Eliminate unnecessary deoptimization environments.

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/dart_entry.h"
 #include "vm/debugger.h"
@@ skipping 183 matching lines @@
 
 Label* FlowGraphCompiler::AddDeoptStub(intptr_t deopt_id,
                                        intptr_t deopt_token_pos,
                                        intptr_t try_index,
                                        DeoptReasonId reason,
                                        Register reg1,
                                        Register reg2,
                                        Register reg3) {
   DeoptimizationStub* stub =
       new DeoptimizationStub(deopt_id, deopt_token_pos, try_index, reason);
+  ASSERT((pending_deoptimization_env_ != NULL) || !is_ssa_);

[srdjan, 2012/07/31 15:53:15]

Alternative would be to split this into two asserts and move them inside the
if-s

[Florian Schneider, 2012/08/01 11:46:36]

Done.

   if (pending_deoptimization_env_ == NULL) {
     frame_register_allocator()->SpillInDeoptStub(stub);
     if (reg1 != kNoRegister) stub->Push(reg1);
     if (reg2 != kNoRegister) stub->Push(reg2);
     if (reg3 != kNoRegister) stub->Push(reg3);
   } else {
     stub->set_deoptimization_env(pending_deoptimization_env_);
   }
   deopt_stubs_.Add(stub);
   return stub->entry_label();
@@ skipping 586 matching lines @@
       return;
     }
   }
 
   // This move is not blocked.
   EmitMove(index);
 }
 
 
 }  // namespace dart