[turbofan] Propagate word32 truncations through tagged-hole checks.

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 1842 matching lines @@
         ProcessInput(node, 0, UseInfo::TruncatingFloat64());
         ProcessRemainingInputs(node, 1);
         SetOutput(node, MachineRepresentation::kFloat64);
         if (truncation.TruncatesToFloat64() &&
             mode == CheckFloat64HoleMode::kAllowReturnHole) {
           if (lower()) DeferReplacement(node, node->InputAt(0));
         }
         return;
       }
       case IrOpcode::kCheckTaggedHole: {
-        ProcessInput(node, 0, UseInfo::AnyTagged());
-        ProcessRemainingInputs(node, 1);
-        SetOutput(node, MachineRepresentation::kTagged);
+        CheckTaggedHoleMode mode = CheckTaggedHoleModeOf(node->op());
+        if (truncation.TruncatesToWord32() &&
+            mode == CheckTaggedHoleMode::kConvertHoleToUndefined) {
+          ProcessInput(node, 0, UseInfo::CheckedSigned32AsWord32());
+          ProcessRemainingInputs(node, 1);
+          SetOutput(node, MachineRepresentation::kWord32);
+          if (lower()) DeferReplacement(node, node->InputAt(0));
+        } else {
+          ProcessInput(node, 0, UseInfo::AnyTagged());
+          ProcessRemainingInputs(node, 1);
+          SetOutput(node, MachineRepresentation::kTagged);
+        }
         return;
       }
 
       //------------------------------------------------------------------
       // Machine-level operators.
       //------------------------------------------------------------------
       case IrOpcode::kLoad: {
         // TODO(jarin) Eventually, we should get rid of all machine stores
         // from the high-level phases, then this becomes UNREACHABLE.
         LoadRepresentation rep = LoadRepresentationOf(node->op());
@@ skipping 1180 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