[dart2js] Avoid collision with getInterceptor.

getInterceptor now always goes via HInterceptor, ensuring the back end
knows to generate the unspecialized interceptor. We no longer generate
the unspecialized interceptor as *shadowing* the js_runtime
definition. In small programs where interceptors are not used except
via js_runtime.getInterceptor, the program would fail on the value
returned by the dummy body, since it was not shadowed.

This gets rid of the two definitions of getInterceptor (issue 9180).

Change-Id: Ibfa73f26d7d432273d5e755e2165ab6c2d48ad4f
Reviewed-on: https://dart-review.googlesource.com/68002
Commit-Queue: Stephen Adams <[email protected]>
Reviewed-by: Sigmund Cherem <[email protected]>

Author: rakudrama

pkg/compiler/lib/src/common_elements.dart

@@ -707,10 +707,6 @@ class CommonElements {
         member.library == interceptorsLibrary;
   }
 
-  FunctionEntity _getInterceptorMethod;
-  FunctionEntity get getInterceptorMethod =>
-      _getInterceptorMethod ??= _findInterceptorsFunction('getInterceptor');
-
   FunctionEntity _getNativeInterceptorMethod;
   FunctionEntity get getNativeInterceptorMethod =>
       _getNativeInterceptorMethod ??=

pkg/compiler/lib/src/js_backend/backend.dart

@@ -843,10 +843,6 @@ class JavaScriptBackend {
   // [ElementEnvironment.getMemberMetadata] in [AnnotationProcessor].
   void processAnnotations(
       JClosedWorld closedWorld, InferredDataBuilder inferredDataBuilder) {
-    // These methods are overwritten with generated versions.
-    inlineCache.markAsNonInlinable(
-        closedWorld.commonElements.getInterceptorMethod,
-        insideLoop: true);
     for (MemberEntity entity in closedWorld.processedMembers) {
       _processMemberAnnotations(closedWorld, inferredDataBuilder, entity);
     }

pkg/compiler/lib/src/js_backend/minify_namer.dart

@@ -166,7 +166,7 @@ class MinifyNamer extends Namer
       r'BoundClosure',
       r'Closure',
       r'StateError$',
-      r'getInterceptor',
+      r'getInterceptor$',
       r'max',
       r'$mul',
       r'Map',

pkg/compiler/lib/src/js_backend/namer.dart

@@ -1481,20 +1481,19 @@ class Namer {
     return names.join();
   }
 
-  /// Property name used for `getInterceptor` or one of its specializations.
+  /// Property name used for a specialization of `getInterceptor`.
+  ///
+  /// js_runtime contains a top-level `getInterceptor` method. The
+  /// specializations have the same name, but with a suffix to avoid name
+  /// collisions.
   jsAst.Name nameForGetInterceptor(Iterable<ClassEntity> classes) {
-    FunctionEntity getInterceptor = _commonElements.getInterceptorMethod;
-    if (classes.contains(_commonElements.jsInterceptorClass)) {
-      // If the base Interceptor class is in the set of intercepted classes, we
-      // need to go through the generic getInterceptorMethod, since any subclass
-      // of the base Interceptor could match.
-      // The unspecialized getInterceptor method can also be accessed through
-      // its element, so we treat this as a user-space global instead of an
-      // internal global.
-      return _disambiguateGlobalMember(getInterceptor);
-    }
-    String suffix = suffixForGetInterceptor(classes);
-    return _disambiguateInternalGlobal("${getInterceptor.name}\$$suffix");
+    // If the base Interceptor class is in the set of intercepted classes, we
+    // need to go through the generic getInterceptor method (any subclass of the
+    // base Interceptor could match), which is encoded as an empty suffix.
+    String suffix = classes.contains(_commonElements.jsInterceptorClass)
+        ? ''
+        : suffixForGetInterceptor(classes);
+    return _disambiguateInternalGlobal('getInterceptor\$$suffix');
   }
 
   /// Property name used for the one-shot interceptor method for the given

pkg/compiler/lib/src/ssa/builder_kernel.dart

@@ -3596,6 +3596,8 @@ class KernelSsaGraphBuilder extends ir.Visitor
       stack.add(graph.addConstantNull(closedWorld));
     } else if (name == 'JS_INTERCEPTOR_CONSTANT') {
       handleJsInterceptorConstant(invocation);
+    } else if (name == 'getInterceptor') {
+      handleForeignGetInterceptor(invocation);
     } else if (name == 'JS_STRING_CONCAT') {
       handleJsStringConcat(invocation);
     } else if (name == '_createInvocationMirror') {
@@ -4024,6 +4026,25 @@ class KernelSsaGraphBuilder extends ir.Visitor
     stack.add(graph.addConstantNull(closedWorld));
   }
 
+  void handleForeignGetInterceptor(ir.StaticInvocation invocation) {
+    // Single argument is the intercepted object.
+    if (_unexpectedForeignArguments(invocation,
+        minPositional: 1, maxPositional: 1)) {
+      // Result expected on stack.
+      stack.add(graph.addConstantNull(closedWorld));
+      return;
+    }
+    ir.Expression argument = invocation.arguments.positional.single;
+    argument.accept(this);
+    HInstruction argumentInstruction = pop();
+
+    SourceInformation sourceInformation =
+        _sourceInformationBuilder.buildCall(invocation, invocation);
+    HInstruction instruction =
+        _interceptorFor(argumentInstruction, sourceInformation);
+    stack.add(instruction);
+  }
+
   void handleForeignJs(ir.StaticInvocation invocation) {
     if (_unexpectedForeignArguments(invocation,
         minPositional: 2, maxPositional: null, typeArgumentCount: 1)) {

sdk/lib/_internal/js_runtime/lib/foreign_helper.dart

@@ -211,6 +211,11 @@ external void JS_SET_STATIC_STATE(staticState);
  */
 external JS_INTERCEPTOR_CONSTANT(Type type);
 
+/// Returns the interceptor for [object].
+///
+/// Calls are replaced with the [HInterceptor] SSA instruction.
+external getInterceptor(object);
+
 /**
  * Returns the object corresponding to Namer.staticStateHolder.
  */

sdk/lib/_internal/js_runtime/lib/interceptors.dart

@@ -45,6 +45,7 @@ import 'dart:_js_helper'
 
 import 'dart:_foreign_helper'
     show
+        getInterceptor,
         JS,
         JS_EFFECT,
         JS_EMBEDDED_GLOBAL,
@@ -70,22 +71,6 @@ _symbolMapToStringMap(Map<Symbol, dynamic> map) {
   return result;
 }
 
-/**
- * Get the interceptor for [object]. Called by the compiler when it needs
- * to emit a call to an intercepted method, that is a method that is
- * defined in an interceptor class.
- */
-@NoInline()
-getInterceptor(object) {
-  // This is a magic method: the compiler does specialization of it
-  // depending on the uses of intercepted methods and instantiated
-  // primitive types.
-
-  // The [JS] call prevents the type analyzer from making assumptions about the
-  // return type.
-  return JS('', 'void 0');
-}
-
 getDispatchProperty(object) {
   return JS(
       '', '#[#]', object, JS_EMBEDDED_GLOBAL('String', DISPATCH_PROPERTY_NAME));

sdk/lib/_internal/js_runtime/lib/js_helper.dart

@@ -30,6 +30,7 @@ import 'dart:async' show Completer, DeferredLoadException, Future;
 import 'dart:_foreign_helper'
     show
         DART_CLOSURE_TO_JS,
+        getInterceptor,
         JS,
         JS_BUILTIN,
         JS_CONST,