Attempt to fix xcode build.

runtime/vm/flow_graph_compiler.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/globals.h"  // Needed here to get TARGET_ARCH_XXX.
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
@@ skipping 1338 matching lines @@
     resolver_->RestoreFpuScratch(reg_);
   }
 }
 
 
 ParallelMoveResolver::ScratchRegisterScope::ScratchRegisterScope(
     ParallelMoveResolver* resolver, Register blocked)
     : resolver_(resolver),
       reg_(kNoRegister),
       spilled_(false) {
-  uword blocked_mask = ((blocked != kNoRegister) ? 1 << blocked : 0)
+  uword blocked_mask = ((blocked > kNoRegister) ? 1 << blocked : 0)
                      | 1 << CTX
                      | 1 << SPREG
                      | 1 << FPREG
-                     | ((TMP != kNoRegister) ? 1 << TMP : 0)
-                     | ((TMP2 != kNoRegister) ? 1 << TMP2 : 0)
-                     | ((PP != kNoRegister) ? 1 << PP : 0);
+                     | ((TMP > kNoRegister) ? 1 << TMP : 0)
+                     | ((TMP2 > kNoRegister) ? 1 << TMP2 : 0)
+                     | ((PP > kNoRegister) ? 1 << PP : 0);
   reg_ = static_cast<Register>(
       resolver_->AllocateScratchRegister(Location::kRegister,
                                          blocked_mask,
                                          kFirstFreeCpuRegister,
                                          kLastFreeCpuRegister,
                                          &spilled_));
 
   if (spilled_) {
     resolver->SpillScratch(reg_);
   }
@@ skipping 83 matching lines @@
     threshold = FLAG_optimization_counter_scale * basic_blocks +
         FLAG_min_optimization_counter_threshold;
     if (threshold > FLAG_optimization_counter_threshold) {
       threshold = FLAG_optimization_counter_threshold;
     }
   }
   return threshold;
 }
 
 }  // namespace dart