[vm] Native effects
Adds a way to express native effects in Dart expressions in kernel.
This CL adds a `void _nativeEffect(Object)` to `dart:internal`.
The semantics of `_nativeEffect` are to not execute its arguments and
return `null`.
This CL uses this `_nativeEffect` to make sure that we never execute
the struct constructor invocations used to simulate the native behavior
of FFI trampolines.
Closes: https://github.com/dart-lang/sdk/issues/45607
TEST=tests/ffi(_2)/native_effect_test.dart
Change-Id: Ie06de145e49f8b1cae9e148c2d5d97d5cd8e6878
Cq-Include-Trybots: luci.dart.try:vm-precomp-ffi-qemu-linux-release-arm-try,vm-ffi-android-debug-arm64-try,vm-kernel-precomp-asan-linux-release-x64-try,vm-kernel-precomp-dwarf-linux-product-x64-try,vm-kernel-precomp-linux-debug-x64-try,vm-kernel-precomp-obfuscate-linux-release-x64-try,analyzer-analysis-server-linux-try,analyzer-linux-release-try,dart-sdk-linux-try,vm-kernel-reload-rollback-linux-debug-x64-try,vm-kernel-reload-linux-debug-x64-try
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/194421
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Commit-Queue: Daco Harkes <dacoharkes@google.com>
diff --git a/pkg/vm/lib/transformations/ffi.dart b/pkg/vm/lib/transformations/ffi.dart
index 84a6dbf..551ee3a 100644
--- a/pkg/vm/lib/transformations/ffi.dart
+++ b/pkg/vm/lib/transformations/ffi.dart
@@ -203,6 +203,7 @@
final Class listClass;
final Class typeClass;
final Procedure unsafeCastMethod;
+ final Procedure nativeEffectMethod;
final Class typedDataClass;
final Procedure typedDataBufferGetter;
final Procedure typedDataOffsetInBytesGetter;
@@ -294,6 +295,8 @@
typeClass = coreTypes.typeClass,
unsafeCastMethod =
index.getTopLevelMember('dart:_internal', 'unsafeCast'),
+ nativeEffectMethod =
+ index.getTopLevelMember('dart:_internal', '_nativeEffect'),
typedDataClass = index.getClass('dart:typed_data', 'TypedData'),
typedDataBufferGetter =
index.getMember('dart:typed_data', 'TypedData', 'get:buffer'),
diff --git a/pkg/vm/lib/transformations/ffi_use_sites.dart b/pkg/vm/lib/transformations/ffi_use_sites.dart
index 1b69f26..20cfbe8 100644
--- a/pkg/vm/lib/transformations/ffi_use_sites.dart
+++ b/pkg/vm/lib/transformations/ffi_use_sites.dart
@@ -387,29 +387,29 @@
}
/// Prevents the struct from being tree-shaken in TFA by invoking its
- /// constructor in a let expression.
- ///
- /// TFA does not recognize this as dead code, only the VM does.
- /// TODO(http://dartbug.com/45607): Wrap with `_nativeEffect` to make the
- /// intent of this code clear.
+ /// constructor in a `_nativeEffect` expression.
Expression _invokeStructConstructor(
- Expression nestedExpression, Class structClass) {
- final constructor = structClass.constructors
+ Expression nestedExpression, Class compositeClass) {
+ final constructor = compositeClass.constructors
.firstWhere((c) => c.name == Name("#fromTypedDataBase"));
- return Let(
- VariableDeclaration.forValue(
- ConstructorInvocation(
- constructor,
- Arguments([
- StaticInvocation(
- uint8ListFactory,
- Arguments([
- ConstantExpression(IntConstant(1)),
- ]))
- ..fileOffset = nestedExpression.fileOffset,
- ]))
- ..fileOffset = nestedExpression.fileOffset,
- type: InterfaceType(structClass, Nullability.nonNullable)),
+ return BlockExpression(
+ Block([
+ ExpressionStatement(StaticInvocation(
+ nativeEffectMethod,
+ Arguments([
+ ConstructorInvocation(
+ constructor,
+ Arguments([
+ StaticInvocation(
+ uint8ListFactory,
+ Arguments([
+ ConstantExpression(IntConstant(1)),
+ ]))
+ ..fileOffset = nestedExpression.fileOffset,
+ ]))
+ ..fileOffset = nestedExpression.fileOffset
+ ])))
+ ]),
nestedExpression)
..fileOffset = nestedExpression.fileOffset;
}
diff --git a/pkg/vm/testcases/transformations/type_flow/transformer/ffi_struct_constructors.dart.expect b/pkg/vm/testcases/transformations/type_flow/transformer/ffi_struct_constructors.dart.expect
index 66de23b..3469672 100644
--- a/pkg/vm/testcases/transformations/type_flow/transformer/ffi_struct_constructors.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/ffi_struct_constructors.dart.expect
@@ -65,13 +65,17 @@
}
static method testLookupFunctionReturn() → void {
final ffi::DynamicLibrary* dylib = [@vm.inferred-type.metadata=dart.ffi::DynamicLibrary?] ffi::DynamicLibrary::executable();
- final () →* self::Struct1* function1 = let final self::Struct1 #t1 = new self::Struct1::#fromTypedDataBase([@vm.inferred-type.metadata=dart.typed_data::_Uint8List] typ::Uint8List::•(#C18)) in ffi::_asFunctionInternal<() →* self::Struct1*, () →* self::Struct1*>([@vm.direct-call.metadata=dart.ffi::DynamicLibrary.lookup??] [@vm.inferred-type.metadata=dart.ffi::Pointer? (skip check)] dylib.{ffi::DynamicLibrary::lookup}<ffi::NativeFunction<() →* self::Struct1*>*>("function1"));
+ final () →* self::Struct1* function1 = block {
+ _in::_nativeEffect(new self::Struct1::#fromTypedDataBase([@vm.inferred-type.metadata=dart.typed_data::_Uint8List] typ::Uint8List::•(#C18)));
+ } =>ffi::_asFunctionInternal<() →* self::Struct1*, () →* self::Struct1*>([@vm.direct-call.metadata=dart.ffi::DynamicLibrary.lookup??] [@vm.inferred-type.metadata=dart.ffi::Pointer? (skip check)] dylib.{ffi::DynamicLibrary::lookup}<ffi::NativeFunction<() →* self::Struct1*>*>("function1"));
final self::Struct1* struct1 = [@vm.call-site-attributes.metadata=receiverType:#lib::Struct1* Function()*] function1.call();
core::print(struct1);
}
static method testAsFunctionReturn() → void {
final ffi::Pointer<ffi::NativeFunction<() →* self::Struct2*>*>* pointer = [@vm.inferred-type.metadata=dart.ffi::Pointer?] ffi::Pointer::fromAddress<ffi::NativeFunction<() →* self::Struct2*>*>(3735928559);
- final () →* self::Struct2* function2 = let final self::Struct2 #t2 = new self::Struct2::#fromTypedDataBase([@vm.inferred-type.metadata=dart.typed_data::_Uint8List] typ::Uint8List::•(#C18)) in ffi::_asFunctionInternal<() →* self::Struct2*, () →* self::Struct2*>(pointer);
+ final () →* self::Struct2* function2 = block {
+ _in::_nativeEffect(new self::Struct2::#fromTypedDataBase([@vm.inferred-type.metadata=dart.typed_data::_Uint8List] typ::Uint8List::•(#C18)));
+ } =>ffi::_asFunctionInternal<() →* self::Struct2*, () →* self::Struct2*>(pointer);
final self::Struct2* struct2 = [@vm.call-site-attributes.metadata=receiverType:#lib::Struct2* Function()*] function2.call();
core::print(struct2);
}
@@ -79,7 +83,9 @@
return 42;
}
static method testFromFunctionArgument() → void {
- final ffi::Pointer<ffi::NativeFunction<(self::Struct3*) →* ffi::Int32*>*>* pointer = let final self::Struct3 #t3 = new self::Struct3::#fromTypedDataBase([@vm.inferred-type.metadata=dart.typed_data::_Uint8List] typ::Uint8List::•(#C18)) in [@vm.inferred-type.metadata=dart.ffi::Pointer?] self::_#ffiCallback0;
+ final ffi::Pointer<ffi::NativeFunction<(self::Struct3*) →* ffi::Int32*>*>* pointer = block {
+ _in::_nativeEffect(new self::Struct3::#fromTypedDataBase([@vm.inferred-type.metadata=dart.typed_data::_Uint8List] typ::Uint8List::•(#C18)));
+ } =>[@vm.inferred-type.metadata=dart.ffi::Pointer?] self::_#ffiCallback0;
core::print(pointer);
}
static method testLookupFunctionArgument() → void {
diff --git a/runtime/lib/object.cc b/runtime/lib/object.cc
index 11b7f60..507ce9d 100644
--- a/runtime/lib/object.cc
+++ b/runtime/lib/object.cc
@@ -279,6 +279,10 @@
return arguments->NativeArgAt(0);
}
+DEFINE_NATIVE_ENTRY(Internal_nativeEffect, 0, 1) {
+ UNREACHABLE();
+}
+
DEFINE_NATIVE_ENTRY(Internal_reachabilityFence, 0, 1) {
UNREACHABLE();
}
diff --git a/runtime/vm/bootstrap_natives.h b/runtime/vm/bootstrap_natives.h
index 3190883..fe0f192 100644
--- a/runtime/vm/bootstrap_natives.h
+++ b/runtime/vm/bootstrap_natives.h
@@ -333,6 +333,7 @@
V(GrowableList_setLength, 2) \
V(GrowableList_setData, 2) \
V(Internal_unsafeCast, 1) \
+ V(Internal_nativeEffect, 1) \
V(Internal_reachabilityFence, 1) \
V(Internal_collectAllGarbage, 0) \
V(Internal_makeListFixedLength, 1) \
diff --git a/runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc b/runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc
index d90c132..9dfcc4e 100644
--- a/runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc
+++ b/runtime/vm/compiler/frontend/kernel_binary_flowgraph.cc
@@ -2643,7 +2643,7 @@
}
Fragment StreamingFlowGraphBuilder::BuildMethodInvocation(TokenPosition* p) {
- const intptr_t offset = ReaderOffset() - 1; // Include the tag.
+ const intptr_t offset = ReaderOffset() - 1; // Include the tag.
const uint8_t flags = ReadFlags(); // read flags.
const bool is_invariant = (flags & kMethodInvocationFlagInvariant) != 0;
@@ -3007,7 +3007,9 @@
}
const auto recognized_kind = target.recognized_kind();
- if (recognized_kind == MethodRecognizer::kFfiAsFunctionInternal) {
+ if (recognized_kind == MethodRecognizer::kNativeEffect) {
+ return BuildNativeEffect();
+ } else if (recognized_kind == MethodRecognizer::kFfiAsFunctionInternal) {
return BuildFfiAsFunctionInternal();
} else if (CompilerState::Current().is_aot() &&
recognized_kind == MethodRecognizer::kFfiNativeCallbackFunction) {
@@ -5018,20 +5020,42 @@
return instructions;
}
+Fragment StreamingFlowGraphBuilder::BuildNativeEffect() {
+ const intptr_t argc = ReadUInt(); // Read argument count.
+ ASSERT(argc == 1); // Native side effect to ignore.
+ const intptr_t list_length = ReadListLength(); // Read types list length.
+ ASSERT(list_length == 0);
+
+ const intptr_t positional_count =
+ ReadListLength(); // Read positional argument count.
+ ASSERT(positional_count == 1);
+
+ BuildExpression(); // Consume expression but don't save the fragment.
+ Pop(); // Restore the stack.
+
+ const intptr_t named_args_len =
+ ReadListLength(); // Skip empty named arguments.
+ ASSERT(named_args_len == 0);
+
+ Fragment code;
+ code += NullConstant(); // Return type is void.
+ return code;
+}
+
Fragment StreamingFlowGraphBuilder::BuildFfiAsFunctionInternal() {
- const intptr_t argc = ReadUInt(); // read argument count.
- ASSERT(argc == 1); // pointer
- const intptr_t list_length = ReadListLength(); // read types list length.
- ASSERT(list_length == 2); // dart signature, then native signature
+ const intptr_t argc = ReadUInt(); // Read argument count.
+ ASSERT(argc == 1); // Pointer.
+ const intptr_t list_length = ReadListLength(); // Read types list length.
+ ASSERT(list_length == 2); // Dart signature, then native signature.
const TypeArguments& type_arguments =
- T.BuildTypeArguments(list_length); // read types.
+ T.BuildTypeArguments(list_length); // Read types.
Fragment code;
const intptr_t positional_count =
- ReadListLength(); // read positional argument count
+ ReadListLength(); // Read positional argument count.
ASSERT(positional_count == 1);
- code += BuildExpression(); // build first positional argument (pointer)
+ code += BuildExpression(); // Build first positional argument (pointer).
const intptr_t named_args_len =
- ReadListLength(); // skip (empty) named arguments list
+ ReadListLength(); // Skip empty named arguments list.
ASSERT(named_args_len == 0);
code += B->BuildFfiAsFunctionInternalCall(type_arguments);
return code;
@@ -5044,24 +5068,24 @@
//
// The FE also guarantees that all three arguments are constants.
- const intptr_t argc = ReadUInt(); // read argument count
- ASSERT(argc == 2); // target, exceptionalReturn
+ const intptr_t argc = ReadUInt(); // Read argument count.
+ ASSERT(argc == 2); // Target, exceptionalReturn.
- const intptr_t list_length = ReadListLength(); // read types list length
- ASSERT(list_length == 1); // native signature
+ const intptr_t list_length = ReadListLength(); // Read types list length.
+ ASSERT(list_length == 1); // The native signature.
const TypeArguments& type_arguments =
- T.BuildTypeArguments(list_length); // read types.
+ T.BuildTypeArguments(list_length); // Read types.
ASSERT(type_arguments.Length() == 1 && type_arguments.IsInstantiated());
const FunctionType& native_sig =
FunctionType::CheckedHandle(Z, type_arguments.TypeAt(0));
Fragment code;
const intptr_t positional_count =
- ReadListLength(); // read positional argument count
+ ReadListLength(); // Read positional argument count.
ASSERT(positional_count == 2);
// Read target expression and extract the target function.
- code += BuildExpression(); // build first positional argument (target)
+ code += BuildExpression(); // Build first positional argument (target).
Definition* target_def = B->Peek();
ASSERT(target_def->IsConstant());
const Closure& target_closure =
@@ -5081,7 +5105,7 @@
code += Drop();
const intptr_t named_args_len =
- ReadListLength(); // skip (empty) named arguments list
+ ReadListLength(); // Skip (empty) named arguments list.
ASSERT(named_args_len == 0);
const Function& result =
diff --git a/runtime/vm/compiler/frontend/kernel_binary_flowgraph.h b/runtime/vm/compiler/frontend/kernel_binary_flowgraph.h
index 7f133f7..47f5bca 100644
--- a/runtime/vm/compiler/frontend/kernel_binary_flowgraph.h
+++ b/runtime/vm/compiler/frontend/kernel_binary_flowgraph.h
@@ -344,11 +344,14 @@
Fragment BuildFunctionNode(TokenPosition parent_position,
StringIndex name_index);
- // Build build FG for '_asFunctionInternal'. Reads an Arguments from the
+ // Build flow graph for '_nativeEffect'.
+ Fragment BuildNativeEffect();
+
+ // Build FG for '_asFunctionInternal'. Reads an Arguments from the
// Kernel buffer and pushes the resulting closure.
Fragment BuildFfiAsFunctionInternal();
- // Build build FG for '_nativeCallbackFunction'. Reads an Arguments from the
+ // Build FG for '_nativeCallbackFunction'. Reads an Arguments from the
// Kernel buffer and pushes the resulting Function object.
Fragment BuildFfiNativeCallbackFunction();
diff --git a/runtime/vm/compiler/recognized_methods_list.h b/runtime/vm/compiler/recognized_methods_list.h
index 8a2fbbc..02acfb7 100644
--- a/runtime/vm/compiler/recognized_methods_list.h
+++ b/runtime/vm/compiler/recognized_methods_list.h
@@ -166,6 +166,7 @@
V(::, _abi, FfiAbi, 0x7c4ab775) \
V(::, _asFunctionInternal, FfiAsFunctionInternal, 0xbbcb235a) \
V(::, _nativeCallbackFunction, FfiNativeCallbackFunction, 0x3ff5ae9c) \
+ V(::, _nativeEffect, NativeEffect, 0x61e00b59) \
V(::, _loadInt8, FfiLoadInt8, 0x0f04dfd6) \
V(::, _loadInt16, FfiLoadInt16, 0xec44312d) \
V(::, _loadInt32, FfiLoadInt32, 0xee223fc3) \
diff --git a/sdk/lib/_internal/vm/lib/internal_patch.dart b/sdk/lib/_internal/vm/lib/internal_patch.dart
index c434ec9..7ee1e6b 100644
--- a/sdk/lib/_internal/vm/lib/internal_patch.dart
+++ b/sdk/lib/_internal/vm/lib/internal_patch.dart
@@ -163,11 +163,16 @@
T unsafeCast<T>(Object? v) native "Internal_unsafeCast";
// This function can be used to keep an object alive til that point.
-//
@pragma("vm:recognized", "other")
@pragma('vm:prefer-inline')
void reachabilityFence(Object object) native "Internal_reachabilityFence";
+// This function can be used to encode native side effects.
+//
+// The function call and it's argument are removed in flow graph construction.
+@pragma("vm:recognized", "other")
+void _nativeEffect(Object object) native "Internal_nativeEffect";
+
void sendAndExit(SendPort sendPort, var message)
native "SendPortImpl_sendAndExitInternal_";
diff --git a/tests/ffi/native_effect_test.dart b/tests/ffi/native_effect_test.dart
new file mode 100644
index 0000000..41d4aea
--- /dev/null
+++ b/tests/ffi/native_effect_test.dart
@@ -0,0 +1,33 @@
+// Copyright (c) 2021, 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
+
+// Tests that the dart:internal _nativeEffect flow graph builder works.
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+
+import 'dylib_utils.dart';
+
+void main() {
+ testReturnStruct1ByteInt();
+}
+
+final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+final returnStruct1ByteInt = ffiTestFunctions.lookupFunction<
+ Struct1ByteInt Function(Int8),
+ Struct1ByteInt Function(int)>("ReturnStruct1ByteInt");
+
+void testReturnStruct1ByteInt() {
+ final result = returnStruct1ByteInt(1);
+ Expect.equals(1, result.a0);
+}
+
+class Struct1ByteInt extends Struct {
+ @Int8()
+ external int a0;
+}
diff --git a/tests/ffi_2/native_effect_test.dart b/tests/ffi_2/native_effect_test.dart
new file mode 100644
index 0000000..1b88d14
--- /dev/null
+++ b/tests/ffi_2/native_effect_test.dart
@@ -0,0 +1,33 @@
+// Copyright (c) 2021, 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
+
+// Tests that the dart:internal _nativeEffect flow graph builder works.
+
+import 'dart:ffi';
+
+import "package:expect/expect.dart";
+
+import 'dylib_utils.dart';
+
+void main() {
+ testReturnStruct1ByteInt();
+}
+
+final ffiTestFunctions = dlopenPlatformSpecific("ffi_test_functions");
+
+final returnStruct1ByteInt = ffiTestFunctions.lookupFunction<
+ Struct1ByteInt Function(Int8),
+ Struct1ByteInt Function(int)>("ReturnStruct1ByteInt");
+
+void testReturnStruct1ByteInt() {
+ final result = returnStruct1ByteInt(1);
+ Expect.equals(1, result.a0);
+}
+
+class Struct1ByteInt extends Struct {
+ @Int8()
+ int a0;
+}
