[turbofan] Fix GVN of projections and add verification for projection uniqueness.

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 "src/compiler/scheduler.h"
 
 #include <iomanip>
 
 #include "src/bit-vector.h"
 #include "src/compiler/common-operator.h"
@@ skipping 1383 matching lines @@
     for (BasicBlock* pred_block : block->predecessors()) {
       DCHECK_LT(pred_block->id().ToSize(), marked_.size());
       if (marked_[pred_block->id().ToSize()]) continue;
       marking_queue_.push_back(pred_block);
     }
   }
 
   BasicBlock* SplitNode(BasicBlock* block, Node* node) {
     // For now, we limit splitting to pure nodes.
     if (!node->op()->HasProperty(Operator::kPure)) return block;
+    // TODO(titzer): fix the special case of splitting of projections.
+    if (node->opcode() == IrOpcode::kProjection) return block;
 
     // The {block} is common dominator of all uses of {node}, so we cannot
     // split anything unless the {block} has at least two successors.
     DCHECK_EQ(block, GetCommonDominatorOfUses(node));
     if (block->SuccessorCount() < 2) return block;
 
     // Clear marking bits.
     DCHECK(marking_queue_.empty());
     std::fill(marked_.begin(), marked_.end(), false);
     marked_.resize(schedule_->BasicBlockCount() + 1, false);
@@ skipping 152 matching lines @@
 
   Node* CloneNode(Node* node) {
     int const input_count = node->InputCount();
     Node** const inputs = scheduler_->zone_->NewArray<Node*>(input_count);
     for (int index = 0; index < input_count; ++index) {
       Node* const input = node->InputAt(index);
       scheduler_->IncrementUnscheduledUseCount(input, index, node);
       inputs[index] = input;
     }
     Node* copy = scheduler_->graph_->NewNode(node->op(), input_count, inputs);
+    TRACE(("clone #%d:%s -> #%d\n"), node->id(), node->op()->mnemonic(),
+          copy->id());
     scheduler_->node_data_.resize(copy->id() + 1,
                                   scheduler_->DefaultSchedulerData());
     scheduler_->node_data_[copy->id()] = scheduler_->node_data_[node->id()];
     return copy;
   }
 
   Scheduler* scheduler_;
   Schedule* schedule_;
   BoolVector marked_;
   ZoneDeque<BasicBlock*> marking_queue_;
@@ skipping 100 matching lines @@
   for (Node* const node : *nodes) {
     schedule_->SetBlockForNode(to, node);
     scheduled_nodes_[to->id().ToSize()].push_back(node);
   }
   nodes->clear();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8