[vm/ffi] Fix alignment of Uint64 fields in structs on some ABIs

Affected ABIs: ia32 Linux, ia32 Android, ia32 MacOS, and arm32 iOS.

Fixes #43693

Change-Id: I35f719abb69bb46d99f647d66847e3d5874d9371
Cq-Include-Trybots: luci.dart.try:vm-kernel-linux-debug-ia32-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/166843
Commit-Queue: Daco Harkes <[email protected]>
Auto-Submit: Daco Harkes <[email protected]>
Reviewed-by: Martin Kustermann <[email protected]>

Author: dcharkes

pkg/vm/lib/transformations/ffi.dart

@@ -137,7 +137,11 @@ const nonSizeAlignment = <Abi, Map<NativeType, int>>{
   //
   // iOS 32 bit alignment:
   // https://developer.apple.com/documentation/uikit/app_and_environment/updating_your_app_from_32-bit_to_64-bit_architecture/updating_data_structures
-  Abi.wordSize32Align32: {NativeType.kDouble: 4, NativeType.kInt64: 4},
+  Abi.wordSize32Align32: {
+    NativeType.kDouble: 4,
+    NativeType.kInt64: 4,
+    NativeType.kUnit64: 4
+  },
 
   // The default for MSVC x86:
   // > The alignment-requirement for all data except structures, unions, and

runtime/bin/ffi_test/ffi_test_functions.cc

@@ -1042,4 +1042,13 @@ DART_EXPORT int32_t PassStruct(void*) {
   return 42;
 }
 
+struct Struct43693 {
+  void* pSomePtr;
+  uint64_t someValue;
+};
+
+DART_EXPORT uint64_t Regress43693(Struct43693* my_struct) {
+  return my_struct->someValue;
+}
+
 }  // namespace dart

tests/ffi/regress_43693_test.dart

@@ -0,0 +1,36 @@
+// Copyright (c) 2020, 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.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'package:ffi/ffi.dart';
+import 'package:expect/expect.dart';
+
+import 'dylib_utils.dart';
+
+class Struct43693 extends Struct {
+  external Pointer<Void> somePtr;
+
+  @Uint64()
+  external int someValue;
+}
+
+final int Function(Pointer<Struct43693>) readMyStructSomeValue =
+    ffiTestFunctions
+        .lookup<NativeFunction<Uint64 Function(Pointer<Struct43693>)>>(
+            "Regress43693")
+        .asFunction<int Function(Pointer<Struct43693>)>();
+
+final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+void main() {
+  final myStructs = allocate<Struct43693>();
+  myStructs[0].somePtr = nullptr;
+  myStructs[0].someValue = 0xAAAAAAAABBBBBBBB;
+  final result = readMyStructSomeValue(myStructs);
+  Expect.equals(0xAAAAAAAABBBBBBBB, result);
+  free(myStructs);
+}

tests/ffi_2/regress_43693_test.dart

@@ -0,0 +1,36 @@
+// Copyright (c) 2020, 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.
+//
+// SharedObjects=ffi_test_functions
+
+import 'dart:ffi';
+
+import 'package:ffi/ffi.dart';
+import 'package:expect/expect.dart';
+
+import 'dylib_utils.dart';
+
+class Struct43693 extends Struct {
+  Pointer<Void> somePtr;
+
+  @Uint64()
+  int someValue;
+}
+
+final int Function(Pointer<Struct43693>) readMyStructSomeValue =
+    ffiTestFunctions
+        .lookup<NativeFunction<Uint64 Function(Pointer<Struct43693>)>>(
+            "Regress43693")
+        .asFunction<int Function(Pointer<Struct43693>)>();
+
+final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+void main() {
+  final myStructs = allocate<Struct43693>();
+  myStructs[0].somePtr = nullptr;
+  myStructs[0].someValue = 0xAAAAAAAABBBBBBBB;
+  final result = readMyStructSomeValue(myStructs);
+  Expect.equals(0xAAAAAAAABBBBBBBB, result);
+  free(myStructs);
+}