org.jetbrains.kotlin.backend.common.lower.RangeContainsLowering.kt Maven / Gradle / Ivy
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/*
* Copyright 2010-2020 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.lower
import org.jetbrains.kotlin.backend.common.BodyLoweringPass
import org.jetbrains.kotlin.backend.common.CommonBackendContext
import org.jetbrains.kotlin.backend.common.IrElementTransformerVoidWithContext
import org.jetbrains.kotlin.backend.common.ir.Symbols
import org.jetbrains.kotlin.backend.common.lower.loops.*
import org.jetbrains.kotlin.backend.common.lower.loops.handlers.*
import org.jetbrains.kotlin.backend.common.phaser.PhaseDescription
import org.jetbrains.kotlin.builtins.PrimitiveType
import org.jetbrains.kotlin.builtins.UnsignedType
import org.jetbrains.kotlin.ir.IrStatement
import org.jetbrains.kotlin.ir.builders.andand
import org.jetbrains.kotlin.ir.builders.irBlock
import org.jetbrains.kotlin.ir.builders.irCall
import org.jetbrains.kotlin.ir.builders.irInt
import org.jetbrains.kotlin.ir.declarations.IrClass
import org.jetbrains.kotlin.ir.declarations.IrDeclaration
import org.jetbrains.kotlin.ir.declarations.IrSymbolOwner
import org.jetbrains.kotlin.ir.expressions.IrBody
import org.jetbrains.kotlin.ir.expressions.IrCall
import org.jetbrains.kotlin.ir.expressions.IrExpression
import org.jetbrains.kotlin.ir.expressions.IrStatementOrigin
import org.jetbrains.kotlin.ir.symbols.IrSymbol
import org.jetbrains.kotlin.ir.types.*
import org.jetbrains.kotlin.ir.util.*
import org.jetbrains.kotlin.ir.visitors.transformChildrenVoid
import org.jetbrains.kotlin.name.FqName
import org.jetbrains.kotlin.util.OperatorNameConventions
import org.jetbrains.kotlin.utils.addIfNotNull
/**
* This lowering pass optimizes calls to contains() (`in` operator) for ClosedRanges.
*
* For example, the expression `X in A..B` is transformed into `A <= X && X <= B`.
*/
@PhaseDescription(
name = "RangeContainsLowering",
description = "Optimizes calls to contains() for ClosedRanges"
)
class RangeContainsLowering(val context: CommonBackendContext) : BodyLoweringPass {
override fun lower(irBody: IrBody, container: IrDeclaration) {
val transformer = Transformer(context, container as IrSymbolOwner)
irBody.transformChildrenVoid(transformer)
}
}
private class Transformer(
val context: CommonBackendContext,
val container: IrSymbolOwner
) : IrElementTransformerVoidWithContext() {
private val headerInfoBuilder = RangeHeaderInfoBuilder(context, this::getScopeOwnerSymbol)
fun getScopeOwnerSymbol() = currentScope?.scope?.scopeOwnerSymbol ?: container.symbol
private fun matchStdlibExtensionContainsCall(expression: IrCall): Boolean {
val callee = expression.symbol.owner
return callee.valueParameters.size == 1 &&
callee.extensionReceiverParameter?.type?.isSubtypeOfClass(context.ir.symbols.closedRange) == true &&
callee.kotlinFqName == FqName("kotlin.ranges.${OperatorNameConventions.CONTAINS}")
}
override fun visitCall(expression: IrCall): IrExpression {
// The call to contains() in `5 in 0..10` has origin=IN:
//
// CALL 'public open fun contains (value: kotlin.Int): kotlin.Boolean [operator] declared in kotlin.ranges.IntRange' type=kotlin.Boolean origin=IN
//
// And when `!in` is used in `5 !in 0..10`, _both_ the not() and contains() calls have origin=NOT_IN:
//
// CALL 'public final fun not (): kotlin.Boolean [operator] declared in kotlin.Boolean' type=kotlin.Boolean origin=NOT_IN
// $this: CALL 'public open fun contains (value: kotlin.Int): kotlin.Boolean [operator] declared in kotlin.ranges.IntRange' type=kotlin.Boolean origin=NOT_IN
//
// We only want to lower the call to contains(); in the `!in` case, the call to not() should be preserved.
val origin = expression.origin
if (origin != IrStatementOrigin.IN && origin != IrStatementOrigin.NOT_IN) {
return super.visitCall(expression) // The call is not an `in` expression.
}
if (origin == IrStatementOrigin.NOT_IN && expression.symbol == context.irBuiltIns.booleanNotSymbol) {
return super.visitCall(expression) // Preserve the call to not().
}
if (expression.extensionReceiver != null && !matchStdlibExtensionContainsCall(expression)) {
// We can only optimize calls to the stdlib extension functions and not a user-defined extension.
// TODO: This breaks the optimization for *Range.reversed().contains(). The function called there is the extension function
// Iterable.contains(). Figure out if we can safely match on that as well.
return super.visitCall(expression)
}
// The HeaderInfoBuilder extracts information (e.g., lower/upper bounds, direction) from the range expression, which is the
// receiver for the contains() call.
val receiver = expression.dispatchReceiver ?: expression.extensionReceiver
val headerInfo = receiver?.accept(headerInfoBuilder, expression)
?: return super.visitCall(expression) // The receiver is not a supported range (or not a range at all).
val argument = expression.getValueArgument(0)!!
if (argument.type.isNullable()) {
// There are stdlib extension functions that return false for null arguments, e.g., IntRange.contains(Int?). We currently
// do not optimize such calls.
return super.visitCall(expression)
}
val builder = context.createIrBuilder(getScopeOwnerSymbol(), expression.startOffset, expression.endOffset)
return builder.buildContainsComparison(headerInfo, argument, origin) ?: super.visitCall(expression) // The call cannot be lowered.
}
private fun DeclarationIrBuilder.buildContainsComparison(
headerInfo: HeaderInfo,
argument: IrExpression,
origin: IrStatementOrigin
): IrExpression? {
// If the lower bound of the range is A, the upper bound is B, and the argument is X, the contains() call is generally transformed
// into `A <= X && X <= B`. However, when any of these expressions (A/B/X) can have side-effects, they must resolve in the order
// in the expression. E.g., for `X in A..B` the order is A -> B -> X (the equivalent call is `(A..B).contains(X)`), and for
// `X in B downTo A` the order is B -> A -> X (the equivalent call is `(B.downTo(A)).contains(X)`).
// Therefore, we need to know in which order the expressions appear in the contains() expression. `shouldUpperComeFirst` is true
// when the expression or variable for `B` (upper) should appear in the lowered IR before `A` (lower).
val lower: IrExpression
val upper: IrExpression
val isUpperInclusive: Boolean
val shouldUpperComeFirst: Boolean
val useCompareTo: Boolean
val isNumericRange: Boolean
val additionalStatements = mutableListOf()
when (headerInfo) {
is NumericHeaderInfo -> {
when (headerInfo) {
is ProgressionHeaderInfo -> {
additionalStatements.addAll(headerInfo.additionalStatements)
}
// None of the handlers in RangeHeaderInfoBuilder should return a IndexedGetHeaderInfo (those are only for loops).
is IndexedGetHeaderInfo -> error("Unexpected IndexedGetHeaderInfo returned by RangeHeaderInfoBuilder")
}
// TODO: Optimize contains() for progressions with |step| > 1 or unknown step and/or direction. These are also not optimized
// in the old JVM backend. contains(x) for a stepped progression returns true if it is one of the elements/steps in the
// progression. e.g., `4 in 0..10 step 2` is true, and `3 in 0..10 step 2` is false. This requires an additional condition
// with a modulo.
when (headerInfo.direction) {
ProgressionDirection.INCREASING -> {
if (headerInfo.step.constLongValue != 1L) return null
// There are 2 cases for an optimizable range with INCREASING direction:
// 1. `X in A..B`:
// Produces HeaderInfo with first = A, last = B, isReversed = false (`first/A` is lower).
// Expression for `lower/A` should come first.
// 2. `X in (B downTo A).reversed()`:
// Produces HeaderInfo with first = A, last = B, isReversed = true (`first/A` is lower).
// Expression for `upper/B` should come first.
lower = headerInfo.first
upper = headerInfo.last
shouldUpperComeFirst = headerInfo.isReversed
}
ProgressionDirection.DECREASING -> {
if (headerInfo.step.constLongValue != -1L) return null
// There are 2 cases for an optimizable range with DECREASING direction:
// 1. `X in B downTo A`:
// Produces HeaderInfo with first = B, last = A, isReversed = false (`last/A` is lower).
// Expression for `upper/B` should come first.
// 2. `X in (A..B).reversed()`:
// Produces HeaderInfo with first = B, last = A, isReversed = true (`last/A` is lower).
// Expression for `lower/A` should come first.
lower = headerInfo.last
upper = headerInfo.first
shouldUpperComeFirst = !headerInfo.isReversed
}
ProgressionDirection.UNKNOWN -> return null
}
// `compareTo` must be used for UInt/ULong; they don't have intrinsic comparison operators.
useCompareTo = headerInfo.progressionType is UnsignedProgressionType
isUpperInclusive = headerInfo.isLastInclusive
isNumericRange = true
}
is FloatingPointRangeHeaderInfo -> {
lower = headerInfo.start
upper = headerInfo.endInclusive
isUpperInclusive = true
shouldUpperComeFirst = false
useCompareTo = false
isNumericRange = true
}
is ComparableRangeInfo -> {
lower = headerInfo.start
upper = headerInfo.endInclusive
isUpperInclusive = true
shouldUpperComeFirst = false
useCompareTo = true
isNumericRange = false
}
else -> return null
}
// The transformed expression is `A <= X && X <= B`. If the argument expression X can have side effects, it must be stored in a
// temp variable before the expression so it does not get evaluated twice. If A and/or B can have side effects, they must also be
// stored in temp variables BEFORE X.
//
// On the other hand, if X can NOT have side effects, it does NOT need to be stored in a temp variable. However, because of
// short-circuit evaluation of &&, if A and/or B can have side effects, we need to make sure they get evaluated regardless.
// We accomplish this be storing it in a temp variable (the alternative is to duplicate A/B in a block in the "else" branch before
// returning false). We can also switch the order of the clauses to ensure evaluation. See below for the expected outcomes:
//
// =======|=======|=======|======================|================|=======================
// Can have side effects? | (Note B is "upper") | |
// X | A | B | shouldUpperComeFirst | Temp var order | Transformed expression
// =======|=======|=======|======================|================|=======================
// True | True | True | False | A -> B -> X | A <= X && X <= B *
// True | True | True | True | B -> A -> X | A <= X && X <= B *
// True | True | False | False/True | A -> X | A <= X && X <= B *
// True | False | True | False/True | B -> X | A <= X && X <= B *
// True | False | False | False/True | X | A <= X && X <= B *
// -------|-------|-------|----------------------|----------------|-----------------------
// False | True | True | False | A ** | X <= B && A <= X ***
// False | True | True | True | B ** | A <= X && X <= B ***
// False | True | False | False/True | [None] | A <= X && X <= B ***
// False | False | True | False/True | [None] | X <= B && A <= X ***
// False | False | False | False/True | [None] | A <= X && X <= B *
// =======|=======|=======|======================|================|=======================
//
// * - Order does not matter.
// ** - Bound with side effect is stored in a temp variable to ensure evaluation even if right side is short-circuited.
// *** - Bound with side effect is on left side of && to make sure it always gets evaluated.
var arg = argument
val builtIns = context.irBuiltIns
val comparisonClass = if (isNumericRange) {
computeComparisonClass([email protected], lower.type, upper.type, arg.type) ?: return null
} else {
assert(headerInfo is ComparableRangeInfo)
[email protected]
}
if (isNumericRange) {
// Convert argument to the "widest" common numeric type for comparisons.
// Note that we do the same for the bounds below. If it is necessary to convert the argument, it's better to do it once and
// store in a temp variable, since it is used twice in the transformed expression (bounds are only used once).
arg = arg.castIfNecessary(comparisonClass)
}
val (argVar, argExpression) = createTemporaryVariableIfNecessary(arg, "containsArg")
var lowerExpression: IrExpression
var upperExpression: IrExpression
val useLowerClauseOnLeftSide: Boolean
if (argVar != null) {
val (lowerVar, tmpLowerExpression) = createTemporaryVariableIfNecessary(lower, "containsLower")
val (upperVar, tmpUpperExpression) = createTemporaryVariableIfNecessary(upper, "containsUpper")
if (shouldUpperComeFirst) {
additionalStatements.addIfNotNull(upperVar)
additionalStatements.addIfNotNull(lowerVar)
} else {
additionalStatements.addIfNotNull(lowerVar)
additionalStatements.addIfNotNull(upperVar)
}
lowerExpression = tmpLowerExpression.shallowCopy()
upperExpression = tmpUpperExpression.shallowCopy()
useLowerClauseOnLeftSide = true
} else if (lower.canHaveSideEffects && upper.canHaveSideEffects) {
if (shouldUpperComeFirst) {
val (upperVar, tmpUpperExpression) = createTemporaryVariableIfNecessary(upper, "containsUpper")
additionalStatements.add(upperVar!!)
lowerExpression = lower
upperExpression = tmpUpperExpression.shallowCopy()
useLowerClauseOnLeftSide = true
} else {
val (lowerVar, tmpLowerExpression) = createTemporaryVariableIfNecessary(lower, "containsLower")
additionalStatements.add(lowerVar!!)
lowerExpression = tmpLowerExpression.shallowCopy()
upperExpression = upper
useLowerClauseOnLeftSide = false
}
} else {
lowerExpression = lower
upperExpression = upper
useLowerClauseOnLeftSide = true
}
additionalStatements.addIfNotNull(argVar)
if (isNumericRange) {
lowerExpression = lowerExpression.castIfNecessary(comparisonClass)
upperExpression = upperExpression.castIfNecessary(comparisonClass)
}
val lowerCompFun = builtIns.lessOrEqualFunByOperandType.getValue(if (useCompareTo) builtIns.intClass else comparisonClass.symbol)
val upperCompFun = if (isUpperInclusive) {
builtIns.lessOrEqualFunByOperandType
} else {
builtIns.lessFunByOperandType
}.getValue(if (useCompareTo) builtIns.intClass else comparisonClass.symbol)
val compareToFun = comparisonClass.functions.singleOrNull {
it.name == OperatorNameConventions.COMPARE_TO &&
it.dispatchReceiverParameter != null && it.extensionReceiverParameter == null &&
it.valueParameters.size == 1 && (!isNumericRange || it.valueParameters[0].type == comparisonClass.defaultType)
} ?: return null
// contains() function for ComparableRange is implemented as `value >= start && value <= endInclusive` (`value` is the argument).
// Therefore the dispatch receiver for the compareTo() calls should be the argument. This is important since the implementation
// for compareTo() may have side effects dependent on which expressions are the receiver and argument
// (see evaluationOrderForComparableRange.kt test).
val lowerClause = if (useCompareTo) {
irCall(lowerCompFun).apply {
putValueArgument(0, irInt(0))
putValueArgument(1, irCall(compareToFun).apply {
dispatchReceiver = argExpression.shallowCopy()
putValueArgument(0, lowerExpression)
})
}
} else {
irCall(lowerCompFun).apply {
putValueArgument(0, lowerExpression)
putValueArgument(1, argExpression.shallowCopy())
}
}
val upperClause = if (useCompareTo) {
irCall(upperCompFun).apply {
putValueArgument(0, irCall(compareToFun).apply {
dispatchReceiver = argExpression.shallowCopy()
putValueArgument(0, upperExpression)
})
putValueArgument(1, irInt(0))
}
} else {
irCall(upperCompFun).apply {
putValueArgument(0, argExpression.shallowCopy())
putValueArgument(1, upperExpression)
}
}
val contains = context.andand(
if (useLowerClauseOnLeftSide) lowerClause else upperClause,
if (useLowerClauseOnLeftSide) upperClause else lowerClause,
origin
)
return if (additionalStatements.isEmpty()) {
contains
} else {
irBlock {
for (stmt in additionalStatements) {
+stmt
}
+contains
}
}
}
private fun computeComparisonClass(
symbols: Symbols,
lowerType: IrType,
upperType: IrType,
argumentType: IrType
): IrClass? {
val commonBoundType = leastCommonPrimitiveNumericType(symbols, lowerType, upperType) ?: return null
return leastCommonPrimitiveNumericType(symbols, argumentType, commonBoundType)?.getClass()
}
private fun leastCommonPrimitiveNumericType(symbols: Symbols, t1: IrType, t2: IrType): IrType? {
val primitive1 = t1.getPrimitiveType()
val primitive2 = t2.getPrimitiveType()
val unsigned1 = t1.getUnsignedType()
val unsigned2 = t2.getUnsignedType()
return when {
primitive1 == PrimitiveType.DOUBLE || primitive2 == PrimitiveType.DOUBLE -> symbols.double
primitive1 == PrimitiveType.FLOAT || primitive2 == PrimitiveType.FLOAT -> symbols.float
unsigned1 == UnsignedType.ULONG || unsigned2 == UnsignedType.ULONG -> symbols.uLong!!
unsigned1.isPromotableToUInt() || unsigned2.isPromotableToUInt() -> symbols.uInt!!
primitive1 == PrimitiveType.LONG || primitive2 == PrimitiveType.LONG -> symbols.long
primitive1.isPromotableToInt() || primitive2.isPromotableToInt() -> symbols.int
primitive1 == PrimitiveType.CHAR || primitive2 == PrimitiveType.CHAR -> symbols.char
else -> error("Unexpected types: t1=${t1.render()}, t2=${t2.render()}")
}.defaultType
}
private fun PrimitiveType?.isPromotableToInt(): Boolean =
this == PrimitiveType.INT || this == PrimitiveType.SHORT || this == PrimitiveType.BYTE
private fun UnsignedType?.isPromotableToUInt(): Boolean =
this == UnsignedType.UINT || this == UnsignedType.USHORT || this == UnsignedType.UBYTE
}
internal open class RangeHeaderInfoBuilder(context: CommonBackendContext, scopeOwnerSymbol: () -> IrSymbol) :
HeaderInfoBuilder(context, scopeOwnerSymbol, allowUnsignedBounds = true) {
override val progressionHandlers = listOf(
CollectionIndicesHandler(context),
ArrayIndicesHandler(context),
CharSequenceIndicesHandler(context),
UntilHandler(context),
RangeUntilHandler(context),
DownToHandler(context),
RangeToHandler(context)
)
override val callHandlers = listOf(
FloatingPointRangeToHandler,
ComparableRangeToHandler(context),
ReversedHandler(context, this)
)
override val expressionHandlers = listOf(DefaultProgressionHandler(context, allowUnsignedBounds = true))
}
/** Builds a [HeaderInfo] for closed floating-point ranges built using the `rangeTo` function. */
internal object FloatingPointRangeToHandler : HeaderInfoHandler {
override fun matchIterable(expression: IrCall): Boolean {
val callee = expression.symbol.owner
return callee.valueParameters.singleOrNull()?.type?.let { it.isFloat() || it.isDouble() } == true &&
callee.extensionReceiverParameter?.type?.let { it.isFloat() || it.isDouble() } == true &&
callee.kotlinFqName == FqName("kotlin.ranges.${OperatorNameConventions.RANGE_TO}")
}
override fun build(expression: IrCall, data: Nothing?, scopeOwner: IrSymbol) =
FloatingPointRangeHeaderInfo(
start = expression.extensionReceiver!!,
endInclusive = expression.getValueArgument(0)!!
)
}
/** Builds a [HeaderInfo] for ranges of Comparables built using the `rangeTo` extension function. */
internal class ComparableRangeToHandler(private val context: CommonBackendContext) : HeaderInfoHandler {
override fun matchIterable(expression: IrCall): Boolean {
val callee = expression.symbol.owner
return callee.valueParameters.size == 1 &&
callee.extensionReceiverParameter?.type?.isSubtypeOfClass(context.ir.symbols.comparable) == true &&
callee.kotlinFqName == FqName("kotlin.ranges.${OperatorNameConventions.RANGE_TO}")
}
override fun build(expression: IrCall, data: Nothing?, scopeOwner: IrSymbol) =
ComparableRangeInfo(
start = expression.extensionReceiver!!,
endInclusive = expression.getValueArgument(0)!!
)
}