[vm/ffi] Tests for aliasing

Issue: #36247
Change-Id: I81f4cb1d34bc25efe6bc4c2d14615356ac52262f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/106906
Commit-Queue: Daco Harkes <dacoharkes@google.com>
Auto-Submit: Daco Harkes <dacoharkes@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>

tests/ffi/aliasing_test.dart

@@ -0,0 +1,218 @@
+// Copyright (c) 2019, 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 test programing for testing that optimizations do wrongly assume loads
+// from and stores to C memory are not aliased.
+//
+// SharedObjects=ffi_test_functions
+// VMOptions=--deterministic --optimization-counter-threshold=50 --enable-inlining-annotations
+
+library FfiTest;
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+
+import 'dylib_utils.dart';
+
+void main() {
+  for (int i = 0; i < 100; ++i) {
+    testNonAlias();
+    testAliasCast();
+    testAliasCast2();
+    testAliasOffsetBy();
+    testAliasOffsetBy2();
+    testAliasElementAt();
+    testAliasElementAt2();
+    testAliasFromAddress();
+    testAliasFromAddress2();
+    testAliasFromAddressViaMemory();
+    testAliasFromAddressViaMemory2();
+    testAliasFromAddressViaNativeFunction();
+    testAliasFromAddressViaNativeFunction2();
+    testPartialOverlap();
+  }
+}
+
+void testNonAlias() {
+  final source = allocate<Int64>();
+  source.store(42);
+  final int a = source.load();
+  source.store(1984);
+  // alias.load() should be re-executed, as we wrote to alias.
+  Expect.notEquals(a, source.load<int>());
+  source.free();
+}
+
+void testAliasCast() {
+  final source = allocate<Int64>();
+  final alias = source.cast<Pointer<Int8>>().cast<Pointer<Int64>>();
+  source.store(42);
+  final int a = source.load();
+  alias.store(1984);
+  // source.load() should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.load<int>());
+  source.free();
+}
+
+void testAliasCast2() {
+  final source = allocate<Int64>();
+  final alias = source.cast<Pointer<Int16>>().cast<Pointer<Int64>>();
+  final alias2 = source.cast<Pointer<Int8>>().cast<Pointer<Int64>>();
+  alias.store(42);
+  final int a = alias.load();
+  alias2.store(1984);
+  // alias.load() should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.load<int>());
+  source.free();
+}
+
+void testAliasOffsetBy() {
+  final source = allocate<Int64>(count: 2);
+  final alias = source.offsetBy(8).offsetBy(-8);
+  source.store(42);
+  final int a = source.load();
+  alias.store(1984);
+  // source.load() should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.load<int>());
+  source.free();
+}
+
+void testAliasOffsetBy2() {
+  final source = allocate<Int64>(count: 3);
+  final alias = source.offsetBy(16).offsetBy(-16);
+  final alias2 = source.offsetBy(8).offsetBy(-8);
+  alias.store(42);
+  final int a = alias.load();
+  alias2.store(1984);
+  // alias.load() should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.load<int>());
+  source.free();
+}
+
+void testAliasElementAt() {
+  final source = allocate<Int64>(count: 2);
+  final alias = source.elementAt(1).elementAt(-1);
+  source.store(42);
+  final int a = source.load();
+  alias.store(1984);
+  // source.load() should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.load<int>());
+  source.free();
+}
+
+void testAliasElementAt2() {
+  final source = allocate<Int64>(count: 3);
+  final alias = source.elementAt(2).elementAt(-2);
+  final alias2 = source.elementAt(1).elementAt(-1);
+  alias.store(42);
+  final int a = alias.load();
+  alias2.store(1984);
+  // alias.load() should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.load<int>());
+  source.free();
+}
+
+void testAliasFromAddress() {
+  final source = allocate<Int64>();
+  final alias = fromAddress<Pointer<Int64>>(source.address);
+  source.store(42);
+  final int a = source.load();
+  alias.store(1984);
+  // source.load() should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.load<int>());
+  source.free();
+}
+
+void testAliasFromAddress2() {
+  final source = allocate<Int64>();
+  final alias = fromAddress<Pointer<Int64>>(source.address);
+  final alias2 = fromAddress<Pointer<Int64>>(source.address);
+  alias.store(42);
+  final int a = alias.load();
+  alias2.store(1984);
+  // alias.load() should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.load<int>());
+  source.free();
+}
+
+void testAliasFromAddressViaMemory() {
+  final helper = allocate<IntPtr>();
+  final source = allocate<Int64>();
+  helper.store(source.address);
+  final alias = fromAddress<Pointer<Int64>>(helper.load());
+  source.store(42);
+  final int a = source.load();
+  alias.store(1984);
+  // source.load() should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.load<int>());
+  helper.free();
+  source.free();
+}
+
+void testAliasFromAddressViaMemory2() {
+  final helper = allocate<IntPtr>();
+  final source = allocate<Int64>();
+  helper.store(source.address);
+  final alias = fromAddress<Pointer<Int64>>(helper.load());
+  final alias2 = fromAddress<Pointer<Int64>>(helper.load());
+  alias.store(42);
+  final int a = alias.load();
+  alias2.store(1984);
+  // alias.load() should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.load<int>());
+  helper.free();
+  source.free();
+}
+
+typedef NativeQuadOpSigned = Int64 Function(Int8, Int16, Int32, Int64);
+typedef QuadOp = int Function(int, int, int, int);
+
+DynamicLibrary ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+QuadOp intComputation = ffiTestFunctions
+    .lookupFunction<NativeQuadOpSigned, QuadOp>("IntComputation");
+
+void testAliasFromAddressViaNativeFunction() {
+  final source = allocate<Int64>();
+  final alias =
+      fromAddress<Pointer<Int64>>(intComputation(0, 0, 0, source.address));
+  source.store(42);
+  final int a = source.load();
+  alias.store(1984);
+  // source.load() should be re-executed, we wrote alias which aliases source.
+  Expect.notEquals(a, source.load<int>());
+  source.free();
+}
+
+void testAliasFromAddressViaNativeFunction2() {
+  final source = allocate<Int64>();
+  final alias =
+      fromAddress<Pointer<Int64>>(intComputation(0, 0, 0, source.address));
+  final alias2 =
+      fromAddress<Pointer<Int64>>(intComputation(0, 0, 0, source.address));
+  alias.store(42);
+  final int a = alias.load();
+  alias2.store(1984);
+  // alias.load() should be re-executed, we wrote alias2 which aliases alias.
+  Expect.notEquals(a, alias.load<int>());
+  source.free();
+}
+
+// TODO(dacoharkes): Replace with @pragma annotations once available.
+const NeverInline = 'NeverInline';
+
+@NeverInline
+Pointer<Int8> makeDerived(Pointer<Int64> source) =>
+    source.offsetBy(7).cast<Pointer<Int8>>();
+
+testPartialOverlap() {
+  final source = allocate<Int64>(count: 2);
+  final derived = makeDerived(source);
+  source.store(0x1122334455667788);
+  final int value = source.load();
+  derived.store(0xaa);
+  Expect.notEquals(value, source.load<int>());
+  source.free();
+}