Refactor loop in SpecialVariablesSendingNode

Author: eregon

src/main/java/org/truffleruby/language/SpecialVariablesSendingNode.java

@@ -16,8 +16,8 @@
 import org.truffleruby.core.kernel.TruffleKernelNodes.GetSpecialVariableStorage;
 import org.truffleruby.language.arguments.ReadCallerVariablesNode;
 
+import org.truffleruby.language.locals.FindDeclarationVariableNodes;
 import org.truffleruby.language.threadlocal.SpecialVariableStorage;
-import org.truffleruby.parser.ParentFrameDescriptor;
 
 /** Some Ruby methods need access to the caller special variables: see usages of {@link ReadCallerVariablesNode}. This
  * is used for methods which need to access the last regexp MatchData or the last IO line.
@@ -42,23 +42,16 @@ public abstract class SpecialVariablesSendingNode extends RubyBaseNode {
     @NeverDefault
     protected Assumption getSpecialVariableAssumption(Frame frame) {
         if (frame == null) {
-            return getValidAssumption();
+            return Assumption.ALWAYS_VALID;
         }
-        var currentFrameDescriptor = frame.getFrameDescriptor();
 
-        while (true) {
-            if (currentFrameDescriptor.getInfo() == null) {
-                return getValidAssumption();
-            }
-            if (currentFrameDescriptor.getInfo() instanceof ParentFrameDescriptor nextDescriptor) {
-                currentFrameDescriptor = nextDescriptor.getDescriptor();
-            } else {
-                return (Assumption) currentFrameDescriptor.getInfo();
-            }
+        var outerFrameDescriptor = FindDeclarationVariableNodes.getOuterFrameDescriptor(frame.getFrameDescriptor());
+
+        if (SpecialVariableStorage.hasSpecialVariableAssumption(outerFrameDescriptor)) {
+            return SpecialVariableStorage.getAssumption(outerFrameDescriptor);
+        } else {
+            return Assumption.ALWAYS_VALID;
         }
     }
 
-    protected Assumption getValidAssumption() {
-        return Assumption.ALWAYS_VALID;
-    }
 }

src/main/java/org/truffleruby/language/dispatch/DispatchNode.java

@@ -14,6 +14,7 @@
 import com.oracle.truffle.api.RootCallTarget;
 import com.oracle.truffle.api.dsl.Cached;
 import com.oracle.truffle.api.dsl.GenerateUncached;
+import com.oracle.truffle.api.dsl.ImportStatic;
 import com.oracle.truffle.api.dsl.NeverDefault;
 import com.oracle.truffle.api.dsl.Specialization;
 import com.oracle.truffle.api.frame.Frame;
@@ -37,6 +38,7 @@
 
 import static org.truffleruby.language.dispatch.DispatchConfiguration.PRIVATE;
 
+@ImportStatic(Assumption.class)
 @GenerateUncached
 public abstract class DispatchNode extends SpecialVariablesSendingNode {
 
@@ -280,7 +282,7 @@ protected Object dispatch(
             DispatchConfiguration config,
             LiteralCallNode literalCallNode,
             @Cached(value = "getSpecialVariableAssumption(frame)",
-                    uncached = "getValidAssumption()") Assumption specialVariableAssumption,
+                    uncached = "ALWAYS_VALID") Assumption specialVariableAssumption,
             @Cached MetaClassNode metaclassNode,
             @Cached LookupMethodNode methodLookup,
             @Cached InlinedConditionProfile methodMissing,

src/main/java/org/truffleruby/language/locals/FindDeclarationVariableNodes.java

@@ -25,6 +25,7 @@
 import com.oracle.truffle.api.dsl.ReportPolymorphism;
 import com.oracle.truffle.api.dsl.Specialization;
 import com.oracle.truffle.api.frame.FrameDescriptor;
+import org.truffleruby.parser.ParentFrameDescriptor;
 
 public abstract class FindDeclarationVariableNodes {
     public static final class FrameSlotAndDepth {
@@ -49,6 +50,13 @@ public static MaterializedFrame getOuterDeclarationFrame(MaterializedFrame topFr
         return frame;
     }
 
+    public static FrameDescriptor getOuterFrameDescriptor(FrameDescriptor descriptor) {
+        while (descriptor.getInfo() instanceof ParentFrameDescriptor nextDescriptor) {
+            descriptor = nextDescriptor.getDescriptor();
+        }
+        return descriptor;
+    }
+
     private static int findSlot(FrameDescriptor descriptor, String name) {
         assert descriptor.getNumberOfAuxiliarySlots() == 0;
         int slots = descriptor.getNumberOfSlots();

src/main/java/org/truffleruby/language/threadlocal/SpecialVariableStorage.java

@@ -51,6 +51,11 @@ public static Assumption getAssumption(FrameDescriptor descriptor) {
         return (Assumption) descriptor.getInfo();
     }
 
+    public static boolean hasSpecialVariableAssumption(FrameDescriptor descriptor) {
+        var info = descriptor.getInfo();
+        return info instanceof Assumption assumption && assumption.getName() == ASSUMPTION_NAME;
+    }
+
     public static boolean hasSpecialVariableStorageSlot(Frame frame) {
         assert RubyArguments.getDeclarationFrame(frame) == null;
         return hasSpecialVariableStorageSlot(frame.getFrameDescriptor());