[Wasm] Add an option to dump declaration IR sizes to file

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JSCompilerArguments.kt

@@ -308,6 +308,20 @@ class K2JSCompilerArguments : CommonCompilerArguments() {
             field = value
         }
 
+    @Argument(
+        value = "-Xir-dump-declaration-ir-sizes-to-file",
+        valueDescription = "<path>",
+        description = "Dump the IR size of each declaration to a file. " +
+                "The format will be chosen automatically depending on the file extension. " +
+                "Supported output formats include JSON for .json, JS const initialized with a plain object containing information for .js, " +
+                "and plain text for all other file types."
+    )
+    var irDceDumpDeclarationIrSizesToFile: String? = null
+        set(value) {
+            checkFrozen()
+            field = value
+        }
+
     @Argument(value = "-Xir-property-lazy-initialization", description = "Perform lazy initialization for properties")
     var irPropertyLazyInitialization = true
         set(value) {

compiler/cli/cli-js/src/org/jetbrains/kotlin/cli/js/K2JsIrCompiler.kt

@@ -44,6 +44,7 @@ import org.jetbrains.kotlin.incremental.js.IncrementalNextRoundChecker
 import org.jetbrains.kotlin.incremental.js.IncrementalResultsConsumer
 import org.jetbrains.kotlin.ir.backend.js.*
 import org.jetbrains.kotlin.ir.backend.js.codegen.JsGenerationGranularity
+import org.jetbrains.kotlin.ir.backend.js.dce.dumpDeclarationIrSizesIfNeed
 import org.jetbrains.kotlin.ir.backend.js.ic.*
 import org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.CompilationOutputsBuilt
 import org.jetbrains.kotlin.ir.backend.js.transformers.irToJs.IrModuleToJsTransformer
@@ -354,6 +355,8 @@ class K2JsIrCompiler : CLICompiler<K2JSCompilerArguments>() {
                     eliminateDeadDeclarations(allModules, backendContext)
                 }
 
+                dumpDeclarationIrSizesIfNeed(arguments.irDceDumpDeclarationIrSizesToFile, allModules)
+
                 val generateSourceMaps = configuration.getBoolean(JSConfigurationKeys.SOURCE_MAP)
 
                 val res = compileWasm(

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/dce/UsefulDeclarationProcessor.kt

@@ -299,11 +299,9 @@ private fun transformToStringBy(
     separator: String,
     transformer: (sourceFqn: String, targetFqn: String, description: String, isTargetContagious: Boolean) -> String
 ): String {
-    fun IrDeclaration.fqnOrUnknown() = (this as? IrDeclarationWithName)?.fqNameWhenAvailable?.asString() ?: "<unknown>"
-
     return reachabilityInfos
         .map {
-            transformer(it.source.fqnOrUnknown(), it.target.fqnOrUnknown(), it.description, it.isTargetContagious)
+            transformer(it.source.fqNameForDceDump(), it.target.fqNameForDceDump(), it.description, it.isTargetContagious)
         }
         .distinct()
         .joinToString(separator)

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/dce/utils.kt

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2010-2023 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.ir.backend.js.dce
+
+import org.jetbrains.kotlin.ir.IrElement
+import org.jetbrains.kotlin.ir.backend.js.lower.PrimaryConstructorLowering
+import org.jetbrains.kotlin.ir.declarations.*
+import org.jetbrains.kotlin.ir.util.dumpKotlinLike
+import org.jetbrains.kotlin.ir.util.fqNameWhenAvailable
+import org.jetbrains.kotlin.ir.visitors.IrElementVisitorVoid
+import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
+import java.io.File
+
+internal fun IrDeclaration.fqNameForDceDump(): String {
+    // TODO: sanitize names
+    val fqn = (this as? IrDeclarationWithName)?.fqNameWhenAvailable?.asString() ?: "<unknown>"
+    val signature = when (this is IrFunction) {
+        true -> this.valueParameters.joinToString(prefix = "(", postfix = ")") { it.type.dumpKotlinLike() }
+        else -> ""
+    }
+    val synthetic = when (this.origin == PrimaryConstructorLowering.SYNTHETIC_PRIMARY_CONSTRUCTOR) {
+        true -> "[synthetic]"
+        else -> ""
+    }
+
+    return (fqn + signature + synthetic)
+}
+
+fun dumpDeclarationIrSizesIfNeed(path: String?, allModules: List<IrModuleFragment>) {
+    if (path == null) return
+
+    val declarations = linkedSetOf<IrDeclaration>()
+
+    allModules.forEach {
+        it.acceptChildrenVoid(object : IrElementVisitorVoid {
+            override fun visitElement(element: IrElement) {
+                element.acceptChildrenVoid(this)
+            }
+
+            override fun visitDeclaration(declaration: IrDeclarationBase) {
+                when (declaration) {
+                    is IrFunction,
+                    is IrProperty,
+                    is IrField,
+                    is IrAnonymousInitializer -> {
+                        declarations.add(declaration)
+                    }
+                }
+
+                super.visitDeclaration(declaration)
+            }
+        })
+    }
+
+    val out = File(path)
+    val (prefix, postfix, separator, indent) = when (out.extension) {
+        "json" -> listOf("{\n", "\n}", ",\n", "    ")
+        "js" -> listOf("const kotlinDeclarationsSize = {\n", "\n};\n", ",\n", "    ")
+        else -> listOf("", "", "\n", "")
+    }
+
+    val value = declarations.joinToString(separator, prefix, postfix) {
+        val fqn = it.fqNameForDceDump()
+        val size = it.dumpKotlinLike().length
+        "$indent\"$fqn\" : $size"
+    }
+
+    out.writeText(value)
+}

wasm/wasm.tests/test/org/jetbrains/kotlin/wasm/test/BasicWasmBoxTest.kt

@@ -21,6 +21,7 @@ import org.jetbrains.kotlin.cli.jvm.compiler.EnvironmentConfigFiles
 import org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment
 import org.jetbrains.kotlin.config.*
 import org.jetbrains.kotlin.idea.KotlinFileType
+import org.jetbrains.kotlin.ir.backend.js.dce.dumpDeclarationIrSizesIfNeed
 import org.jetbrains.kotlin.ir.backend.js.prepareAnalyzedSourceModule
 import org.jetbrains.kotlin.ir.declarations.impl.IrFactoryImpl
 import org.jetbrains.kotlin.js.config.JSConfigurationKeys
@@ -37,7 +38,6 @@ import org.jetbrains.kotlin.test.*
 import org.jetbrains.kotlin.test.util.KtTestUtil
 import java.io.Closeable
 import java.io.File
-import kotlin.math.abs
 
 abstract class BasicWasmBoxTest(
     private val pathToTestDir: String,
@@ -167,6 +167,8 @@ abstract class BasicWasmBoxTest(
 
             eliminateDeadDeclarations(allModules, backendContext)
 
+            dumpDeclarationIrSizesIfNeed(System.getProperty("kotlin.wasm.dump.declaration.ir.size.to.file"), allModules)
+
             val compilerResultWithDCE = compileWasm(
                 allModules = allModules,
                 backendContext = backendContext,