[turbofan] Propagate "deferredness" to dominated basic blocks.

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

Review URL: https://codereview.chromium.org/686273005

Cr-Commit-Position: refs/heads/master@{#25141}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25141 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/compiler/scheduler.cc

@@ -415,8 +415,6 @@ class CFGBuilder {
                            IrOpcode::kIfFalse);
 
     // Consider branch hints.
-    // TODO(turbofan): Propagate the deferred flag to all blocks dominated by
-    // this IfTrue/IfFalse later.
     switch (BranchHintOf(branch->op())) {
       case BranchHint::kNone:
         break;
@@ -1061,6 +1059,8 @@ void Scheduler::GenerateImmediateDominatorTree() {
     }
     current->set_dominator(dominator);
     current->set_dominator_depth(dominator->dominator_depth() + 1);
+    // Propagate "deferredness" of the dominator.
+    if (dominator->deferred()) current->set_deferred(true);
     Trace("Block B%d's idom is B%d, depth = %d\n", current->id().ToInt(),
           dominator->id().ToInt(), current->dominator_depth());
   }

test/cctest/compiler/test-scheduler.cc

@@ -34,6 +34,17 @@ static void CheckRPONumbers(BasicBlockVector* order, size_t expected,
       CHECK_EQ(NULL, order->at(i)->loop_header());
     }
   }
+  int number = 0;
+  for (auto const block : *order) {
+    if (block->deferred()) continue;
+    CHECK_EQ(number, block->ao_number());
+    ++number;
+  }
+  for (auto const block : *order) {
+    if (!block->deferred()) continue;
+    CHECK_EQ(number, block->ao_number());
+    ++number;
+  }
 }
 
 
@@ -155,6 +166,7 @@ TEST(RPOLine) {
     BasicBlock* last = schedule.start();
     for (int j = 0; j < i; j++) {
       BasicBlock* block = schedule.NewBasicBlock();
+      block->set_deferred(i & 1);
       schedule.AddGoto(last, block);
       last = block;
     }