[turbofan] Add support for deferred code.

src/compiler/scheduler.cc

 // Copyright 2013 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 <deque>
 #include <queue>
 
 #include "src/compiler/scheduler.h"
 
 #include "src/compiler/graph.h"
@@ skipping 260 matching lines @@
     BasicBlock* branch_block = schedule_->block(branch_block_node);
     DCHECK(branch_block != NULL);
 
     BasicBlock* successor_blocks[2];
     CollectSuccessorBlocks(branch, successor_blocks, IrOpcode::kIfTrue,
                            IrOpcode::kIfFalse);
 
     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]);
   }
 
   void ConnectMerge(Node* merge) {
     // Don't connect the special merge at the end to its predecessors.
     if (IsFinalMerge(merge)) return;
 
     BasicBlock* block = schedule_->block(merge);
     DCHECK(block != NULL);
@@ skipping 897 matching lines @@
     current->set_loop_depth(loop_depth);
     if (current->loop_header() == NULL) {
       Trace("B%d is not in a loop (depth == %d)\n", current->id().ToInt(),
             current->loop_depth());
     } else {
       Trace("B%d has loop header B%d, (depth == %d)\n", current->id().ToInt(),
             current->loop_header()->id().ToInt(), current->loop_depth());
     }
   }
 
+  // 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);
 #endif
   return final_order;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8