[turbofan] Introduce TruncateTaggedToWord32 simplified operator.

src/compiler/arm/instruction-selector-arm.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/base/adapters.h"
 #include "src/base/bits.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
@@ skipping 1124 matching lines @@
   VisitRR(this, kArmVcvtU32F64, node);
 }
 
 void InstructionSelector::VisitTruncateFloat64ToUint32(Node* node) {
   VisitRR(this, kArmVcvtU32F64, node);
 }
 void InstructionSelector::VisitTruncateFloat64ToFloat32(Node* node) {
   VisitRR(this, kArmVcvtF32F64, node);
 }
 
+void InstructionSelector::VisitTruncateFloat64ToWord32(Node* node) {
+  VisitRR(this, kArchTruncateDoubleToI, node);
+}
 
-void InstructionSelector::VisitTruncateFloat64ToInt32(Node* node) {
-  switch (TruncationModeOf(node->op())) {
-    case TruncationMode::kJavaScript:
-      return VisitRR(this, kArchTruncateDoubleToI, node);
-    case TruncationMode::kRoundToZero:
-      return VisitRR(this, kArmVcvtS32F64, node);
-  }
-  UNREACHABLE();
+void InstructionSelector::VisitRoundFloat64ToInt32(Node* node) {
+  VisitRR(this, kArmVcvtS32F64, node);
 }
 
 
 void InstructionSelector::VisitBitcastFloat32ToInt32(Node* node) {
   VisitRR(this, kArmVmovLowU32F64, node);
 }
 
 
 void InstructionSelector::VisitBitcastInt32ToFloat32(Node* node) {
   ArmOperandGenerator g(this);
@@ skipping 697 matching lines @@
              MachineOperatorBuilder::kFloat32Max |
              MachineOperatorBuilder::kFloat64Min |
              MachineOperatorBuilder::kFloat64Max;
   }
   return flags;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8