Avoid "=== true" inside code by calling a function that does this for us.

lib/compiler/implementation/ssa/optimize.dart

 // Copyright (c) 2011, 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.
 
 interface OptimizationPhase {
   String get name();
   void visitGraph(HGraph graph);
 }
 
 class SsaOptimizerTask extends CompilerTask {
@@ skipping 275 matching lines @@
     }
 
     if (left.isNonPrimitive() && node.operation.isUserDefinable()) {
       SourceString methodName = Elements.constructOperatorName(
           const SourceString('operator'), node.operation.name);
       return fromInterceptorToDynamicInvocation(node, methodName);
     }
     return node;
   }
 
+  bool allUsersAreBoolifies(HInstruction instruction) {
+    List<HInstruction> users = instruction.usedBy;
+    int length = users.length;
+    for (int i = 0; i < length; i++) {
+      if (users[i] is! HBoolify) return false;
+    }
+    return true;
+  }
+
+  HInstruction visitRelational(HRelational node) {
+    if (allUsersAreBoolifies(node)) {
+      Interceptors interceptors = compiler.builder.interceptors;
+      HStatic oldTarget = node.target;
+      Element boolifiedInterceptor =
+          interceptors.getBoolifiedVersionOf(oldTarget.element);
+      if (boolifiedInterceptor !== null) {
+        HStatic boolifiedTarget = new HStatic(boolifiedInterceptor);
+        // We don't remove the [oldTarget] in case it is used by other
+        // instructions. If it is unused it will be treated as dead code and
+        // discarded.
+        oldTarget.block.addAfter(oldTarget, boolifiedTarget);
+        // Remove us as user from the [oldTarget].
+        HBasicBlock.removeUser(oldTarget, node);
+        // Replace old target with boolified target.
+        assert(node.target == node.inputs[0]);
+        node.inputs[0] = boolifiedTarget;
+        boolifiedTarget.usedBy.add(node);
+        node.usesBoolifiedInterceptor = true;
+        node.propagatedType = HType.BOOLEAN;
+      }
+      // This node stays the same, but the Boolify node will go away.
+    }
+    // Note that we still have to call [super] to make sure that we end up
+    // in the remaining optimizations.
+    return super.visitRelational(node);
+  }
+
   HInstruction visitEquals(HEquals node) {
     HInstruction left = node.left;
     HInstruction right = node.right;
 
     if (left.isConstant() && right.isConstant()) {
-      return visitInvokeBinary(node);
+      return super.visitEquals(node);
     }
 
     if (left.isNonPrimitive()) {
       HNonPrimitiveType type = left.propagatedType;
       Element element = type.lookupMember(Namer.OPERATOR_EQUALS);
       if (element !== null) {
         // If the left-hand side is guaranteed to be a non-primitive
         // type and and it defines operator==, we emit a call to that
         // operator.
-        return visitInvokeBinary(node);
+        return super.visitEquals(node);
       } else if (right.isConstantNull()) {
         return graph.addConstantBool(false);
       } else {
         // We can just emit an identity check because the type does
         // not implement operator=.
         // TODO(floitsch): cache interceptors.
         HStatic target = new HStatic(
             compiler.builder.interceptors.getTripleEqualsInterceptor());
         node.block.addBefore(node, target);
         return new HIdentity(target, left, right);
       }
     }
 
 
     if (right.isConstantNull()) {
       if (left.propagatedType.isUseful()) {
         return graph.addConstantBool(false);
       } else {
         // TODO(floitsch): cache interceptors.
-        HStatic target = new HStatic(
-            compiler.builder.interceptors.getEqualsNullInterceptor());
+        Interceptors interceptors = compiler.builder.interceptors;
+        Element targetElement = interceptors.getEqualsNullInterceptor();
+        bool onlyUsedInBoolify = allUsersAreBoolifies(node);
+        if (onlyUsedInBoolify) {
+          targetElement = interceptors.getBoolifiedVersionOf(targetElement);
+        }
+        HStatic target = new HStatic(targetElement);
         node.block.addBefore(node, target);
-        return new HEquals(target, node.left, node.right);
+        HEquals result = new HEquals(target, node.left, node.right);
+        if (onlyUsedInBoolify) {
+          result.usesBoolifiedInterceptor = true;
+          result.propagatedType = HType.BOOLEAN;
+        }
+        return result;
       }
     }
 
-    // All other cases are dealt with by the [visitInvokeBinary].
-    return visitInvokeBinary(node);
+    // All other cases are dealt with by the [visitRelational] and
+    // [visitInvokeBinary], which are visited by invoking the [super]'s
+    // visit method.
+    return super.visitEquals(node);
   }
 
   HInstruction visitTypeGuard(HTypeGuard node) {
     HInstruction value = node.guarded;
     HType combinedType = value.propagatedType.combine(node.guardedType);
     return (combinedType == value.propagatedType) ? value : node;
   }
 
   HInstruction visitIs(HIs node) {
     Type type = node.typeName;
@@ skipping 513 matching lines @@
         }
       }
       if (!canBeMoved) continue;
 
       // This is safe because we are running after GVN.
       // TODO(ngeoffray): ensure GVN has been run.
       set_.add(current);
     }
   }
 }