JVM IR: Implement CHECK_NOT_NULL as a lowering

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/nullCheck/RedundantNullCheckMethodTransformer.kt

@@ -142,9 +142,9 @@ class RedundantNullCheckMethodTransformer(private val generationState: Generatio
 
         private fun transformTrivialCheckNotNull(insn: AbstractInsnNode, nullability: Nullability) {
             if (nullability != Nullability.NOT_NULL) return
-            val dupInsn = insn.previous?.takeIf { it.opcode == Opcodes.DUP } ?: return
+            val previousInsn = insn.previous?.takeIf { it.opcode == Opcodes.DUP || it.opcode == Opcodes.ALOAD } ?: return
             methodNode.instructions.run {
-                remove(dupInsn)
+                remove(previousInsn)
                 remove(insn)
             }
         }
@@ -184,9 +184,10 @@ class RedundantNullCheckMethodTransformer(private val generationState: Generatio
                         }
 
                         insn.isCheckNotNull() -> {
-                            val dupInsn = insn.previous ?: continue@insnLoop
-                            if (dupInsn.opcode != Opcodes.DUP) continue@insnLoop
-                            val aLoadInsn = dupInsn.previous ?: continue@insnLoop
+                            val previous = insn.previous ?: continue@insnLoop
+                            val aLoadInsn = if (previous.opcode == Opcodes.DUP) {
+                                previous.previous ?: continue@insnLoop
+                            } else previous
                             if (aLoadInsn.opcode != Opcodes.ALOAD) continue@insnLoop
                             addDependentCheck(insn, aLoadInsn as VarInsnNode)
                         }
@@ -303,6 +304,10 @@ class RedundantNullCheckMethodTransformer(private val generationState: Generatio
                 //  INVOKESTATIC checkNotNull
                 //  <...>   -- v is not null here (otherwise an exception was thrown)
 
+                //  ALOAD v
+                //  INVOKESTATIC checkNotNull
+                //  <...>   -- v is not null here (otherwise an exception was thrown)
+
                 //  ALOAD v
                 //  LDC *
                 //  INVOKESTATIC checkParameterIsNotNull

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

@@ -189,6 +189,7 @@ private val jvmFilePhases =
         annotationPhase then
         varargPhase then
         arrayConstructorPhase then
+        checkNotNullPhase then
 
         lateinitPhase then
 

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

@@ -120,6 +120,10 @@ class JvmSymbols(
             addValueParameter("self", irBuiltIns.stringType.makeNullable())
             addValueParameter("other", irBuiltIns.anyNType)
         }
+        klass.addFunction("checkNotNull", irBuiltIns.unitType, isStatic = true).apply {
+            addValueParameter("object", irBuiltIns.anyNType)
+        }
+        klass.addFunction("throwNpe", irBuiltIns.unitType, isStatic = true)
     }
 
     val checkExpressionValueIsNotNull: IrSimpleFunctionSymbol =
@@ -128,6 +132,12 @@ class JvmSymbols(
     val checkNotNullExpressionValue: IrSimpleFunctionSymbol =
         intrinsicsClass.functions.single { it.owner.name.asString() == "checkNotNullExpressionValue" }
 
+    val checkNotNull: IrSimpleFunctionSymbol =
+        intrinsicsClass.functions.single { it.owner.name.asString() == "checkNotNull" }
+
+    val throwNpe: IrSimpleFunctionSymbol =
+        intrinsicsClass.functions.single { it.owner.name.asString() == "throwNpe" }
+
     override val ThrowUninitializedPropertyAccessException: IrSimpleFunctionSymbol =
         intrinsicsClass.functions.single { it.owner.name.asString() == "throwUninitializedPropertyAccessException" }
 

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

@@ -1,37 +0,0 @@
-/*
- * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * 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.intrinsics
-
-import org.jetbrains.kotlin.backend.jvm.codegen.BlockInfo
-import org.jetbrains.kotlin.backend.jvm.codegen.ExpressionCodegen
-import org.jetbrains.kotlin.backend.jvm.codegen.PromisedValue
-import org.jetbrains.kotlin.codegen.AsmUtil
-import org.jetbrains.kotlin.codegen.intrinsics.IntrinsicMethods
-import org.jetbrains.kotlin.config.ApiVersion
-import org.jetbrains.kotlin.ir.expressions.IrFunctionAccessExpression
-import org.jetbrains.org.objectweb.asm.Label
-
-object IrCheckNotNull : IntrinsicMethod() {
-    override fun invoke(expression: IrFunctionAccessExpression, codegen: ExpressionCodegen, data: BlockInfo): PromisedValue? {
-        val arg0 = expression.getValueArgument(0)!!.accept(codegen, data)
-        if (AsmUtil.isPrimitive(arg0.type)) return arg0
-
-        return object : PromisedValue(codegen, arg0.type, expression.type) {
-            override fun materialize() {
-                arg0.materialize()
-                mv.dup()
-                if (codegen.state.languageVersionSettings.apiVersion >= ApiVersion.KOTLIN_1_4) {
-                    mv.invokestatic(IntrinsicMethods.INTRINSICS_CLASS_NAME, "checkNotNull", "(Ljava/lang/Object;)V", false)
-                } else {
-                    val ifNonNullLabel = Label()
-                    mv.ifnonnull(ifNonNullLabel)
-                    mv.invokestatic(IntrinsicMethods.INTRINSICS_CLASS_NAME, "throwNpe", "()V", false)
-                    mv.mark(ifNonNullLabel)
-                }
-            }
-        }
-    }
-}

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

@@ -87,7 +87,6 @@ class IrIntrinsicMethods(val irBuiltIns: IrBuiltIns, val symbols: JvmSymbols) {
                 irBuiltIns.enumValueOfSymbol.toKey()!! to IrEnumValueOf,
                 irBuiltIns.noWhenBranchMatchedExceptionSymbol.toKey()!! to IrNoWhenBranchMatchedException,
                 irBuiltIns.illegalArgumentExceptionSymbol.toKey()!! to IrIllegalArgumentException,
-                irBuiltIns.checkNotNullSymbol.toKey()!! to IrCheckNotNull,
                 irBuiltIns.andandSymbol.toKey()!! to AndAnd,
                 irBuiltIns.ororSymbol.toKey()!! to OrOr,
                 symbols.unsafeCoerceIntrinsic.toKey()!! to UnsafeCoerce,

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

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * 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.common.IrElementTransformerVoidWithContext
+import org.jetbrains.kotlin.backend.common.lower.createIrBuilder
+import org.jetbrains.kotlin.backend.common.lower.irIfThen
+import org.jetbrains.kotlin.backend.common.phaser.makeIrFilePhase
+import org.jetbrains.kotlin.backend.jvm.JvmBackendContext
+import org.jetbrains.kotlin.config.ApiVersion
+import org.jetbrains.kotlin.ir.builders.*
+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.expressions.IrGetValue
+
+internal val checkNotNullPhase = makeIrFilePhase(
+    ::CheckNotNullLowering,
+    name = "CheckNotNullLowering",
+    description = "Lower calls to the CHECK_NOT_NULL intrinsic, which are generated by psi2ir for \"!!\" expressions."
+)
+
+private class CheckNotNullLowering(private val backendContext: JvmBackendContext) : FileLoweringPass, IrElementTransformerVoidWithContext() {
+    override fun lower(irFile: IrFile) = irFile.transformChildrenVoid()
+
+    override fun visitCall(expression: IrCall): IrExpression {
+        if (expression.symbol != backendContext.irBuiltIns.checkNotNullSymbol)
+            return super.visitCall(expression)
+
+        expression.transformChildrenVoid()
+        return backendContext.createIrBuilder(currentScope!!.scope.scopeOwnerSymbol, expression.startOffset, expression.endOffset).irBlock {
+            val valueArgument = expression.getValueArgument(0)!!
+
+            // For a null-check on a variable we should not introduce a temporary, since null checks are
+            // optimized by RedundantNullCheckMethodTransformer, which remembers that the argument variable
+            // is non-nullable if this call succeeds.
+            val argument = if (valueArgument is IrGetValue) valueArgument.symbol.owner else irTemporary(valueArgument)
+
+            // Starting with Kotlin 1.4 null-checks are lowered to calls to the "checkNotNull" intrinsic, which
+            // throws a NullPointerException on failure. Prior to Kotlin 1.4 we instead inline the null-check and
+            // call the "throwNpe" intrinsic on failure which throws a KotlinNullPointerException.
+            if (backendContext.state.languageVersionSettings.apiVersion >= ApiVersion.KOTLIN_1_4) {
+                +irCall(backendContext.ir.symbols.checkNotNull).apply {
+                    putValueArgument(0, irGet(argument))
+                }
+            } else {
+                +irIfThen(irEqualsNull(irGet(argument)), irCall(backendContext.ir.symbols.throwNpe))
+            }
+
+            +irImplicitCast(irGet(argument), expression.type)
+        }
+    }
+}