diff --git a/compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArguments.kt b/compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArguments.kt
index e6d9213b001..33791b24287 100644
--- a/compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArguments.kt
+++ b/compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/CommonCompilerArguments.kt
@@ -238,6 +238,18 @@ abstract class CommonCompilerArguments : CommonToolArguments() {
     )
     var profilePhases: Boolean by FreezableVar(false)
 
+    @Argument(
+        value = "-Xcheck-conditions",
+        description = "Check pre- and postconditions on phases"
+    )
+    var checkPhaseConditions: Boolean by FreezableVar(false)
+
+    @Argument(
+        value = "-Xcheck-sticky-conditions",
+        description = "Run sticky condition checks on subsequent phases as well. Implies -Xcheck-conditions"
+    )
+    var checkStickyConditions: Boolean by FreezableVar(false)
+
     open fun configureAnalysisFlags(collector: MessageCollector): MutableMap<AnalysisFlag<*>, Any> {
         return HashMap<AnalysisFlag<*>, Any>().apply {
             put(AnalysisFlags.skipMetadataVersionCheck, skipMetadataVersionCheck)
diff --git a/compiler/cli/src/org/jetbrains/kotlin/cli/common/arguments.kt b/compiler/cli/src/org/jetbrains/kotlin/cli/common/arguments.kt
index d3804b581fd..a793750bed4 100644
--- a/compiler/cli/src/org/jetbrains/kotlin/cli/common/arguments.kt
+++ b/compiler/cli/src/org/jetbrains/kotlin/cli/common/arguments.kt
@@ -53,6 +53,8 @@ fun <A : CommonCompilerArguments> CompilerConfiguration.setupCommonArguments(
     }
 
     put(CommonConfigurationKeys.PROFILE_PHASES, arguments.profilePhases)
+    put(CommonConfigurationKeys.CHECK_PHASE_CONDITIONS, arguments.checkPhaseConditions or arguments.checkStickyConditions)
+    put(CommonConfigurationKeys.CHECK_STICKY_CONDITIONS, arguments.checkStickyConditions)
 }
 
 fun <A : CommonCompilerArguments> CompilerConfiguration.setupLanguageVersionSettings(arguments: A) {
diff --git a/compiler/frontend/src/org/jetbrains/kotlin/config/CommonConfigurationKeys.kt b/compiler/frontend/src/org/jetbrains/kotlin/config/CommonConfigurationKeys.kt
index 26037f867d4..2b9db8b581d 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/config/CommonConfigurationKeys.kt
+++ b/compiler/frontend/src/org/jetbrains/kotlin/config/CommonConfigurationKeys.kt
@@ -72,6 +72,12 @@ object CommonConfigurationKeys {
     @JvmField
     val PROFILE_PHASES = CompilerConfigurationKey.create<Boolean>("profile backend phase execution")
 
+    @JvmField
+    val CHECK_PHASE_CONDITIONS = CompilerConfigurationKey.create<Boolean>("run pre- and postcondition checkers for phases")
+
+    @JvmField
+    val CHECK_STICKY_CONDITIONS = CompilerConfigurationKey.create<Boolean>("run sticky postcondition checkers on subsequent phases as well")
+
     @JvmField
     val EXCLUDED_ELEMENTS_FROM_DUMPING = CompilerConfigurationKey.create<Set<String>>("lowering elements which shouldn't be dumped at all")
 }
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/CompilerPhase.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/CompilerPhase.kt
index c431ced6974..275ce8a2799 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/CompilerPhase.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/CompilerPhase.kt
@@ -8,22 +8,30 @@ package org.jetbrains.kotlin.backend.common.phaser
 import org.jetbrains.kotlin.backend.common.CommonBackendContext
 import kotlin.system.measureTimeMillis
 
-class PhaserState {
-    val alreadyDone = mutableSetOf<AnyNamedPhase>()
-    var depth = 0
-}
+class PhaserState<Data>(
+    val alreadyDone: MutableSet<AnyNamedPhase> = mutableSetOf(),
+    var depth: Int = 0,
+    val stickyPostconditions: MutableSet<Checker<Data>> = mutableSetOf()
+)
 
-fun <R> PhaserState.downlevel(nlevels: Int = 1, block: () -> R): R {
+// Copy state, forgetting the sticky postconditions (which will not be applicable to the new type)
+fun <Input, Output> PhaserState<Input>.changeType() = PhaserState<Output>(alreadyDone, depth, mutableSetOf())
+
+
+fun <R, D> PhaserState<D>.downlevel(nlevels: Int = 1, block: () -> R): R {
     depth += nlevels
     val result = block()
     depth -= nlevels
     return result
 }
 
-interface CompilerPhase<in Context : CommonBackendContext, in Input, out Output> {
-    fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, input: Input): Output
+interface CompilerPhase<in Context : CommonBackendContext, Input, Output> {
+    fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState<Input>, context: Context, input: Input): Output
 
-    fun getNamedSubphases(startDepth: Int = 0): List<Pair<Int, NamedCompilerPhase<*, *, *>>> = emptyList()
+    fun getNamedSubphases(startDepth: Int = 0): List<Pair<Int, AnyNamedPhase>> = emptyList()
+
+    // In phase trees, `stickyPostconditions` is inherited along the right edge to be used in `then`.
+    val stickyPostconditions: Set<Checker<Output>> get() = emptySet()
 }
 
 fun <Context: CommonBackendContext, Input, Output> CompilerPhase<Context,  Input, Output>.invokeToplevel(
@@ -34,14 +42,18 @@ fun <Context: CommonBackendContext, Input, Output> CompilerPhase<Context,  Input
 
 interface SameTypeCompilerPhase<in Context: CommonBackendContext, Data> : CompilerPhase<Context, Data, Data>
 
-interface NamedCompilerPhase<in Context : CommonBackendContext, in Input, out Output> : CompilerPhase<Context, Input, Output> {
+// A failing checker should just throw an exception.
+typealias Checker<Data> = (Data) -> Unit
+
+interface NamedCompilerPhase<in Context : CommonBackendContext, Input, Output> : CompilerPhase<Context, Input, Output> {
     val name: String
     val description: String
     val prerequisite: Set<AnyNamedPhase> get() = emptySet()
+    val preconditions: Set<Checker<Input>>
+    val postconditions: Set<Checker<Output>>
 }
 
 typealias AnyNamedPhase = NamedCompilerPhase<*, *, *>
-
 enum class BeforeOrAfter { BEFORE, AFTER }
 
 interface PhaseDumperVerifier<in Context : CommonBackendContext, Data> {
@@ -53,13 +65,16 @@ abstract class AbstractNamedPhaseWrapper<in Context : CommonBackendContext, Inpu
     override val name: String,
     override val description: String,
     override val prerequisite: Set<AnyNamedPhase>,
-    private val nlevels: Int = 0,
-    private val lower: CompilerPhase<Context, Input, Output>
+    private val lower: CompilerPhase<Context, Input, Output>,
+    override val preconditions: Set<Checker<Input>> = emptySet(),
+    override val postconditions: Set<Checker<Output>> = emptySet(),
+    override val stickyPostconditions: Set<Checker<Output>> = emptySet(),
+    private val nlevels: Int = 0
 ) : NamedCompilerPhase<Context, Input, Output> {
     abstract val inputDumperVerifier: PhaseDumperVerifier<Context, Input>
     abstract val outputDumperVerifier: PhaseDumperVerifier<Context, Output>
 
-    override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, input: Input): Output {
+    override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState<Input>, context: Context, input: Input): Output {
         if (this is SameTypeCompilerPhase<*, *> &&
             this !in phaseConfig.enabled
         ) {
@@ -71,7 +86,7 @@ abstract class AbstractNamedPhaseWrapper<in Context : CommonBackendContext, Inpu
 
         runBefore(phaseConfig, context, input)
         val output = runBody(phaseConfig, phaserState, context, input)
-        runAfter(phaseConfig, context, output)
+        runAfter(phaseConfig, phaserState, context, output)
 
         phaserState.alreadyDone.add(this)
 
@@ -81,9 +96,12 @@ abstract class AbstractNamedPhaseWrapper<in Context : CommonBackendContext, Inpu
     private fun runBefore(phaseConfig: PhaseConfig, context: Context, input: Input) {
         checkAndRun(phaseConfig.toDumpStateBefore) { inputDumperVerifier.dump(this, context, input, BeforeOrAfter.BEFORE) }
         checkAndRun(phaseConfig.toValidateStateBefore) { inputDumperVerifier.verify(context, input) }
+        if (phaseConfig.checkConditions) {
+            for (pre in preconditions) pre(input)
+        }
     }
 
-    private fun runBody(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, input: Input): Output {
+    private fun runBody(phaseConfig: PhaseConfig, phaserState: PhaserState<Input>, context: Context, input: Input): Output {
         return if (phaseConfig.needProfiling) {
             runAndProfile(phaseConfig, phaserState, context, input)
         } else {
@@ -93,12 +111,20 @@ abstract class AbstractNamedPhaseWrapper<in Context : CommonBackendContext, Inpu
         }
     }
 
-    private fun runAfter(phaseConfig: PhaseConfig, context: Context, output: Output) {
+    private fun runAfter(phaseConfig: PhaseConfig, phaserState: PhaserState<Input>, context: Context, output: Output) {
         checkAndRun(phaseConfig.toDumpStateAfter) { outputDumperVerifier.dump(this, context, output, BeforeOrAfter.AFTER) }
         checkAndRun(phaseConfig.toValidateStateAfter) { outputDumperVerifier.verify(context, output) }
+        if (phaseConfig.checkConditions) {
+            for (post in postconditions) post(output)
+            for (post in stickyPostconditions) post(output)
+            if (phaseConfig.checkStickyConditions && this is SameTypeCompilerPhase<*, *>) {
+                val phaserStateO = phaserState as PhaserState<Output>
+                for (post in phaserStateO.stickyPostconditions) post(output)
+            }
+        }
     }
 
-    private fun runAndProfile(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, source: Input): Output {
+    private fun runAndProfile(phaseConfig: PhaseConfig, phaserState: PhaserState<Input>, context: Context, source: Input): Output {
         var result: Output? = null
         val msec = measureTimeMillis {
             result = phaserState.downlevel(nlevels) {
@@ -124,10 +150,15 @@ class SameTypeNamedPhaseWrapper<in Context : CommonBackendContext, Data>(
     name: String,
     description: String,
     prerequisite: Set<AnyNamedPhase>,
-    nlevels: Int = 0,
     lower: CompilerPhase<Context, Data, Data>,
+    preconditions: Set<Checker<Data>> = emptySet(),
+    postconditions: Set<Checker<Data>> = emptySet(),
+    stickyPostconditions: Set<Checker<Data>> = lower.stickyPostconditions,
+    nlevels: Int = 0,
     val dumperVerifier: PhaseDumperVerifier<Context, Data>
-) : AbstractNamedPhaseWrapper<Context, Data, Data>(name, description, prerequisite, nlevels, lower), SameTypeCompilerPhase<Context, Data> {
+) : AbstractNamedPhaseWrapper<Context, Data, Data>(
+    name, description, prerequisite, lower, preconditions, postconditions, stickyPostconditions, nlevels
+), SameTypeCompilerPhase<Context, Data> {
     override val inputDumperVerifier get() = dumperVerifier
     override val outputDumperVerifier get() = dumperVerifier
 }
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/PhaseBuilders.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/PhaseBuilders.kt
index 23b7f757bce..d3829f0907e 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/PhaseBuilders.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/PhaseBuilders.kt
@@ -8,155 +8,218 @@ import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
 
 // Phase composition.
 infix fun <Context : CommonBackendContext, Input, Mid, Output> CompilerPhase<Context, Input, Mid>.then(
-        other: CompilerPhase<Context, Mid, Output>
+    other: CompilerPhase<Context, Mid, Output>
 ) = object : CompilerPhase<Context, Input, Output> {
-    override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, input: Input): Output =
-            this@then.invoke(phaseConfig, phaserState, context, input).let { mid ->
-                other.invoke(phaseConfig, phaserState, context, mid)
-            }
+    override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState<Input>, context: Context, input: Input): Output =
+        this@then.invoke(phaseConfig, phaserState, context, input).let { mid ->
+            val newPhaserState = if (other is SameTypeCompilerPhase<*, *>)
+                // Keep `stickyPostconditions`.
+                phaserState as PhaserState<Mid>
+            else
+                // Discard `stickyPostcoditions`, they are useless since data type is changing.
+                phaserState.changeType()
+            newPhaserState.stickyPostconditions.addAll(this@then.stickyPostconditions)
+            other.invoke(phaseConfig, newPhaserState, context, mid)
+        }
 
     override fun getNamedSubphases(startDepth: Int) =
-            this@then.getNamedSubphases(startDepth) + other.getNamedSubphases(startDepth)
+        this@then.getNamedSubphases(startDepth) + other.getNamedSubphases(startDepth)
+
+    override val stickyPostconditions get() = other.stickyPostconditions
 }
 
 fun <Context : CommonBackendContext> namedIrModulePhase(
-        name: String,
-        description: String,
-        prerequisite: Set<AnyNamedPhase> = emptySet(),
-        verify: (Context, IrModuleFragment) -> Unit = { _, _ -> },
-        nlevels: Int = 1,
-        lower: CompilerPhase<Context, IrModuleFragment, IrModuleFragment>
-) = SameTypeNamedPhaseWrapper(name, description, prerequisite, nlevels, lower, IrModuleDumperVerifier(verify))
+    name: String,
+    description: String,
+    prerequisite: Set<AnyNamedPhase> = emptySet(),
+    lower: CompilerPhase<Context, IrModuleFragment, IrModuleFragment>,
+    preconditions: Set<Checker<IrModuleFragment>> = emptySet(),
+    postconditions: Set<Checker<IrModuleFragment>> = emptySet(),
+    stickyPostconditions: Set<Checker<IrModuleFragment>> = lower.stickyPostconditions,
+    verify: (Context, IrModuleFragment) -> Unit = { _, _ -> },
+    nlevels: Int = 1
+) = SameTypeNamedPhaseWrapper(
+    name,
+    description,
+    prerequisite,
+    lower,
+    preconditions,
+    postconditions,
+    stickyPostconditions,
+    nlevels,
+    IrModuleDumperVerifier(verify)
+)
 
 fun <Context : CommonBackendContext> namedIrFilePhase(
-        name: String,
-        description: String,
-        prerequisite: Set<AnyNamedPhase> = emptySet(),
-        verify: (Context, IrFile) -> Unit = { _, _ -> },
-        nlevels: Int = 1,
-        lower: CompilerPhase<Context, IrFile, IrFile>
-) = SameTypeNamedPhaseWrapper(name, description, prerequisite, nlevels, lower, IrFileDumperVerifier(verify))
+    name: String,
+    description: String,
+    prerequisite: Set<AnyNamedPhase> = emptySet(),
+    lower: CompilerPhase<Context, IrFile, IrFile>,
+    preconditions: Set<Checker<IrFile>> = emptySet(),
+    postconditions: Set<Checker<IrFile>> = emptySet(),
+    stickyPostconditions: Set<Checker<IrFile>> = lower.stickyPostconditions,
+    verify: (Context, IrFile) -> Unit = { _, _ -> },
+    nlevels: Int = 1
+) = SameTypeNamedPhaseWrapper(
+    name,
+    description,
+    prerequisite,
+    lower,
+    preconditions,
+    postconditions,
+    stickyPostconditions,
+    nlevels,
+    IrFileDumperVerifier(verify)
+)
 
 fun <Context : CommonBackendContext> namedUnitPhase(
-        name: String,
-        description: String,
-        prerequisite: Set<AnyNamedPhase> = emptySet(),
-        nlevels: Int = 1,
-        lower: CompilerPhase<Context, Unit, Unit>
-) = SameTypeNamedPhaseWrapper(name, description, prerequisite, nlevels, lower, EmptyDumperVerifier())
+    name: String,
+    description: String,
+    prerequisite: Set<AnyNamedPhase> = emptySet(),
+    nlevels: Int = 1,
+    lower: CompilerPhase<Context, Unit, Unit>
+) = SameTypeNamedPhaseWrapper(
+    name, description, prerequisite,
+    lower = lower,
+    nlevels = nlevels,
+    dumperVerifier = EmptyDumperVerifier()
+)
 
 fun <Context : CommonBackendContext> namedOpUnitPhase(
-        name: String,
-        description: String,
-        prerequisite: Set<AnyNamedPhase>,
-        op: Context.() -> Unit
+    name: String,
+    description: String,
+    prerequisite: Set<AnyNamedPhase>,
+    op: Context.() -> Unit
 ) = namedUnitPhase(
-        name, description, prerequisite,
-        nlevels = 0,
-        lower = object : SameTypeCompilerPhase<Context, Unit> {
-            override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, input: Unit) {
-                context.op()
-            }
+    name, description, prerequisite,
+    nlevels = 0,
+    lower = object : SameTypeCompilerPhase<Context, Unit> {
+        override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState<Unit>, context: Context, input: Unit) {
+            context.op()
         }
+    }
 )
 
 fun <Context : CommonBackendContext> performByIrFile(
-        name: String = "PerformByIrFile",
-        description: String = "Perform phases by IrFile",
-        prerequisite: Set<AnyNamedPhase> = emptySet(),
-        verify: (Context, IrModuleFragment) -> Unit = { _, _ -> },
-        lower: CompilerPhase<Context, IrFile, IrFile>
+    name: String = "PerformByIrFile",
+    description: String = "Perform phases by IrFile",
+    prerequisite: Set<AnyNamedPhase> = emptySet(),
+    preconditions: Set<Checker<IrModuleFragment>> = emptySet(),
+    postconditions: Set<Checker<IrModuleFragment>> = emptySet(),
+    stickyPostconditions: Set<Checker<IrModuleFragment>> = emptySet(),
+    verify: (Context, IrModuleFragment) -> Unit = { _, _ -> },
+    lower: CompilerPhase<Context, IrFile, IrFile>
 ) = namedIrModulePhase(
-        name, description, prerequisite, verify,
-        nlevels = 1,
-        lower = object : SameTypeCompilerPhase<Context, IrModuleFragment> {
-            override fun invoke(
-                    phaseConfig: PhaseConfig,
-                    phaserState: PhaserState,
-                    context: Context,
-                    input: IrModuleFragment
-            ): IrModuleFragment {
-                for (irFile in input.files) {
-                    lower.invoke(phaseConfig, phaserState, context, irFile)
-                }
-
-                // TODO: no guarantee that module identity is preserved by `lower`
-                return input
+    name, description, prerequisite,
+    preconditions = preconditions,
+    postconditions = postconditions,
+    stickyPostconditions = stickyPostconditions,
+    verify = verify,
+    nlevels = 1,
+    lower = object : SameTypeCompilerPhase<Context, IrModuleFragment> {
+        override fun invoke(
+            phaseConfig: PhaseConfig,
+            phaserState: PhaserState<IrModuleFragment>,
+            context: Context,
+            input: IrModuleFragment
+        ): IrModuleFragment {
+            for (irFile in input.files) {
+                lower.invoke(phaseConfig, phaserState.changeType(), context, irFile)
             }
 
-            override fun getNamedSubphases(startDepth: Int) = lower.getNamedSubphases(startDepth)
+            // TODO: no guarantee that module identity is preserved by `lower`
+            return input
         }
+
+        override fun getNamedSubphases(startDepth: Int) = lower.getNamedSubphases(startDepth)
+    }
 )
 
 fun <Context : CommonBackendContext> makeIrFilePhase(
-        lowering: (Context) -> FileLoweringPass,
-        name: String,
-        description: String,
-        prerequisite: Set<AnyNamedPhase> = emptySet(),
-        verify: (Context, IrFile) -> Unit = { _, _ -> }
+    lowering: (Context) -> FileLoweringPass,
+    name: String,
+    description: String,
+    prerequisite: Set<AnyNamedPhase> = emptySet(),
+    preconditions: Set<Checker<IrFile>> = emptySet(),
+    postconditions: Set<Checker<IrFile>> = emptySet(),
+    stickyPostconditions: Set<Checker<IrFile>> = emptySet(),
+    verify: (Context, IrFile) -> Unit = { _, _ -> }
 ) = namedIrFilePhase(
-        name, description, prerequisite, verify,
-        nlevels = 0,
-        lower = object : SameTypeCompilerPhase<Context, IrFile> {
-            override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, input: IrFile): IrFile {
-                lowering(context).lower(input)
-                return input
-            }
+    name, description, prerequisite,
+    preconditions = preconditions,
+    postconditions = postconditions,
+    stickyPostconditions = stickyPostconditions,
+    verify = verify,
+    nlevels = 0,
+    lower = object : SameTypeCompilerPhase<Context, IrFile> {
+        override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState<IrFile>, context: Context, input: IrFile): IrFile {
+            lowering(context).lower(input)
+            return input
         }
+    }
 )
 
 fun <Context : CommonBackendContext> makeIrModulePhase(
-        lowering: (Context) -> FileLoweringPass,
-        name: String,
-        description: String,
-        prerequisite: Set<AnyNamedPhase> = emptySet(),
-        verify: (Context, IrModuleFragment) -> Unit = { _, _ -> }
+    lowering: (Context) -> FileLoweringPass,
+    name: String,
+    description: String,
+    prerequisite: Set<AnyNamedPhase> = emptySet(),
+    preconditions: Set<Checker<IrModuleFragment>> = emptySet(),
+    postconditions: Set<Checker<IrModuleFragment>> = emptySet(),
+    stickyPostconditions: Set<Checker<IrModuleFragment>> = emptySet(),
+    verify: (Context, IrModuleFragment) -> Unit = { _, _ -> }
 ) = namedIrModulePhase(
-        name, description, prerequisite, verify,
-        nlevels = 0,
-        lower = object : SameTypeCompilerPhase<Context, IrModuleFragment> {
-            override fun invoke(
-                    phaseConfig: PhaseConfig,
-                    phaserState: PhaserState,
-                    context: Context,
-                    input: IrModuleFragment
-            ): IrModuleFragment {
-                lowering(context).lower(input)
-                return input
-            }
+    name, description, prerequisite,
+    preconditions=preconditions,
+    postconditions = postconditions,
+    stickyPostconditions = stickyPostconditions,
+    verify = verify,
+    nlevels = 0,
+    lower = object : SameTypeCompilerPhase<Context, IrModuleFragment> {
+        override fun invoke(
+            phaseConfig: PhaseConfig,
+            phaserState: PhaserState<IrModuleFragment>,
+            context: Context,
+            input: IrModuleFragment
+        ): IrModuleFragment {
+            lowering(context).lower(input)
+            return input
         }
+    }
 )
 
 fun <Context : CommonBackendContext, Input> unitPhase(
-        name: String,
-        description: String,
-        prerequisite: Set<AnyNamedPhase>,
-        op: Context.() -> Unit
+    name: String,
+    description: String,
+    prerequisite: Set<AnyNamedPhase>,
+    preconditions: Set<Checker<Input>>,
+    op: Context.() -> Unit
 ) =
-        object : AbstractNamedPhaseWrapper<Context, Input, Unit>(
-                name, description, prerequisite,
-                nlevels = 0,
-                lower = object : CompilerPhase<Context, Input, Unit> {
-                    override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, input: Input) {
-                        context.op()
-                    }
-                }
-        ) {
-            override val inputDumperVerifier = EmptyDumperVerifier<Context, Input>()
-            override val outputDumperVerifier = EmptyDumperVerifier<Context, Unit>()
+    object : AbstractNamedPhaseWrapper<Context, Input, Unit>(
+        name, description, prerequisite,
+        preconditions = preconditions,
+        nlevels = 0,
+        lower = object : CompilerPhase<Context, Input, Unit> {
+            override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState<Input>, context: Context, input: Input) {
+                context.op()
+            }
         }
+    ) {
+        override val inputDumperVerifier = EmptyDumperVerifier<Context, Input>()
+        override val outputDumperVerifier = EmptyDumperVerifier<Context, Unit>()
+    }
 
 fun <Context : CommonBackendContext, Input> unitSink() = object : CompilerPhase<Context, Input, Unit> {
-    override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, input: Input) {}
+    override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState<Input>, context: Context, input: Input) {}
 }
 
 // Intermediate phases to change the object of transformations
 fun <Context : CommonBackendContext, OldData, NewData> takeFromContext(op: (Context) -> NewData) =
-        object : CompilerPhase<Context, OldData, NewData> {
-            override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, input: OldData) = op(context)
-        }
+    object : CompilerPhase<Context, OldData, NewData> {
+        override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState<OldData>, context: Context, input: OldData) = op(context)
+    }
 
 fun <Context : CommonBackendContext, OldData, NewData> transform(op: (OldData) -> NewData) =
-        object : CompilerPhase<Context, OldData, NewData> {
-            override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState, context: Context, input: OldData) = op(input)
-        }
+    object : CompilerPhase<Context, OldData, NewData> {
+        override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState<OldData>, context: Context, input: OldData) = op(input)
+    }
diff --git a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/PhaseConfig.kt b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/PhaseConfig.kt
index 7079cd7a29d..0121d8a728a 100644
--- a/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/PhaseConfig.kt
+++ b/compiler/ir/backend.common/src/org/jetbrains/kotlin/backend/common/phaser/PhaseConfig.kt
@@ -35,6 +35,8 @@ class PhaseConfig(private val compoundPhase: CompilerPhase<*, *, *>, config: Com
     }
 
     val needProfiling = config.getBoolean(CommonConfigurationKeys.PROFILE_PHASES)
+    val checkConditions = config.getBoolean(CommonConfigurationKeys.CHECK_PHASE_CONDITIONS)
+    val checkStickyConditions = config.getBoolean(CommonConfigurationKeys.CHECK_STICKY_CONDITIONS)
 
     fun known(name: String): String {
         if (phases[name] == null) {
diff --git a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt
index 2c73700a80f..e42601b6618 100644
--- a/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt
+++ b/compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt
@@ -57,7 +57,7 @@ private fun makeCustomJsModulePhase(
     lower = object : SameTypeCompilerPhase<JsIrBackendContext, IrModuleFragment> {
         override fun invoke(
             phaseConfig: PhaseConfig,
-            phaserState: PhaserState,
+            phaserState: PhaserState<IrModuleFragment>,
             context: JsIrBackendContext,
             input: IrModuleFragment
         ): IrModuleFragment {
diff --git a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt
index 07e7a72ed30..5fd498df549 100644
--- a/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt
+++ b/compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/JvmLower.kt
@@ -26,7 +26,7 @@ import org.jetbrains.kotlin.ir.visitors.acceptVoid
 
 private fun makePatchParentsPhase(number: Int) = namedIrFilePhase(
     lower = object : SameTypeCompilerPhase<CommonBackendContext, IrFile> {
-        override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState, context: CommonBackendContext, input: IrFile): IrFile {
+        override fun invoke(phaseConfig: PhaseConfig, phaserState: PhaserState<IrFile>, context: CommonBackendContext, input: IrFile): IrFile {
             input.acceptVoid(PatchDeclarationParentsVisitor())
             return input
         }