Whenever possible use length passed to the List constructor for bounds checks instead of loading it…

runtime/vm/intermediate_language.cc

 // 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.
 
 #include "vm/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
 #include "vm/flow_graph_builder.h"
@@ skipping 1107 matching lines @@
 RawAbstractType* CheckSmiInstr::CompileType() const {
   return AbstractType::null();
 }
 
 
 RawAbstractType* CheckArrayBoundInstr::CompileType() const {
   return AbstractType::null();
 }
 
 
+RawAbstractType* CheckBoundInstr::CompileType() const {
+  return AbstractType::null();
+}
+
+
 RawAbstractType* CheckEitherNonSmiInstr::CompileType() const {
   return AbstractType::null();
 }
 
 
 // Optimizations that eliminate or simplify individual computations.
 Definition* Definition::Canonicalize() {
   return this;
 }
 
@@ skipping 36 matching lines @@
 
 Definition* CheckEitherNonSmiInstr::Canonicalize() {
   if ((left()->ResultCid() == kDoubleCid) ||
       (right()->ResultCid() == kDoubleCid)) {
     return NULL;  // Remove from the graph.
   }
   return this;
 }
 
 
+Definition* CheckArrayBoundInstr::Canonicalize() {
+  if (array_type() == kArrayCid) {
+    // For fixed length arrays check if array is the result of a constructor
+    // call. In this case we can use the length passed to the constructor
+    // instead of loading it from array itself.
+    StaticCallInstr* allocation = array()->definition()->AsStaticCall();
+    if ((allocation != NULL) &&
+        allocation->is_known_constructor() &&
+        (allocation->ResultCid() == kArrayCid)) {
+      CheckBoundInstr* check =
+          new CheckBoundInstr(allocation->ArgumentAt(0)->value()->Copy(),
+                              index(),
+                              deopt_id_);
+      check->set_env(env());
+      set_env(NULL);
+      return check;
+    }
+  }
+  return this;
+}
+
+
 // Shared code generation methods (EmitNativeCode, MakeLocationSummary, and
 // PrepareEntry). Only assembly code that can be shared across all architectures
 // can be used. Machine specific register allocation and code generation
 // is located in intermediate_language_<arch>.cc
 
 #define __ compiler->assembler()->
 
 void GraphEntryInstr::PrepareEntry(FlowGraphCompiler* compiler) {
   // Nothing to do.
 }
@@ skipping 469 matching lines @@
     value->set_use_index(use_index++);
     value->AddToEnvUseList();
   }
   instr->set_env(copy);
 }
 
 
 #undef __
 
 }  // namespace dart