Implement RootNode#prepareForCompilation to disable compilation of uncached nodes

Author: DSouzaM

truffle/src/com.oracle.truffle.dsl.processor/src/com/oracle/truffle/dsl/processor/bytecode/generator/BytecodeRootNodeElement.java

@@ -383,8 +383,10 @@ final class BytecodeRootNodeElement extends CodeTypeElement {
         this.add(createTransitionToCached());
         this.add(createUpdateBytecode());
 
+        // Other root node overrides.
         this.add(createIsInstrumentable());
         this.addOptional(createPrepareForInstrumentation());
+        this.addOptional(createPrepareForCompilation());
 
         this.add(createEncodeTags());
         if (model.enableTagInstrumentation) {
@@ -1650,6 +1652,18 @@ private CodeExecutableElement createPrepareForInstrumentation() {
         return ex;
     }
 
+    private CodeExecutableElement createPrepareForCompilation() {
+        if (!model.enableUncachedInterpreter) {
+            return null;
+        }
+
+        CodeExecutableElement ex = overrideImplementRootNodeMethod(model, "prepareForCompilation", new String[]{"rootCompilation", "compilationTier", "lastTier"});
+        CodeTreeBuilder b = ex.createBuilder();
+        // Disable compilation for the uncached interpreter.
+        b.startReturn().string("bytecode.getTier() != ").staticReference(types.BytecodeTier, "UNCACHED").end();
+        return ex;
+    }
+
     private CodeExecutableElement createEncodeTags() {
         CodeExecutableElement ex = new CodeExecutableElement(Set.of(PRIVATE, STATIC), type(int.class), "encodeTags");
         ex.addParameter(new CodeVariableElement(arrayOf(type(Class.class)), "tags"));
@@ -13104,8 +13118,6 @@ private List<CodeExecutableElement> createContinueAt() {
                 b.statement("$root.transitionToCached()");
                 b.startReturn().string("startState").end();
                 return methods;
-            } else if (tier.isUncached()) {
-                b.tree(GeneratorUtils.createTransferToInterpreterAndInvalidate());
             }
 
             b.startDeclaration(types.VirtualFrame, "frame").startCall("ACCESS.uncheckedCast").string("frame_").string("FRAME_TYPE").end().end();
@@ -16273,6 +16285,7 @@ void lazyInit() {
             // RootNode overrides.
             this.add(createIsCloningAllowed());
             this.add(createIsCloneUninitializedSupported());
+            this.addOptional(createPrepareForCompilation());
             // Should appear last. Uses current method set to determine which methods need to be
             // implemented.
             this.addAll(createRootNodeProxyMethods());
@@ -16432,6 +16445,17 @@ private CodeExecutableElement createIsCloneUninitializedSupported() {
             return ex;
         }
 
+        private CodeExecutableElement createPrepareForCompilation() {
+            if (!model.enableUncachedInterpreter) {
+                return null;
+            }
+
+            CodeExecutableElement ex = overrideImplementRootNodeMethod(model, "prepareForCompilation", new String[]{"rootCompilation", "compilationTier", "lastTier"});
+            CodeTreeBuilder b = ex.createBuilder();
+            b.startReturn().startCall("root.prepareForCompilation").string("rootCompilation").string("compilationTier").string("lastTier").end(2);
+            return ex;
+        }
+
         private List<CodeExecutableElement> createRootNodeProxyMethods() {
             List<CodeExecutableElement> result = new ArrayList<>();