Scheduler checks that end block doesn't have successors.

R=jarin@chromium.org
TEST=cctest/test-scheduler/RPOLoop

Review URL: https://codereview.chromium.org/710333002

Cr-Commit-Position: refs/heads/master@{#25281}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25281 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler/scheduler.cc

@@ -534,9 +534,9 @@ class SpecialRPONumberer : public ZoneObject {
   // Computes the special reverse-post-order for the main control flow graph,
   // that is for the graph spanned between the schedule's start and end blocks.
   void ComputeSpecialRPO() {
+    DCHECK(schedule_->end()->SuccessorCount() == 0);
     DCHECK_EQ(NULL, order_);  // Main order does not exist yet.
-    // TODO(mstarzinger): Should use Schedule::end() after tests are fixed.
-    ComputeAndInsertSpecialRPO(schedule_->start(), NULL);
+    ComputeAndInsertSpecialRPO(schedule_->start(), schedule_->end());
   }
 
   // Computes the special reverse-post-order for a partial control flow graph,

test/cctest/compiler/test-scheduler.cc

@@ -201,12 +201,13 @@ TEST(RPOSelfLoop) {
 TEST(RPOEntryLoop) {
   HandleAndZoneScope scope;
   Schedule schedule(scope.main_zone());
-  schedule.AddSuccessorForTesting(schedule.start(), schedule.end());
-  schedule.AddSuccessorForTesting(schedule.end(), schedule.start());
+  BasicBlock* body = schedule.NewBasicBlock();
+  schedule.AddSuccessorForTesting(schedule.start(), body);
+  schedule.AddSuccessorForTesting(body, schedule.start());
   BasicBlockVector* order =
       Scheduler::ComputeSpecialRPO(scope.main_zone(), &schedule);
   CheckRPONumbers(order, 2, true);
-  BasicBlock* loop[] = {schedule.start(), schedule.end()};
+  BasicBlock* loop[] = {schedule.start(), body};
   CheckLoop(order, loop, 2);
 }
 
@@ -648,7 +649,7 @@ TEST(RPOLoopMultibackedge) {
   BasicBlock* A = schedule.start();
   BasicBlock* B = schedule.NewBasicBlock();
   BasicBlock* C = schedule.NewBasicBlock();
-  BasicBlock* D = schedule.end();
+  BasicBlock* D = schedule.NewBasicBlock();
   BasicBlock* E = schedule.NewBasicBlock();
 
   schedule.AddSuccessorForTesting(A, B);