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

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)
+}