ForLoopsLowering: Add support for unsigned progressions.

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/ir/Ir.kt

@@ -64,9 +64,13 @@ open class BuiltinSymbolsBase(protected val irBuiltIns: IrBuiltIns, protected va
         )
 
     private fun getClass(name: Name, vararg packageNameSegments: String = arrayOf("kotlin")): IrClassSymbol =
-        symbolTable.referenceClass(
-            builtInsPackage(*packageNameSegments).getContributedClassifier(name, NoLookupLocation.FROM_BACKEND) as ClassDescriptor
-        )
+        getClassOrNull(name, *packageNameSegments) ?: error("Class '$name' not found in package '${packageNameSegments.joinToString(".")}'")
+
+    private fun getClassOrNull(name: Name, vararg packageNameSegments: String = arrayOf("kotlin")): IrClassSymbol? =
+        (builtInsPackage(*packageNameSegments).getContributedClassifier(
+            name,
+            NoLookupLocation.FROM_BACKEND
+        ) as? ClassDescriptor)?.let { symbolTable.referenceClass(it) }
 
     /**
      * Use this table to reference external dependencies.
@@ -89,11 +93,22 @@ open class BuiltinSymbolsBase(protected val irBuiltIns: IrBuiltIns, protected va
         .map { symbolTable.referenceFunction(it) }
 
     private fun progression(name: String) = getClass(Name.identifier(name), "kotlin", "ranges")
+    private fun progressionOrNull(name: String) = getClassOrNull(Name.identifier(name), "kotlin", "ranges")
+
+    // The "...OrNull" variants are used for unsigned (and progressions) because the minimal stdlib used in tests do not include those
+    // those classes. It was not feasible to add them to the JS reduced runtime because all its transitive dependencies also need to be
+    // added, which would include a lot of the full stdlib.
+    open val uByte = getClassOrNull(Name.identifier("UByte"), "kotlin")
+    open val uShort = getClassOrNull(Name.identifier("UShort"), "kotlin")
+    open val uInt = getClassOrNull(Name.identifier("UInt"), "kotlin")
+    open val uLong = getClassOrNull(Name.identifier("ULong"), "kotlin")
+    val uIntProgression = progressionOrNull("UIntProgression")
+    val uLongProgression = progressionOrNull("ULongProgression")
 
     val charProgression = progression("CharProgression")
     val intProgression = progression("IntProgression")
     val longProgression = progression("LongProgression")
-    val progressionClasses = listOf(charProgression, intProgression, longProgression)
+    val progressionClasses = listOfNotNull(charProgression, intProgression, longProgression, uIntProgression, uLongProgression)
     val progressionClassesTypes = progressionClasses.map { it.descriptor.defaultType }.toSet()
 
     val getProgressionLastElementByReturnType = builtInsPackage("kotlin", "internal")
@@ -105,6 +120,18 @@ open class BuiltinSymbolsBase(protected val irBuiltIns: IrBuiltIns, protected va
             c to f
         }.toMap()
 
+    val toUIntByExtensionReceiver = builtInsPackage("kotlin").getContributedFunctions(
+        Name.identifier("toUInt"),
+        NoLookupLocation.FROM_BACKEND
+    ).filter { it.containingDeclaration !is BuiltInsPackageFragment && it.extensionReceiverParameter != null }
+        .map { Pair(it.extensionReceiverParameter!!.type, symbolTable.referenceSimpleFunction(it)) }.toMap()
+
+    val toULongByExtensionReceiver = builtInsPackage("kotlin").getContributedFunctions(
+        Name.identifier("toULong"),
+        NoLookupLocation.FROM_BACKEND
+    ).filter { it.containingDeclaration !is BuiltInsPackageFragment && it.extensionReceiverParameter != null }
+        .map { Pair(it.extensionReceiverParameter!!.type, symbolTable.referenceSimpleFunction(it)) }.toMap()
+
     val any = symbolTable.referenceClass(builtIns.any)
     val unit = symbolTable.referenceClass(builtIns.unit)
 

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/ForLoopsLowering.kt

@@ -7,7 +7,6 @@ package org.jetbrains.kotlin.backend.common.lower.loops
 
 import org.jetbrains.kotlin.backend.common.BodyLoweringPass
 import org.jetbrains.kotlin.backend.common.CommonBackendContext
-import org.jetbrains.kotlin.backend.common.FileLoweringPass
 import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.common.phaser.makeIrFilePhase
@@ -238,7 +237,7 @@ private class RangeLoopTransformer(
                 mainLoopVariable.endOffset,
                 context.irBuiltIns.unitType,
                 IrStatementOrigin.FOR_LOOP_NEXT,
-                loopHeader.initializeIteration(mainLoopVariable, loopVariableComponents, symbols, this)
+                loopHeader.initializeIteration(mainLoopVariable, loopVariableComponents, this)
             )
         }
 

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/HeaderInfo.kt

@@ -14,46 +14,77 @@ import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.symbols.IrClassSymbol
+import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
-import org.jetbrains.kotlin.ir.types.IrType
-import org.jetbrains.kotlin.ir.types.isSubtypeOfClass
+import org.jetbrains.kotlin.ir.types.*
+import org.jetbrains.kotlin.ir.util.functions
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.utils.addToStdlib.firstNotNullResult
 
-// TODO: Handle withIndex()
-// TODO: Handle UIntProgression, ULongProgression
-
 /** Represents a progression type in the Kotlin stdlib. */
-internal enum class ProgressionType(val elementCastFunctionName: Name, val stepCastFunctionName: Name) {
+internal enum class ProgressionType(
+    private val elementCastFunctionName: Name,
+    private val stepCastFunctionName: Name,
+    val isLong: Boolean = false,
+    val isUnsigned: Boolean = false
+) {
     INT_PROGRESSION(Name.identifier("toInt"), Name.identifier("toInt")),
-    LONG_PROGRESSION(Name.identifier("toLong"), Name.identifier("toLong")),
-    CHAR_PROGRESSION(Name.identifier("toChar"), Name.identifier("toInt"));
+    LONG_PROGRESSION(Name.identifier("toLong"), Name.identifier("toLong"), isLong = true),
+    CHAR_PROGRESSION(Name.identifier("toChar"), Name.identifier("toInt")),
+    UINT_PROGRESSION(Name.identifier("toUInt"), Name.identifier("toInt"), isUnsigned = true),
+    ULONG_PROGRESSION(Name.identifier("toULong"), Name.identifier("toLong"), isLong = true, isUnsigned = true);
 
     /** Returns the [IrType] of the `first`/`last` properties and elements in the progression. */
-    fun elementType(builtIns: IrBuiltIns): IrType = when (this) {
-        INT_PROGRESSION -> builtIns.intType
-        LONG_PROGRESSION -> builtIns.longType
-        CHAR_PROGRESSION -> builtIns.charType
+    fun elementType(symbols: Symbols<CommonBackendContext>): IrType = elementClassifier(symbols).defaultType
+
+    /** Returns the [IrClassSymbol] of the `first`/`last` properties and elements in the progression. */
+    fun elementClassifier(symbols: Symbols<CommonBackendContext>): IrClassSymbol = when (this) {
+        INT_PROGRESSION -> symbols.int
+        LONG_PROGRESSION -> symbols.long
+        CHAR_PROGRESSION -> symbols.char
+        UINT_PROGRESSION -> symbols.uInt!!
+        ULONG_PROGRESSION -> symbols.uLong!!
     }
 
     /** Returns the [IrType] of the `step` property in the progression. */
     fun stepType(builtIns: IrBuiltIns): IrType = when (this) {
-        INT_PROGRESSION, CHAR_PROGRESSION -> builtIns.intType
-        LONG_PROGRESSION -> builtIns.longType
+        INT_PROGRESSION, CHAR_PROGRESSION, UINT_PROGRESSION -> builtIns.intType
+        LONG_PROGRESSION, ULONG_PROGRESSION -> builtIns.longType
     }
 
     /** Returns the [IrClassSymbol] of the `step` property type constructor in the progression. */
     fun stepClassifier(builtIns: IrBuiltIns): IrClassSymbol = when(this) {
-        INT_PROGRESSION, CHAR_PROGRESSION -> builtIns.intClass
-        LONG_PROGRESSION -> builtIns.longClass
+        INT_PROGRESSION, CHAR_PROGRESSION , UINT_PROGRESSION-> builtIns.intClass
+        LONG_PROGRESSION, ULONG_PROGRESSION -> builtIns.longClass
     }
 
+    fun castElementIfNecessary(element: IrExpression, context: CommonBackendContext) =
+        element.castIfNecessary(elementType(context.ir.symbols), elementCastFunctionName)
+
+    fun castStepIfNecessary(step: IrExpression, context: CommonBackendContext) =
+        step.castIfNecessary(stepType(context.irBuiltIns), stepCastFunctionName)
+
+    private fun IrExpression.castIfNecessary(targetType: IrType, numberCastFunctionName: Name) =
+        // This expression's type could be Nothing from an exception throw.
+        if (type == targetType || type.isNothing()) {
+            this
+        } else {
+            val castFun = type.getClass()!!.functions.single {
+                it.name == numberCastFunctionName &&
+                        it.dispatchReceiverParameter != null && it.extensionReceiverParameter == null && it.valueParameters.isEmpty()
+            }
+            IrCallImpl(startOffset, endOffset, castFun.returnType, castFun.symbol)
+                .apply { dispatchReceiver = this@castIfNecessary }
+        }
+
     companion object {
         fun fromIrType(irType: IrType, symbols: Symbols<CommonBackendContext>): ProgressionType? = when {
             irType.isSubtypeOfClass(symbols.charProgression) -> CHAR_PROGRESSION
             irType.isSubtypeOfClass(symbols.intProgression) -> INT_PROGRESSION
             irType.isSubtypeOfClass(symbols.longProgression) -> LONG_PROGRESSION
+            symbols.uIntProgression != null && irType.isSubtypeOfClass(symbols.uIntProgression) -> UINT_PROGRESSION
+            symbols.uLongProgression != null && irType.isSubtypeOfClass(symbols.uLongProgression) -> ULONG_PROGRESSION
             else -> null
         }
     }
@@ -113,12 +144,18 @@ internal class ProgressionHeaderInfo(
     additionalNotEmptyCondition = additionalNotEmptyCondition
 ) {
 
+    @ExperimentalUnsignedTypes
     val canOverflow: Boolean by lazy {
         if (canOverflow != null) return@lazy canOverflow
 
         // We can't determine the safe limit at compile-time if "step" is not const.
         val stepValueAsLong = step.constLongValue ?: return@lazy true
 
+        if (direction == ProgressionDirection.UNKNOWN) {
+            // If we don't know the direction, we can't be sure which limit to use.
+            return@lazy true
+        }
+
         // Induction variable can NOT overflow if "last" is const and is <= (MAX/MIN_VALUE - step) (depending on direction).
         //
         // Examples that can NOT overflow:
@@ -137,26 +174,51 @@ internal class ProgressionHeaderInfo(
         //   - `0..10 step someStep()` CAN overflow (we don't know the step and hence can't determine the safe limit)
         //   - `0..someLast()` CAN overflow (we don't know the direction)
         //   - `someProgression()` CAN overflow (we don't know the direction)
-        val lastValueAsLong = last.constLongValue ?: return@lazy true  // If "last" is not a const Number or Char.
-        when (direction) {
-            ProgressionDirection.UNKNOWN ->
-                // If we don't know the direction, we can't be sure which limit to use.
-                true
-            ProgressionDirection.DECREASING -> {
-                val constLimitAsLong = when (progressionType) {
-                    ProgressionType.INT_PROGRESSION -> Int.MIN_VALUE.toLong()
-                    ProgressionType.CHAR_PROGRESSION -> Char.MIN_VALUE.toLong()
-                    ProgressionType.LONG_PROGRESSION -> Long.MIN_VALUE
+
+        if (progressionType.isUnsigned) {
+            // "step" is still signed for unsigned progressions.
+            val lastValueAsULong = last.constLongValue?.toULong() ?: return@lazy true  // If "last" is not a const Number or Char.
+            when (direction) {
+                ProgressionDirection.DECREASING -> {
+                    val constLimitAsULong = when (progressionType) {
+                        ProgressionType.UINT_PROGRESSION -> UInt.MIN_VALUE.toULong()
+                        ProgressionType.ULONG_PROGRESSION -> ULong.MIN_VALUE
+                        else -> error("Unexpected progression type")
+                    }
+                    lastValueAsULong < (constLimitAsULong - stepValueAsLong.toULong())
                 }
-                lastValueAsLong < (constLimitAsLong - stepValueAsLong)
+                ProgressionDirection.INCREASING -> {
+                    val constLimitAsULong = when (progressionType) {
+                        ProgressionType.UINT_PROGRESSION -> UInt.MAX_VALUE.toULong()
+                        ProgressionType.ULONG_PROGRESSION -> ULong.MAX_VALUE
+                        else -> error("Unexpected progression type")
+                    }
+                    lastValueAsULong > (constLimitAsULong - stepValueAsLong.toULong())
+                }
+                else -> error("Unexpected progression direction")
             }
-            ProgressionDirection.INCREASING -> {
-                val constLimitAsLong = when (progressionType) {
-                    ProgressionType.INT_PROGRESSION -> Int.MAX_VALUE.toLong()
-                    ProgressionType.CHAR_PROGRESSION -> Char.MAX_VALUE.toLong()
-                    ProgressionType.LONG_PROGRESSION -> Long.MAX_VALUE
+        } else {
+            val lastValueAsLong = last.constLongValue ?: return@lazy true  // If "last" is not a const Number or Char.
+            when (direction) {
+                ProgressionDirection.DECREASING -> {
+                    val constLimitAsLong = when (progressionType) {
+                        ProgressionType.INT_PROGRESSION -> Int.MIN_VALUE.toLong()
+                        ProgressionType.CHAR_PROGRESSION -> Char.MIN_VALUE.toLong()
+                        ProgressionType.LONG_PROGRESSION -> Long.MIN_VALUE
+                        else -> error("Unexpected progression type")
+                    }
+                    lastValueAsLong < (constLimitAsLong - stepValueAsLong)
                 }
-                lastValueAsLong > (constLimitAsLong - stepValueAsLong)
+                ProgressionDirection.INCREASING -> {
+                    val constLimitAsLong = when (progressionType) {
+                        ProgressionType.INT_PROGRESSION -> Int.MAX_VALUE.toLong()
+                        ProgressionType.CHAR_PROGRESSION -> Char.MAX_VALUE.toLong()
+                        ProgressionType.LONG_PROGRESSION -> Long.MAX_VALUE
+                        else -> error("Unexpected progression type")
+                    }
+                    lastValueAsLong > (constLimitAsLong - stepValueAsLong)
+                }
+                else -> error("Unexpected progression direction")
             }
         }
     }
@@ -268,14 +330,17 @@ internal abstract class HeaderInfoBuilder(context: CommonBackendContext, private
 
     private val symbols = context.ir.symbols
 
-    // TODO: Include unsigned types
-    private val progressionElementTypes = listOf(
-        context.irBuiltIns.byteType,
-        context.irBuiltIns.shortType,
-        context.irBuiltIns.intType,
-        context.irBuiltIns.longType,
-        context.irBuiltIns.charType
-    )
+    private val progressionElementTypes = listOfNotNull(
+        symbols.byte,
+        symbols.short,
+        symbols.int,
+        symbols.long,
+        symbols.char,
+        symbols.uByte,
+        symbols.uShort,
+        symbols.uInt,
+        symbols.uLong
+    ).map { it.defaultType }
 
     private val progressionHandlers = listOf(
         CollectionIndicesHandler(context),

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/HeaderProcessor.kt

@@ -6,7 +6,6 @@
 package org.jetbrains.kotlin.backend.common.lower.loops
 
 import org.jetbrains.kotlin.backend.common.CommonBackendContext
-import org.jetbrains.kotlin.backend.common.ir.Symbols
 import org.jetbrains.kotlin.backend.common.lower.DeclarationIrBuilder
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.common.lower.irIfThen
@@ -50,7 +49,6 @@ internal interface ForLoopHeader {
     fun initializeIteration(
         loopVariable: IrVariable?,
         loopVariableComponents: Map<Int, IrVariable>,
-        symbols: Symbols<CommonBackendContext>,
         builder: DeclarationIrBuilder
     ): List<IrStatement>
 
@@ -61,6 +59,7 @@ internal interface ForLoopHeader {
 internal abstract class NumericForLoopHeader<T : NumericHeaderInfo>(
     protected val headerInfo: T,
     builder: DeclarationIrBuilder,
+    context: CommonBackendContext,
     protected val isLastInclusive: Boolean
 ) : ForLoopHeader {
 
@@ -68,16 +67,18 @@ internal abstract class NumericForLoopHeader<T : NumericHeaderInfo>(
 
     val inductionVariable: IrVariable
     val stepVariable: IrVariable
+    val stepVariableForIncrement: IrVariable?
     protected val lastVariableIfCanCacheLast: IrVariable?
     protected val lastExpression: IrExpression
         // Always copy `lastExpression` is it may be used in multiple conditions.
         get() = field.deepCopyWithSymbols()
 
+    private val symbols = context.ir.symbols
     private val elementType: IrType
 
     init {
         with(builder) {
-            elementType = headerInfo.progressionType.elementType(context.irBuiltIns)
+            elementType = headerInfo.progressionType.elementType(symbols)
 
             // For this loop:
             //
@@ -89,10 +90,7 @@ internal abstract class NumericForLoopHeader<T : NumericHeaderInfo>(
             // In the above example, if first() is a Long and last() is an Int, this creates a
             // LongProgression so last() should be cast to a Long.
             inductionVariable = scope.createTemporaryVariable(
-                headerInfo.first.castIfNecessary(
-                    elementType,
-                    headerInfo.progressionType.elementCastFunctionName
-                ),
+                headerInfo.progressionType.castElementIfNecessary(headerInfo.first, context),
                 nameHint = "inductionVariable",
                 isMutable = true
             )
@@ -101,12 +99,7 @@ internal abstract class NumericForLoopHeader<T : NumericHeaderInfo>(
             // they are non-nullable (the frontend takes care about this). So we need to cast
             // them to non-nullable.
             // TODO: Confirm if casting to non-nullable is still necessary
-            val last = ensureNotNullable(
-                headerInfo.last.castIfNecessary(
-                    elementType,
-                    headerInfo.progressionType.elementCastFunctionName
-                )
-            )
+            val last = ensureNotNullable(headerInfo.progressionType.castElementIfNecessary(headerInfo.last, context))
 
             lastVariableIfCanCacheLast = if (headerInfo.canCacheLast) {
                 scope.createTemporaryVariable(
@@ -117,17 +110,29 @@ internal abstract class NumericForLoopHeader<T : NumericHeaderInfo>(
 
             lastExpression = if (headerInfo.canCacheLast) irGet(lastVariableIfCanCacheLast!!) else last
 
-            stepVariable = headerInfo.progressionType.stepType(context.irBuiltIns).let {
+            stepVariable =
                 scope.createTemporaryVariable(
-                    ensureNotNullable(
-                        headerInfo.step.castIfNecessary(
-                            it,
-                            headerInfo.progressionType.stepCastFunctionName
-                        )
-                    ),
+                    ensureNotNullable(headerInfo.progressionType.castStepIfNecessary(headerInfo.step, context)),
                     nameHint = "step",
-                    irType = it
+                    irType = headerInfo.progressionType.stepType(context.irBuiltIns)
                 )
+
+            stepVariableForIncrement = when (headerInfo.progressionType) {
+                ProgressionType.UINT_PROGRESSION -> {
+                    val castFun = context.ir.symbols.toUIntByExtensionReceiver.getValue(stepVariable.type.toKotlinType())
+                    scope.createTemporaryVariable(
+                        irCall(castFun).apply { extensionReceiver = irGet(stepVariable) },
+                        nameHint = "stepForIncrement"
+                    )
+                }
+                ProgressionType.ULONG_PROGRESSION -> {
+                    val castFun = context.ir.symbols.toULongByExtensionReceiver.getValue(stepVariable.type.toKotlinType())
+                    scope.createTemporaryVariable(
+                        irCall(castFun).apply { extensionReceiver = irGet(stepVariable) },
+                        nameHint = "stepForIncrement"
+                    )
+                }
+                else -> null
             }
         }
     }
@@ -142,16 +147,17 @@ internal abstract class NumericForLoopHeader<T : NumericHeaderInfo>(
     /** Statement used to increment the induction variable. */
     protected fun incrementInductionVariable(builder: DeclarationIrBuilder): IrStatement = with(builder) {
         // inductionVariable = inductionVariable + step
+        val stepVariableToUse = stepVariableForIncrement ?: stepVariable
         val plusFun = elementType.getClass()!!.functions.single {
             it.name == OperatorNameConventions.PLUS &&
                     it.valueParameters.size == 1 &&
-                    it.valueParameters[0].type == stepVariable.type
+                    it.valueParameters[0].type == stepVariableToUse.type
         }
         irSetVar(
             inductionVariable.symbol, irCallOp(
                 plusFun.symbol, plusFun.returnType,
                 irGet(inductionVariable),
-                irGet(stepVariable)
+                irGet(stepVariableToUse)
             )
         )
     }
@@ -160,25 +166,65 @@ internal abstract class NumericForLoopHeader<T : NumericHeaderInfo>(
         with(builder) {
             val builtIns = context.irBuiltIns
             val progressionType = headerInfo.progressionType
-            val progressionElementType = progressionType.elementType(builtIns)
-            val compFun =
-                if (isLastInclusive) builtIns.lessOrEqualFunByOperandType[progressionElementType.classifierOrFail]!!
-                else builtIns.lessFunByOperandType[progressionElementType.classifierOrFail]!!
+            val progressionElementType = progressionType.elementType(symbols)
 
-            // The default condition depends on the direction.
-            when (headerInfo.direction) {
-                ProgressionDirection.DECREASING ->
-                    // last <= inductionVar (use `<` if last is exclusive)
-                    irCall(compFun).apply {
+            // `compareTo` must be used for UInt/ULong; they don't have intrinsic comparison operators.
+            val intCompFun = if (isLastInclusive) {
+                builtIns.lessOrEqualFunByOperandType.getValue(builtIns.intClass)
+            } else {
+                builtIns.lessFunByOperandType.getValue(builtIns.intClass)
+            }
+            val elementCompareToFun = progressionElementType.getClass()!!.functions.single {
+                it.name == OperatorNameConventions.COMPARE_TO &&
+                        it.dispatchReceiverParameter != null && it.extensionReceiverParameter == null &&
+                        it.valueParameters.size == 1 && it.valueParameters[0].type == progressionElementType
+            }
+
+            val elementCompFun =
+                if (isLastInclusive) {
+                    builtIns.lessOrEqualFunByOperandType[progressionElementType.classifierOrFail]
+                } else {
+                    builtIns.lessFunByOperandType[progressionElementType.classifierOrFail]
+                }
+
+            fun conditionForDecreasing(): IrExpression =
+                // last <= inductionVar (use `<` if last is exclusive)
+                if (progressionType.isUnsigned) {
+                    irCall(intCompFun).apply {
+                        putValueArgument(0, irCall(elementCompareToFun).apply {
+                            dispatchReceiver = lastExpression
+                            putValueArgument(0, irGet(inductionVariable))
+                        })
+                        putValueArgument(1, irInt(0))
+                    }
+                } else {
+                    irCall(elementCompFun!!).apply {
                         putValueArgument(0, lastExpression)
                         putValueArgument(1, irGet(inductionVariable))
                     }
-                ProgressionDirection.INCREASING ->
-                    // inductionVar <= last (use `<` if last is exclusive)
-                    irCall(compFun).apply {
+                }
+
+            fun conditionForIncreasing(): IrExpression =
+                // inductionVar <= last (use `<` if last is exclusive)
+                if (progressionType.isUnsigned) {
+                    irCall(intCompFun).apply {
+                        putValueArgument(0, irCall(elementCompareToFun).apply {
+                            dispatchReceiver = irGet(inductionVariable)
+                            putValueArgument(0, lastExpression)
+                        })
+                        putValueArgument(1, irInt(0))
+                    }
+                } else {
+                    irCall(elementCompFun!!).apply {
                         putValueArgument(0, irGet(inductionVariable))
                         putValueArgument(1, lastExpression)
                     }
+                }
+
+            // The default condition depends on the direction.
+            when (headerInfo.direction) {
+                ProgressionDirection.DECREASING -> conditionForDecreasing()
+                ProgressionDirection.INCREASING -> conditionForIncreasing()
                 ProgressionDirection.UNKNOWN -> {
                     // If the direction is unknown, we check depending on the "step" value:
                     //   // (use `<` if last is exclusive)
@@ -187,33 +233,31 @@ internal abstract class NumericForLoopHeader<T : NumericHeaderInfo>(
                     val isLong = progressionType == ProgressionType.LONG_PROGRESSION
                     context.oror(
                         context.andand(
-                            irCall(builtIns.greaterFunByOperandType[stepTypeClassifier]!!).apply {
+                            irCall(builtIns.greaterFunByOperandType.getValue(stepTypeClassifier)).apply {
                                 putValueArgument(0, irGet(stepVariable))
-                                putValueArgument(1, if (isLong) irLong(0) else irInt(0))
+                                putValueArgument(1, if (progressionType.isLong) irLong(0) else irInt(0))
                             },
-                            irCall(compFun).apply {
-                                putValueArgument(0, irGet(inductionVariable))
-                                putValueArgument(1, lastExpression)
-                            }),
+                            conditionForIncreasing()
+                        ),
                         context.andand(
-                            irCall(builtIns.lessFunByOperandType[stepTypeClassifier]!!).apply {
+                            irCall(builtIns.lessFunByOperandType.getValue(stepTypeClassifier)).apply {
                                 putValueArgument(0, irGet(stepVariable))
-                                putValueArgument(1, if (isLong) irLong(0) else irInt(0))
+                                putValueArgument(1, if (progressionType.isLong) irLong(0) else irInt(0))
                             },
-                            irCall(compFun).apply {
-                                putValueArgument(0, lastExpression)
-                                putValueArgument(1, irGet(inductionVariable))
-                            })
+                            conditionForDecreasing()
+                        )
                     )
                 }
             }
+
         }
 }
 
 internal class ProgressionLoopHeader(
     headerInfo: ProgressionHeaderInfo,
-    builder: DeclarationIrBuilder
-) : NumericForLoopHeader<ProgressionHeaderInfo>(headerInfo, builder, isLastInclusive = true) {
+    builder: DeclarationIrBuilder,
+    context: CommonBackendContext
+) : NumericForLoopHeader<ProgressionHeaderInfo>(headerInfo, builder, context, isLastInclusive = true) {
 
     // For this loop:
     //
@@ -230,14 +274,14 @@ internal class ProgressionLoopHeader(
             else
                 listOfNotNull(inductionVariable, lastVariableIfCanCacheLast)
             ) +
-            stepVariable
+            listOfNotNull(stepVariable, stepVariableForIncrement)
 
     private var loopVariable: IrVariable? = null
 
+    @ExperimentalUnsignedTypes
     override fun initializeIteration(
         loopVariable: IrVariable?,
         loopVariableComponents: Map<Int, IrVariable>,
-        symbols: Symbols<CommonBackendContext>,
         builder: DeclarationIrBuilder
     ) =
         with(builder) {
@@ -258,6 +302,7 @@ internal class ProgressionLoopHeader(
             listOfNotNull(loopVariable, incrementInductionVariable(this))
         }
 
+    @ExperimentalUnsignedTypes
     override fun buildLoop(builder: DeclarationIrBuilder, oldLoop: IrLoop, newBody: IrExpression?) =
         with(builder) {
             val newLoop = if (headerInfo.canOverflow) {
@@ -322,15 +367,16 @@ private class InitializerCallReplacer(symbolRemapper: SymbolRemapper, typeRemapp
 
 internal class IndexedGetLoopHeader(
     headerInfo: IndexedGetHeaderInfo,
-    builder: DeclarationIrBuilder
-) : NumericForLoopHeader<IndexedGetHeaderInfo>(headerInfo, builder, isLastInclusive = false) {
+    builder: DeclarationIrBuilder,
+    context: CommonBackendContext
+) : NumericForLoopHeader<IndexedGetHeaderInfo>(headerInfo, builder, context, isLastInclusive = false) {
 
-    override val loopInitStatements = listOfNotNull(headerInfo.objectVariable, inductionVariable, lastVariableIfCanCacheLast, stepVariable)
+    override val loopInitStatements =
+        listOfNotNull(headerInfo.objectVariable, inductionVariable, lastVariableIfCanCacheLast, stepVariable, stepVariableForIncrement)
 
     override fun initializeIteration(
         loopVariable: IrVariable?,
         loopVariableComponents: Map<Int, IrVariable>,
-        symbols: Symbols<CommonBackendContext>,
         builder: DeclarationIrBuilder
     ) =
         with(builder) {
@@ -371,7 +417,8 @@ internal class IndexedGetLoopHeader(
 
 internal class WithIndexLoopHeader(
     headerInfo: WithIndexHeaderInfo,
-    builder: DeclarationIrBuilder
+    builder: DeclarationIrBuilder,
+    context: CommonBackendContext
 ) : ForLoopHeader {
 
     private val nestedLoopHeader: ForLoopHeader
@@ -384,8 +431,8 @@ internal class WithIndexLoopHeader(
             // To build the optimized/lowered `for` loop over a `withIndex()` call, we first need the header for the underlying iterable so
             // so that we know how to build the loop for that iterable. More info in comments in initializeIteration().
             nestedLoopHeader = when (val nestedInfo = headerInfo.nestedInfo) {
-                is IndexedGetHeaderInfo -> IndexedGetLoopHeader(nestedInfo, this@with)
-                is ProgressionHeaderInfo -> ProgressionLoopHeader(nestedInfo, this@with)
+                is IndexedGetHeaderInfo -> IndexedGetLoopHeader(nestedInfo, this@with, context)
+                is ProgressionHeaderInfo -> ProgressionLoopHeader(nestedInfo, this@with, context)
                 is IterableHeaderInfo -> IterableLoopHeader(nestedInfo)
                 is WithIndexHeaderInfo -> throw IllegalStateException("Nested WithIndexHeaderInfo not allowed for WithIndexLoopHeader")
             }
@@ -409,7 +456,7 @@ internal class WithIndexLoopHeader(
                 )
                 ownsIndexVariable = true
                 // `index++` during iteration initialization
-                // TODO: MUSTDO: Check for overflow for Iterable and Sequence (call to checkIndexOverflow()).
+                // TODO: KT-34665: Check for overflow for Iterable and Sequence (call to checkIndexOverflow()).
                 val plusFun = indexVariable.type.getClass()!!.functions.first {
                     it.name == OperatorNameConventions.PLUS &&
                             it.valueParameters.size == 1 &&
@@ -435,7 +482,6 @@ internal class WithIndexLoopHeader(
     override fun initializeIteration(
         loopVariable: IrVariable?,
         loopVariableComponents: Map<Int, IrVariable>,
-        symbols: Symbols<CommonBackendContext>,
         builder: DeclarationIrBuilder
     ) =
         with(builder) {
@@ -508,7 +554,6 @@ internal class WithIndexLoopHeader(
             listOfNotNull(loopVariableComponents[1], incrementIndexStatement) + nestedLoopHeader.initializeIteration(
                 loopVariableComponents[2],
                 linkedMapOf(),
-                symbols,
                 builder
             )
         }
@@ -528,7 +573,6 @@ internal class IterableLoopHeader(
     override fun initializeIteration(
         loopVariable: IrVariable?,
         loopVariableComponents: Map<Int, IrVariable>,
-        symbols: Symbols<CommonBackendContext>,
         builder: DeclarationIrBuilder
     ) =
         with(builder) {
@@ -615,9 +659,9 @@ internal class HeaderProcessor(
 
         val builder = context.createIrBuilder(scopeOwnerSymbol(), variable.startOffset, variable.endOffset)
         return when (headerInfo) {
-            is IndexedGetHeaderInfo -> IndexedGetLoopHeader(headerInfo, builder)
-            is ProgressionHeaderInfo -> ProgressionLoopHeader(headerInfo, builder)
-            is WithIndexHeaderInfo -> WithIndexLoopHeader(headerInfo, builder)
+            is IndexedGetHeaderInfo -> IndexedGetLoopHeader(headerInfo, builder, context)
+            is ProgressionHeaderInfo -> ProgressionLoopHeader(headerInfo, builder, context)
+            is WithIndexHeaderInfo -> WithIndexLoopHeader(headerInfo, builder, context)
             is IterableHeaderInfo -> IterableLoopHeader(headerInfo)
         }
     }

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/ProgressionHandlers.kt

@@ -17,10 +17,12 @@ import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.declarations.IrVariable
 import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.types.asSimpleType
 import org.jetbrains.kotlin.util.OperatorNameConventions
 import kotlin.math.absoluteValue
 
@@ -73,12 +75,19 @@ internal class DownToHandler(private val context: CommonBackendContext, private
 internal class UntilHandler(private val context: CommonBackendContext, private val progressionElementTypes: Collection<IrType>) :
     ProgressionHandler {
 
+    private val symbols = context.ir.symbols
+    private val uByteType = symbols.uByte?.defaultType
+    private val uShortType = symbols.uShort?.defaultType
+    private val uIntType = symbols.uInt?.defaultType
+    private val uLongType = symbols.uLong?.defaultType
+
     override val matcher = SimpleCalleeMatcher {
         singleArgumentExtension(FqName("kotlin.ranges.until"), progressionElementTypes)
         parameterCount { it == 1 }
         parameter(0) { it.type in progressionElementTypes }
     }
 
+    @ExperimentalUnsignedTypes
     override fun build(expression: IrCall, data: ProgressionType, scopeOwner: IrSymbol): HeaderInfo? =
         with(context.createIrBuilder(scopeOwner, expression.startOffset, expression.endOffset)) {
             // `A until B` is essentially the same as `A .. (B-1)`. However, B could be MIN_VALUE and hence `(B-1)` could underflow.
@@ -121,10 +130,7 @@ internal class UntilHandler(private val context: CommonBackendContext, private v
             val untilArg = expression.getValueArgument(0)!!
 
             // Ensure that the argument conforms to the progression type before we decrement.
-            val untilArgCasted = untilArg.castIfNecessary(
-                data.elementType(context.irBuiltIns),
-                data.elementCastFunctionName
-            )
+            val untilArgCasted = data.castElementIfNecessary(untilArg, this@UntilHandler.context)
 
             // To reduce local variable usage, we create and use temporary variables only if necessary.
             var receiverValueVar: IrVariable? = null
@@ -147,6 +153,24 @@ internal class UntilHandler(private val context: CommonBackendContext, private v
                     ProgressionType.INT_PROGRESSION -> Pair(Int.MIN_VALUE.toLong(), irInt(Int.MIN_VALUE))
                     ProgressionType.CHAR_PROGRESSION -> Pair(Char.MIN_VALUE.toLong(), irChar(Char.MIN_VALUE))
                     ProgressionType.LONG_PROGRESSION -> Pair(Long.MIN_VALUE, irLong(Long.MIN_VALUE))
+                    ProgressionType.UINT_PROGRESSION -> Pair(
+                        UInt.MIN_VALUE.toLong(),
+                        IrConstImpl.int(
+                            startOffset,
+                            endOffset,
+                            symbols.uInt!!.defaultType,
+                            UInt.MIN_VALUE.toInt()
+                        )
+                    )
+                    ProgressionType.ULONG_PROGRESSION -> Pair(
+                        ULong.MIN_VALUE.toLong(),
+                        IrConstImpl.long(
+                            startOffset,
+                            endOffset,
+                            symbols.uLong!!.defaultType,
+                            ULong.MIN_VALUE.toLong()
+                        )
+                    )
                 }
             val additionalNotEmptyCondition = untilArg.constLongValue.let {
                 when {
@@ -197,11 +221,14 @@ internal class UntilHandler(private val context: CommonBackendContext, private v
         //   infix fun Long.until(to: Short): LongRange
         //   infix fun Long.until(to: Int): LongRange
         //   infix fun Long.until(to: Long): LongRange
+        //   infix fun UByte.until(to: UByte): UIntRange
+        //   infix fun UShort.until(to: UShort): UIntRange
+        //   infix fun UInt.until(to: UInt): UIntRange
+        //   infix fun ULong.until(to: ULong): ULongRange
         //
         // The combinations where the range element type is strictly larger than the argument type do NOT need the additional condition.
         // In such combinations, there is no possibility of underflow when the argument (casted to the range element type) is decremented.
         // For unexpected combinations that currently don't exist (e.g., Int until Char), we assume the check is needed to be safe.
-        // TODO: Include unsigned types
         return with(context.irBuiltIns) {
             when (receiverType) {
                 charType -> true
@@ -213,7 +240,11 @@ internal class UntilHandler(private val context: CommonBackendContext, private v
                     byteType, shortType, intType -> false
                     else -> true
                 }
-                else -> true
+                uByteType -> false
+                uShortType -> false
+                uIntType -> true
+                uLongType -> true
+                else -> true  // Default in case a new `until` overload is added to stdlib and this function was not updated.
             }
         }
     }
@@ -258,7 +289,7 @@ internal class StepHandler(
             // We insert this check in the lowered form only if necessary.
             val stepType = data.stepType(context.irBuiltIns)
             val stepGreaterFun = context.irBuiltIns.greaterFunByOperandType[data.stepClassifier(context.irBuiltIns)]!!
-            val zeroStep = if (data == ProgressionType.LONG_PROGRESSION) irLong(0) else irInt(0)
+            val zeroStep = if (data.isLong) irLong(0) else irInt(0)
             val throwIllegalStepExceptionCall = {
                 irCall(context.irBuiltIns.illegalArgumentExceptionSymbol).apply {
                     val exceptionMessage = irConcat()
@@ -458,29 +489,29 @@ internal class StepHandler(
             return last
         }
 
-        // Call `getProgressionLastElement(first, last, step)`
-        val stepTypeClassifier = progressionType.stepClassifier(context.irBuiltIns)
-        val getProgressionLastElementFun = symbols.getProgressionLastElementByReturnType[stepTypeClassifier]
-            ?: throw IllegalArgumentException("No `getProgressionLastElement` for step type $stepTypeClassifier")
+        // Call `getProgressionLastElement(first, last, step)`. The following overloads are present in the stdlib:
+        //   - getProgressionLastElement(Int, Int, Int): Int          // Used by IntProgression and CharProgression (uses Int step)
+        //   - getProgressionLastElement(Long, Long, Long): Long      // Used by LongProgression
+        //   - getProgressionLastElement(UInt, UInt, Int): UInt       // Used by UIntProgression (uses Int step)
+        //   - getProgressionLastElement(ULong, ULong, Long): ULong   // Used by ULongProgression (uses Long step)
+        //
+        // We make sure to retrieve the correct symbol and use the correct argument types.
+        val returnTypeClassifier = if (progressionType.isUnsigned) {
+            progressionType.elementClassifier(symbols)
+        } else {
+            progressionType.stepClassifier(context.irBuiltIns)
+        }
+        val getProgressionLastElementFun = symbols.getProgressionLastElementByReturnType[returnTypeClassifier]
+            ?: throw IllegalArgumentException("No `getProgressionLastElement` for return type ${returnTypeClassifier.defaultType}")
         return irCall(getProgressionLastElementFun).apply {
-            putValueArgument(
-                0, first.deepCopyWithSymbols().castIfNecessary(
-                    progressionType.stepType(context.irBuiltIns),
-                    progressionType.stepCastFunctionName
-                )
-            )
-            putValueArgument(
-                1, last.deepCopyWithSymbols().castIfNecessary(
-                    progressionType.stepType(context.irBuiltIns),
-                    progressionType.stepCastFunctionName
-                )
-            )
-            putValueArgument(
-                2, step.deepCopyWithSymbols().castIfNecessary(
-                    progressionType.stepType(context.irBuiltIns),
-                    progressionType.stepCastFunctionName
-                )
-            )
+            if (progressionType.isUnsigned) {
+                putValueArgument(0, progressionType.castElementIfNecessary(first.deepCopyWithSymbols(), this@StepHandler.context))
+                putValueArgument(1, progressionType.castElementIfNecessary(last.deepCopyWithSymbols(), this@StepHandler.context))
+            } else {
+                putValueArgument(0, progressionType.castStepIfNecessary(first.deepCopyWithSymbols(), this@StepHandler.context))
+                putValueArgument(1, progressionType.castStepIfNecessary(last.deepCopyWithSymbols(), this@StepHandler.context))
+            }
+            putValueArgument(2, progressionType.castStepIfNecessary(step.deepCopyWithSymbols(), this@StepHandler.context))
         }
     }
 }

compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/lower/loops/Utils.kt

@@ -14,24 +14,11 @@ import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.expressions.IrGetValue
 import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
 import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
-import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.getClass
 import org.jetbrains.kotlin.ir.types.isNothing
 import org.jetbrains.kotlin.ir.util.functions
-import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.util.OperatorNameConventions
 
-internal fun IrExpression.castIfNecessary(targetType: IrType, numberCastFunctionName: Name): IrExpression {
-    // This expression's type could be Nothing from an exception throw.
-    return if (type == targetType || type.isNothing()) {
-        this
-    } else {
-        val castFun = type.getClass()!!.functions.single { it.name == numberCastFunctionName && it.valueParameters.isEmpty() }
-        IrCallImpl(startOffset, endOffset, castFun.returnType, castFun.symbol)
-            .apply { dispatchReceiver = this@castIfNecessary }
-    }
-}
-
 /** Return the negated value if the expression is const, otherwise call unaryMinus(). */
 internal fun IrExpression.negate(): IrExpression {
     return when (val value = (this as? IrConst<*>)?.value as? Number) {

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt

@@ -299,6 +299,7 @@ private val jvmFilePhases =
         anonymousObjectSuperConstructorPhase then
         tailrecPhase then
 
+        forLoopsPhase then
         jvmInlineClassPhase then
 
         sharedVariablesPhase then
@@ -318,7 +319,6 @@ private val jvmFilePhases =
 
         jvmDefaultConstructorPhase then
 
-        forLoopsPhase then
         flattenStringConcatenationPhase then
         foldConstantLoweringPhase then
         computeStringTrimPhase then

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/lower/JvmInlineClassLowering.kt

@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.backend.common.ir.copyParameterDeclarationsFrom
 import org.jetbrains.kotlin.backend.common.ir.passTypeArgumentsFrom
 import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
 import org.jetbrains.kotlin.backend.common.lower.irBlockBody
+import org.jetbrains.kotlin.backend.common.lower.loops.forLoopsPhase
 import org.jetbrains.kotlin.backend.common.phaser.makeIrFilePhase
 import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
 import org.jetbrains.kotlin.backend.jvm.JvmLoweredDeclarationOrigin
@@ -42,7 +43,9 @@ import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 val jvmInlineClassPhase = makeIrFilePhase(
     ::JvmInlineClassLowering,
     name = "Inline Classes",
-    description = "Lower inline classes"
+    description = "Lower inline classes",
+    // forLoopsPhase may produce UInt and ULong which are inline classes.
+    prerequisite = setOf(forLoopsPhase)
 )
 
 /**

compiler/testData/codegen/bytecodeText/forLoop/forInOptimizableUnsignedRange.kt

@@ -1,5 +1,4 @@
-// IGNORE_BACKEND: JVM_IR
-// TODO KT-36773 Use counter loop when generating 'for' loop over an unsigned range in JVM_IR
+// WITH_RUNTIME
 
 fun testUIntRangeLiteral(a: UInt, b: UInt): Int {
     var s = 0