Make special RPO computation iterative during scheduling.

test/cctest/compiler/test-scheduler.cc

Index: test/cctest/compiler/test-scheduler.cc
diff --git a/test/cctest/compiler/test-scheduler.cc b/test/cctest/compiler/test-scheduler.cc
index 0ade4d15ed1a6aa31083009d42676865ba280616..3a0103d8ac7749fe70e9364fb402e627007c859d 100644
--- a/test/cctest/compiler/test-scheduler.cc
+++ b/test/cctest/compiler/test-scheduler.cc
@@ -30,7 +30,7 @@ static void CheckRPONumbers(BasicBlockVector* order, size_t expected,
   for (int i = 0; i < static_cast<int>(order->size()); i++) {
     CHECK(order->at(i)->rpo_number() == i);
     if (!loops_allowed) {
-      CHECK_LT(order->at(i)->loop_end(), 0);
+      CHECK_EQ(NULL, order->at(i)->loop_end());
       CHECK_EQ(NULL, order->at(i)->loop_header());
     }
   }
@@ -40,19 +40,21 @@ static void CheckRPONumbers(BasicBlockVector* order, size_t expected,
 static void CheckLoop(BasicBlockVector* order, BasicBlock** blocks,
                       int body_size) {
   BasicBlock* header = blocks[0];
-  CHECK_GT(header->loop_end(), 0);
-  CHECK_EQ(body_size, (header->loop_end() - header->rpo_number()));
+  BasicBlock* end = header->loop_end();
+  CHECK_NE(NULL, end);
+  CHECK_GT(end->rpo_number(), 0);
+  CHECK_EQ(body_size, end->rpo_number() - header->rpo_number());
   for (int i = 0; i < body_size; i++) {
-    int num = blocks[i]->rpo_number();
-    CHECK(num >= header->rpo_number() && num < header->loop_end());
+    CHECK_GE(blocks[i]->rpo_number(), header->rpo_number());
+    CHECK_LT(blocks[i]->rpo_number(), end->rpo_number());
     CHECK(header->LoopContains(blocks[i]));
     CHECK(header->IsLoopHeader() || blocks[i]->loop_header() == header);
   }
   if (header->rpo_number() > 0) {
     CHECK_NE(order->at(header->rpo_number() - 1)->loop_header(), header);
   }
-  if (header->loop_end() < static_cast<int>(order->size())) {
-    CHECK_NE(order->at(header->loop_end())->loop_header(), header);
+  if (end->rpo_number() < static_cast<int>(order->size())) {
+    CHECK_NE(order->at(end->rpo_number())->loop_header(), header);
   }
 }