VM: Propagate non-nullness from instance calls.

runtime/vm/intermediate_language.cc

 // 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.
 
 #include "vm/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/bootstrap.h"
 #include "vm/compiler.h"
 #include "vm/constant_propagator.h"
@@ skipping 1920 matching lines @@
 Instruction* Instruction::Canonicalize(FlowGraph* flow_graph) {
   return this;
 }
 
 
 Definition* Definition::Canonicalize(FlowGraph* flow_graph) {
   return this;
 }
 
 
+Definition* RedefinitionInstr::Canonicalize(FlowGraph* flow_graph) {
+  if (!HasUses()) {
+    return NULL;
+  }
+  if ((constrained_type() != NULL) &&
+      Type()->IsEqualTo(value()->definition()->Type())) {
+    return value()->definition();
+  }
+  return this;
+}
+
+
 bool LoadFieldInstr::IsImmutableLengthLoad() const {
   switch (recognized_kind()) {
     case MethodRecognizer::kObjectArrayLength:
     case MethodRecognizer::kImmutableArrayLength:
     case MethodRecognizer::kTypedDataLength:
     case MethodRecognizer::kStringBaseLength:
       return true;
     default:
       return false;
   }
@@ skipping 2018 matching lines @@
   set_native_c_function(native_function);
   function().SetIsNativeAutoSetupScope(auto_setup_scope);
   Dart_NativeEntryResolver resolver = library.native_entry_resolver();
   bool is_bootstrap_native = Bootstrap::IsBootstapResolver(resolver);
   set_is_bootstrap_native(is_bootstrap_native);
 }
 
 #undef __
 
 }  // namespace dart