[vm,dyn_modules] Initial support for FFI calls in the interpreter

Limitations:
* Compounds (structs, unions, arrays) are not supported yet.
* Only x64 and arm64 are supported.

TEST=ci

Change-Id: I2929d514dc49015369d29dad31f479c661161655
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/446282
Commit-Queue: Alexander Markov <[email protected]>
Reviewed-by: Ryan Macnak <[email protected]>

Author: alexmarkov

pkg/dart2bytecode/docs/bytecode.md

@@ -801,6 +801,10 @@ type ConstantDynamicCall extends ConstantPoolEntry {
 type ConstantExternalCall extends ConstantPoolEntry {
   Byte tag = 15;
 }
+
+type ConstantFfiCall extends ConstantPoolEntry {
+  Byte tag = 16;
+}
 ```
 
 ### Exceptions table
@@ -1267,6 +1271,11 @@ arguments descriptor.
 Invoke body of an external method.
 ContantPool[D] is a ConstantExternalCall.
 
+#### FfiCall D
+
+Invoke native target of FFI call.
+ContantPool[D] is a ConstantFfiCall.
+
 #### ReturnTOS
 
 Return to the caller using SP[0] as a result.

pkg/dart2bytecode/lib/assembler.dart

@@ -558,6 +558,11 @@ class BytecodeAssembler {
     _emitInstructionD(Opcode.kExternalCall, rd);
   }
 
+  @pragma('vm:prefer-inline')
+  void emitFfiCall(int rd) {
+    _emitInstructionD(Opcode.kFfiCall, rd);
+  }
+
   @pragma('vm:prefer-inline')
   void emitLoadStatic(int rd) {
     _emitInstructionD(Opcode.kLoadStatic, rd);

pkg/dart2bytecode/lib/bytecode_generator.dart

@@ -104,6 +104,7 @@ class BytecodeGenerator extends RecursiveVisitor {
   final PragmaAnnotationParser pragmaParser;
   final RecognizedMethods recognizedMethods;
   final Map<Uri, Source> astUriToSource;
+  final LibraryIndex ffiLibraryIndex;
   late StringTable stringTable;
   late ObjectTable objectTable;
   late Component bytecodeComponent;
@@ -164,7 +165,8 @@ class BytecodeGenerator extends RecursiveVisitor {
       this.pragmaParser,
       this.staticTypeContext)
       : recognizedMethods = new RecognizedMethods(staticTypeContext),
-        astUriToSource = component.uriToSource {
+        astUriToSource = component.uriToSource,
+        ffiLibraryIndex = LibraryIndex(component, const ['dart:ffi']) {
     bytecodeComponent = new Component(coreTypes);
     stringTable = bytecodeComponent.stringTable;
     objectTable = bytecodeComponent.objectTable;
@@ -596,6 +598,11 @@ class BytecodeGenerator extends RecursiveVisitor {
     if (member.isExternal) {
       final String? externalName = getExternalName(coreTypes, member);
       if (externalName == null) {
+        if (pragmaParser
+            .parsedPragmas<ParsedFfiNativePragma>(member.annotations)
+            .isNotEmpty) {
+          flags |= FunctionDeclaration.isNativeFlag;
+        }
         flags |= FunctionDeclaration.isExternalFlag;
       } else {
         flags |= FunctionDeclaration.isNativeFlag;
@@ -741,6 +748,10 @@ class BytecodeGenerator extends RecursiveVisitor {
         if (node.isExternal) {
           if (getExternalName(coreTypes, node) != null) {
             _genExternalCall(node);
+          } else if (pragmaParser
+              .parsedPragmas<ParsedFfiNativePragma>(node.annotations)
+              .isNotEmpty) {
+            _generateFfiCall(null);
           } else {
             _genNoSuchMethodForExternal(node);
           }
@@ -839,6 +850,21 @@ class BytecodeGenerator extends RecursiveVisitor {
     asm.emitExternalCall(externalCallCpIndex);
   }
 
+  void _generateFfiCall(Expression? target) {
+    final function = enclosingFunction!;
+    for (var param in function.positionalParameters) {
+      asm.emitPush(locals.getVarIndexInFrame(param));
+    }
+    for (var param in locals.originalNamedParameters) {
+      asm.emitPush(locals.getVarIndexInFrame(param));
+    }
+    if (target != null) {
+      _generateNode(target);
+    }
+    final ffiCallCpIndex = cp.addFfiCall();
+    asm.emitFfiCall(ffiCallCpIndex);
+  }
+
   LibraryIndex get libraryIndex => coreTypes.index;
 
   late Procedure growableListLiteral =
@@ -976,7 +1002,11 @@ class BytecodeGenerator extends RecursiveVisitor {
   late Field syncStarIteratorYieldStarIterable = libraryIndex.getField(
       'dart:async', '_SyncStarIterator', '_yieldStarIterable');
 
-  late Library? dartFfiLibrary = libraryIndex.tryGetLibrary('dart:ffi');
+  late Library? dartFfiLibrary = ffiLibraryIndex.tryGetLibrary('dart:ffi');
+
+  late Procedure? ffiCall = (dartFfiLibrary != null)
+      ? ffiLibraryIndex.getTopLevelProcedure('dart:ffi', '_ffiCall')
+      : null;
 
   // Selector for implicit dynamic calls 'foo(...)' where
   // variable 'foo' has type 'dynamic'.
@@ -3436,6 +3466,10 @@ class BytecodeGenerator extends RecursiveVisitor {
       // Skip over AST of the argument, return null.
       asm.emitPushNull();
       return;
+    } else if (target == ffiCall) {
+      assert(args.named.isEmpty);
+      _generateFfiCall(args.positional.single);
+      return;
     }
     if (target.isFactory) {
       final constructedClass = target.enclosingClass!;

pkg/dart2bytecode/lib/constant_pool.dart

@@ -31,6 +31,7 @@ enum ConstantTag {
   kInstantiatedInterfaceCall,
   kDynamicCall,
   kExternalCall,
+  kFfiCall,
 }
 
 String constantTagToString(ConstantTag tag) =>
@@ -87,6 +88,8 @@ abstract class ConstantPoolEntry {
         return new ConstantDynamicCall.read(reader);
       case ConstantTag.kExternalCall:
         return new ConstantExternalCall.read(reader);
+      case ConstantTag.kFfiCall:
+        return new ConstantFfiCall.read(reader);
     }
     throw 'Unexpected constant tag $tag';
   }
@@ -530,6 +533,29 @@ class ConstantExternalCall extends ConstantPoolEntry {
   bool operator ==(other) => identical(this, other);
 }
 
+class ConstantFfiCall extends ConstantPoolEntry {
+  ConstantFfiCall();
+
+  @override
+  ConstantTag get tag => ConstantTag.kFfiCall;
+
+  @override
+  void writeValue(BufferedWriter writer) {}
+
+  ConstantFfiCall.read(BufferedReader reader);
+
+  @override
+  String toString() => 'FfiCall';
+
+  // Do not merge ConstantFfiCall entries.
+
+  @override
+  int get hashCode => identityHashCode(this);
+
+  @override
+  bool operator ==(other) => identical(this, other);
+}
+
 /// Reserved constant pool entry.
 class _ReservedConstantPoolEntry extends ConstantPoolEntry {
   const _ReservedConstantPoolEntry();
@@ -607,6 +633,8 @@ class ConstantPool {
 
   int addExternalCall() => _add(ConstantExternalCall());
 
+  int addFfiCall() => _add(ConstantFfiCall());
+
   int addStaticField(Field field) =>
       _add(new ConstantStaticField(objectTable.getHandle(field)!));
 

pkg/dart2bytecode/lib/dbc.dart

@@ -213,6 +213,10 @@ enum Opcode {
   kAllocateRecord_Wide,
   kLoadRecordField,
   kLoadRecordField_Wide,
+
+  // FFI
+  kFfiCall,
+  kFfiCall_Wide,
 }
 
 /// Compact variants of opcodes are always even.
@@ -464,6 +468,8 @@ const Map<Opcode, Format> BytecodeFormats = const {
       Encoding.kD, const [Operand.lit, Operand.none, Operand.none]),
   Opcode.kLoadRecordField: const Format(
       Encoding.kD, const [Operand.imm, Operand.none, Operand.none]),
+  Opcode.kFfiCall: const Format(
+      Encoding.kD, const [Operand.lit, Operand.none, Operand.none]),
 };
 
 // Should match constant in runtime/vm/stack_frame_kbc.h.

pkg/vm/lib/transformations/pragma.dart

@@ -16,6 +16,7 @@ const kVmDisableUnboxedParametersPragmaName = "vm:disable-unboxed-parameters";
 const kVmKeepNamePragmaName = "vm:keep-name";
 const kVmPlatformConstPragmaName = "vm:platform-const";
 const kVmPlatformConstIfPragmaName = "vm:platform-const-if";
+const kVmFfiNative = "vm:ffi:native";
 
 // Pragmas recognized by dart2wasm
 const kWasmEntryPointPragmaName = "wasm:entry-point";
@@ -81,6 +82,10 @@ class ParsedPlatformConstPragma implements ParsedPragma {
   const ParsedPlatformConstPragma();
 }
 
+class ParsedFfiNativePragma implements ParsedPragma {
+  const ParsedFfiNativePragma();
+}
+
 class ParsedDynModuleEntryPointPragma implements ParsedPragma {
   const ParsedDynModuleEntryPointPragma();
 }
@@ -206,6 +211,8 @@ class ConstantPragmaAnnotationParser implements PragmaAnnotationParser {
               "pragma: $options";
         }
         return options.value ? const ParsedPlatformConstPragma() : null;
+      case kVmFfiNative:
+        return const ParsedFfiNativePragma();
       case kWasmEntryPointPragmaName:
         return const ParsedEntryPointPragma(PragmaEntryPointType.Default);
       case kWasmExportPragmaName:

runtime/vm/BUILD.gn

@@ -166,7 +166,7 @@ source_set("libprotozero") {
   }
 
   public_configs = [ ":libprotozero_config" ]
-  deps = [ "$perfetto_root_path/src/protozero:protozero" ]
+  deps = [ "$perfetto_root_path/src/protozero" ]
 }
 
 library_for_all_configs("libdart_vm") {
@@ -210,7 +210,7 @@ library_for_all_configs("libdart_vm") {
     sources += [ "thread_interrupter_android_arm.S" ]
   }
   if (!is_win) {
-    sources += [ "simulator_arm64_trampolines.S" ]
+    sources += [ "ffi_trampolines_arm64.S" ]
   }
   include_dirs = [ ".." ]
 }

runtime/vm/bytecode_reader.cc

@@ -522,6 +522,7 @@ intptr_t BytecodeReaderHelper::ReadConstantPool(const Function& function,
     kInstantiatedInterfaceCall,
     kDynamicCall,
     kExternalCall,
+    kFfiCall,
   };
 
   Object& obj = Object::Handle(Z);
@@ -691,6 +692,14 @@ intptr_t BytecodeReaderHelper::ReadConstantPool(const Function& function,
         pool.SetRawValueAt(i, 0);
         continue;
       }
+      case ConstantPoolTag::kFfiCall: {
+        // FfiCall constant has 1 raw value entry.
+        pool.SetTypeAt(i, ObjectPool::EntryType::kNativeFunction,
+                       ObjectPool::Patchability::kNotPatchable,
+                       ObjectPool::SnapshotBehavior::kNotSnapshotable);
+        pool.SetRawValueAt(i, 0);
+        continue;
+      }
       default:
         UNREACHABLE();
     }
@@ -2107,7 +2116,9 @@ void BytecodeReaderHelper::ReadFunctionDeclarations(const Class& cls) {
 
     if (is_native) {
       name ^= ReadObject();
-      function.set_native_name(name);
+      if (!name.IsNull()) {
+        function.set_native_name(name);
+      }
     }
 
     if ((flags & kIsAbstractFlag) == 0) {