JVM IR: link via descriptors instead of signatures by default

Doing so speeds up psi2ir ~2 times, and thus improves total compiler
performance by about 6-8%.

Unless JVM IR is in the mode where linking via signatures is the only
way (-Xserialize-ir, -Xklib), signatures are actually not needed at all,
SymbolTable can use the frontend representation (descriptors for FE1.0,
and hopefully FIR elements for K2) as hash table keys. The only catch is
that since other backends still need to work with signatures, all the
common IR utilities, such as irTypePredicates.kt, need to work correctly
for IR elements both with signatures and without.

Also, introduce a fallback compiler flag -Xlink-via-signatures, in case
something goes wrong, to be able to troubleshoot and workaround any
issues.

 #KT-48233

compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/backend/jvm/serialization/DisabledIdSignatureDescriptor.kt

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2010-2022 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.jvm.serialization
+
+import org.jetbrains.kotlin.backend.common.serialization.mangle.SpecialDeclarationType
+import org.jetbrains.kotlin.backend.common.serialization.signature.IdSignatureDescriptor
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
+import org.jetbrains.kotlin.descriptors.PropertyDescriptor
+import org.jetbrains.kotlin.ir.util.IdSignature
+import org.jetbrains.kotlin.ir.util.KotlinMangler
+
+object DisabledDescriptorMangler : KotlinMangler.DescriptorMangler {
+    override val String.hashMangle: Long
+        get() = error("Should not be called")
+
+    override fun DeclarationDescriptor.isExported(compatibleMode: Boolean): Boolean =
+        error("Should not be called")
+
+    override fun DeclarationDescriptor.mangleString(compatibleMode: Boolean): String =
+        error("Should not be called")
+
+    override fun DeclarationDescriptor.signatureString(compatibleMode: Boolean): String =
+        error("Should not be called")
+
+    override fun DeclarationDescriptor.fqnString(compatibleMode: Boolean): String =
+        error("Should not be called")
+
+    override fun ClassDescriptor.mangleEnumEntryString(compatibleMode: Boolean): String =
+        error("Should not be called")
+
+    override fun PropertyDescriptor.mangleFieldString(compatibleMode: Boolean): String =
+        error("Should not be called")
+}
+
+object DisabledIdSignatureDescriptor : IdSignatureDescriptor(DisabledDescriptorMangler) {
+    override fun composeSignature(descriptor: DeclarationDescriptor): IdSignature? = null
+
+    override fun composeEnumEntrySignature(descriptor: ClassDescriptor): IdSignature? = null
+
+    override fun composeFieldSignature(descriptor: PropertyDescriptor): IdSignature? = null
+
+    override fun composeAnonInitSignature(descriptor: ClassDescriptor): IdSignature? = null
+
+    override fun createSignatureBuilder(type: SpecialDeclarationType): DescriptorBasedSignatureBuilder =
+        error("Should not be called")
+}

compiler/ir/serialization.jvm/src/org/jetbrains/kotlin/ir/backend/jvm/serialization/JvmIrLinker.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.descriptors.*
 import org.jetbrains.kotlin.descriptors.konan.KlibModuleOrigin
 import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.builders.TranslationPluginContext
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.declarations.IrField
 import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
 import org.jetbrains.kotlin.ir.declarations.impl.IrModuleFragmentImpl
@@ -38,7 +39,8 @@ class JvmIrLinker(
     symbolTable: SymbolTable,
     override val translationPluginContext: TranslationPluginContext?,
     private val stubGenerator: DeclarationStubGenerator,
-    private val manglerDesc: JvmDescriptorMangler
+    private val manglerDesc: JvmDescriptorMangler,
+    private val enableIdSignatures: Boolean,
 ) : KotlinIrLinker(currentModule, messageLogger, typeSystem.irBuiltIns, symbolTable, emptyList()) {
 
     // TODO: provide friend modules
@@ -91,6 +93,8 @@ class JvmIrLinker(
         }
     }
 
+    override fun getDeclaration(symbol: IrSymbol): IrDeclaration? =
+        deserializeOrResolveDeclaration(symbol, !enableIdSignatures)
 
     override fun createCurrentModuleDeserializer(moduleFragment: IrModuleFragment, dependencies: Collection<IrModuleDeserializer>): IrModuleDeserializer =
         JvmCurrentModuleDeserializer(moduleFragment, dependencies)