Implement a list tracer phase, that tries to find element types in individual lists.

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

 // Copyright (c) 2012, 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;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 3322 matching lines @@
     Send send = node.send;
     assert(invariant(send,
                      !compiler.enableTypeAssertions || !type.isMalformed,
                      message: '$type is malformed in checked mode'));
     bool isListConstructor = false;
     computeType(element) {
       Element originalElement = elements[send];
       if (Elements.isFixedListConstructorCall(
               originalElement, send, compiler)) {
         isListConstructor = true;
-        return backend.fixedArrayType;
+        HType inferred =
+            new HType.inferredForNode(currentElement, node, compiler);
+        return inferred.isUnknown() ? backend.fixedArrayType : inferred;
       } else if (Elements.isGrowableListConstructorCall(
                     originalElement, send, compiler)) {
         isListConstructor = true;
-        return backend.extendableArrayType;
+        HType inferred =
+            new HType.inferredForNode(currentElement, node, compiler);
+        return inferred.isUnknown() ? backend.extendableArrayType : inferred;
       } else if (element.isGenerativeConstructor()) {
         ClassElement cls = element.getEnclosingClass();
         return new HType.nonNullExact(cls.thisType, compiler);
       } else {
         return new HType.inferredTypeForElement(originalElement, compiler);
       }
     }
 
     Element constructor = elements[send];
     Selector selector = elements.getSelector(send);
@@ skipping 737 matching lines @@
       return;
     }
 
     List<HInstruction> inputs = <HInstruction>[];
     for (Link<Node> link = node.elements.nodes;
          !link.isEmpty;
          link = link.tail) {
       visit(link.head);
       inputs.add(pop());
     }
-    push(buildLiteralList(inputs));
+    HInstruction instruction = buildLiteralList(inputs);
+    HType type = new HType.inferredForNode(currentElement, node, compiler);
+    if (!type.isUnknown()) instruction.instructionType = type;
+    push(instruction);
   }
 
   visitConditional(Conditional node) {
     SsaBranchBuilder brancher = new SsaBranchBuilder(this, node);
     brancher.handleConditional(() => visit(node.condition),
                                () => visit(node.thenExpression),
                                () => visit(node.elseExpression));
   }
 
   visitStringInterpolation(StringInterpolation node) {
@@ skipping 1264 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }