Optimize memory footprint related to empty/single element collections

^KT-47926 Related

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tower/KotlinToResolvedCallTransformer.kt

@@ -48,7 +48,6 @@ import org.jetbrains.kotlin.resolve.constants.IntegerLiteralTypeConstructor
 import org.jetbrains.kotlin.resolve.constants.IntegerValueTypeConstant
 import org.jetbrains.kotlin.resolve.constants.evaluate.ConstantExpressionEvaluator
 import org.jetbrains.kotlin.resolve.deprecation.DeprecationResolver
-import org.jetbrains.kotlin.resolve.diagnostics.MutableDiagnosticsWithSuppression
 import org.jetbrains.kotlin.resolve.scopes.receivers.CastImplicitClassReceiver
 import org.jetbrains.kotlin.resolve.scopes.receivers.ImplicitClassReceiver
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue
@@ -64,9 +63,8 @@ import org.jetbrains.kotlin.types.typeUtil.makeNotNullable
 import org.jetbrains.kotlin.types.typeUtil.makeNullable
 import org.jetbrains.kotlin.utils.SmartList
 import org.jetbrains.kotlin.utils.addToStdlib.cast
+import org.jetbrains.kotlin.utils.addToStdlib.compactIfPossible
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
-import java.util.*
-import kotlin.collections.LinkedHashMap
 
 class KotlinToResolvedCallTransformer(
     private val callCheckers: Iterable<CallChecker>,
@@ -677,7 +675,7 @@ sealed class NewAbstractResolvedCall<D : CallableDescriptor>() : ResolvedCall<D>
                     result[parameter] = argument
                 }
             }
-        }
+        }.compactIfPossible()
 
 }
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tower/NewResolutionOldInference.kt

@@ -21,13 +21,13 @@ import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.synthetic.SyntheticMemberDescriptor
 import org.jetbrains.kotlin.diagnostics.Errors
+import org.jetbrains.kotlin.extensions.internal.CandidateInterceptor
 import org.jetbrains.kotlin.incremental.components.LookupLocation
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.Call
 import org.jetbrains.kotlin.psi.KtReferenceExpression
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.BindingTrace
-import org.jetbrains.kotlin.extensions.internal.CandidateInterceptor
 import org.jetbrains.kotlin.resolve.TemporaryBindingTrace
 import org.jetbrains.kotlin.resolve.calls.CallResolver
 import org.jetbrains.kotlin.resolve.calls.CallTransformer
@@ -61,8 +61,8 @@ import org.jetbrains.kotlin.types.expressions.OperatorConventions
 import org.jetbrains.kotlin.types.isDynamic
 import org.jetbrains.kotlin.util.OperatorNameConventions
 import org.jetbrains.kotlin.utils.addIfNotNull
+import org.jetbrains.kotlin.utils.addToStdlib.compactIfPossible
 import org.jetbrains.kotlin.utils.sure
-import java.util.*
 
 class NewResolutionOldInference(
     private val candidateResolver: CandidateResolver,
@@ -601,7 +601,7 @@ fun transformToReceiverWithSmartCastInfo(
     val dataFlowValue = dataFlowValueFactory.createDataFlowValue(receiver, bindingContext, containingDescriptor)
     return ReceiverValueWithSmartCastInfo(
         receiver,
-        dataFlowInfo.getCollectedTypes(dataFlowValue, languageVersionSettings),
+        dataFlowInfo.getCollectedTypes(dataFlowValue, languageVersionSettings).compactIfPossible(),
         dataFlowValue.isStable
     )
 }

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tower/PSICallResolver.kt

@@ -47,6 +47,7 @@ import org.jetbrains.kotlin.types.*
 import org.jetbrains.kotlin.types.expressions.*
 import org.jetbrains.kotlin.types.model.TypeSystemInferenceExtensionContext
 import org.jetbrains.kotlin.utils.KotlinExceptionWithAttachments
+import org.jetbrains.kotlin.utils.addToStdlib.compactIfPossible
 import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstanceOrNull
 import java.util.*
 
@@ -542,7 +543,7 @@ class PSICallResolver(
                 dataFlowValueFactory.createDataFlowValue(variableReceiver, temporaryTrace.bindingContext, context.scope.ownerDescriptor)
             return ReceiverValueWithSmartCastInfo(
                 variableReceiver,
-                context.dataFlowInfo.getCollectedTypes(dataFlowValue, context.languageVersionSettings),
+                context.dataFlowInfo.getCollectedTypes(dataFlowValue, context.languageVersionSettings).compactIfPossible(),
                 dataFlowValue.isStable
             ).prepareReceiverRegardingCaptureTypes()
         }

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/ArgumentsToParametersMapper.kt

@@ -23,7 +23,7 @@ import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 import org.jetbrains.kotlin.descriptors.ValueParameterDescriptor
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.calls.model.*
-import java.util.*
+import org.jetbrains.kotlin.utils.addToStdlib.compactIfPossible
 
 class ArgumentsToParametersMapper(
     languageVersionSettings: LanguageVersionSettings
@@ -63,7 +63,7 @@ class ArgumentsToParametersMapper(
             }
             processor.processDefaultsAndRunChecks()
 
-            return ArgumentMapping(processor.result, processor.getDiagnostics())
+            return ArgumentMapping(processor.result.compactIfPossible(), processor.getDiagnostics())
         }
     }
 

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/ResolutionParts.kt

@@ -31,6 +31,7 @@ import org.jetbrains.kotlin.types.typeUtil.makeNotNullable
 import org.jetbrains.kotlin.types.typeUtil.makeNullable
 import org.jetbrains.kotlin.utils.SmartList
 import org.jetbrains.kotlin.utils.addToStdlib.cast
+import org.jetbrains.kotlin.utils.addToStdlib.compactIfPossible
 import org.jetbrains.kotlin.utils.addToStdlib.safeAs
 
 internal object CheckVisibility : ResolutionPart() {
@@ -96,7 +97,7 @@ internal object ArgumentsToCandidateParameterDescriptor : ResolutionPart() {
                 map[argument] = valueParameter
             }
         }
-        resolvedCall.argumentToCandidateParameter = map
+        resolvedCall.argumentToCandidateParameter = map.compactIfPossible()
     }
 }
 

core/util.runtime/src/org/jetbrains/kotlin/utils/addToStdlib.kt

@@ -185,6 +185,20 @@ inline fun <K, V, VA : V> MutableMap<K, V>.getOrPut(key: K, defaultValue: (K) ->
     }
 }
 
+fun <T> Set<T>.compactIfPossible(): Set<T> =
+    when (size) {
+        0 -> emptySet()
+        1 -> setOf(single())
+        else -> this
+    }
+
+fun <K, V> Map<K, V>.compactIfPossible(): Map<K, V> =
+    when (size) {
+        0 -> emptyMap()
+        1 -> Collections.singletonMap(keys.single(), values.single())
+        else -> this
+    }
+
 inline fun <T> T.applyIf(`if`: Boolean, body: T.() -> T): T =
     if (`if`) body() else this