Implementing returnNow as ControlFlowException

Jaroslav Tulach · Jaroslav Tulach · commit 1db91dcf2479 · 2021-09-08T05:57:35.000+02:00
diff --git a/tools/src/com.oracle.truffle.tools.agentscript/src/com/oracle/truffle/tools/agentscript/impl/EventContextObject.java b/tools/src/com.oracle.truffle.tools.agentscript/src/com/oracle/truffle/tools/agentscript/impl/EventContextObject.java
@@ -88,7 +88,7 @@ static boolean isMemberReadable(EventContextObject obj, String member) {
     @ExportMessage
     static Object invokeMember(EventContextObject obj, String member, Object[] args) throws ArityException, UnknownIdentifierException, UnsupportedTypeException {
         if ("returnNow".equals(member)) {
-            throw InsightHookNode.returnNow(obj.context, args);
+            throw InsightHookNode.returnNow(args);
         }
         if ("returnValue".equals(member)) {
             if (args.length == 0 || !(args[0] instanceof VariablesObject)) {
diff --git a/tools/src/com.oracle.truffle.tools.agentscript/src/com/oracle/truffle/tools/agentscript/impl/InsightHookNode.java b/tools/src/com.oracle.truffle.tools.agentscript/src/com/oracle/truffle/tools/agentscript/impl/InsightHookNode.java
@@ -35,6 +35,7 @@
 import com.oracle.truffle.api.interop.InteropLibrary;
 import com.oracle.truffle.api.interop.NodeLibrary;
 import com.oracle.truffle.api.interop.UnsupportedMessageException;
+import com.oracle.truffle.api.nodes.ControlFlowException;
 import com.oracle.truffle.api.nodes.Node;
 import com.oracle.truffle.api.source.Source;
 
@@ -68,73 +69,62 @@ private InsightHookNode(InsightInstrument.Key key, InsightInstrument insight, Ev
 
     @Override
     protected void onEnter(VirtualFrame frame) {
-        final int len = key.functionsMaxCount();
-        CompilerAsserts.partialEvaluationConstant(len);
-        final InsightPerContext ipc = insight.findCtx();
-        for (int i = 0; i < len; i++) {
-            InsightFilter.Data data = (InsightFilter.Data) ipc.functionFor(key, i);
-            if (!isApplicable(data, AgentType.ENTER)) {
-                continue;
-            }
-            final EventContextObject eco = eventCtxObj();
-            try {
-                enterDispatch.execute(data.fn, eco, getVariables(frame, true, null));
-            } catch (InteropException ex) {
-                throw EventContextObject.wrap(data.fn, 2, ex);
-            } catch (RuntimeException ex) {
-                throw EventContextObject.rethrow(ex, exceptionDispatch);
-            }
-        }
+        loopHooks(frame, AgentType.ENTER, null);
     }
 
     @Override
     protected void onReturnValue(VirtualFrame frame, Object returnValue) {
-        final int len = key.functionsMaxCount();
-        CompilerAsserts.partialEvaluationConstant(len);
-        final InsightPerContext ipc = insight.findCtx();
-        for (int i = 0; i < len; i++) {
-            InsightFilter.Data data = (InsightFilter.Data) ipc.functionFor(key, i);
-            if (!isApplicable(data, AgentType.RETURN)) {
-                continue;
-            }
-            final EventContextObject eco = eventCtxObj();
-            try {
-                exitDispatch.execute(data.fn, eco, getVariables(frame, false, returnValue));
-            } catch (InteropException ex) {
-                throw EventContextObject.wrap(data.fn, 2, ex);
-            } catch (RuntimeException ex) {
-                throw EventContextObject.rethrow(ex, exceptionDispatch);
-            }
-        }
+        loopHooks(frame, AgentType.RETURN, returnValue);
     }
 
     @Override
     protected void onReturnExceptional(VirtualFrame frame, Throwable exception) {
+        loopHooks(frame, AgentType.RETURN, null);
+    }
+
+    @Override
+    protected Object onUnwind(VirtualFrame frame, Object info) {
+        return info;
+    }
+
+    private void loopHooks(VirtualFrame frame, final AgentType type, Object returnValue) throws RuntimeException, ThreadDeath {
         final int len = key.functionsMaxCount();
         CompilerAsserts.partialEvaluationConstant(len);
         final InsightPerContext ipc = insight.findCtx();
+        ReturnNow returnNow = null;
         for (int i = 0; i < len; i++) {
             InsightFilter.Data data = (InsightFilter.Data) ipc.functionFor(key, i);
-            if (!isApplicable(data, AgentType.RETURN)) {
+            if (!isApplicable(data, type)) {
                 continue;
             }
             final EventContextObject eco = eventCtxObj();
             try {
-                exitDispatch.execute(data.fn, eco, getVariables(frame, false, null));
+                exitDispatch.execute(data.fn, eco, getVariables(frame, type == AgentType.ENTER, returnValue));
+            } catch (ReturnNow ex) {
+                if (returnNow == null) {
+                    returnNow = ex;
+                }
             } catch (InteropException ex) {
                 throw EventContextObject.wrap(data.fn, 2, ex);
             } catch (RuntimeException ex) {
                 throw EventContextObject.rethrow(ex, exceptionDispatch);
             }
         }
+        if (returnNow != null) {
+            throw ctx.createUnwind(NullObject.nullCheck(returnNow.returnValue));
+        }
     }
 
-    @Override
-    protected Object onUnwind(VirtualFrame frame, Object info) {
-        return info;
+    private static final class ReturnNow extends ControlFlowException {
+        static final long serialVersionUID = 49092343L;
+        final Object returnValue;
+
+        ReturnNow(Object returnValue) {
+            this.returnValue = returnValue;
+        }
     }
 
-    static ThreadDeath returnNow(EventContext context, Object[] args) throws ArityException, ThreadDeath {
+    static ControlFlowException returnNow(Object[] args) throws ArityException {
         Object returnValue;
         switch (args.length) {
             case 0:
@@ -146,7 +136,7 @@ static ThreadDeath returnNow(EventContext context, Object[] args) throws ArityEx
             default:
                 throw ArityException.create(1, 1, args.length);
         }
-        return context.createUnwind(NullObject.nullCheck(returnValue));
+        return new ReturnNow(returnValue);
     }
 
     private Object getVariables(VirtualFrame frame, boolean nodeEnter, Object returnValue) {
diff --git a/vm/tests/all/agentscript/agent-sum.test b/vm/tests/all/agentscript/agent-sum.test
@@ -5,6 +5,7 @@
 > js --insight=agent-summul2.js agent-sum.js
 720
 > js --insight=agent-sumneg.js  agent-sum.js
+Original value was 21, but returning -21
 -21
 > js --insight=agent-summul2.js agent-fib.js
 Three is the result 80
diff --git a/vm/tests/all/agentscript/agent-sumneg.js b/vm/tests/all/agentscript/agent-sumneg.js
@@ -3,7 +3,7 @@ insight.on('return', function(ctx, frame) {
     try {
         ctx.returnNow(-positive);
     } finally {
-        ctx.returnNow('Never reached!');
+        print(`Original value was ${positive}, but returning ${-positive}`);
     }
 }, {
     roots: true,

Original file line number	Diff line number	Diff line change
`@@ -88,7 +88,7 @@ static boolean isMemberReadable(EventContextObject obj, String member) {`
`88`	`88`	`@ExportMessage`
`89`	`89`	`static Object invokeMember(EventContextObject obj, String member, Object[] args) throws ArityException, UnknownIdentifierException, UnsupportedTypeException {`
`90`	`90`	`if ("returnNow".equals(member)) {`
`91`		`- throw InsightHookNode.returnNow(obj.context, args);`
	`91`	`+ throw InsightHookNode.returnNow(args);`
`92`	`92`	`}`
`93`	`93`	`if ("returnValue".equals(member)) {`
`94`	`94`	`if (args.length == 0 \|\| !(args[0] instanceof VariablesObject)) {`
Original file line number	Diff line number	Diff line change
`@@ -5,6 +5,7 @@`
`5`	`5`	`> js --insight=agent-summul2.js agent-sum.js`
`6`	`6`	`720`
`7`	`7`	`> js --insight=agent-sumneg.js agent-sum.js`
	`8`	`+Original value was 21, but returning -21`
`8`	`9`	`-21`
`9`	`10`	`> js --insight=agent-summul2.js agent-fib.js`
`10`	`11`	`Three is the result 80`
Original file line number	Diff line number	Diff line change
`@@ -3,7 +3,7 @@ insight.on('return', function(ctx, frame) {`
`3`	`3`	`try {`
`4`	`4`	`ctx.returnNow(-positive);`
`5`	`5`	`} finally {`
`6`		`- ctx.returnNow('Never reached!');`
	`6`	+ print(`Original value was ${positive}, but returning ${-positive}`);
`7`	`7`	`}`
`8`	`8`	`}, {`
`9`	`9`	`roots: true,`