Make floating merges respected minimum RPO of coupled pihs.

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 984 matching lines @@
 
   // Propagates {block} as another minimum RPO placement into the given {node}.
   // This has the net effect of computing the maximum of the minimum RPOs for
   // all inputs to {node} when the queue has been fully processed.
   void PropagateMinimumRPOToNode(BasicBlock* block, Node* node) {
     Scheduler::SchedulerData* data = scheduler_->GetData(node);
 
     // No need to propagate to fixed node, it's guaranteed to be a root.
     if (scheduler_->GetPlacement(node) == Scheduler::kFixed) return;
 
+    // Coupled nodes influence schedule early position of their control.
+    if (scheduler_->GetPlacement(node) == Scheduler::kCoupled) {
+      Node* control = NodeProperties::GetControlInput(node);
+      PropagateMinimumRPOToNode(block, control);
+    }
+
     // Propagate new position if it is larger than the current.
     if (block->rpo_number() > data->minimum_block_->rpo_number()) {
       data->minimum_block_ = block;
       queue_.push(node);
       Trace("Propagating #%d:%s minimum_rpo = %d\n", node->id(),
             node->op()->mnemonic(), data->minimum_block_->rpo_number());
     }
   }
 
   Scheduler* scheduler_;
@@ skipping 282 matching lines @@
   start->ReplaceInput(NodeProperties::FirstControlIndex(start), block_start);
 
   Trace("  Connecting floating control start %d:%s to %d:%s\n", start->id(),
         start->op()->mnemonic(), block_start->id(),
         block_start->op()->mnemonic());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8