Fix concurrent access issues in CallableReference implementations

Because of multiple reads from the same non-volatile variable, NPE was possible
to achieve in a multi-threaded application

core/runtime.jvm/src/kotlin/jvm/internal/CallableReference.java

@@ -122,17 +122,19 @@ public abstract class CallableReference implements KCallable {
     }
 
     public KCallable compute() {
-        if (reflected == null) {
-            reflected = computeReflected();
+        KCallable result = reflected;
+        if (result == null) {
+            result = computeReflected();
+            reflected = result;
         }
-        return reflected;
+        return result;
     }
 
     protected KCallable getReflected() {
-        compute();
-        if (reflected == this) {
+        KCallable result = compute();
+        if (result == this) {
             throw new KotlinReflectionNotSupportedError();
         }
-        return reflected;
+        return result;
     }
 }

core/runtime.jvm/src/kotlin/jvm/internal/FunctionReference.java

@@ -146,8 +146,7 @@ public class FunctionReference extends FunctionImpl implements KFunction {
                    getSignature().equals(other.getSignature());
         }
         if (obj instanceof KFunction) {
-            compute();
-            return obj.equals(reflected);
+            return obj.equals(compute());
         }
         return false;
     }
@@ -159,7 +158,7 @@ public class FunctionReference extends FunctionImpl implements KFunction {
 
     @Override
     public String toString() {
-        compute();
+        KFunction reflected = compute();
         if (reflected != this) {
             return reflected.toString();
         }
@@ -171,17 +170,19 @@ public class FunctionReference extends FunctionImpl implements KFunction {
     }
 
     public KFunction compute() {
-        if (reflected == null) {
-            reflected = Reflection.function(this);
+        KFunction result = reflected;
+        if (result == null) {
+            result = Reflection.function(this);
+            reflected = result;
         }
-        return reflected;
+        return result;
     }
 
     private KFunction getReflected() {
-        compute();
-        if (reflected == this) {
+        KFunction result = compute();
+        if (result == this) {
             throw new KotlinReflectionNotSupportedError();
         }
-        return reflected;
+        return result;
     }
 }

core/runtime.jvm/src/kotlin/jvm/internal/PropertyReference.java

@@ -16,6 +16,7 @@
 
 package kotlin.jvm.internal;
 
+import kotlin.reflect.KCallable;
 import kotlin.reflect.KProperty;
 
 public abstract class PropertyReference extends CallableReference implements KProperty {
@@ -57,7 +58,7 @@ public abstract class PropertyReference extends CallableReference implements KPr
 
     @Override
     public String toString() {
-        compute();
+        KCallable reflected = compute();
         if (reflected != this) {
             return reflected.toString();
         }