[vm,aot] Use inferred type arguments to remove type checks

When TFA is able to infer type arguments, write _exact type_ into
the inferred types metadata.

Use inferred exact type in the VM: load it from metadata and
attach to a field if necessary. CompileType is extended to hold
exact type if it is known.

In the instruction canonicalizer, if type arguments are loaded from
a value which has a known exact type, then replace this LoadField with
Constant type arguments from exact type.

This allows VM to use inferred type arguments to remove parameter
type checks.

TEST=runtime/tests/vm/dart/eliminate_type_check_using_exact_type_il_test.dart

Closes #61083

Change-Id: I766c5e8c49be406f3e12d38e8d966e5813500c4d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/440064
Commit-Queue: Alexander Markov <[email protected]>
Reviewed-by: Slava Egorov <[email protected]>

Author: alexmarkov

pkg/vm/lib/metadata/inferred_type.dart

@@ -9,6 +9,7 @@ import 'package:kernel/src/printer.dart';
 
 /// Metadata for annotating nodes with an inferred type information.
 class InferredType {
+  final InterfaceType? exactType;
   final Reference? _concreteClassReference;
   final Constant? _constantValue;
   final Reference? _closureMemberReference;
@@ -29,27 +30,21 @@ class InferredType {
   // Contains inferred closure value.
   static const int flagClosure = 1 << 5;
 
-  // Entire list may be null if no type arguments were inferred.
-  // Will always be null if `concreteClass` is null.
-  //
-  // Each component may be null if that particular type argument was not
-  // inferred.
-  //
-  // Otherwise, a non-null type argument indicates that that particular type
-  // argument (in the runtime type) is always exactly a particular `DartType`.
-  final List<DartType?>? exactTypeArguments;
+  // Contains exact type.
+  static const int flagExactType = 1 << 6;
 
   InferredType(
+    InterfaceType? exactType,
     Class? concreteClass,
     bool nullable,
     bool isInt,
     Constant? constantValue,
     Member? closureMember,
     int closureId, {
-    List<DartType?>? exactTypeArguments,
     bool skipCheck = false,
     bool receiverNotInt = false,
   }) : this._byReference(
+         exactType,
          concreteClass?.reference,
          constantValue,
          closureMember?.reference,
@@ -59,19 +54,25 @@ class InferredType {
              (skipCheck ? flagSkipCheck : 0) |
              (constantValue != null ? flagConstant : 0) |
              (receiverNotInt ? flagReceiverNotInt : 0) |
-             (closureMember != null ? flagClosure : 0),
-         exactTypeArguments,
+             (closureMember != null ? flagClosure : 0) |
+             (exactType != null ? flagExactType : 0),
        );
 
   InferredType._byReference(
+    this.exactType,
     this._concreteClassReference,
     this._constantValue,
     this._closureMemberReference,
     this._closureId,
     this._flags,
-    this.exactTypeArguments,
   ) {
-    assert(exactTypeArguments == null || _concreteClassReference != null);
+    assert(
+      exactType == null || _concreteClassReference == exactType!.classReference,
+    );
+    assert(
+      exactType == null ||
+          (nullable == (exactType!.nullability == Nullability.nullable)),
+    );
     assert(_constantValue == null || _concreteClassReference != null);
     assert(_closureMemberReference == null || _concreteClassReference != null);
     assert(_closureId >= 0);
@@ -94,27 +95,25 @@ class InferredType {
   @override
   String toString() {
     final StringBuffer buf = new StringBuffer();
-    if (concreteClass != null) {
-      buf.write(concreteClass!.toText(astTextStrategyForTesting));
+    final exactType = this.exactType;
+    final concreteClass = this.concreteClass;
+    if (exactType != null) {
+      buf.write(exactType.toText(astTextStrategyForTesting));
+    } else if (concreteClass != null) {
+      buf.write(concreteClass.toText(astTextStrategyForTesting));
+      if (nullable) {
+        buf.write('?');
+      }
     } else if (isInt) {
       buf.write('int');
+      if (nullable) {
+        buf.write('?');
+      }
+    } else if (nullable) {
+      buf.write('?');
     } else {
       buf.write('!');
     }
-    if (nullable) {
-      buf.write('?');
-    }
-    if (exactTypeArguments != null) {
-      buf.write('<');
-      buf.write(
-        exactTypeArguments!
-            .map(
-              (t) => t != null ? "${t.toText(astTextStrategyForTesting)}" : "?",
-            )
-            .join(", "),
-      );
-      buf.write('>');
-    }
     if (skipCheck) {
       buf.write(' (skip check)');
     }
@@ -147,13 +146,15 @@ class InferredTypeMetadataRepository extends MetadataRepository<InferredType> {
 
   @override
   void writeToBinary(InferredType metadata, Node node, BinarySink sink) {
-    // TODO(sjindel/tfa): Implement serialization of type arguments when can use
-    // them for optimizations.
-    sink.writeNullAllowedCanonicalNameReference(
-      metadata.concreteClass?.reference,
-    );
     final flags = metadata._flags;
-    sink.writeByte(metadata._flags);
+    sink.writeUInt30(metadata._flags);
+    if ((flags & InferredType.flagExactType) != 0) {
+      sink.writeDartType(metadata.exactType!);
+    } else {
+      sink.writeNullAllowedCanonicalNameReference(
+        metadata.concreteClass?.reference,
+      );
+    }
     if ((flags & InferredType.flagConstant) != 0) {
       sink.writeConstantReference(metadata.constantValue!);
     }
@@ -167,11 +168,16 @@ class InferredTypeMetadataRepository extends MetadataRepository<InferredType> {
 
   @override
   InferredType readFromBinary(Node node, BinarySource source) {
-    // TODO(sjindel/tfa): Implement serialization of type arguments when can use
-    // them for optimizations.
-    final concreteClassReference =
-        source.readNullableCanonicalNameReference()?.reference;
-    final flags = source.readByte();
+    final flags = source.readUInt30();
+    InterfaceType? exactType;
+    Reference? concreteClassReference;
+    if ((flags & InferredType.flagExactType) != 0) {
+      exactType = source.readDartType() as InterfaceType;
+      concreteClassReference = exactType.classReference;
+    } else {
+      concreteClassReference =
+          source.readNullableCanonicalNameReference()?.reference;
+    }
     final constantValue =
         (flags & InferredType.flagConstant) != 0
             ? source.readConstantReference()
@@ -183,12 +189,12 @@ class InferredTypeMetadataRepository extends MetadataRepository<InferredType> {
     final closureId =
         (flags & InferredType.flagClosure) != 0 ? source.readUInt30() : 0;
     return new InferredType._byReference(
+      exactType,
       concreteClassReference,
       constantValue,
       closureMemberReference,
       closureId,
       flags,
-      null,
     );
   }
 }

pkg/vm/lib/transformations/type_flow/transformer.dart

@@ -468,6 +468,7 @@ class AnnotateKernel extends RecursiveVisitor {
     bool skipCheck = false,
     bool receiverNotInt = false,
   }) {
+    InterfaceType? exactType;
     Class? concreteClass;
     Constant? constantValue;
     Member? closureMember;
@@ -515,35 +516,42 @@ class AnnotateKernel extends RecursiveVisitor {
       }
     }
 
-    List<DartType?>? typeArgs;
     if (type is ConcreteType && type.typeArgs != null) {
-      typeArgs =
-          type.typeArgs!
-              .take(type.numImmediateTypeArgs)
-              .map(
-                (t) =>
-                    t is UnknownType
-                        ? null
-                        : (t as RuntimeType).representedType,
-              )
-              .toList();
-    }
-
-    if (concreteClass != null ||
+      final typeArgs = <DartType>[];
+      bool allKnown = true;
+      for (int i = 0, n = type.numImmediateTypeArgs; i < n; ++i) {
+        final t = type.typeArgs![i];
+        if (t is UnknownType) {
+          allKnown = false;
+          break;
+        }
+        typeArgs.add((t as RuntimeType).representedType);
+      }
+      if (allKnown) {
+        exactType = InterfaceType(
+          concreteClass!,
+          nullable ? Nullability.nullable : Nullability.nonNullable,
+          typeArgs,
+        );
+      }
+    }
+
+    if (exactType != null ||
+        concreteClass != null ||
         !nullable ||
         isInt ||
         constantValue != null ||
         skipCheck ||
         receiverNotInt ||
         closureMember != null) {
       return new InferredType(
+        exactType,
         concreteClass,
         nullable,
         isInt,
         constantValue,
         closureMember,
         closureId,
-        exactTypeArguments: typeArgs,
         skipCheck: skipCheck,
         receiverNotInt: receiverNotInt,
       );

pkg/vm/testcases/transformations/ffi/abi_specific_int.dart.aot.expect

@@ -103,7 +103,7 @@ static method testStoreLoad() → void {
   final ffi::Pointer<self::WChar> p = let final core::int #t1 = [@vm.inferred-type.metadata=dart.core::_Smi] self::WChar::#sizeOf in [@vm.direct-call.metadata=#lib::_DummyAllocator.allocate] [@vm.inferred-type.metadata=dart.ffi::Pointer (skip check)] #C33.{ffi::Allocator::allocate}<self::WChar>(){(core::int, {alignment: core::int?}) → ffi::Pointer<self::WChar>};
   ffi::_storeAbiSpecificInt<self::WChar>(p, #C19, 10);
   core::print([@vm.inferred-type.metadata=int] ffi::_loadAbiSpecificInt<self::WChar>(p, #C19));
-  [@vm.direct-call.metadata=#lib::_DummyAllocator.free] [@vm.inferred-type.metadata=!? (skip check)] #C33.{self::_DummyAllocator::free}(){(ffi::Pointer<ffi::NativeType>) → void};
+  [@vm.direct-call.metadata=#lib::_DummyAllocator.free] [@vm.inferred-type.metadata=? (skip check)] #C33.{self::_DummyAllocator::free}(){(ffi::Pointer<ffi::NativeType>) → void};
 }
 
 [@vm.inferred-return-type.metadata=dart.core::Null? (value: null)]
@@ -113,17 +113,17 @@ static method testStoreLoadIndexed() → void {
   ffi::_storeAbiSpecificIntAtIndex<self::WChar>(p, #C19, 1, 3);
   core::print([@vm.inferred-type.metadata=int] ffi::_loadAbiSpecificIntAtIndex<self::WChar>(p, #C19, 0));
   core::print([@vm.inferred-type.metadata=int] ffi::_loadAbiSpecificIntAtIndex<self::WChar>(p, #C19, 1));
-  [@vm.direct-call.metadata=#lib::_DummyAllocator.free] [@vm.inferred-type.metadata=!? (skip check)] #C33.{self::_DummyAllocator::free}(){(ffi::Pointer<ffi::NativeType>) → void};
+  [@vm.direct-call.metadata=#lib::_DummyAllocator.free] [@vm.inferred-type.metadata=? (skip check)] #C33.{self::_DummyAllocator::free}(){(ffi::Pointer<ffi::NativeType>) → void};
 }
 
 [@vm.inferred-return-type.metadata=dart.core::Null? (value: null)]
 static method testStruct() → void {
   final ffi::Pointer<self::WCharStruct> p = let final core::int #t3 = [@vm.inferred-type.metadata=dart.core::_Smi] self::WCharStruct::#sizeOf in [@vm.direct-call.metadata=#lib::_DummyAllocator.allocate] [@vm.inferred-type.metadata=dart.ffi::Pointer (skip check)] #C33.{ffi::Allocator::allocate}<self::WCharStruct>(){(core::int, {alignment: core::int?}) → ffi::Pointer<self::WCharStruct>};
-  [@vm.direct-call.metadata=#lib::WCharStruct.a0] [@vm.inferred-type.metadata=!? (skip check)] new self::WCharStruct::#fromTypedDataBase(_in::unsafeCast<ffi::Pointer<self::WCharStruct>>(p)).{self::WCharStruct::a0} = 1;
+  [@vm.direct-call.metadata=#lib::WCharStruct.a0] [@vm.inferred-type.metadata=? (skip check)] new self::WCharStruct::#fromTypedDataBase(_in::unsafeCast<ffi::Pointer<self::WCharStruct>>(p)).{self::WCharStruct::a0} = 1;
   core::print([@vm.direct-call.metadata=#lib::WCharStruct.a0] [@vm.inferred-type.metadata=int] new self::WCharStruct::#fromTypedDataBase(_in::unsafeCast<ffi::Pointer<self::WCharStruct>>(p)).{self::WCharStruct::a0}{core::int});
-  [@vm.direct-call.metadata=#lib::WCharStruct.a0] [@vm.inferred-type.metadata=!? (skip check)] new self::WCharStruct::#fromTypedDataBase(_in::unsafeCast<ffi::Pointer<self::WCharStruct>>(p)).{self::WCharStruct::a0} = 2;
+  [@vm.direct-call.metadata=#lib::WCharStruct.a0] [@vm.inferred-type.metadata=? (skip check)] new self::WCharStruct::#fromTypedDataBase(_in::unsafeCast<ffi::Pointer<self::WCharStruct>>(p)).{self::WCharStruct::a0} = 2;
   core::print([@vm.direct-call.metadata=#lib::WCharStruct.a0] [@vm.inferred-type.metadata=int] new self::WCharStruct::#fromTypedDataBase(_in::unsafeCast<ffi::Pointer<self::WCharStruct>>(p)).{self::WCharStruct::a0}{core::int});
-  [@vm.direct-call.metadata=#lib::_DummyAllocator.free] [@vm.inferred-type.metadata=!? (skip check)] #C33.{self::_DummyAllocator::free}(){(ffi::Pointer<ffi::NativeType>) → void};
+  [@vm.direct-call.metadata=#lib::_DummyAllocator.free] [@vm.inferred-type.metadata=? (skip check)] #C33.{self::_DummyAllocator::free}(){(ffi::Pointer<ffi::NativeType>) → void};
 }
 
 [@vm.inferred-return-type.metadata=dart.core::Null? (value: null)]
@@ -134,17 +134,17 @@ static method testInlineArray() → void {
     block {
       synthesized ffi::Array<dynamic> #array = _in::unsafeCast<ffi::Array<self::WChar>>(array);
       synthesized core::int #index = _in::unsafeCast<core::int>(i);
-      [@vm.direct-call.metadata=dart.ffi::Array._checkIndex] [@vm.inferred-type.metadata=!? (skip check)] #array.{ffi::Array::_checkIndex}(#index){(core::int) → void};
+      [@vm.direct-call.metadata=dart.ffi::Array._checkIndex] [@vm.inferred-type.metadata=? (skip check)] #array.{ffi::Array::_checkIndex}(#index){(core::int) → void};
     } =>ffi::_storeAbiSpecificIntAtIndex<self::WChar>([@vm.direct-call.metadata=dart.ffi::_Compound._typedDataBase] #array.{ffi::_Compound::_typedDataBase}{core::Object}, [@vm.direct-call.metadata=dart.ffi::_Compound._offsetInBytes] [@vm.inferred-type.metadata=int?] #array.{ffi::_Compound::_offsetInBytes}{core::int}, #index, i);
   }
   for (core::int i = 0; [@vm.direct-call.metadata=dart.core::_IntegerImplementation.<] [@vm.inferred-type.metadata=dart.core::bool (skip check)] i.{core::num::<}(100){(core::num) → core::bool}; i = [@vm.direct-call.metadata=dart.core::_IntegerImplementation.+] [@vm.inferred-type.metadata=int (skip check)] i.{core::num::+}(1){(core::num) → core::int}) {
     core::print( block {
       synthesized ffi::Array<dynamic> #array = _in::unsafeCast<ffi::Array<self::WChar>>(array);
       synthesized core::int #index = _in::unsafeCast<core::int>(i);
-      [@vm.direct-call.metadata=dart.ffi::Array._checkIndex] [@vm.inferred-type.metadata=!? (skip check)] #array.{ffi::Array::_checkIndex}(#index){(core::int) → void};
+      [@vm.direct-call.metadata=dart.ffi::Array._checkIndex] [@vm.inferred-type.metadata=? (skip check)] #array.{ffi::Array::_checkIndex}(#index){(core::int) → void};
     } =>[@vm.inferred-type.metadata=int] ffi::_loadAbiSpecificIntAtIndex<self::WChar>([@vm.direct-call.metadata=dart.ffi::_Compound._typedDataBase] #array.{ffi::_Compound::_typedDataBase}{core::Object}, [@vm.direct-call.metadata=dart.ffi::_Compound._offsetInBytes] [@vm.inferred-type.metadata=int?] #array.{ffi::_Compound::_offsetInBytes}{core::int}, #index));
   }
-  [@vm.direct-call.metadata=#lib::_DummyAllocator.free] [@vm.inferred-type.metadata=!? (skip check)] #C33.{self::_DummyAllocator::free}(){(ffi::Pointer<ffi::NativeType>) → void};
+  [@vm.direct-call.metadata=#lib::_DummyAllocator.free] [@vm.inferred-type.metadata=? (skip check)] #C33.{self::_DummyAllocator::free}(){(ffi::Pointer<ffi::NativeType>) → void};
 }
 constants  {
   #C1 = "vm:ffi:abi-specific-mapping"