Make special RPO computation iterative during scheduling.

test/cctest/compiler/test-instruction.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 #include "test/cctest/cctest.h"
 
 #include "src/compiler/code-generator.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
@@ skipping 121 matching lines @@
 
   BasicBlockVector* blocks = R.schedule.rpo_order();
   CHECK_EQ(static_cast<int>(blocks->size()), R.code->InstructionBlockCount());
 
   int index = 0;
   for (BasicBlockVectorIter i = blocks->begin(); i != blocks->end();
        i++, index++) {
     BasicBlock* block = *i;
     CHECK_EQ(block->rpo_number(), R.BlockAt(block)->rpo_number().ToInt());
     CHECK_EQ(block->id().ToInt(), R.BlockAt(block)->id().ToInt());
-    CHECK_EQ(-1, block->loop_end());
+    CHECK_EQ(NULL, block->loop_end());
   }
 }
 
 
 TEST(InstructionGetBasicBlock) {
   InstructionTester R;
 
   BasicBlock* b0 = R.schedule.start();
   BasicBlock* b1 = R.schedule.NewBasicBlock();
   BasicBlock* b2 = R.schedule.NewBasicBlock();
@@ skipping 205 matching lines @@
           CHECK_EQ(inputs[z], m->InputAt(z));
         }
 
         for (size_t z = 0; z < k; z++) {
           CHECK_EQ(temps[z], m->TempAt(z));
         }
       }
     }
   }
 }