VM: Constant fold more loads from constants in the optimizer.

runtime/vm/constant_propagator.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/constant_propagator.h"
 
 #include "vm/bit_vector.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
 #include "vm/flow_graph_range_analysis.h"
@@ skipping 813 matching lines @@
                               ->num_elements();
     if (num_elements->BindsToConstant() &&
         num_elements->BoundConstant().IsSmi()) {
       intptr_t length = Smi::Cast(num_elements->BoundConstant()).Value();
       const Object& result = Smi::ZoneHandle(Z, Smi::New(length));
       SetValue(instr, result);
       return;
     }
   }
 
-  if (instr->IsImmutableLengthLoad()) {
-    ConstantInstr* constant =
-        instance->definition()->OriginalDefinition()->AsConstant();
-    if (constant != NULL) {
-      if (constant->value().IsString()) {
+  const Object& constant = instance->definition()->constant_value();
+  if (IsConstant(constant)) {
+    if (instr->IsImmutableLengthLoad()) {
+      if (constant.IsString()) {
         SetValue(instr,
-                 Smi::ZoneHandle(
-                     Z, Smi::New(String::Cast(constant->value()).Length())));
+                 Smi::ZoneHandle(Z, Smi::New(String::Cast(constant).Length())));
         return;
       }
-      if (constant->value().IsArray()) {
+      if (constant.IsArray()) {
         SetValue(instr,
-                 Smi::ZoneHandle(
-                     Z, Smi::New(Array::Cast(constant->value()).Length())));
+                 Smi::ZoneHandle(Z, Smi::New(Array::Cast(constant).Length())));
         return;
       }
-      if (constant->value().IsTypedData()) {
-        SetValue(instr,
-                 Smi::ZoneHandle(
-                     Z, Smi::New(TypedData::Cast(constant->value()).Length())));
+      if (constant.IsTypedData()) {
+        SetValue(instr, Smi::ZoneHandle(
+                            Z, Smi::New(TypedData::Cast(constant).Length())));
+        return;
+      }
+    } else {
+      Object& value = Object::Handle();
+      if (instr->Evaluate(constant, &value)) {
+        SetValue(instr, Object::ZoneHandle(Z, value.raw()));
         return;
       }
     }
   }
+
   SetValue(instr, non_constant_);
 }
 
 
 void ConstantPropagator::VisitInstantiateType(InstantiateTypeInstr* instr) {
   const Object& object =
       instr->instantiator_type_arguments()->definition()->constant_value();
   if (IsNonConstant(object)) {
     SetValue(instr, non_constant_);
     return;
@@ skipping 863 matching lines @@
   GrowableArray<BitVector*> dominance_frontier;
   graph_->ComputeDominators(&dominance_frontier);
 
   if (FLAG_trace_constant_propagation &&
       FlowGraphPrinter::ShouldPrint(graph_->function())) {
     FlowGraphPrinter::PrintGraph("After CP", graph_);
   }
 }
 
 }  // namespace dart