[turbofan] Add support for deferred code.

src/compiler/scheduler.cc

Index: src/compiler/scheduler.cc
diff --git a/src/compiler/scheduler.cc b/src/compiler/scheduler.cc
index 42ee0c4fb44ea8eb4f240877533197136e09b9ca..eb18b3939a55b4ec9fb8454867339d4630adc134 100644
--- a/src/compiler/scheduler.cc
+++ b/src/compiler/scheduler.cc
@@ -278,6 +278,20 @@ class CFGBuilder {
     TraceConnect(branch, branch_block, successor_blocks[0]);
     TraceConnect(branch, branch_block, successor_blocks[1]);
 
+    // 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;
+      case BranchHint::kTrue:
+        successor_blocks[1]->set_deferred(true);
+        break;
+      case BranchHint::kFalse:
+        successor_blocks[0]->set_deferred(true);
+        break;
+    }
+
     schedule_->AddBranch(branch_block, branch, successor_blocks[0],
                          successor_blocks[1]);
   }
@@ -1195,6 +1209,18 @@ BasicBlockVector* Scheduler::ComputeSpecialRPO(ZonePool* zone_pool,
     }
   }
 
+  // Compute the assembly order (non-deferred code first, deferred code
+  // afterwards).
+  int32_t number = 0;
+  for (auto block : *final_order) {
+    if (block->deferred()) continue;
+    block->set_ao_number(number++);
+  }
+  for (auto block : *final_order) {
+    if (!block->deferred()) continue;
+    block->set_ao_number(number++);
+  }
+
 #if DEBUG
   if (FLAG_trace_turbo_scheduler) PrintRPO(num_loops, loops, final_order);
   VerifySpecialRPO(num_loops, loops, final_order);