Extract simple inlining utility from ArrayConstructorLowering

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

@@ -0,0 +1,51 @@
+/*
+ * 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.common.ir
+
+import org.jetbrains.kotlin.backend.common.lower.VariableRemapper
+import org.jetbrains.kotlin.ir.declarations.IrFunction
+import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
+import org.jetbrains.kotlin.ir.declarations.IrValueDeclaration
+import org.jetbrains.kotlin.ir.expressions.*
+import org.jetbrains.kotlin.ir.expressions.impl.IrReturnImpl
+import org.jetbrains.kotlin.ir.expressions.impl.IrReturnableBlockImpl
+import org.jetbrains.kotlin.ir.symbols.impl.IrReturnableBlockSymbolImpl
+import org.jetbrains.kotlin.ir.util.isVararg
+import org.jetbrains.kotlin.ir.util.statements
+
+// Return the underlying function for a lambda argument without bound or default parameters or varargs.
+fun IrExpression.asSimpleLambda(): IrSimpleFunction? {
+    // A lambda is represented as a block with a function declaration and a reference to it.
+    if (this !is IrBlock || statements.size != 2)
+        return null
+    val (function, reference) = statements
+    if (function !is IrSimpleFunction || reference !is IrFunctionReference || function.symbol != reference.symbol)
+        return null
+    if ((0 until reference.valueArgumentsCount).any { reference.getValueArgument(it) != null })
+        return null
+    if (function.valueParameters.any { it.isVararg || it.defaultValue != null })
+        return null
+    return function
+}
+
+// TODO use a generic inliner (e.g. JS/Native's FunctionInlining.Inliner)
+// Inline simple function calls without type parameters, default parameters, or varargs.
+fun IrFunction.inline(arguments: List<IrValueDeclaration> = listOf()): IrReturnableBlock {
+    require(body != null)
+    val argumentMap = valueParameters.zip(arguments).toMap()
+    val blockSymbol = IrReturnableBlockSymbolImpl(descriptor)
+    val block = IrReturnableBlockImpl(startOffset, endOffset, returnType, blockSymbol, null, symbol)
+    val remapper = object : VariableRemapper(argumentMap) {
+        override fun visitReturn(expression: IrReturn): IrExpression = super.visitReturn(
+            if (expression.returnTargetSymbol == symbol)
+                IrReturnImpl(expression.startOffset, expression.endOffset, expression.type, blockSymbol, expression.value)
+            else
+                expression
+        )
+    }
+    body!!.statements.mapTo(block.statements) { it.transform(remapper, null) }
+    return block
+}

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

@@ -8,16 +8,22 @@ package org.jetbrains.kotlin.backend.common.lower
 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.ir.asSimpleLambda
+import org.jetbrains.kotlin.backend.common.ir.inline
 import org.jetbrains.kotlin.ir.builders.*
-import org.jetbrains.kotlin.ir.declarations.*
-import org.jetbrains.kotlin.ir.expressions.*
-import org.jetbrains.kotlin.ir.expressions.impl.IrReturnImpl
-import org.jetbrains.kotlin.ir.expressions.impl.IrReturnableBlockImpl
+import org.jetbrains.kotlin.ir.declarations.IrConstructor
+import org.jetbrains.kotlin.ir.declarations.IrFile
+import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
+import org.jetbrains.kotlin.ir.expressions.IrConstructorCall
+import org.jetbrains.kotlin.ir.expressions.IrExpression
+import org.jetbrains.kotlin.ir.expressions.copyTypeArgumentsFrom
 import org.jetbrains.kotlin.ir.symbols.IrFunctionSymbol
-import org.jetbrains.kotlin.ir.symbols.impl.IrReturnableBlockSymbolImpl
 import org.jetbrains.kotlin.ir.types.getClass
 import org.jetbrains.kotlin.ir.types.toKotlinType
-import org.jetbrains.kotlin.ir.util.*
+import org.jetbrains.kotlin.ir.util.constructedClass
+import org.jetbrains.kotlin.ir.util.constructors
+import org.jetbrains.kotlin.ir.util.functions
+import org.jetbrains.kotlin.ir.util.patchDeclarationParents
 import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
 import org.jetbrains.kotlin.util.OperatorNameConventions
 
@@ -38,15 +44,10 @@ class ArrayConstructorLowering(val context: CommonBackendContext) : IrElementTra
     }
 
     private fun IrExpression.asSingleArgumentLambda(): IrSimpleFunction? {
-        // A lambda is represented as a block with a function declaration and a reference to it.
-        if (this !is IrBlock || statements.size != 2)
-            return null
-        val (function, reference) = statements
-        if (function !is IrSimpleFunction || reference !is IrFunctionReference || function.symbol != reference.symbol)
-            return null
+        val function = asSimpleLambda() ?: return null
         // Only match the one that has exactly one non-vararg argument, as the code below
         // does not handle defaults or varargs.
-        if (function.valueParameters.size != 1 || function.valueParameters[0].isVararg || reference.getValueArgument(0) != null)
+        if (function.valueParameters.size != 1)
             return null
         return function
     }
@@ -105,28 +106,4 @@ class ArrayConstructorLowering(val context: CommonBackendContext) : IrElementTra
             it.patchDeclarationParents(scope.getLocalDeclarationParent())
         }
     }
-
-    // TODO use a generic inliner (e.g. JS/Native's FunctionInlining.Inliner)
-    private fun IrFunction.inline(arguments: List<IrValueDeclaration>): IrReturnableBlock {
-        val argumentMap = valueParameters.zip(arguments).toMap()
-        val blockSymbol = IrReturnableBlockSymbolImpl(descriptor)
-        val block = IrReturnableBlockImpl(startOffset, endOffset, returnType, blockSymbol, null, symbol)
-        val remapper = object : AbstractVariableRemapper() {
-            override fun remapVariable(value: IrValueDeclaration): IrValueDeclaration? =
-                argumentMap[value]
-
-            override fun visitReturn(expression: IrReturn): IrExpression = super.visitReturn(
-                if (expression.returnTargetSymbol == symbol)
-                    IrReturnImpl(expression.startOffset, expression.endOffset, expression.type, blockSymbol, expression.value)
-                else
-                    expression
-            )
-        }
-        when (val transformed = body?.transform(remapper, null)) {
-            is IrBlockBody -> block.statements += transformed.statements
-            is IrExpressionBody -> block.statements += transformed.expression
-            else -> throw AssertionError("unexpected body type: $this")
-        }
-        return block
-    }
 }

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

@@ -61,7 +61,7 @@ abstract class AbstractVariableRemapper : IrElementTransformerVoid() {
         } ?: expression
 }
 
-class VariableRemapper(val mapping: Map<IrValueParameter, IrValueParameter>) : AbstractVariableRemapper() {
+open class VariableRemapper(val mapping: Map<IrValueParameter, IrValueDeclaration>) : AbstractVariableRemapper() {
     override fun remapVariable(value: IrValueDeclaration): IrValueDeclaration? =
         mapping[value]
 }

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

@@ -203,8 +203,8 @@ val IrBody.statements: List<IrStatement>
     get() = when (this) {
         is IrBlockBody -> statements
         is IrExpressionBody -> listOf(expression)
-        is IrSyntheticBody -> error("Synthetic body contains no statements $this")
-        else -> error("Unknown subclass of IrBody")
+        is IrSyntheticBody -> error("Synthetic body contains no statements: $this")
+        else -> error("Unknown subclass of IrBody: $this")
     }
 
 val IrClass.defaultType: IrSimpleType