Optimize function at its entry instead of at exit.

runtime/vm/flow_graph_compiler.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/globals.h"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/cha.h"
 #include "vm/dart_entry.h"
@@ skipping 160 matching lines @@
   return parsed_function().function().has_finally();
 }
 
 
 void FlowGraphCompiler::InitCompiler() {
   pc_descriptors_list_ = new DescriptorList(64);
   exception_handlers_list_ = new ExceptionHandlerList();
   block_info_.Clear();
   for (int i = 0; i < block_order_.length(); ++i) {
     block_info_.Add(new BlockInfo());
+    if (is_optimizing()) {
+      BlockEntryInstr* entry = block_order_[i];
+      for (ForwardInstructionIterator it(entry); !it.Done(); it.Advance()) {
+        Instruction* current = it.Current();
+        const ICData* ic_data = NULL;
+        if (current->IsBranch()) {
+          current = current->AsBranch()->comparison();
+        }
+        // In optimized code, ICData is always set in the instructions.
+        if (current->IsInstanceCall()) {
+          ic_data = current->AsInstanceCall()->ic_data();
+          ASSERT(ic_data != NULL);
+        } else if (current->IsRelationalOp()) {
+          ic_data = current->AsRelationalOp()->ic_data();
+          ASSERT(ic_data != NULL);
+        } else if (current->IsEqualityCompare()) {
+          ic_data = current->AsEqualityCompare()->ic_data();
+          ASSERT(ic_data != NULL);
+        }
+        if ((ic_data != NULL) && (ic_data->NumberOfChecks() == 0)) {
+          may_reoptimize_ = true;
+          break;
+        }
+      }
+    }
   }
 }
 
 
 bool FlowGraphCompiler::CanOptimize() {
   return !FLAG_report_usage_count &&
          (FLAG_optimization_counter_threshold >= 0);
 }
 
 
@@ skipping 318 matching lines @@
       label_address = StubCode::ClosureCallInlineCacheEntryPoint();
       ExternalLabel target_label("InlineCache", label_address);
       EmitInstanceCall(&target_label,
                        ICData::ZoneHandle(ic_data.AsUnaryClassChecks()),
                        arguments_descriptor, argument_count,
                        deopt_id, token_pos, locs);
       return;
     }
     // Emit IC call that will count and thus may need reoptimization at
     // return instruction.
-    may_reoptimize_ = true;
+    ASSERT(!is_optimizing() || may_reoptimize());
     switch (ic_data.num_args_tested()) {
       case 1:
         label_address = StubCode::OneArgOptimizedCheckInlineCacheEntryPoint();
         break;
       case 2:
         label_address = StubCode::TwoArgsOptimizedCheckInlineCacheEntryPoint();
         break;
       case 3:
         label_address =
             StubCode::ThreeArgsOptimizedCheckInlineCacheEntryPoint();
@@ skipping 555 matching lines @@
     const AbstractTypeArguments& type_arguments =
         AbstractTypeArguments::Handle(type.arguments());
     const bool is_raw_type = type_arguments.IsNull() ||
         type_arguments.IsRaw(type_arguments.Length());
     return is_raw_type;
   }
   return true;
 }
 
 }  // namespace dart