Split voidValue into immaterialUnitValue and defaultValue

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt

@@ -34,6 +34,7 @@ import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.*
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 import org.jetbrains.kotlin.resolve.jvm.AsmTypes
+import org.jetbrains.kotlin.resolve.jvm.AsmTypes.DEFAULT_CONSTRUCTOR_MARKER
 import org.jetbrains.kotlin.resolve.jvm.AsmTypes.OBJECT_TYPE
 import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstanceOrNull
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
@@ -169,7 +170,8 @@ class ExpressionCodegen(
                 irFunction.markLineNumber(startOffset = irFunction is IrConstructor && irFunction.isPrimary)
             }
             val returnType = typeMapper.mapReturnType(irFunction)
-            result.coerce(returnType, if (irFunction !is IrConstructor) irFunction.returnType else null).materialize()
+            val returnIrType = if (irFunction !is IrConstructor) irFunction.returnType else context.irBuiltIns.unitType
+            result.coerce(returnType, returnIrType).materialize()
             mv.areturn(returnType)
         }
         val endLabel = markNewLabel()
@@ -278,7 +280,7 @@ class ExpressionCodegen(
     }
 
     private fun visitStatementContainer(container: IrStatementContainer, data: BlockInfo) =
-        container.statements.fold(voidValue as PromisedValue) { prev, exp ->
+        container.statements.fold(immaterialUnitValue as PromisedValue) { prev, exp ->
             prev.discard()
             exp.accept(this, data).also { (exp as? IrExpression)?.markEndOfStatementIfNeeded() }
         }
@@ -396,12 +398,12 @@ class ExpressionCodegen(
             returnType.substitute(typeSubstitutionMap).isNothing() -> {
                 mv.aconst(null)
                 mv.athrow()
-                voidValue
+                immaterialUnitValue
             }
             expression is IrConstructorCall ->
                 MaterialValue(this, asmType, expression.type)
             expression is IrDelegatingConstructorCall ->
-                voidValue
+                immaterialUnitValue
             expression.type.isUnit() ->
                 // NewInference allows casting `() -> T` to `() -> Unit`. A CHECKCAST here will fail.
                 MaterialValue(this, callable.returnType, returnType).discard().coerce(expression.type)
@@ -423,7 +425,7 @@ class ExpressionCodegen(
         }
 
         data.variables.add(VariableInfo(declaration, index, varType, markNewLabel()))
-        return voidValue
+        return immaterialUnitValue
     }
 
     override fun visitGetValue(expression: IrGetValue, data: BlockInfo): PromisedValue {
@@ -442,7 +444,7 @@ class ExpressionCodegen(
             assert(expression is IrSetField) { "read of const val ${expression.symbol.owner.name} not inlined by ConstLowering" }
             // This can only be the field's initializer; JVM implementations are required
             // to generate those for ConstantValue-marked fields automatically, so this is redundant.
-            return voidValue.coerce(expression.type)
+            return defaultValue(expression.type)
         }
 
         val realField = expression.symbol.owner.resolveFakeOverride()!!
@@ -458,7 +460,7 @@ class ExpressionCodegen(
                 isStatic -> mv.putstatic(ownerType, fieldName, fieldType.descriptor)
                 else -> mv.putfield(ownerType, fieldName, fieldType.descriptor)
             }
-            voidValue.coerce(expression.type)
+            defaultValue(expression.type)
         } else {
             when {
                 isStatic ->
@@ -480,7 +482,7 @@ class ExpressionCodegen(
         val isFieldInitializer = expression.origin == null
         val skip = (inPrimaryConstructor || inClassInit) && isFieldInitializer && expressionValue is IrConst<*> &&
                 isDefaultValueForType(expression.symbol.owner.type.asmType, expressionValue.value)
-        return if (skip) voidValue.coerce(expression.type) else super.visitSetField(expression, data)
+        return if (skip) defaultValue(expression.type) else super.visitSetField(expression, data)
     }
 
     /**
@@ -511,7 +513,7 @@ class ExpressionCodegen(
         expression.value.markLineNumber(startOffset = true)
         expression.value.accept(this, data).coerce(expression.symbol.owner.type).materialize()
         mv.store(findLocalIndex(expression.symbol), expression.symbol.owner.asmType)
-        return voidValue.coerce(expression.type)
+        return defaultValue(expression.type)
     }
 
     override fun <T> visitConst(expression: IrConst<T>, data: BlockInfo): PromisedValue {
@@ -544,7 +546,7 @@ class ExpressionCodegen(
     // TODO maybe remove?
     override fun visitClass(declaration: IrClass, data: BlockInfo): PromisedValue {
         classCodegen.generateLocalClass(declaration)
-        return voidValue
+        return immaterialUnitValue
     }
 
     override fun visitVararg(expression: IrVararg, data: BlockInfo): PromisedValue {
@@ -662,7 +664,7 @@ class ExpressionCodegen(
                 mv, "java/lang/UnsupportedOperationException",
                 "Non-local returns are not allowed with inlining disabled"
             )
-            return voidValue
+            return immaterialUnitValue
         }
 
         val target = data.findBlock<ReturnableBlockInfo> { it.returnSymbol == expression.returnTargetSymbol }
@@ -682,7 +684,7 @@ class ExpressionCodegen(
         }
         mv.mark(afterReturnLabel)
         mv.nop()/*TODO check RESTORE_STACK_IN_TRY_CATCH processor*/
-        return voidValue
+        return immaterialUnitValue
     }
 
     override fun visitWhen(expression: IrWhen, data: BlockInfo): PromisedValue {
@@ -715,7 +717,7 @@ class ExpressionCodegen(
         }
         // Produce the default value for the type. Doesn't really matter right now, as non-exhaustive
         // conditionals cannot be used as expressions.
-        val result = voidValue.coerce(expression.type).materialized
+        val result = defaultValue(expression.type).materialized
         mv.mark(endLabel)
         return result
     }
@@ -727,7 +729,7 @@ class ExpressionCodegen(
             IrTypeOperator.IMPLICIT_COERCION_TO_UNIT -> {
                 expression.argument.accept(this, data).discard()
                 expression.argument.markEndOfStatementIfNeeded()
-                voidValue.coerce(expression.asmType)
+                defaultValue(expression.type)
             }
 
             IrTypeOperator.IMPLICIT_CAST, IrTypeOperator.IMPLICIT_INTEGER_COERCION -> {
@@ -736,7 +738,7 @@ class ExpressionCodegen(
 
             IrTypeOperator.CAST, IrTypeOperator.SAFE_CAST -> {
                 val result = expression.argument.accept(this, data)
-                val boxedLeftType = result.irType?.let { typeMapper.boxType(it) } ?: OBJECT_TYPE
+                val boxedLeftType = typeMapper.boxType(result.irType)
                 result.coerce(boxedLeftType, expression.argument.type).materialize()
                 val boxedRightType = typeMapper.boxType(typeOperand)
 
@@ -851,7 +853,7 @@ class ExpressionCodegen(
         }
         mv.goTo(continueLabel)
         mv.mark(endLabel)
-        return voidValue
+        return immaterialUnitValue
     }
 
     override fun visitDoWhileLoop(loop: IrDoWhileLoop, data: BlockInfo): PromisedValue {
@@ -868,7 +870,7 @@ class ExpressionCodegen(
         loop.condition.markLineNumber(true)
         loop.condition.accept(this, data).coerceToBoolean().jumpIfTrue(entry)
         mv.mark(endLabel)
-        return voidValue
+        return immaterialUnitValue
     }
 
     private fun unwindBlockStack(endLabel: Label, data: BlockInfo, stop: (ExpressionInfo) -> Boolean): ExpressionInfo? {
@@ -886,7 +888,7 @@ class ExpressionCodegen(
             ?: throw AssertionError("Target label for break/continue not found")
         mv.fixStackAndJump(if (jump is IrBreak) stackElement.breakLabel else stackElement.continueLabel)
         mv.mark(endLabel)
-        return voidValue
+        return immaterialUnitValue
     }
 
     override fun visitTry(aTry: IrTry, data: BlockInfo): PromisedValue {
@@ -985,7 +987,7 @@ class ExpressionCodegen(
             frameMap.leaveTemp(tryAsmType)
             return aTry.onStack
         }
-        return voidValue
+        return immaterialUnitValue
     }
 
     private fun genTryCatchCover(catchStart: Label, tryStart: Label, tryEnd: Label, tryGaps: List<Pair<Label, Label>>, type: String?) {
@@ -1030,9 +1032,11 @@ class ExpressionCodegen(
 
     override fun visitThrow(expression: IrThrow, data: BlockInfo): PromisedValue {
         expression.markLineNumber(startOffset = true)
-        expression.value.accept(this, data).coerce(AsmTypes.JAVA_THROWABLE_TYPE).materialize()
+        expression.value.accept(this, data)
+            .coerce(AsmTypes.JAVA_THROWABLE_TYPE, context.irBuiltIns.throwableType)
+            .materialize()
         mv.athrow()
-        return voidValue
+        return immaterialUnitValue
     }
 
     override fun visitGetClass(expression: IrGetClass, data: BlockInfo) =
@@ -1213,7 +1217,7 @@ fun DefaultCallArgs.generateOnStackIfNeeded(callGenerator: IrCallGenerator, isCo
             callGenerator.putValueIfNeeded(Type.INT_TYPE, StackValue.constant(mask, Type.INT_TYPE), ValueKind.DEFAULT_MASK, -1, codegen)
         }
 
-        val parameterType = if (isConstructor) AsmTypes.DEFAULT_CONSTRUCTOR_MARKER else OBJECT_TYPE
+        val parameterType = if (isConstructor) DEFAULT_CONSTRUCTOR_MARKER else OBJECT_TYPE
         callGenerator.putValueIfNeeded(
             parameterType,
             StackValue.constant(null, parameterType),

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/PromisedValue.kt

@@ -19,7 +19,7 @@ import org.jetbrains.org.objectweb.asm.commons.InstructionAdapter
 
 // A value that may not have been fully constructed yet. The ability to "roll back" code generation
 // is useful for certain optimizations.
-abstract class PromisedValue(val codegen: ExpressionCodegen, val type: Type, val irType: IrType?) {
+abstract class PromisedValue(val codegen: ExpressionCodegen, val type: Type, val irType: IrType) {
     // If this value is immaterial, construct an object on the top of the stack. This
     // must always be done before generating other values or emitting raw bytecode.
     abstract fun materialize()
@@ -30,12 +30,17 @@ abstract class PromisedValue(val codegen: ExpressionCodegen, val type: Type, val
     val typeMapper: IrTypeMapper
         get() = codegen.typeMapper
 
-    val kotlinType: KotlinType?
-        get() = irType?.toKotlinType()
+    val kotlinType: KotlinType
+        get() = irType.toKotlinType()
 }
 
 // A value that *has* been fully constructed.
-class MaterialValue(codegen: ExpressionCodegen, type: Type, irType: IrType?) : PromisedValue(codegen, type, irType) {
+class MaterialValue(codegen: ExpressionCodegen, type: Type, irType: IrType) : PromisedValue(codegen, type, irType) {
+    override fun materialize() {}
+}
+
+// A value that is only materialized through coercion.
+class ImmaterialValue(codegen: ExpressionCodegen, type: Type, irType: IrType) : PromisedValue(codegen, type, irType) {
     override fun materialize() {}
 }
 
@@ -66,11 +71,11 @@ val PromisedValue.materialized: MaterialValue
 
 // Materialize and disregard this value. Materialization is forced because, presumably,
 // we only wanted the side effects anyway.
-fun PromisedValue.discard(): MaterialValue {
+fun PromisedValue.discard(): PromisedValue {
     materialize()
     if (type !== Type.VOID_TYPE)
         AsmUtil.pop(mv, type)
-    return codegen.voidValue
+    return codegen.immaterialUnitValue
 }
 
 private val IrType.unboxed: IrType
@@ -103,9 +108,8 @@ fun PromisedValue.coerceInlineClasses(type: Type, irType: IrType, target: Type,
 }
 
 // On materialization, cast the value to a different type.
-fun PromisedValue.coerce(target: Type, irTarget: IrType? = null): PromisedValue {
-    if (irType != null && irTarget != null)
-        coerceInlineClasses(type, irType, target, irTarget)?.let { return it }
+fun PromisedValue.coerce(target: Type, irTarget: IrType): PromisedValue {
+    coerceInlineClasses(type, irType, target, irTarget)?.let { return it }
     return when (type) {
         // All unsafe coercions between irTypes should use the UnsafeCoerce intrinsic
         target -> this
@@ -129,14 +133,26 @@ fun PromisedValue.boxInlineClasses(irTarget: IrType) =
         coerceToBoxed(irTarget) else this
 
 // Same as above, but with a return type that allows conditional jumping.
-fun PromisedValue.coerceToBoolean() = when (val coerced = coerce(Type.BOOLEAN_TYPE)) {
-    is BooleanValue -> coerced
-    else -> object : BooleanValue(codegen) {
-        override fun jumpIfFalse(target: Label) = coerced.materialize().also { mv.ifeq(target) }
-        override fun jumpIfTrue(target: Label) = coerced.materialize().also { mv.ifne(target) }
-        override fun materialize() = coerced.materialize()
+fun PromisedValue.coerceToBoolean() =
+    when (val coerced = coerce(Type.BOOLEAN_TYPE, codegen.context.irBuiltIns.booleanType)) {
+        is BooleanValue -> coerced
+        else -> object : BooleanValue(codegen) {
+            override fun jumpIfFalse(target: Label) = coerced.materialize().also { mv.ifeq(target) }
+            override fun jumpIfTrue(target: Label) = coerced.materialize().also { mv.ifne(target) }
+            override fun materialize() = coerced.materialize()
+        }
     }
-}
 
-val ExpressionCodegen.voidValue: MaterialValue
-    get() = MaterialValue(this, Type.VOID_TYPE, null)
+// Non-materialized value of Unit type
+// This value is only materialized when calling coerce, which is why it is represented
+// as a MaterialValue even though there is nothing on the stack.
+val ExpressionCodegen.immaterialUnitValue: ImmaterialValue
+    get() = ImmaterialValue(this, Type.VOID_TYPE, context.irBuiltIns.unitType)
+
+// Non-materialized default value for the given type
+fun ExpressionCodegen.defaultValue(irType: IrType): PromisedValue =
+    object : PromisedValue(this, typeMapper.mapType(irType), irType) {
+        override fun materialize() {
+            StackValue.coerce(Type.VOID_TYPE, type, codegen.mv)
+        }
+    }

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/SwitchGenerator.kt

@@ -217,7 +217,7 @@ class SwitchGenerator(private val expression: IrWhen, private val data: BlockInf
             }
         }
 
-        protected fun genBranchTargets(): PromisedValue {
+        private fun genBranchTargets(): PromisedValue {
             with(codegen) {
                 val endLabel = Label()
                 for ((thenExpression, label) in expressionToLabels) {
@@ -226,8 +226,8 @@ class SwitchGenerator(private val expression: IrWhen, private val data: BlockInf
                     mv.goTo(endLabel)
                 }
                 mv.visitLabel(defaultLabel)
-                val stackValue = elseExpression?.accept(codegen, data) ?: voidValue
-                val result = stackValue.coerce(expression.type).materialized
+                val stackValue = elseExpression?.accept(codegen, data)?.coerce(expression.type) ?: defaultValue(expression.type)
+                val result = stackValue.materialized
                 mv.mark(endLabel)
                 return result
             }

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/intrinsics/JavaClassProperty.kt

@@ -33,8 +33,8 @@ object JavaClassProperty : IntrinsicMethod() {
     fun invokeWith(value: PromisedValue) =
         when {
             value.type == Type.VOID_TYPE ->
-                invokeGetClass(value.coerce(AsmTypes.UNIT_TYPE))
-            value.irType?.isInlined() == true ->
+                invokeGetClass(value.coerce(AsmTypes.UNIT_TYPE, value.codegen.context.irBuiltIns.unitType))
+            value.irType.isInlined() ->
                 invokeGetClass(value.coerceToBoxed(value.irType))
             isPrimitive(value.type) -> {
                 value.discard()