From 896675c462df4f2c9bd9dc66fca3442b203863cd Mon Sep 17 00:00:00 2001
From: Martin Kustermann <kustermann@google.com>
Date: Wed, 7 Dec 2022 00:48:28 +0000
Subject: [PATCH] [vm] Always share double/float32x4/float64x2/int32x4 in
 inter-isolate messages

The JIT support for dynamically unboxing has been removed in [0]. As
such all double/float32x4/float64x2/int32x4 objects are immutable and
can therefore be shared across isolates.

[0] https://dart-review.googlesource.com/c/sdk/+/256211

TEST=ci

Change-Id: Ifd4e7c2444415b2e3b5269d9fbeb6570cc5d6768
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/273680
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Martin Kustermann <kustermann@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>
---
 .../vm/dart/isolates/fast_object_copy2_test.dart |  5 ++---
 .../dart_2/isolates/fast_object_copy2_test.dart  |  5 ++---
 runtime/vm/object_graph_copy.cc                  | 16 ++--------------
 3 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/runtime/tests/vm/dart/isolates/fast_object_copy2_test.dart b/runtime/tests/vm/dart/isolates/fast_object_copy2_test.dart
index 76e5679df3f..8ec58da1dca 100644
--- a/runtime/tests/vm/dart/isolates/fast_object_copy2_test.dart
+++ b/runtime/tests/vm/dart/isolates/fast_object_copy2_test.dart
@@ -7,9 +7,6 @@
 // VMOptions=--no-enable-fast-object-copy --gc-on-foc-slow-path --force-evacuation
 // VMOptions=--enable-fast-object-copy --gc-on-foc-slow-path --force-evacuation
 
-// The tests in this file will only succeed when isolate groups are enabled
-// (hence the VMOptions above).
-
 import 'dart:async';
 import 'dart:isolate';
 import 'dart:typed_data';
@@ -75,6 +72,8 @@ final sharableObjects = [
   const {1, 2, 3},
   Isolate.current.pauseCapability,
   Int32x4(1, 2, 3, 4),
+  Float32x4(1.0, 2.0, 3.0, 4.0),
+  Float64x2(1.0, 2.0),
   StackTrace.current,
 ];
 
diff --git a/runtime/tests/vm/dart_2/isolates/fast_object_copy2_test.dart b/runtime/tests/vm/dart_2/isolates/fast_object_copy2_test.dart
index 0c48bc018b2..a52bd160e87 100644
--- a/runtime/tests/vm/dart_2/isolates/fast_object_copy2_test.dart
+++ b/runtime/tests/vm/dart_2/isolates/fast_object_copy2_test.dart
@@ -9,9 +9,6 @@
 // VMOptions=--no-enable-fast-object-copy --gc-on-foc-slow-path --force-evacuation
 // VMOptions=--enable-fast-object-copy --gc-on-foc-slow-path --force-evacuation
 
-// The tests in this file will only succeed when isolate groups are enabled
-// (hence the VMOptions above).
-
 import 'dart:async';
 import 'dart:isolate';
 import 'dart:typed_data';
@@ -76,6 +73,8 @@ final sharableObjects = [
   const {1, 2, 3},
   Isolate.current.pauseCapability,
   Int32x4(1, 2, 3, 4),
+  Float32x4(1.0, 2.0, 3.0, 4.0),
+  Float64x2(1.0, 2.0),
   StackTrace.current,
 ];
 
diff --git a/runtime/vm/object_graph_copy.cc b/runtime/vm/object_graph_copy.cc
index b6e102d3f02..2fc3446cd6e 100644
--- a/runtime/vm/object_graph_copy.cc
+++ b/runtime/vm/object_graph_copy.cc
@@ -159,15 +159,10 @@ static bool CanShareObject(ObjectPtr obj, uword tags) {
   if (cid == kNeverCid) return true;
   if (cid == kSentinelCid) return true;
   if (cid == kStackTraceCid) return true;
-#if defined(DART_PRECOMPILED_RUNTIME)
-  // In JIT mode we have field guards enabled which means
-  // double/float32x4/float64x2 boxes can be mutable and we therefore cannot
-  // share them.
-  if (cid == kDoubleCid || cid == kFloat32x4Cid || cid == kFloat64x2Cid) {
+  if (cid == kDoubleCid || cid == kFloat32x4Cid || cid == kFloat64x2Cid ||
+      cid == kInt32x4Cid) {
     return true;
   }
-#endif
-  if (cid == kInt32x4Cid) return true;  // No field guards here.
   if (cid == kSendPortCid) return true;
   if (cid == kCapabilityCid) return true;
 
@@ -227,13 +222,6 @@ static bool MightNeedReHashing(ObjectPtr object) {
 #endif
   if (cid == kInt32x4Cid) return false;
 
-  // We copy those (instead of sharing them) - see [CanShareObjct]. They rely
-  // on the default hashCode implementation which uses identity hash codes
-  // (instead of structural hash code).
-  if (cid == kFloat32x4Cid || cid == kFloat64x2Cid) {
-    return !kDartPrecompiledRuntime;
-  }
-
   // If the [tags] indicates this is a canonical object we'll share it instead
   // of copying it. That would suggest we don't have to re-hash maps/sets
   // containing this object on the receiver side.