[turbofan] Handle impossible types (Type::None()) in the backend.

src/compiler/simplified-lowering.cc

 // Copyright 2014 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/simplified-lowering.h"
 
 #include <limits>
 
 #include "src/address-map.h"
 #include "src/base/bits.h"
@@ skipping 550 matching lines @@
     // Run propagation phase to a fixpoint.
     TRACE("--{Propagation phase}--\n");
     phase_ = PROPAGATE;
     EnqueueInitial(jsgraph_->graph()->end());
     // Process nodes from the queue until it is empty.
     while (!queue_.empty()) {
       Node* node = queue_.front();
       NodeInfo* info = GetInfo(node);
       queue_.pop();
       info->set_visited();
-      TRACE(" visit #%d: %s\n", node->id(), node->op()->mnemonic());
+      TRACE(" visit #%d: %s (trunc: %s)\n", node->id(), node->op()->mnemonic(),
+            info->truncation().description());
       VisitNode(node, info->truncation(), nullptr);
       TRACE("  ==> output ");
       PrintOutputInfo(info);
       TRACE("\n");
     }
   }
 
   void Run(SimplifiedLowering* lowering) {
     RunTruncationPropagationPhase();
 
@@ skipping 46 matching lines @@
 #ifdef DEBUG
     // Check monotonicity of input requirements.
     node_input_use_infos_[use_node->id()].SetAndCheckInput(use_node, index,
                                                            use_info);
 #endif  // DEBUG
     if (info->unvisited()) {
       // First visit of this node.
       info->set_queued();
       nodes_.push_back(node);
       queue_.push(node);
-      TRACE("  initial: ");
+      TRACE("  initial #%i: ", node->id());
       info->AddUse(use_info);
       PrintTruncation(info->truncation());
       return;
     }
-    TRACE("   queue?: ");
+    TRACE("   queue #%i?: ", node->id());
     PrintTruncation(info->truncation());
     if (info->AddUse(use_info)) {
       // New usage information for the node is available.
       if (!info->queued()) {
         queue_.push(node);
         info->set_queued();
         TRACE("   added: ");
       } else {
         TRACE(" inqueue: ");
       }
@@ skipping 2784 matching lines @@
         isolate(), graph()->zone(), callable.descriptor(), 0, flags,
         Operator::kNoProperties);
     to_number_operator_.set(common()->Call(desc));
   }
   return to_number_operator_.get();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8