[turbofan] Don't propagate truncations if output is tagged.

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 894 matching lines @@
     if (lower()) {
       // Update the select operator.
       SelectParameters p = SelectParametersOf(node->op());
       if (output != p.representation()) {
         NodeProperties::ChangeOp(node,
                                  lowering->common()->Select(output, p.hint()));
       }
     }
     // Convert inputs to the output representation of this phi, pass the
     // truncation truncation along.
+    if (output == MachineRepresentation::kTagged) {
+      truncation = Truncation::Any();
+    }
     UseInfo input_use(output, truncation);
     ProcessInput(node, 1, input_use);
     ProcessInput(node, 2, input_use);
   }
 
   // Helper for handling phis.
   void VisitPhi(Node* node, Truncation truncation,
                 SimplifiedLowering* lowering) {
     MachineRepresentation output =
         GetOutputInfoForPhi(node, TypeOf(node), truncation);
     // Only set the output representation if not running with type
     // feedback. (Feedback typing will set the representation.)
     SetOutput(node, output);
 
     int values = node->op()->ValueInputCount();
     if (lower()) {
       // Update the phi operator.
       if (output != PhiRepresentationOf(node->op())) {
         NodeProperties::ChangeOp(node, lowering->common()->Phi(output, values));
       }
     }
 
     // Convert inputs to the output representation of this phi, pass the
     // truncation along.
+    if (output == MachineRepresentation::kTagged) {
+      truncation = Truncation::Any();
+    }
     UseInfo input_use(output, truncation);
     for (int i = 0; i < node->InputCount(); i++) {
       ProcessInput(node, i, i < values ? input_use : UseInfo::None());
     }
   }
 
   void VisitCall(Node* node, SimplifiedLowering* lowering) {
     const CallDescriptor* desc = CallDescriptorOf(node->op());
     int params = static_cast<int>(desc->ParameterCount());
     int value_input_count = node->op()->ValueInputCount();
@@ skipping 1459 matching lines @@
         return;
       case IrOpcode::kStateValues:
         return VisitStateValues(node);
       case IrOpcode::kTypeGuard: {
         // We just get rid of the sigma here. In principle, it should be
         // possible to refine the truncation and representation based on
         // the sigma's type.
         MachineRepresentation output =
             GetOutputInfoForPhi(node, TypeOf(node->InputAt(0)), truncation);
 
+        if (output == MachineRepresentation::kTagged) {
+          truncation = Truncation::Any();
+        }
         VisitUnop(node, UseInfo(output, truncation), output);
         if (lower()) DeferReplacement(node, node->InputAt(0));
         return;
       }
 
       // Operators with all inputs tagged and no or tagged output have uniform
       // handling.
       case IrOpcode::kEnd:
       case IrOpcode::kReturn:
       case IrOpcode::kIfSuccess:
@@ skipping 766 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