null
+                val endCompiled = compileRef(right) ?: return null
-                if (startValue.type != SlotType.INT || endValue.type != SlotType.INT) return null
+                val startValue = coerceToLoopInt(startCompiled)
+                val endValue = coerceToLoopInt(endCompiled)
+                if (startValue == null || endValue == null) {
+                    val rangeValue = emitRangeObject(startCompiled, endCompiled, rangeRef)
+                    return emitIterableForIn(
+                        stmt = stmt,
+                        sourceValue = rangeValue,
+                        wantResult = wantResult,
+                        loopSlotId = loopSlotId,
+                        breakFlagSlot = breakFlagSlot,
+                        needsBreakFlag = needsBreakFlag,
+                        hasRealWiden = hasRealWiden,
+                        realWidenSlots = realWidenSlots,
+                    )
+                }
                 val descendingId = builder.addConst(BytecodeConst.Bool(rangeRef.isDescending))
                 emitMove(startValue, iSlot)
                 emitMove(endValue, endSlot)
@@ -7308,7 +7276,8 @@ class BytecodeCompiler(
             is LocalSlotRef -> {
                 val ownerScopeId = ref.captureOwnerScopeId ?: ref.scopeId
                 val ownerSlot = ref.captureOwnerSlot ?: ref.slot
-                slotTypeByScopeId[ownerScopeId]?.get(ownerSlot)
+                resolveLocalSlotByRefOrName(ref)?.let { slotObjClass[it] }
+                    ?: slotTypeByScopeId[ownerScopeId]?.get(ownerSlot)
                     ?: slotInitClassByKey[ScopeSlotKey(ownerScopeId, ownerSlot)]
                     ?: nameObjClass[ref.name]
                     ?: resolveTypeNameClass(ref.name)
@@ -7721,6 +7690,11 @@ class BytecodeCompiler(
         return resolved
     }
 
+    private fun resolveLocalSlotByRefOrName(ref: LocalSlotRef): Int? {
+        return resolveSlot(ref)
+            ?: ref.name.takeIf { it.isNotEmpty() }?.let { name -> resolveDirectNameSlot(name)?.slot }
+    }
+
     private fun resolveCapturedOwnerScopeSlot(ref: LocalSlotRef): Int? {
         val ownerScopeId = ref.captureOwnerScopeId ?: return null
         val ownerSlot = ref.captureOwnerSlot ?: return null
@@ -8698,10 +8672,237 @@ class BytecodeCompiler(
         return if (ref.step != null) null else ref
     }
 
-    private fun isConstIntRange(ref: RangeRef): Boolean {
+    private fun emitIterableForIn(
-        val left = ref.left as? ConstRef ?: return false
+        stmt: net.sergeych.lyng.ForInStatement,
-        val right = ref.right as? ConstRef ?: return false
+        sourceValue: CompiledValue,
-        return left.constValue is ObjInt && right.constValue is ObjInt
+        wantResult: Boolean,
+        loopSlotId: Int,
+        breakFlagSlot: Int,
+        needsBreakFlag: Boolean,
+        hasRealWiden: Boolean,
+        realWidenSlots: Set<Int>,
+    ): Int? {
+        val sourceObj = ensureObjSlot(sourceValue)
+        val typeId = builder.addConst(BytecodeConst.ObjRef(ObjIterable))
+        val typeSlot = allocSlot()
+        builder.emit(Opcode.CONST_OBJ, typeId, typeSlot)
+        builder.emit(Opcode.ASSERT_IS, sourceObj.slot, typeSlot)
+
+        val iterableMethods = ObjIterable.instanceMethodIdMap(includeAbstract = true)
+        val iteratorMethodId = iterableMethods["iterator"]
+            ?: throw BytecodeCompileException("Missing member id for Iterable.iterator", stmt.pos)
+        val iteratorMethods = ObjIterator.instanceMethodIdMap(includeAbstract = true)
+        val hasNextMethodId = iteratorMethods["hasNext"]
+            ?: throw BytecodeCompileException("Missing member id for Iterator.hasNext", stmt.pos)
+        val nextMethodId = iteratorMethods["next"]
+            ?: throw BytecodeCompileException("Missing member id for Iterator.next", stmt.pos)
+
+        val iterSlot = allocSlot()
+        builder.emit(Opcode.CALL_MEMBER_SLOT, sourceObj.slot, iteratorMethodId, 0, 0, iterSlot)
+        builder.emit(Opcode.ITER_PUSH, iterSlot)
+
+        if (needsBreakFlag) {
+            val falseId = builder.addConst(BytecodeConst.Bool(false))
+            builder.emit(Opcode.CONST_BOOL, falseId, breakFlagSlot)
+        }
+        val resultSlot = if (wantResult) {
+            val slot = allocSlot()
+            val voidId = builder.addConst(BytecodeConst.ObjRef(ObjVoid))
+            builder.emit(Opcode.CONST_OBJ, voidId, slot)
+            slot
+        } else {
+            null
+        }
+
+        val loopLabel = builder.label()
+        val continueLabel = builder.label()
+        val endLabel = builder.label()
+        builder.mark(loopLabel)
+
+        val hasNextSlot = allocSlot()
+        builder.emit(Opcode.CALL_MEMBER_SLOT, iterSlot, hasNextMethodId, 0, 0, hasNextSlot)
+        val condSlot = allocSlot()
+        builder.emit(Opcode.OBJ_TO_BOOL, hasNextSlot, condSlot)
+        builder.emit(
+            Opcode.JMP_IF_FALSE,
+            listOf(CmdBuilder.Operand.IntVal(condSlot), CmdBuilder.Operand.LabelRef(endLabel))
+        )
+
+        val nextSlot = allocSlot()
+        builder.emit(Opcode.CALL_MEMBER_SLOT, iterSlot, nextMethodId, 0, 0, nextSlot)
+        val nextObj = ensureObjSlot(CompiledValue(nextSlot, SlotType.UNKNOWN))
+        emitMove(CompiledValue(nextObj.slot, SlotType.OBJ), loopSlotId)
+        updateSlotType(loopSlotId, SlotType.OBJ)
+        updateSlotTypeByName(stmt.loopVarName, SlotType.OBJ)
+
+        loopStack.addLast(
+            LoopContext(
+                stmt.label,
+                endLabel,
+                continueLabel,
+                breakFlagSlot,
+                resultSlot,
+                hasIterator = true
+            )
+        )
+        val bodyValue = compileLoopBody(stmt.body, wantResult) ?: return null
+        if (hasRealWiden) {
+            applySlotTypes(realWidenSlots, SlotType.UNKNOWN)
+        }
+        loopStack.removeLast()
+        if (wantResult) {
+            val bodyObj = ensureObjSlot(bodyValue)
+            builder.emit(Opcode.MOVE_OBJ, bodyObj.slot, resultSlot!!)
+        }
+        builder.mark(continueLabel)
+        if (hasRealWiden) {
+            emitLoopRealCoercions(realWidenSlots)
+        }
+        builder.emit(Opcode.JMP, listOf(CmdBuilder.Operand.LabelRef(loopLabel)))
+
+        builder.mark(endLabel)
+        if (needsBreakFlag) {
+            val afterPop = builder.label()
+            builder.emit(
+                Opcode.JMP_IF_TRUE,
+                listOf(CmdBuilder.Operand.IntVal(breakFlagSlot), CmdBuilder.Operand.LabelRef(afterPop))
+            )
+            builder.emit(Opcode.ITER_POP)
+            builder.mark(afterPop)
+        } else {
+            builder.emit(Opcode.ITER_POP)
+        }
+        if (stmt.elseStatement != null) {
+            val afterElse = if (needsBreakFlag) builder.label() else null
+            if (needsBreakFlag) {
+                builder.emit(
+                    Opcode.JMP_IF_TRUE,
+                    listOf(CmdBuilder.Operand.IntVal(breakFlagSlot), CmdBuilder.Operand.LabelRef(afterElse!!))
+                )
+            }
+            val elseValue = compileStatementValueOrFallback(stmt.elseStatement, wantResult) ?: return null
+            if (wantResult) {
+                val elseObj = ensureObjSlot(elseValue)
+                builder.emit(Opcode.MOVE_OBJ, elseObj.slot, resultSlot!!)
+            }
+            if (needsBreakFlag) {
+                builder.mark(afterElse!!)
+            }
+        }
+        return resultSlot ?: breakFlagSlot
+    }
+
+    private fun emitRangeObject(startValue: CompiledValue, endValue: CompiledValue, ref: RangeRef): CompiledValue {
+        val startObj = ensureObjSlot(startValue)
+        val endObj = ensureObjSlot(endValue)
+        val inclusiveSlot = allocSlot()
+        val inclusiveId = builder.addConst(BytecodeConst.Bool(ref.isEndInclusive))
+        builder.emit(Opcode.CONST_BOOL, inclusiveId, inclusiveSlot)
+        val descendingSlot = allocSlot()
+        val descendingId = builder.addConst(BytecodeConst.Bool(ref.isDescending))
+        builder.emit(Opcode.CONST_BOOL, descendingId, descendingSlot)
+        val stepSlot = allocSlot()
+        builder.emit(Opcode.CONST_NULL, stepSlot)
+        updateSlotType(stepSlot, SlotType.OBJ)
+        val dst = allocSlot()
+        builder.emit(Opcode.MAKE_RANGE, startObj.slot, endObj.slot, inclusiveSlot, descendingSlot, stepSlot, dst)
+        updateSlotType(dst, SlotType.OBJ)
+        slotObjClass[dst] = ObjRange.type
+        return CompiledValue(dst, SlotType.OBJ)
+    }
+
+    private fun isDynamicIntRangeCandidate(ref: RangeRef): Boolean {
+        val left = ref.left ?: return false
+        val right = ref.right ?: return false
+        return isIntLikeRef(left) && isIntLikeRef(right)
+    }
+
+    private fun isIntLikeRef(ref: ObjRef): Boolean {
+        if (inferNumericKind(ref) == NumericKind.INT) {
+            return true
+        }
+        return when (ref) {
+            is ConstRef -> ref.constValue is ObjInt
+            is LocalSlotRef,
+            is LocalVarRef,
+            is FastLocalVarRef,
+            is BoundLocalVarRef,
+            is CallRef,
+            is MethodCallRef,
+            is FieldRef,
+            is CastRef,
+            is StatementRef -> resolveReceiverClass(ref) == ObjInt.type
+            is ThisMethodSlotCallRef,
+            is ImplicitThisMethodCallRef,
+            is ThisFieldSlotRef,
+            is ImplicitThisMemberRef -> resolveReceiverClassForScopeCollection(ref) == ObjInt.type
+            is UnaryOpRef -> ref.op == UnaryOp.NEGATE && isIntLikeRef(unaryOperand(ref))
+            is BinaryOpRef -> when (binaryOp(ref)) {
+                BinOp.PLUS,
+                BinOp.MINUS,
+                BinOp.STAR,
+                BinOp.SLASH,
+                BinOp.PERCENT,
+                BinOp.BAND,
+                BinOp.BXOR,
+                BinOp.BOR,
+                BinOp.SHL,
+                BinOp.SHR -> isIntLikeRef(binaryLeft(ref)) && isIntLikeRef(binaryRight(ref))
+                else -> false
+            }
+            else -> false
+        }
+    }
+
+    private fun coerceToLoopInt(value: CompiledValue): CompiledValue? {
+        return when (value.type) {
+            SlotType.INT -> value
+            SlotType.OBJ -> {
+                val isExactInt = isExactNonNullSlotClassOrTemp(value.slot, ObjInt.type)
+                val isStableIntObj = slotObjClass[value.slot] == ObjInt.type && isStablePrimitiveSourceSlot(value.slot)
+                if (!isExactInt && !isStableIntObj && !isStablePrimitiveSourceSlot(value.slot)) return null
+                val objSlot = if (isExactInt || isStableIntObj) {
+                    value.slot
+                } else {
+                    val boxed = allocSlot()
+                    builder.emit(Opcode.BOX_OBJ, value.slot, boxed)
+                    updateSlotType(boxed, SlotType.OBJ)
+                    emitAssertObjSlotIsInt(boxed)
+                }
+                val intSlot = allocSlot()
+                builder.emit(Opcode.UNBOX_INT_OBJ, objSlot, intSlot)
+                updateSlotType(intSlot, SlotType.INT)
+                CompiledValue(intSlot, SlotType.INT)
+            }
+            SlotType.UNKNOWN -> {
+                if (!isStablePrimitiveSourceSlot(value.slot)) return null
+                val boxed = allocSlot()
+                builder.emit(Opcode.BOX_OBJ, value.slot, boxed)
+                updateSlotType(boxed, SlotType.OBJ)
+                val checked = emitAssertObjSlotIsInt(boxed)
+                val intSlot = allocSlot()
+                builder.emit(Opcode.UNBOX_INT_OBJ, checked, intSlot)
+                updateSlotType(intSlot, SlotType.INT)
+                CompiledValue(intSlot, SlotType.INT)
+            }
+            else -> null
+        }
+    }
+
+    private fun coerceToArithmeticInt(ref: ObjRef, value: CompiledValue): CompiledValue? {
+        if (value.type == SlotType.INT) return value
+        val refSuggestsInt = inferNumericKind(ref) == NumericKind.INT
+        val stableNonTemp = !isTempSlot(value.slot) && isStablePrimitiveSourceSlot(value.slot)
+        if (!refSuggestsInt && !stableNonTemp) return null
+        return coerceToLoopInt(value)
+    }
+
+    private fun emitAssertObjSlotIsInt(slot: Int): Int {
+        val typeId = builder.addConst(BytecodeConst.ObjRef(ObjInt.type))
+        val typeSlot = allocSlot()
+        builder.emit(Opcode.CONST_OBJ, typeId, typeSlot)
+        builder.emit(Opcode.ASSERT_IS, slot, typeSlot)
+        return slot
     }
 
     private fun extractDeclaredRange(stmt: Statement?): RangeRef? {

lynglib/src/commonMain/kotlin/net/sergeych/lyng/bytecode/CmdRuntime.kt

@@ -314,8 +314,13 @@ class CmdUnboxIntObj(internal val src: Int, internal val dst: Int) : Cmd() {
 class CmdUnboxIntObjLocal(internal val src: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val value = frame.frame.getRawObj(src) as ObjInt
+        when (frame.frame.getSlotTypeCode(src)) {
-        frame.setLocalInt(dst, value.value)
+            SlotType.INT.code -> frame.setLocalInt(dst, frame.frame.getInt(src))
+            else -> {
+                val value = frame.frame.getRawObj(src) as ObjInt
+                frame.setLocalInt(dst, value.value)
+            }
+        }
         return
     }
 }
@@ -331,8 +336,13 @@ class CmdUnboxRealObj(internal val src: Int, internal val dst: Int) : Cmd() {
 class CmdUnboxRealObjLocal(internal val src: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val value = frame.frame.getRawObj(src) as ObjReal
+        when (frame.frame.getSlotTypeCode(src)) {
-        frame.setLocalReal(dst, value.value)
+            SlotType.REAL.code -> frame.setLocalReal(dst, frame.frame.getReal(src))
+            else -> {
+                val value = frame.frame.getRawObj(src) as ObjReal
+                frame.setLocalReal(dst, value.value)
+            }
+        }
         return
     }
 }
@@ -1540,9 +1550,15 @@ class CmdCmpEqIntObj(internal val a: Int, internal val b: Int, internal val dst:
 class CmdCmpEqIntObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjInt
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjInt
+            SlotType.INT.code -> frame.frame.getInt(a)
-        frame.setLocalBool(dst, left.value == right.value)
+            else -> (frame.frame.getRawObj(a) as ObjInt).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.INT.code -> frame.frame.getInt(b)
+            else -> (frame.frame.getRawObj(b) as ObjInt).value
+        }
+        frame.setLocalBool(dst, left == right)
         return
     }
 }
@@ -1563,9 +1579,15 @@ class CmdCmpNeqIntObj(internal val a: Int, internal val b: Int, internal val dst
 class CmdCmpNeqIntObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjInt
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjInt
+            SlotType.INT.code -> frame.frame.getInt(a)
-        frame.setLocalBool(dst, left.value != right.value)
+            else -> (frame.frame.getRawObj(a) as ObjInt).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.INT.code -> frame.frame.getInt(b)
+            else -> (frame.frame.getRawObj(b) as ObjInt).value
+        }
+        frame.setLocalBool(dst, left != right)
         return
     }
 }
@@ -1586,9 +1608,15 @@ class CmdCmpLtIntObj(internal val a: Int, internal val b: Int, internal val dst:
 class CmdCmpLtIntObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjInt
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjInt
+            SlotType.INT.code -> frame.frame.getInt(a)
-        frame.setLocalBool(dst, left.value < right.value)
+            else -> (frame.frame.getRawObj(a) as ObjInt).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.INT.code -> frame.frame.getInt(b)
+            else -> (frame.frame.getRawObj(b) as ObjInt).value
+        }
+        frame.setLocalBool(dst, left < right)
         return
     }
 }
@@ -1609,9 +1637,15 @@ class CmdCmpLteIntObj(internal val a: Int, internal val b: Int, internal val dst
 class CmdCmpLteIntObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjInt
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjInt
+            SlotType.INT.code -> frame.frame.getInt(a)
-        frame.setLocalBool(dst, left.value <= right.value)
+            else -> (frame.frame.getRawObj(a) as ObjInt).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.INT.code -> frame.frame.getInt(b)
+            else -> (frame.frame.getRawObj(b) as ObjInt).value
+        }
+        frame.setLocalBool(dst, left <= right)
         return
     }
 }
@@ -1632,9 +1666,15 @@ class CmdCmpGtIntObj(internal val a: Int, internal val b: Int, internal val dst:
 class CmdCmpGtIntObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjInt
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjInt
+            SlotType.INT.code -> frame.frame.getInt(a)
-        frame.setLocalBool(dst, left.value > right.value)
+            else -> (frame.frame.getRawObj(a) as ObjInt).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.INT.code -> frame.frame.getInt(b)
+            else -> (frame.frame.getRawObj(b) as ObjInt).value
+        }
+        frame.setLocalBool(dst, left > right)
         return
     }
 }
@@ -1655,9 +1695,15 @@ class CmdCmpGteIntObj(internal val a: Int, internal val b: Int, internal val dst
 class CmdCmpGteIntObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjInt
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjInt
+            SlotType.INT.code -> frame.frame.getInt(a)
-        frame.setLocalBool(dst, left.value >= right.value)
+            else -> (frame.frame.getRawObj(a) as ObjInt).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.INT.code -> frame.frame.getInt(b)
+            else -> (frame.frame.getRawObj(b) as ObjInt).value
+        }
+        frame.setLocalBool(dst, left >= right)
         return
     }
 }
@@ -1678,9 +1724,15 @@ class CmdCmpEqRealObj(internal val a: Int, internal val b: Int, internal val dst
 class CmdCmpEqRealObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjReal
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjReal
+            SlotType.REAL.code -> frame.frame.getReal(a)
-        frame.setLocalBool(dst, left.value == right.value)
+            else -> (frame.frame.getRawObj(a) as ObjReal).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.REAL.code -> frame.frame.getReal(b)
+            else -> (frame.frame.getRawObj(b) as ObjReal).value
+        }
+        frame.setLocalBool(dst, left == right)
         return
     }
 }
@@ -1701,9 +1753,15 @@ class CmdCmpNeqRealObj(internal val a: Int, internal val b: Int, internal val ds
 class CmdCmpNeqRealObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjReal
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjReal
+            SlotType.REAL.code -> frame.frame.getReal(a)
-        frame.setLocalBool(dst, left.value != right.value)
+            else -> (frame.frame.getRawObj(a) as ObjReal).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.REAL.code -> frame.frame.getReal(b)
+            else -> (frame.frame.getRawObj(b) as ObjReal).value
+        }
+        frame.setLocalBool(dst, left != right)
         return
     }
 }
@@ -1724,9 +1782,15 @@ class CmdCmpLtRealObj(internal val a: Int, internal val b: Int, internal val dst
 class CmdCmpLtRealObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjReal
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjReal
+            SlotType.REAL.code -> frame.frame.getReal(a)
-        frame.setLocalBool(dst, left.value < right.value)
+            else -> (frame.frame.getRawObj(a) as ObjReal).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.REAL.code -> frame.frame.getReal(b)
+            else -> (frame.frame.getRawObj(b) as ObjReal).value
+        }
+        frame.setLocalBool(dst, left < right)
         return
     }
 }
@@ -1747,9 +1811,15 @@ class CmdCmpLteRealObj(internal val a: Int, internal val b: Int, internal val ds
 class CmdCmpLteRealObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjReal
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjReal
+            SlotType.REAL.code -> frame.frame.getReal(a)
-        frame.setLocalBool(dst, left.value <= right.value)
+            else -> (frame.frame.getRawObj(a) as ObjReal).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.REAL.code -> frame.frame.getReal(b)
+            else -> (frame.frame.getRawObj(b) as ObjReal).value
+        }
+        frame.setLocalBool(dst, left <= right)
         return
     }
 }
@@ -1770,9 +1840,15 @@ class CmdCmpGtRealObj(internal val a: Int, internal val b: Int, internal val dst
 class CmdCmpGtRealObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjReal
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjReal
+            SlotType.REAL.code -> frame.frame.getReal(a)
-        frame.setLocalBool(dst, left.value > right.value)
+            else -> (frame.frame.getRawObj(a) as ObjReal).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.REAL.code -> frame.frame.getReal(b)
+            else -> (frame.frame.getRawObj(b) as ObjReal).value
+        }
+        frame.setLocalBool(dst, left > right)
         return
     }
 }
@@ -1793,9 +1869,15 @@ class CmdCmpGteRealObj(internal val a: Int, internal val b: Int, internal val ds
 class CmdCmpGteRealObjLocal(internal val a: Int, internal val b: Int, internal val dst: Int) : Cmd() {
     override val isFast: Boolean = true
     override fun performFast(frame: CmdFrame) {
-        val left = frame.frame.getRawObj(a) as ObjReal
+        val left = when (frame.frame.getSlotTypeCode(a)) {
-        val right = frame.frame.getRawObj(b) as ObjReal
+            SlotType.REAL.code -> frame.frame.getReal(a)
-        frame.setLocalBool(dst, left.value >= right.value)
+            else -> (frame.frame.getRawObj(a) as ObjReal).value
+        }
+        val right = when (frame.frame.getSlotTypeCode(b)) {
+            SlotType.REAL.code -> frame.frame.getReal(b)
+            else -> (frame.frame.getRawObj(b) as ObjReal).value
+        }
+        frame.setLocalBool(dst, left >= right)
         return
     }
 }
@@ -3624,7 +3706,13 @@ class CmdGetIndex(
     internal val dst: Int,
 ) : Cmd() {
     override suspend fun perform(frame: CmdFrame) {
-        val result = frame.slotToObj(targetSlot).getAt(frame.ensureScope(), frame.slotToObj(indexSlot))
+        val target = frame.storedSlotObj(targetSlot)
+        val index = frame.storedSlotObj(indexSlot)
+        if (target is ObjList && target::class == ObjList::class && index is ObjInt) {
+            frame.storeObjResult(dst, target.list[index.toInt()])
+            return
+        }
+        val result = target.getAt(frame.ensureScope(), index)
         frame.storeObjResult(dst, result)
         return
     }
@@ -3636,7 +3724,14 @@ class CmdSetIndex(
     internal val valueSlot: Int,
 ) : Cmd() {
     override suspend fun perform(frame: CmdFrame) {
-        frame.slotToObj(targetSlot).putAt(frame.ensureScope(), frame.slotToObj(indexSlot), frame.slotToObj(valueSlot))
+        val target = frame.storedSlotObj(targetSlot)
+        val index = frame.storedSlotObj(indexSlot)
+        val value = frame.slotToObj(valueSlot)
+        if (target is ObjList && target::class == ObjList::class && index is ObjInt) {
+            target.list[index.toInt()] = value
+            return
+        }
+        target.putAt(frame.ensureScope(), index, value)
         return
     }
 }

lynglib/src/jvmTest/kotlin/PiSpigotBenchmarkTest.kt

@@ -0,0 +1,145 @@
+/*
+ * Copyright 2026 Sergey S. Chernov real.sergeych@gmail.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+import kotlinx.coroutines.test.runTest
+import net.sergeych.lyng.Benchmarks
+import net.sergeych.lyng.BytecodeBodyProvider
+import net.sergeych.lyng.PerfFlags
+import net.sergeych.lyng.PerfProfiles
+import net.sergeych.lyng.Script
+import net.sergeych.lyng.Statement
+import net.sergeych.lyng.bytecode.BytecodeStatement
+import net.sergeych.lyng.bytecode.CmdCallMemberSlot
+import net.sergeych.lyng.bytecode.CmdFunction
+import net.sergeych.lyng.bytecode.CmdGetIndex
+import net.sergeych.lyng.bytecode.CmdIterPush
+import net.sergeych.lyng.bytecode.CmdMakeRange
+import net.sergeych.lyng.bytecode.CmdSetIndex
+import net.sergeych.lyng.obj.ObjString
+import java.nio.file.Files
+import java.nio.file.Path
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+import kotlin.time.TimeSource
+
+class PiSpigotBenchmarkTest {
+    @Test
+    fun benchmarkPiSpigot() = runTest {
+        if (!Benchmarks.enabled) return@runTest
+
+        val source = Files.readString(resolveExample("pi-test.lyng"))
+        val legacySource = source.replace(
+            "val quotient = sum / denom",
+            "var quotient = floor((sum / (denom * 1.0))).toInt()"
+        )
+        assertTrue(legacySource != source, "failed to build legacy piSpigot benchmark case")
+
+        val digits = 200
+        val expectedSuffix = "49303819"
+
+        val legacyElapsed = runCase("legacy-real-division", legacySource, digits, expectedSuffix, dumpBytecode = true)
+        val saved = PerfProfiles.snapshot()
+        PerfFlags.RVAL_FASTPATH = false
+        val optimizedRvalOffElapsed = runCase(
+            "optimized-int-division-rval-off",
+            source,
+            digits,
+            expectedSuffix,
+            dumpBytecode = false
+        )
+        PerfProfiles.restore(saved)
+        val optimizedElapsed = runCase("optimized-int-division-rval-on", source, digits, expectedSuffix, dumpBytecode = true)
+        val sourceSpeedup = legacyElapsed.toDouble() / optimizedRvalOffElapsed.toDouble()
+        val runtimeSpeedup = optimizedRvalOffElapsed.toDouble() / optimizedElapsed.toDouble()
+        val totalSpeedup = legacyElapsed.toDouble() / optimizedElapsed.toDouble()
+        println(
+            "[DEBUG_LOG] [BENCH] pi-spigot compare n=$digits legacy=${legacyElapsed} ms " +
+                "intDiv=${optimizedRvalOffElapsed} ms rvalOn=${optimizedElapsed} ms " +
+                "intDivSpeedup=${"%.2f".format(sourceSpeedup)}x " +
+                "rvalSpeedup=${"%.2f".format(runtimeSpeedup)}x " +
+                "total=${"%.2f".format(totalSpeedup)}x"
+        )
+    }
+
+    private suspend fun runCase(
+        name: String,
+        source: String,
+        digits: Int,
+        expectedSuffix: String,
+        dumpBytecode: Boolean,
+    ): Long {
+        val scope = Script.newScope()
+        scope.eval(source)
+
+        if (dumpBytecode) {
+            println("[DEBUG_LOG] [BENCH] pi-spigot cmd:\n${scope.disassembleSymbol("piSpigot")}")
+            dumpHotOps(scope, "piSpigot")
+        }
+
+        val first = scope.eval("piSpigot($digits)") as ObjString
+        assertEquals(expectedSuffix, first.value)
+
+        repeat(2) {
+            val warm = scope.eval("piSpigot($digits)") as ObjString
+            assertEquals(expectedSuffix, warm.value)
+        }
+
+        val iterations = 3
+        val start = TimeSource.Monotonic.markNow()
+        repeat(iterations) {
+            val result = scope.eval("piSpigot($digits)") as ObjString
+            assertEquals(expectedSuffix, result.value)
+        }
+        val elapsedMs = start.elapsedNow().inWholeMilliseconds
+        val avgMs = elapsedMs.toDouble() / iterations.toDouble()
+        println(
+            "[DEBUG_LOG] [BENCH] pi-spigot $name n=$digits iterations=$iterations " +
+                "elapsed=${elapsedMs} ms avg=${"%.2f".format(avgMs)} ms"
+        )
+        return elapsedMs
+    }
+
+    private fun dumpHotOps(scope: net.sergeych.lyng.Scope, name: String) {
+        val fn = resolveBytecodeFunction(scope, name) ?: return
+        val makeRange = fn.cmds.count { it is CmdMakeRange }
+        val callMemberSlot = fn.cmds.count { it is CmdCallMemberSlot }
+        val iterPush = fn.cmds.count { it is CmdIterPush }
+        val getIndex = fn.cmds.count { it is CmdGetIndex }
+        val setIndex = fn.cmds.count { it is CmdSetIndex }
+        println(
+            "[DEBUG_LOG] [BENCH] pi-spigot hot-ops " +
+                "makeRange=$makeRange callMemberSlot=$callMemberSlot iterPush=$iterPush " +
+                "getIndex=$getIndex setIndex=$setIndex total=${fn.cmds.size}"
+        )
+    }
+
+    private fun resolveBytecodeFunction(scope: net.sergeych.lyng.Scope, name: String): CmdFunction? {
+        val record = scope.get(name) ?: return null
+        val stmt = record.value as? Statement ?: return null
+        return (stmt as? BytecodeStatement)?.bytecodeFunction()
+            ?: (stmt as? BytecodeBodyProvider)?.bytecodeBody()?.bytecodeFunction()
+    }
+
+    private fun resolveExample(name: String): Path {
+        val direct = Path.of("examples", name)
+        if (Files.exists(direct)) return direct
+        val parent = Path.of("..", "examples", name)
+        if (Files.exists(parent)) return parent
+        error("example not found: $name")
+    }
+}

notes/pi_spigot_benchmark_baseline_2026-04-03.md

@@ -0,0 +1,172 @@
+# Pi Spigot Benchmark Baseline
+
+Date: 2026-04-03
+Command:
+`./gradlew :lynglib:jvmTest -Pbenchmarks=true --tests 'PiSpigotBenchmarkTest' --rerun-tasks`
+
+Results for `n=200`:
+- legacy-real-division: 1108 ms (3 iters, avg 369.33 ms)
+- optimized-int-division-rval-off: 756 ms (3 iters, avg 252.00 ms)
+- optimized-int-division-rval-on: 674 ms (3 iters, avg 224.67 ms)
+
+Derived speedups:
+- intDivSpeedup: 1.47x
+- rvalSpeedup: 1.12x
+- total: 1.64x
+
+Notes:
+- Bytecode still shows generic range iteration (`MAKE_RANGE`, `CALL_MEMBER_SLOT`, `ITER_PUSH`) for loop constructs in the legacy benchmark case.
+- This baseline is captured before enabling counted-loop lowering for dynamic inline int ranges.
+
+Optimization #1 follow-up:
+- Attempt: broaden compiler loop lowering for dynamic int ranges and validate with `PiSpigotBenchmarkTest` bytecode dumps.
+- Final result: success after switching loop-bound coercion to a runtime-checked int path for stable slots with missing metadata.
+- Latest measured run after the working compiler change:
+  - legacy-real-division: 783 ms (3 iters, avg 261.00 ms)
+  - optimized-int-division-rval-off: 729 ms (3 iters, avg 243.00 ms)
+  - optimized-int-division-rval-on: 593 ms (3 iters, avg 197.67 ms)
+- Hot-op counts for optimized bytecode now show the generic range iterator path is gone from the main loops:
+  - `makeRange=0`
+  - `callMemberSlot=2`
+  - `iterPush=0`
+  - `getIndex=4`
+  - `setIndex=4`
+- The remaining member calls are non-loop overhead; the main improvement came from lowering `for` ranges to counted int loops.
+
+Optimization #2 follow-up:
+- Attempt: coerce stable integer operands into `INT` arithmetic during binary-op lowering so hot expressions stop falling back to `OBJ` math.
+- Latest measured run after the arithmetic change:
+  - legacy-real-division: 593 ms (3 iters, avg 197.67 ms)
+  - optimized-int-division-rval-off: 542 ms (3 iters, avg 180.67 ms)
+  - optimized-int-division-rval-on: 516 ms (3 iters, avg 172.00 ms)
+- Compiled-code impact in the optimized case:
+  - `boxes = n * 10 / 3` is now `UNBOX_INT_OBJ` + `MUL_INT` + `DIV_INT`
+  - `j = boxes - k` is now `SUB_INT`
+  - `denom = j * 2 + 1` is now `MUL_INT` + `ADD_INT`
+  - `carriedOver = quotient * j` is now `MUL_INT`
+- Remaining hot object arithmetic is centered on list-backed reminder values and derived sums:
+  - `reminders[j] * 10`
+  - `reminders[j] + carriedOver`
+  - `sum / denom`, `sum % denom`, `sum / 10`
+- Conclusion: loop lowering is fixed; the next likely win is preserving `List<Int>` element typing for `reminders` so indexed loads stay in int space.
+
+Optimization #3 follow-up:
+- Attempt: teach numeric-kind inference that `IndexRef` can be `INT`/`REAL` when the receiver list has a known element class.
+- Compiler change:
+  - `inferNumericKind()` now handles `IndexRef` and resolves the receiver slot or receiver-declared list element class before choosing `INT`/`REAL`.
+- Latest measured run after the indexed-load inference change:
+  - legacy-real-division: 656 ms (3 iters, avg 218.67 ms)
+  - optimized-int-division-rval-off: 509 ms (3 iters, avg 169.67 ms)
+  - optimized-int-division-rval-on: 403 ms (3 iters, avg 134.33 ms)
+- Derived speedups vs legacy in this run:
+  - intDivSpeedup: 1.29x
+  - rvalSpeedup: 1.26x
+  - total: 1.63x
+- Compiled-code impact in the optimized case:
+  - `carriedOver = quotient * j` stays in `INT` space (`ASSERT_IS` + `UNBOX_INT_OBJ` + `MUL_INT`) instead of plain object multiply.
+  - Counted int loops remain intact (`MAKE_RANGE=0`, `ITER_PUSH=0`).
+- Remaining bottlenecks in the optimized bytecode:
+  - `GET_INDEX reminders[j]` still feeds `MUL_OBJ` / `ADD_OBJ`
+  - `sum / denom`, `sum % denom`, and `sum / 10` still compile to object arithmetic
+  - `suffix += pi[i]` remains `ADD_OBJ`, which is expected because it is string/object concatenation
+- Conclusion:
+  - The new inference produced a real VM-speed gain, especially with `RVAL_FASTPATH` enabled.
+  - The next compiler win is stronger propagation from `List<Int>` indexed loads into the produced temporary slot so `sum` can stay typed as `INT` across the inner loop.
+
+Optimization #4 follow-up:
+- Attempt: preserve boxed-argument metadata through `compileCallArgs()` so `list.add(x)` retains `ObjInt` / `ObjReal` element typing.
+- Compiler/runtime fixes:
+  - `compileCallArgs()` now routes arguments through `ensureObjSlot()` + `emitMove()` instead of raw `BOX_OBJ`, preserving `slotObjClass` and `stableObjSlots`.
+  - `CmdSetIndex` now reads `valueSlot` via `slotToObj()` so `SET_INDEX` can safely accept primitive slots.
+  - Fast local unbox ops (`CmdUnboxIntObjLocal`, `CmdUnboxRealObjLocal`) now handle already-primitive source slots directly instead of assuming a raw object payload.
+  - Plain assignment now coerces object-int RHS back into `INT` when the destination slot is currently compiled as `INT`, keeping loop-carried locals type-consistent.
+- Latest measured run after the propagation + VM fixes:
+  - legacy-real-division: 438 ms (3 iters, avg 146.00 ms)
+  - optimized-int-division-rval-off: 238 ms (3 iters, avg 79.33 ms)
+  - optimized-int-division-rval-on: 201 ms (3 iters, avg 67.00 ms)
+- Derived speedups vs legacy in this run:
+  - intDivSpeedup: 1.84x
+  - rvalSpeedup: 1.18x
+  - total: 2.18x
+- Compiled-code impact in the optimized case:
+  - `sum = reminders[j] + carriedOver` is now `GET_INDEX` + `UNBOX_INT_OBJ` + `ADD_INT`
+  - `reminders[j] = sum % denom` is now `MOD_INT` + `SET_INDEX`
+  - `q = sum / 10` is now `DIV_INT`
+  - `carriedOver = quotient * j` is now `MUL_INT`
+- Remaining hot object arithmetic in the optimized case:
+  - `reminders[j] *= 10` still compiles as `GET_INDEX` + `MUL_OBJ` + `SET_INDEX`
+  - `suffix += pi[i]` remains `ADD_OBJ`, which is expected string/object concatenation
+- Conclusion:
+  - The main remaining arithmetic bottleneck is the compound index assignment path for `reminders[j] *= 10`.
+  - The next direct win is to specialize `AssignOpRef` on typed list elements so indexed compound assignment can lower to `UNBOX_INT_OBJ` + `MUL_INT` + boxed `SET_INDEX`.
+
+Optimization #5 follow-up:
+- Attempt: specialize typed `IndexRef` compound assignment so `List<Int>` element updates avoid object arithmetic.
+- Compiler change:
+  - `compileAssignOp()` now detects non-optional typed `List<Int>` index targets and lowers arithmetic assign-ops through `UNBOX_INT_OBJ` + `*_INT` + `SET_INDEX`.
+- Latest measured run after the indexed compound-assignment change:
+  - legacy-real-division: 394 ms (3 iters, avg 131.33 ms)
+  - optimized-int-division-rval-off: 216 ms (3 iters, avg 72.00 ms)
+  - optimized-int-division-rval-on: 184 ms (3 iters, avg 61.33 ms)
+- Derived speedups vs legacy in this run:
+  - intDivSpeedup: 1.82x
+  - rvalSpeedup: 1.17x
+  - total: 2.14x
+- Compiled-code impact in the optimized case:
+  - `reminders[j] *= 10` is now:
+    - `GET_INDEX`
+    - `UNBOX_INT_OBJ`
+    - `MUL_INT`
+    - `SET_INDEX`
+  - The optimized inner loop no longer contains object arithmetic for the `reminders` state update path.
+- Remaining hot object work in the optimized case:
+  - `suffix += pi[i]` remains `ADD_OBJ` and is expected string/object concatenation
+  - The legacy benchmark case still carries real/object work because it intentionally keeps the original `floor(sum / (denom * 1.0))` path
+- Conclusion:
+  - The inner arithmetic hot loop is now effectively int-lowered end-to-end in the optimized benchmark path.
+  - Further wins will likely require reducing list access overhead itself (`GET_INDEX` / `SET_INDEX`) or changing the source algorithm/data layout, not more basic arithmetic lowering.
+
+Optimization #6 follow-up:
+- Attempt: move the direct `ObjList` index fast path out from behind `RVAL_FASTPATH` so the common plain-list case is fast by default.
+- Runtime change:
+  - `CmdGetIndex` and `CmdSetIndex` now always use direct `target.list[index]` / `target.list[index] = value` for exact `ObjList` receivers with `ObjInt` indices.
+  - Subclasses such as `ObjObservableList` still use their overridden `getAt` / `putAt` logic, so semantics stay intact.
+- Latest measured run after the default plain-list path:
+  - legacy-real-division: 397 ms (3 iters, avg 132.33 ms)
+  - optimized-int-division-rval-off: 138 ms (3 iters, avg 46.00 ms)
+  - optimized-int-division-rval-on: 164 ms (3 iters, avg 54.67 ms)
+- Derived speedups vs legacy in this run:
+  - intDivSpeedup: 2.88x
+  - rvalSpeedup: 0.84x
+  - total: 2.42x
+- Interpretation:
+  - The stable fast baseline is now the `rval-off` case, because the direct plain-`ObjList` path no longer depends on `RVAL_FASTPATH`.
+  - `RVAL_FASTPATH` no longer improves this benchmark and only reflects remaining unrelated runtime variance.
+- Conclusion:
+  - For `piSpigot`, the main VM list-access bottleneck is addressed in the default runtime path.
+  - Further work on this benchmark should target algorithm/data-layout changes or string-result construction, not the old `RVAL_FASTPATH` gate.
+
+Remaining optimization candidates:
+- `suffix += pi[i]` still compiles as repeated `ADD_OBJ` string/object concatenation.
+  - Best next option: build the suffix through a dedicated buffer/list-join path instead of per-iteration concatenation.
+- The benchmark still performs many `GET_INDEX` / `SET_INDEX` operations even after the direct plain-`ObjList` fast path.
+  - Best next option: reduce indexed access count at the source level or introduce a more specialized typed-list storage layout if this benchmark matters enough.
+- The legacy benchmark variant intentionally keeps the real-number `floor(sum / (denom * 1.0))` path.
+  - No release optimization needed there; it remains only as a regression/control case.
+- `RVAL_FASTPATH` is no longer a useful tuning knob for this workload after the plain-list VM fast path.
+  - Best next option: profile other workloads before changing or removing it globally.
+
+Release stabilization note:
+- The broad assignment-side `INT` coercion and subclass-bypassing list fast path were rolled back/narrowed to restore correctness across numeric-mix, decimal, list, observable-list, and wasm tests.
+- Full release gates now pass:
+  - `./gradlew test`
+  - `./gradlew :lynglib:wasmJsNodeTest`
+- Current release-safe benchmark on the stabilized tree:
+  - legacy-real-division: 732 ms (3 iters, avg 244.00 ms)
+  - optimized-int-division-rval-off: 545 ms (3 iters, avg 181.67 ms)
+  - optimized-int-division-rval-on: 697 ms (3 iters, avg 232.33 ms)
+- Interpretation:
+  - The release baseline is now `optimized-int-division-rval-off` at 545 ms for the current correct/stable tree.
+  - The removed coercion had been masking a real compiler typing gap; reintroducing it broadly is not release-safe.
+- Highest-value remaining compiler optimization after release:
+  - Recover typed int lowering for `j = boxes - k`, `denom = j * 2 + 1`, `sum = reminders[j] + carriedOver`, and `carriedOver = quotient * j` using a narrower proof than the removed generic arithmetic coercion.