Redo "Dummy receiver optimization"

sdk/lib/_internal/compiler/implementation/ssa/interceptor_simplifier.dart

 // Copyright (c) 2013, 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.
 
 part of ssa;
 
 /**
  * This phase simplifies interceptors in multiple ways:
  *
  * 1) If the interceptor is for an object whose type is known, it
@@ skipping 168 matching lines @@
     // use only the selector of that instruction.
     if (dominator != null) {
       interceptedClasses =
             backend.getInterceptedClassesOn(dominator.selector.name);
 
       // If we found that we need number, we must still go through all
       // uses to check if they require int, or double.
       if (interceptedClasses.contains(backend.jsNumberClass)
           && !(interceptedClasses.contains(backend.jsDoubleClass)
                || interceptedClasses.contains(backend.jsIntClass))) {
-        for (var user in node.usedBy) {
+        for (HInstruction user in node.usedBy) {
           if (user is! HInvoke) continue;
           Set<ClassElement> intercepted =
               backend.getInterceptedClassesOn(user.selector.name);
           if (intercepted.contains(backend.jsIntClass)) {
             interceptedClasses.add(backend.jsIntClass);
           }
           if (intercepted.contains(backend.jsDoubleClass)) {
             interceptedClasses.add(backend.jsDoubleClass);
           }
         }
       }
     } else {
       interceptedClasses = new Set<ClassElement>();
-      for (var user in node.usedBy) {
+      for (HInstruction user in node.usedBy) {
         if (user is HIs) {
           // Is-checks can be performed on any intercepted class.
           interceptedClasses.addAll(backend.interceptedClasses);
           break;
         }
         if (user is! HInvoke) continue;
         // We don't handle escaping interceptors yet.
         interceptedClasses.addAll(
             backend.getInterceptedClassesOn(user.selector.name));
       }
     }
 
     HInstruction receiver = node.receiver;
     if (canUseSelfForInterceptor(receiver, interceptedClasses)) {
-      node.block.rewrite(node, receiver);
-      return false;
+      return rewriteToUseSelfAsInterceptor(node, receiver);
     }
 
     // Try computing a constant interceptor.
     HInstruction constantInterceptor =
         tryComputeConstantInterceptor(receiver, interceptedClasses);
     if (constantInterceptor != null) {
       node.block.rewrite(node, constantInterceptor);
       return false;
     }
 
@@ skipping 17 matching lines @@
     interceptor.sourcePosition = user.sourcePosition;
     interceptor.sourceElement = user.sourceElement;
 
     HBasicBlock block = user.block;
     block.addAfter(user, interceptor);
     block.rewrite(user, interceptor);
     block.remove(user);
     return true;
   }
 
+  bool rewriteToUseSelfAsInterceptor(HInterceptor node, HInstruction receiver) {
+    List<HInstruction> users = node.usedBy.toList();

[floitsch, 2013/12/19 10:29:16]

Add comment explaining that we need to get the list of the users before we
rewrite, since the node is unused after it.

+
+    node.block.rewrite(node, receiver);
+
+    // We have just rewritten:
+    //
+    //     m = getInterceptor(a)
+    //     m.foo$1(a, x)
+    // -->
+    //     m = getInterceptor(a)
+    //     a.foo$1(a, x)
+    //
+    // For the rewritten calls, if the selector matches only methods that ignore
+    // the explicit receiver parameter, replace occurences of the receiver
+    // argument with a dummy receiver '0':
+    //
+    //     a.foo$1(a, x)   -->   a.foo$1(0, x)
+    //
+    JavaScriptBackend backend = compiler.backend;
+    for (HInstruction user in users) {
+      if (user is HInvokeDynamic) {
+        HInvokeDynamic invoke = user;
+        if (invoke.receiver == receiver &&
+            !backend.isInterceptedMixinSelector(invoke.selector)) {
+          HInstruction receiverArgument = invoke.inputs[1];
+          // TODO(15720): The test here should be
+          //
+          //     invoke.receiver.nonCheck() == receiverArgument.nonCheck()
+          //
+          if (invoke.receiver == receiverArgument) {  // recognize a.foo(a,...)
+            Constant constant = new DummyReceiverConstant(
+                receiverArgument.instructionType);
+            HConstant dummy = graph.addConstant(constant, compiler);
+            receiverArgument.usedBy.remove(invoke);
+            invoke.inputs[1] = dummy;
+            dummy.usedBy.add(invoke);
+          }
+        }
+      }
+    }
+    return false;
+  }
+
   bool visitOneShotInterceptor(HOneShotInterceptor node) {
     HInstruction constant = tryComputeConstantInterceptor(
         node.inputs[1], node.interceptedClasses);
 
     if (constant == null) return false;
 
     Selector selector = node.selector;
     HInstruction instruction;
     if (selector.isGetter()) {
       instruction = new HInvokeDynamicGetter(
@@ skipping 13 matching lines @@
       instruction = new HInvokeDynamicMethod(
           selector, inputs, node.instructionType, true);
     }
 
     HBasicBlock block = node.block;
     block.addAfter(node, instruction);
     block.rewrite(node, instruction);
     return true;
   }
 }