EA-81358: use volatile store / volatile load to guarantee publication of deferred clinit results

compiler/backend/src/org/jetbrains/kotlin/codegen/MultifileClassPartCodegen.kt

@@ -93,18 +93,24 @@ class MultifileClassPartCodegen(
 
         if (requiresDeferredStaticInitialization) {
             staticInitClassBuilder.apply {
+                newField(OtherOrigin(packageFragment), Opcodes.ACC_STATIC or Opcodes.ACC_PRIVATE or Opcodes.ACC_VOLATILE,
+                         CLINIT_SYNC_NAME, "I", null, null)
+
                 newSpecialMethod(packageFragment, CLINIT_TRIGGER_NAME).apply {
                     visitCode()
+                    visitFieldInsn(Opcodes.GETSTATIC, staticInitClassType.internalName, CLINIT_SYNC_NAME, "I")
                     visitInsn(Opcodes.RETURN)
-                    visitMaxs(0, 0)
+                    visitMaxs(1, 0)
                     visitEnd()
                 }
 
                 newSpecialMethod(packageFragment, "<clinit>").apply {
                     visitCode()
                     visitMethodInsn(Opcodes.INVOKESTATIC, partType.internalName, DEFERRED_PART_CLINIT_NAME, "()V", false)
+                    visitInsn(Opcodes.ICONST_0)
+                    visitFieldInsn(Opcodes.PUTSTATIC, staticInitClassType.internalName, CLINIT_SYNC_NAME, "I")
                     visitInsn(Opcodes.RETURN)
-                    visitMaxs(0, 0)
+                    visitMaxs(1, 0)
                     visitEnd()
                 }
             }
@@ -187,6 +193,7 @@ class MultifileClassPartCodegen(
 
         private val STATIC_INIT_CLASS_SUFFIX = "__Clinit"
         private val CLINIT_TRIGGER_NAME = "\$\$clinitTrigger"
+        private val CLINIT_SYNC_NAME = "\$\$clinitSync"
         private val DEFERRED_PART_CLINIT_NAME = "\$\$clinit"
 
         @JvmStatic fun isStaticInitTrigger(insn: AbstractInsnNode) =