Some micro-optimizations in the scheduler.

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/bit-vector.h"
@@ skipping 1045 matching lines @@
 
 
 void Scheduler::GenerateImmediateDominatorTree() {
   Trace("--- IMMEDIATE BLOCK DOMINATORS -----------------------------\n");
 
   // TODO(danno): Consider using Lengauer & Tarjan's if this becomes too slow.
 
   // Build the block dominator tree.
   schedule_->start()->set_dominator_depth(0);
   typedef SpecialRPONumberer::BlockList BlockList;
-  for (BlockList* l = special_rpo_->order_; l != NULL; l = l->next) {
+  DCHECK_EQ(schedule_->start(), special_rpo_->order_->block);
+  for (BlockList* l = special_rpo_->order_->next; l != NULL; l = l->next) {
     BasicBlock* current = l->block;
-    if (current == schedule_->start()) continue;
     BasicBlock::Predecessors::iterator pred = current->predecessors_begin();
     BasicBlock::Predecessors::iterator end = current->predecessors_end();
     DCHECK(pred != end);  // All blocks except start have predecessors.
     BasicBlock* dominator = *pred;
     // For multiple predecessors, walk up the dominator tree until a common
     // dominator is found. Visitation order guarantees that all predecessors
     // except for backwards edges have been visited.
     for (++pred; pred != end; ++pred) {
       // Don't examine backwards edges.
       if ((*pred)->dominator_depth() < 0) continue;
@@ skipping 424 matching lines @@
   for (NodeVectorIter i = nodes->begin(); i != nodes->end(); ++i) {
     schedule_->SetBlockForNode(to, *i);
     scheduled_nodes_[to->id().ToSize()].push_back(*i);
   }
   nodes->clear();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8