FIR2IR: optimize coerceToUnitIfNeeded in implicit cast inserter

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrImplicitCastInserter.kt

@@ -21,20 +21,16 @@ import org.jetbrains.kotlin.fir.typeContext
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.visitors.FirDefaultVisitor
 import org.jetbrains.kotlin.ir.IrElement
+import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrTypeOperatorCallImpl
-import org.jetbrains.kotlin.ir.types.IrType
-import org.jetbrains.kotlin.ir.types.makeNotNull
-import org.jetbrains.kotlin.ir.types.removeAnnotations
-import org.jetbrains.kotlin.ir.types.withHasQuestionMark
+import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.ir.util.classId
-import org.jetbrains.kotlin.ir.util.coerceToUnitIfNeeded
 import org.jetbrains.kotlin.ir.util.parentAsClass
 import org.jetbrains.kotlin.types.AbstractTypeChecker
 
 class Fir2IrImplicitCastInserter(
-    private val components: Fir2IrComponents,
-    private val visitor: Fir2IrVisitor
+    private val components: Fir2IrComponents
 ) : Fir2IrComponents by components, FirDefaultVisitor<IrElement, IrElement>() {
 
     private fun FirTypeRef.toIrType(): IrType = with(typeConverter) { toIrType() }
@@ -333,4 +329,17 @@ class Fir2IrImplicitCastInserter(
             original
         )
     }
+
+    private fun IrExpression.coerceToUnitIfNeeded(valueType: IrType, irBuiltIns: IrBuiltIns): IrExpression {
+        return if (valueType.isUnit() || valueType.isNothing())
+            this
+        else
+            IrTypeOperatorCallImpl(
+                startOffset, endOffset,
+                irBuiltIns.unitType,
+                IrTypeOperator.IMPLICIT_COERCION_TO_UNIT,
+                irBuiltIns.unitType,
+                this
+            )
+    }
 }

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrVisitor.kt

@@ -52,7 +52,7 @@ class Fir2IrVisitor(
     private val conversionScope: Fir2IrConversionScope
 ) : Fir2IrComponents by components, FirDefaultVisitor<IrElement, Any?>(), IrGeneratorContextInterface {
 
-    internal val implicitCastInserter = Fir2IrImplicitCastInserter(components, this)
+    internal val implicitCastInserter = Fir2IrImplicitCastInserter(components)
 
     private val memberGenerator = ClassMemberGenerator(components, this, conversionScope)