From f02213ae2bd47123f4619aba1147cd24e3c1fd3b Mon Sep 17 00:00:00 2001
From: Pavel Marek <pavel.marek@enso.org>
Date: Tue, 5 Mar 2024 12:00:16 +0100
Subject: [PATCH] Enable splitting for EqualsSimpleNode (#9268)

Fixes the regression introduced by #9070 in `org.enso.benchmarks.generated.Collections.list_meta_fold` benchmark.

# Important Notes
As can be seen on the graph in IGV:
![image](https://github.com/enso-org/enso/assets/14013887/31b6ceca-4909-4a8f-987f-b456b3fb0a1b)
For some reason, `EqualsSimpleNode` is POLYMORPHIC. That seems to be the most visible performance problem.

First, I tried to introduce `ConditionProfile` with:
```diff
diff --git a/engine/runtime/src/main/java/org/enso/interpreter/node/expression/builtin/meta/EqualsNode.java b/engine/runtime/src/main/java/org/enso/interpreter/node/expression/builtin/meta/EqualsNode.java
index b368fb7fe..57274b37e 100644
--- a/engine/runtime/src/main/java/org/enso/interpreter/node/expression/builtin/meta/EqualsNode.java
+++ b/engine/runtime/src/main/java/org/enso/interpreter/node/expression/builtin/meta/EqualsNode.java
@@ -9,6 +9,7 @@ import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.frame.VirtualFrame;
import com.oracle.truffle.api.interop.ArityException;
import com.oracle.truffle.api.nodes.Node;
+import com.oracle.truffle.api.profiles.ConditionProfile;
import org.enso.interpreter.dsl.AcceptsError;
import org.enso.interpreter.dsl.BuiltinMethod;
import org.enso.interpreter.node.EnsoRootNode;
@@ -46,6 +47,7 @@ public final class EqualsNode extends Node {
@Child private EqualsSimpleNode node;
@Child private TypeOfNode types;
@Child private WithConversionNode convert;
+  private final ConditionProfile equalsProfile = ConditionProfile.create();

private static final EqualsNode UNCACHED =
new EqualsNode(EqualsSimpleNodeGen.getUncached(), TypeOfNode.getUncached(), true);
@@ -85,7 +87,7 @@ public final class EqualsNode extends Node {
public boolean execute(
VirtualFrame frame, @AcceptsError Object self, @AcceptsError Object other) {
var areEqual = node.execute(frame, self, other);
-    if (!areEqual) {
+    if (!equalsProfile.profile(areEqual)) {
var selfType = types.execute(self);
var otherType = types.execute(other);
if (selfType != otherType) {

```
But that did not resolve the issue.

My second attempt was to enable splitting for `EqualsSimpleNode` with `@com.oracle.truffle.api.dsl.ReportPolymorphism` annotation, which seems to resolve the issue. The benchmark is back to its original score, and `EqualsSimpleNode` is no longer POLYMORPHIC.
---
 .../node/expression/builtin/meta/EqualsSimpleNode.java          | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/engine/runtime/src/main/java/org/enso/interpreter/node/expression/builtin/meta/EqualsSimpleNode.java b/engine/runtime/src/main/java/org/enso/interpreter/node/expression/builtin/meta/EqualsSimpleNode.java
index 78b2369f43..2669acc6c9 100644
--- a/engine/runtime/src/main/java/org/enso/interpreter/node/expression/builtin/meta/EqualsSimpleNode.java
+++ b/engine/runtime/src/main/java/org/enso/interpreter/node/expression/builtin/meta/EqualsSimpleNode.java
@@ -4,6 +4,7 @@ import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.dsl.Cached;
 import com.oracle.truffle.api.dsl.Cached.Shared;
 import com.oracle.truffle.api.dsl.GenerateUncached;
+import com.oracle.truffle.api.dsl.ReportPolymorphism;
 import com.oracle.truffle.api.dsl.Specialization;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.interop.InteropLibrary;
@@ -23,6 +24,7 @@ import org.enso.interpreter.runtime.number.EnsoBigInteger;
 import org.enso.polyglot.common_utils.Core_Text_Utils;
 
 @GenerateUncached
+@ReportPolymorphism
 public abstract class EqualsSimpleNode extends Node {
 
   public static EqualsSimpleNode build() {