[turbofan] Also track Float64 fields in LoadElimination (on 64-bit platforms).

src/compiler/load-elimination.cc

 // Copyright 2016 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/load-elimination.h"
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/simplified-operator.h"
@@ skipping 879 matching lines @@
   if (field_index >= static_cast<int>(kMaxTrackedFields)) return -1;
   return field_index;
 }
 
 // static
 int LoadElimination::FieldIndexOf(FieldAccess const& access) {
   MachineRepresentation rep = access.machine_type.representation();
   switch (rep) {
     case MachineRepresentation::kNone:
     case MachineRepresentation::kBit:
+    case MachineRepresentation::kSimd128:
       UNREACHABLE();
       break;
     case MachineRepresentation::kWord32:
     case MachineRepresentation::kWord64:
       if (rep != MachineType::PointerRepresentation()) {
         return -1;  // We currently only track pointer size fields.
       }
       break;
     case MachineRepresentation::kWord8:
     case MachineRepresentation::kWord16:
     case MachineRepresentation::kFloat32:
       return -1;  // Currently untracked.
     case MachineRepresentation::kFloat64:
-    case MachineRepresentation::kSimd128:
-      return -1;  // Currently untracked.
+      if (kDoubleSize != kPointerSize) {
+        return -1;  // We currently only track pointer size fields.
+      }
+    // Fall through.
     case MachineRepresentation::kTaggedSigned:
     case MachineRepresentation::kTaggedPointer:
     case MachineRepresentation::kTagged:
       // TODO(bmeurer): Check that we never do overlapping load/stores of
-      // individual parts of Float64/Simd128 values.
+      // individual parts of Float64 values.
       break;
   }
-  DCHECK_EQ(kTaggedBase, access.base_is_tagged);
+  if (access.base_is_tagged != kTaggedBase) {
+    return -1;  // We currently only track tagged objects.
+  }
   return FieldIndexOf(access.offset);
 }
 
 CommonOperatorBuilder* LoadElimination::common() const {
   return jsgraph()->common();
 }
 
 Graph* LoadElimination::graph() const { return jsgraph()->graph(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8