JVM_IR: Optimize null checks.

Introduce lowering to remove null checks for primitive type
expressions and replace them with true/false. Side-effects
are preserved.

Generate ifnull/ifnonnull instructions for null checks instead
of materializing a null literal for an equality check.

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

@@ -217,10 +217,10 @@ private val ToArrayPhase = makeJvmPhase(
     description = "Handle toArray functions"
 )
 
-private val NegatedExpressionLowering = makeJvmPhase(
-    { context, file -> NegatedExpressionLowering(context).lower(file) },
-    name = "NegatedExpression",
-    description = "Handle negated expressions"
+private val JvmBuiltinOptimizationLowering = makeJvmPhase(
+    { context, file -> JvmBuiltinOptimizationLowering(context).lower(file) },
+    name = "JvmBuiltinOptimizationLowering",
+    description = "Optimize builtin calls for JVM code generation"
 )
 
 object IrFileEndPhase : CompilerPhase<BackendContext, IrFile> {
@@ -273,7 +273,7 @@ val jvmPhases = listOf(
 
     TailrecPhase,
     ToArrayPhase,
-    NegatedExpressionLowering,
+    JvmBuiltinOptimizationLowering,
 
     makePatchParentsPhase(3),
 

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

@@ -9,8 +9,8 @@ import org.jetbrains.kotlin.backend.jvm.JvmLoweredDeclarationOrigin
 import org.jetbrains.kotlin.backend.jvm.intrinsics.IrIntrinsicFunction
 import org.jetbrains.kotlin.backend.jvm.intrinsics.IrIntrinsicMethods
 import org.jetbrains.kotlin.backend.jvm.lower.CrIrType
-import org.jetbrains.kotlin.backend.jvm.lower.NegatedExpressionLowering.Companion.isNegation
-import org.jetbrains.kotlin.backend.jvm.lower.NegatedExpressionLowering.Companion.negationArgument
+import org.jetbrains.kotlin.backend.jvm.lower.JvmBuiltinOptimizationLowering.Companion.isNegation
+import org.jetbrains.kotlin.backend.jvm.lower.JvmBuiltinOptimizationLowering.Companion.negationArgument
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.codegen.*
 import org.jetbrains.kotlin.codegen.AsmUtil.*
@@ -35,6 +35,7 @@ import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.symbols.IrSymbol
 import org.jetbrains.kotlin.ir.types.toKotlinType
 import org.jetbrains.kotlin.ir.util.dump
+import org.jetbrains.kotlin.ir.util.isNullConst
 import org.jetbrains.kotlin.ir.util.render
 import org.jetbrains.kotlin.ir.visitors.IrElementVisitor
 import org.jetbrains.kotlin.resolve.DescriptorUtils
@@ -631,30 +632,18 @@ class ExpressionCodegen(
         return expression.onStack
     }
 
-
     override fun visitWhen(expression: IrWhen, data: BlockInfo): StackValue {
         expression.markLineNumber(startOffset = true)
         return genIfWithBranches(expression.branches[0], data, expression.type.toKotlinType(), expression.branches.drop(1))
     }
 
-
     private fun genIfWithBranches(branch: IrBranch, data: BlockInfo, type: KotlinType, otherBranches: List<IrBranch>): StackValue {
         val elseLabel = Label()
-        var condition = branch.condition
         val thenBranch = branch.result
         //TODO don't generate condition for else branch - java verifier fails with empty stack
         val elseBranch = branch is IrElseBranch
         if (!elseBranch) {
-            var jumpIfFalse = true
-            if (isNegation(condition, classCodegen.context)) {
-                // Instead of materializing a negated value when used for control flow, flip the branch
-                // targets instead. This significantly cuts down the amount of branches and loads of
-                // const_0 and const_1 in the generated java bytecode.
-                condition = negationArgument(condition as IrCall)
-                jumpIfFalse = false
-            }
-            gen(condition, data).put(condition.asmType, mv)
-            BranchedValue.condJump(StackValue.onStack(condition.asmType), elseLabel, jumpIfFalse, mv)
+            genConditionWithOptimizationsIfPossible(branch, data, elseLabel)
         }
 
         val end = Label()
@@ -676,6 +665,40 @@ class ExpressionCodegen(
         return result
     }
 
+    private fun genConditionWithOptimizationsIfPossible(branch: IrBranch, data: BlockInfo, elseLabel: Label) {
+        var condition = branch.condition
+        var jumpIfFalse = true
+        if (isNegation(condition, classCodegen.context)) {
+            // Instead of materializing a negated value when used for control flow, flip the branch
+            // targets instead. This significantly cuts down the amount of branches and loads of
+            // const_0 and const_1 in the generated java bytecode.
+            condition = negationArgument(condition as IrCall)
+            jumpIfFalse = false
+        }
+        if (isNullCheck(condition)) {
+            // Do not materialize null constants to check for null. Instead use the JVM bytecode
+            // ifnull and ifnonnull instructions.
+            val call = condition as IrCall
+            val left = call.getValueArgument(0)!!
+            val right = call.getValueArgument(1)!!
+            val other = if (left.isNullConst()) right else left
+            gen(other, data).put(other.asmType, mv)
+            if (jumpIfFalse) {
+                mv.ifnonnull(elseLabel)
+            } else {
+                mv.ifnull(elseLabel)
+            }
+        } else {
+            gen(condition, data).put(condition.asmType, mv)
+            BranchedValue.condJump(onStack(condition.asmType), elseLabel, jumpIfFalse, mv)
+        }
+    }
+
+    private fun isNullCheck(expression: IrExpression): Boolean {
+        return expression is IrCall
+                && expression.symbol == classCodegen.context.irBuiltIns.eqeqSymbol
+                && (expression.getValueArgument(0)!!.isNullConst() || expression.getValueArgument(1)!!.isNullConst())
+    }
 
     override fun visitTypeOperator(expression: IrTypeOperatorCall, data: BlockInfo): StackValue {
         val asmType = expression.typeOperand.toKotlinType().asmType

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

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.backend.jvm.lower
+
+import org.jetbrains.kotlin.backend.common.FileLoweringPass
+import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
+import org.jetbrains.kotlin.codegen.intrinsics.Not
+import org.jetbrains.kotlin.ir.declarations.IrFile
+import org.jetbrains.kotlin.ir.expressions.IrCall
+import org.jetbrains.kotlin.ir.expressions.IrConst
+import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.IrGetValue
+import org.jetbrains.kotlin.ir.expressions.impl.IrBlockImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrConstImpl
+import org.jetbrains.kotlin.ir.types.isPrimitiveType
+import org.jetbrains.kotlin.ir.types.toKotlinType
+import org.jetbrains.kotlin.ir.util.coerceToUnitIfNeeded
+import org.jetbrains.kotlin.ir.util.isNullConst
+import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
+import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
+
+class JvmBuiltinOptimizationLowering(val context: JvmBackendContext) : FileLoweringPass {
+
+    companion object {
+        fun isNegation(expression: IrExpression, context: JvmBackendContext): Boolean {
+            // TODO: there should be only one representation of the 'not' operator.
+            return expression is IrCall &&
+                    (expression.symbol == context.irBuiltIns.booleanNotSymbol ||
+                            context.state.intrinsics.getIntrinsic(expression.symbol.descriptor) is Not)
+        }
+
+        fun negationArgument(call: IrCall): IrExpression {
+            // TODO: there should be only one representation of the 'not' operator.
+            // Once there is only the IR definition the negation argument will
+            // always be a value argument and this method can be removed.
+            return call.dispatchReceiver ?: call.getValueArgument(0)!!
+        }
+    }
+
+    private fun hasNoSideEffectsForNullCompare(expression: IrExpression): Boolean {
+        return expression.type.isPrimitiveType() && (expression is IrConst<*> || expression is IrGetValue)
+    }
+
+    private fun isNullCheckOfPrimitiveTypeValue(call: IrCall, context: JvmBackendContext): Boolean {
+        if (call.symbol == context.irBuiltIns.eqeqSymbol) {
+            val left = call.getValueArgument(0)!!
+            val right = call.getValueArgument(1)!!
+            // When used for null checks, it is safe to eliminate constants and local variable loads.
+            // Even if a local variable of simple type is updated via the debugger it still cannot
+            // be null.
+            return (right.isNullConst() && left.type.isPrimitiveType())
+                    || (left.isNullConst() && right.type.isPrimitiveType())
+        }
+        return false
+    }
+
+    private fun isNullCheckOfNullConstant(call: IrCall, context: JvmBackendContext): Boolean {
+        if (call.symbol == context.irBuiltIns.eqeqSymbol) {
+            val left = call.getValueArgument(0)!!
+            val right = call.getValueArgument(1)!!
+            return right.isNullConst() && left.isNullConst()
+        }
+        return false
+    }
+
+    override fun lower(irFile: IrFile) {
+        irFile.transformChildrenVoid(object : IrElementTransformerVoid() {
+            override fun visitCall(expression: IrCall): IrExpression {
+                expression.transformChildrenVoid(this)
+                return if (isNegation(expression, context) && isNegation(negationArgument(expression), context)) {
+                    // TODO: This lowering is currently JvmBackend specific because there are multiple
+                    // definitions of the boolean 'not' operator. Once there is only the irBuiltins
+                    // definition this lowering could be shared with other backends.
+                    negationArgument(negationArgument(expression) as IrCall)
+                } else if (isNullCheckOfPrimitiveTypeValue(expression, context)) {
+                    val left = expression.getValueArgument(0)!!
+                    val nonNullArgument = if (left.isNullConst()) expression.getValueArgument(1)!! else left
+                    val constFalse = IrConstImpl.constFalse(expression.startOffset, expression.endOffset, context.irBuiltIns.booleanType)
+                    if (hasNoSideEffectsForNullCompare(nonNullArgument)) {
+                        constFalse
+                    } else {
+                        IrBlockImpl(expression.startOffset, expression.endOffset, expression.type, expression.origin).apply {
+                            statements.add(nonNullArgument.coerceToUnitIfNeeded(nonNullArgument.type.toKotlinType(), context.irBuiltIns))
+                            statements.add(constFalse)
+                        }
+                    }
+                } else if (isNullCheckOfNullConstant(expression, context)) {
+                    IrConstImpl.constTrue(expression.startOffset, expression.endOffset, context.irBuiltIns.booleanType)
+                } else {
+                    expression
+                }
+            }
+        })
+    }
+}

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

@@ -14,6 +14,7 @@ import org.jetbrains.kotlin.ir.expressions.IrCall
 import org.jetbrains.kotlin.ir.expressions.IrExpression
 import org.jetbrains.kotlin.ir.types.toKotlinType
 import org.jetbrains.kotlin.ir.util.TypeTranslator
+import org.jetbrains.kotlin.ir.util.coerceToUnitIfNeeded
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 import org.jetbrains.kotlin.psi2ir.transformations.InsertImplicitCasts
 
@@ -30,7 +31,7 @@ class JvmCoercionToUnitPatcher(val context: JvmBackendContext) :
 
     override fun IrExpression.coerceToUnit(): IrExpression {
         if (type.isSubtypeOf(context.irBuiltIns.unitType) && this is IrCall) {
-            return coerceToUnitIfNeeded(symbol.owner.returnType.toKotlinType())
+            return coerceToUnitIfNeeded(symbol.owner.returnType.toKotlinType(), context.irBuiltIns)
         }
 
         return this

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

@@ -1,50 +0,0 @@
-/*
- * Copyright 2010-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
- * that can be found in the license/LICENSE.txt file.
- */
-
-package org.jetbrains.kotlin.backend.jvm.lower
-
-import org.jetbrains.kotlin.backend.common.FileLoweringPass
-import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
-import org.jetbrains.kotlin.codegen.intrinsics.Not
-import org.jetbrains.kotlin.ir.declarations.IrFile
-import org.jetbrains.kotlin.ir.expressions.IrCall
-import org.jetbrains.kotlin.ir.expressions.IrExpression
-import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
-import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
-
-// TODO: This lowering is currently JvmBackend specific because there are multiple
-// definitions of the boolean 'not' operator. Once there is only the irBuiltins
-// definition this lowering could be shared with other backends.
-class NegatedExpressionLowering(val context: JvmBackendContext) : FileLoweringPass {
-
-    companion object {
-        fun isNegation(expression: IrExpression, context: JvmBackendContext) : Boolean {
-            // TODO: there should be only one representation of the 'not' operator.
-            return expression is IrCall &&
-                    (expression.symbol == context.irBuiltIns.booleanNotSymbol ||
-                            context.state.intrinsics.getIntrinsic(expression.symbol.descriptor) is Not)
-        }
-
-        fun negationArgument(call: IrCall) : IrExpression {
-            // TODO: there should be only one representation of the 'not' operator.
-            // Once there is only the IR definition the negation argument will
-            // always be a value argument and this method can be removed.
-            return call.dispatchReceiver ?: call.getValueArgument(0)!!
-        }
-    }
-
-    override fun lower(irFile: IrFile) {
-        irFile.transformChildrenVoid(object : IrElementTransformerVoid() {
-            override fun visitCall(expression: IrCall): IrExpression {
-                expression.transformChildrenVoid(this)
-                return if (isNegation(expression, context) && isNegation(negationArgument(expression), context))
-                    negationArgument(negationArgument(expression) as IrCall)
-                else
-                    expression
-            }
-        })
-    }
-
-}

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/transformations/InsertImplicitCasts.kt

@@ -30,6 +30,7 @@ import org.jetbrains.kotlin.ir.types.IrType
 import org.jetbrains.kotlin.ir.types.classifierOrFail
 import org.jetbrains.kotlin.ir.types.impl.originalKotlinType
 import org.jetbrains.kotlin.ir.util.TypeTranslator
+import org.jetbrains.kotlin.ir.util.coerceToUnitIfNeeded
 import org.jetbrains.kotlin.ir.util.render
 import org.jetbrains.kotlin.ir.visitors.IrElementTransformerVoid
 import org.jetbrains.kotlin.load.java.descriptors.JavaClassDescriptor
@@ -259,28 +260,12 @@ open class InsertImplicitCasts(
 
     protected open fun IrExpression.coerceToUnit(): IrExpression {
         val valueType = getKotlinType(this)
-        return coerceToUnitIfNeeded(valueType)
+        return coerceToUnitIfNeeded(valueType, irBuiltIns)
     }
 
     protected fun getKotlinType(irExpression: IrExpression) =
         irExpression.type.originalKotlinType!!
 
-    protected fun IrExpression.coerceToUnitIfNeeded(valueType: KotlinType): IrExpression {
-        return if (isUnitSubtype(valueType))
-            this
-        else
-            IrTypeOperatorCallImpl(
-                startOffset, endOffset,
-                irBuiltIns.unitType,
-                IrTypeOperator.IMPLICIT_COERCION_TO_UNIT,
-                irBuiltIns.unitType, irBuiltIns.unitType.classifierOrFail,
-                this
-            )
-    }
-
-    protected fun isUnitSubtype(valueType: KotlinType) =
-        KotlinTypeChecker.DEFAULT.isSubtypeOf(valueType, builtIns.unitType)
-
     private fun KotlinType.isBuiltInIntegerType(): Boolean =
         KotlinBuiltIns.isByte(this) ||
                 KotlinBuiltIns.isShort(this) ||

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/IrUtils.kt

@@ -14,8 +14,10 @@ import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.declarations.impl.IrFieldImpl
 import org.jetbrains.kotlin.ir.declarations.impl.IrTypeParameterImpl
 import org.jetbrains.kotlin.ir.declarations.impl.IrValueParameterImpl
+import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrTypeOperatorCallImpl
 import org.jetbrains.kotlin.ir.symbols.*
 import org.jetbrains.kotlin.ir.types.*
 import org.jetbrains.kotlin.name.FqName
@@ -24,6 +26,8 @@ import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameSafe
 import org.jetbrains.kotlin.resolve.source.PsiSourceElement
+import org.jetbrains.kotlin.types.KotlinType
+import org.jetbrains.kotlin.types.checker.KotlinTypeChecker
 
 /**
  * Binds the arguments explicitly represented in the IR to the parameters of the accessed function.
@@ -140,6 +144,20 @@ fun IrMemberAccessExpression.addArguments(args: List<Pair<ParameterDescriptor, I
 
 fun IrExpression.isNullConst() = this is IrConst<*> && this.kind == IrConstKind.Null
 
+
+fun IrExpression.coerceToUnitIfNeeded(valueType: KotlinType, irBuiltIns: IrBuiltIns): IrExpression {
+    return if (KotlinTypeChecker.DEFAULT.isSubtypeOf(valueType, irBuiltIns.unitType.toKotlinType()))
+        this
+    else
+        IrTypeOperatorCallImpl(
+            startOffset, endOffset,
+            irBuiltIns.unitType,
+            IrTypeOperator.IMPLICIT_COERCION_TO_UNIT,
+            irBuiltIns.unitType, irBuiltIns.unitType.classifierOrFail,
+            this
+        )
+}
+
 fun IrMemberAccessExpression.usesDefaultArguments(): Boolean =
     this.descriptor.valueParameters.any { this.getValueArgument(it) == null }
 

compiler/testData/codegen/box/nullCheckOptimization/primitiveCheckWithSideEffect.kt

@@ -0,0 +1,23 @@
+var result = "fail 1"
+
+fun withSideEffect() : Int {
+    result = "OK"
+    return 42
+}
+
+fun box(): String {
+    if (withSideEffect() == null) {
+        return "fail 2"
+    }
+
+    if (result != "OK") {
+        return "fail 3"
+    }
+
+    result = "fail 4"
+    if (withSideEffect() != null) {
+        return result
+    }
+
+    return result
+}

compiler/testData/codegen/bytecodeText/boxingOptimization/kt7224.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun box(): String {
     230?.hashCode()
 

compiler/testData/codegen/bytecodeText/boxingOptimization/simpleUninitializedMerge.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun box(): String {
     var result = 0
     if (1 == 1) {

compiler/testData/codegen/bytecodeText/boxingOptimization/unsafeRemoving.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun returningBoxed() : Int? = 1
 fun acceptingBoxed(x : Int?) : Int ? = x
 

compiler/testData/codegen/bytecodeText/conditions/negatedNullCompare.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun main(p: String?) {
     if (!(p == null)) {
         "then"

compiler/testData/codegen/bytecodeText/conditions/nullCompare.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun main(p: String?) {
     if (p == null) {
         "then"

compiler/testData/codegen/bytecodeText/deadCodeElimination/boxing.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 class A
 
 fun foo(x: Any?) {}

compiler/testData/codegen/bytecodeText/deadCodeElimination/literal.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun box() {
     val x: Any? = "abc"
     val y: Any? = if (1 == 1) x else "cde"

compiler/testData/codegen/bytecodeText/deadCodeElimination/simpleConstructor.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 class A
 fun box() {
     val x: A? = A()

compiler/testData/codegen/bytecodeText/deadCodeElimination/simpleConstructorNotRedundant.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 class A
 fun box() {
     val x: A? = A()

compiler/testData/codegen/bytecodeText/ieee754/smartCastsForDouble.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +ProperIeee754Comparisons
-// IGNORE_BACKEND: JVM_IR
 fun equals5(a: Any?, b: Any?) = if (a is Double && b is Double?) a == b else null!!
 
 fun equals6(a: Any?, b: Any?) = if (a is Double? && b is Double) a == b else null!!

compiler/testData/codegen/bytecodeText/ieee754/smartCastsForFloat.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +ProperIeee754Comparisons
-// IGNORE_BACKEND: JVM_IR
 fun equals5(a: Any?, b: Any?) = if (a is Float && b is Float?) a == b else null!!
 
 fun equals6(a: Any?, b: Any?) = if (a is Float? && b is Float) a == b else null!!

compiler/testData/codegen/bytecodeText/intConstantNullable.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 val a : Int? = 10
 
 fun foo() = a!!.toString()

compiler/testData/codegen/bytecodeText/nullCheckOptimization/alreadyCheckedForNull.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun test(x: String?) {
     if (x == null) return
 

compiler/testData/codegen/bytecodeText/nullCheckOptimization/ifNullEqualsNull.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun test1() {
     val a = null
 

compiler/testData/codegen/bytecodeText/nullCheckOptimization/ifUnitEqualsNull.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun test1() {
     val a = Unit
 

compiler/testData/codegen/bytecodeText/nullCheckOptimization/kt12839.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun test() {
     val value = System.getProperty("key")
     if (value != null) {

compiler/testData/codegen/bytecodeText/nullCheckOptimization/localLateinit/checkedAlways.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun almostAlwaysTrue() = true
 
 fun runNoInline(f: () -> Unit) = f()

compiler/testData/codegen/bytecodeText/nullCheckOptimization/localLateinit/initialized.kt

@@ -1,3 +1,4 @@
+// IGNORE_BACKEND: JVM_IR
 fun test() {
     lateinit var z: String
     run {

compiler/testData/codegen/bytecodeText/nullCheckOptimization/primitiveCheck.kt

@@ -0,0 +1,18 @@
+fun f() : Int {
+    return 42
+}
+
+fun box(): String {
+    if (f() == null) {
+        return "fail 1"
+    }
+
+    if (f() != null) {
+        return "OK"
+    }
+
+    return "fail 2"
+}
+
+// 0 IF
+// 0 ACONST_NULL

compiler/testData/codegen/bytecodeText/when/kt18818.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun findUserId(username: String): Long? = null
 
 fun main(args: Array<String>) {

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -15977,6 +15977,11 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");
         }
 
+        @TestMetadata("primitiveCheckWithSideEffect.kt")
+        public void testPrimitiveCheckWithSideEffect() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/primitiveCheckWithSideEffect.kt");
+        }
+
         @TestMetadata("trivialInstanceOf.kt")
         public void testTrivialInstanceOf() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/trivialInstanceOf.kt");

compiler/tests/org/jetbrains/kotlin/codegen/BytecodeTextTestGenerated.java

@@ -2798,6 +2798,11 @@ public class BytecodeTextTestGenerated extends AbstractBytecodeTextTest {
             runTest("compiler/testData/codegen/bytecodeText/nullCheckOptimization/notNullAsNotNullable.kt");
         }
 
+        @TestMetadata("primitiveCheck.kt")
+        public void testPrimitiveCheck() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/nullCheckOptimization/primitiveCheck.kt");
+        }
+
         @TestMetadata("redundantSafeCall.kt")
         public void testRedundantSafeCall() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/nullCheckOptimization/redundantSafeCall.kt");

compiler/tests/org/jetbrains/kotlin/codegen/IrBytecodeTextTestGenerated.java

@@ -2798,6 +2798,11 @@ public class IrBytecodeTextTestGenerated extends AbstractIrBytecodeTextTest {
             runTest("compiler/testData/codegen/bytecodeText/nullCheckOptimization/notNullAsNotNullable.kt");
         }
 
+        @TestMetadata("primitiveCheck.kt")
+        public void testPrimitiveCheck() throws Exception {
+            runTest("compiler/testData/codegen/bytecodeText/nullCheckOptimization/primitiveCheck.kt");
+        }
+
         @TestMetadata("redundantSafeCall.kt")
         public void testRedundantSafeCall() throws Exception {
             runTest("compiler/testData/codegen/bytecodeText/nullCheckOptimization/redundantSafeCall.kt");

compiler/tests/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -15977,6 +15977,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");
         }
 
+        @TestMetadata("primitiveCheckWithSideEffect.kt")
+        public void testPrimitiveCheckWithSideEffect() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/primitiveCheckWithSideEffect.kt");
+        }
+
         @TestMetadata("trivialInstanceOf.kt")
         public void testTrivialInstanceOf() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/trivialInstanceOf.kt");

compiler/tests/org/jetbrains/kotlin/codegen/ir/IrBlackBoxCodegenTestGenerated.java

@@ -15982,6 +15982,11 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");
         }
 
+        @TestMetadata("primitiveCheckWithSideEffect.kt")
+        public void testPrimitiveCheckWithSideEffect() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/primitiveCheckWithSideEffect.kt");
+        }
+
         @TestMetadata("trivialInstanceOf.kt")
         public void testTrivialInstanceOf() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/trivialInstanceOf.kt");

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/IrJsCodegenBoxTestGenerated.java

@@ -12372,6 +12372,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");
         }
 
+        @TestMetadata("primitiveCheckWithSideEffect.kt")
+        public void testPrimitiveCheckWithSideEffect() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/primitiveCheckWithSideEffect.kt");
+        }
+
         @TestMetadata("trivialInstanceOf.kt")
         public void testTrivialInstanceOf() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/trivialInstanceOf.kt");

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -13427,6 +13427,11 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/kt7774.kt");
         }
 
+        @TestMetadata("primitiveCheckWithSideEffect.kt")
+        public void testPrimitiveCheckWithSideEffect() throws Exception {
+            runTest("compiler/testData/codegen/box/nullCheckOptimization/primitiveCheckWithSideEffect.kt");
+        }
+
         @TestMetadata("trivialInstanceOf.kt")
         public void testTrivialInstanceOf() throws Exception {
             runTest("compiler/testData/codegen/box/nullCheckOptimization/trivialInstanceOf.kt");