From ec9a660ccca94edaf04051192282c7ecaf2bcccc Mon Sep 17 00:00:00 2001
From: Vyacheslav Egorov <vegorov@google.com>
Date: Fri, 1 Jul 2022 12:31:47 +0000
Subject: [PATCH] [vm] Avoid clobbering array length in AllocateArray stub on
 ARM

It was calling EnsureIsNewOrRemembered on the slow path which
was forgetting to preserve registers around a runtime call.

Fixes https://github.com/flutter/flutter/issues/106510

TEST=vm/dart{,_2}/flutter_regress_106510

Cq-Include-Trybots: luci.dart.try:vm-kernel-linux-release-simarm-try,vm-kernel-precomp-linux-release-simarm-try
Change-Id: I621e392304fcd1fd643c009fbcde3f88b6f19b7f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/250168
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Slava Egorov <vegorov@google.com>
---
 .../vm/dart/flutter_regress_106510_test.dart  | 49 ++++++++++++++++++
 .../dart_2/flutter_regress_106510_test.dart   | 50 +++++++++++++++++++
 runtime/vm/compiler/stub_code_compiler_arm.cc |  2 +-
 3 files changed, 100 insertions(+), 1 deletion(-)
 create mode 100644 runtime/tests/vm/dart/flutter_regress_106510_test.dart
 create mode 100644 runtime/tests/vm/dart_2/flutter_regress_106510_test.dart

diff --git a/runtime/tests/vm/dart/flutter_regress_106510_test.dart b/runtime/tests/vm/dart/flutter_regress_106510_test.dart
new file mode 100644
index 00000000000..7c41c20d793
--- /dev/null
+++ b/runtime/tests/vm/dart/flutter_regress_106510_test.dart
@@ -0,0 +1,49 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// VMOptions=--use_slow_path --stress_write_barrier_elimination
+
+// Test that array allocation in noSuchMethod dispatcher is preserving the
+// length register correctly.
+
+import 'dart:async';
+
+import 'package:expect/expect.dart';
+
+final List<dynamic> list = <dynamic>[];
+
+final List<int> invocations = <int>[];
+
+abstract class B {
+  void someMethod(int v);
+}
+
+class A {
+  noSuchMethod(Invocation i) {
+    Expect.equals(#someMethod, i.memberName);
+    invocations.add(i.positionalArguments[0] as int);
+  }
+}
+
+class C implements B {
+  void someMethod(int v) {
+    invocations.add(v);
+  }
+}
+
+void main() {
+  for (var i = 0; i < 10; i++) {
+    list.add(A());
+    list.add(C());
+  }
+
+  for (var i = 0; i < list.length; i++) {
+    list[i].someMethod(i);
+  }
+
+  Expect.equals(list.length, invocations.length);
+  for (var i = 0; i < list.length; i++) {
+    Expect.equals(i, invocations[i]);
+  }
+}
diff --git a/runtime/tests/vm/dart_2/flutter_regress_106510_test.dart b/runtime/tests/vm/dart_2/flutter_regress_106510_test.dart
new file mode 100644
index 00000000000..5139e5783e8
--- /dev/null
+++ b/runtime/tests/vm/dart_2/flutter_regress_106510_test.dart
@@ -0,0 +1,50 @@
+// Copyright (c) 2022, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+// @dart=2.9
+
+// VMOptions=--use_slow_path --stress_write_barrier_elimination
+
+// Test that array allocation in noSuchMethod dispatcher is preserving the
+// length register correctly.
+
+import 'dart:async';
+
+import 'package:expect/expect.dart';
+
+final List<dynamic> list = <dynamic>[];
+
+final List<int> invocations = <int>[];
+
+abstract class B {
+  void someMethod(int v);
+}
+
+class A {
+  noSuchMethod(Invocation i) {
+    Expect.equals(#someMethod, i.memberName);
+    invocations.add(i.positionalArguments[0] as int);
+  }
+}
+
+class C implements B {
+  void someMethod(int v) {
+    invocations.add(v);
+  }
+}
+
+void main() {
+  for (var i = 0; i < 10; i++) {
+    list.add(A());
+    list.add(C());
+  }
+
+  for (var i = 0; i < list.length; i++) {
+    list[i].someMethod(i);
+  }
+
+  Expect.equals(list.length, invocations.length);
+  for (var i = 0; i < list.length; i++) {
+    Expect.equals(i, invocations[i]);
+  }
+}
diff --git a/runtime/vm/compiler/stub_code_compiler_arm.cc b/runtime/vm/compiler/stub_code_compiler_arm.cc
index fc6b0ea553e..6f624566f02 100644
--- a/runtime/vm/compiler/stub_code_compiler_arm.cc
+++ b/runtime/vm/compiler/stub_code_compiler_arm.cc
@@ -46,7 +46,7 @@ void StubCodeCompiler::EnsureIsNewOrRemembered(Assembler* assembler,
   {
     LeafRuntimeScope rt(assembler,
                         /*frame_size=*/0,
-                        /*preserve_registers=*/false);
+                        /*preserve_registers=*/preserve_registers);
     // [R0] already contains first argument.
     __ mov(R1, Operand(THR));
     rt.Call(kEnsureRememberedAndMarkingDeferredRuntimeEntry, 2);