Improve array bounds check elimination for growable lists.

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/bigint_operations.h"
 #include "vm/bit_vector.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
@@ skipping 111 matching lines @@
       unary_checks().HasReceiverClassId(kTwoByteStringCid);
   return externalizable ? EffectSet::Externalization() : EffectSet::None();
 }
 
 
 bool GuardFieldInstr::AttributesEqual(Instruction* other) const {
   return field().raw() == other->AsGuardField()->field().raw();
 }
 
 
-bool CheckArrayBoundInstr::AttributesEqual(Instruction* other) const {
-  CheckArrayBoundInstr* other_check = other->AsCheckArrayBound();
-  ASSERT(other_check != NULL);
-  return array_type() == other_check->array_type();
-}
-
-
 bool AssertAssignableInstr::AttributesEqual(Instruction* other) const {
   AssertAssignableInstr* other_assert = other->AsAssertAssignable();
   ASSERT(other_assert != NULL);
   // This predicate has to be commutative for DominatorBasedCSE to work.
   // TODO(fschneider): Eliminate more asserts with subtype relation.
   return dst_type().raw() == other_assert->dst_type().raw();
 }
 
 
 bool StrictCompareInstr::AttributesEqual(Instruction* other) const {
@@ skipping 2191 matching lines @@
   return false;
 }
 
 
 bool CheckArrayBoundInstr::IsFixedLengthArrayType(intptr_t cid) {
   return LoadFieldInstr::IsFixedLengthArrayCid(cid);
 }
 
 
 bool CheckArrayBoundInstr::IsRedundant(RangeBoundary length) {
-  // Check that array has an immutable length.
-  if (!IsFixedLengthArrayType(array_type())) {
-    return false;
-  }
-
   Range* index_range = index()->definition()->range();
 
   // Range of the index is unknown can't decide if the check is redundant.
   if (index_range == NULL) {
     return false;
   }
 
   // Range of the index is not positive. Check can't be redundant.
   if (Range::ConstantMin(index_range).value() < 0) {
     return false;
@@ skipping 138 matching lines @@
     default:
       UNREACHABLE();
   }
   return kPowRuntimeEntry;
 }
 
 
 #undef __
 
 }  // namespace dart