S390: [turbofan] Introduce TruncateTaggedToWord32 simplified operator.

src/compiler/s390/instruction-selector-s390.cc

Index: src/compiler/s390/instruction-selector-s390.cc
diff --git a/src/compiler/s390/instruction-selector-s390.cc b/src/compiler/s390/instruction-selector-s390.cc
index 78b352bc11b3ae77224ee941eedd80b0be9a99fd..d74845ba4934fee851fa53e50cb363a52f8099f5 100644
--- a/src/compiler/s390/instruction-selector-s390.cc
+++ b/src/compiler/s390/instruction-selector-s390.cc
@@ -1043,13 +1043,11 @@ void InstructionSelector::VisitTruncateFloat64ToFloat32(Node* node) {
 }
 
 void InstructionSelector::VisitTruncateFloat64ToWord32(Node* node) {
-  switch (TruncationModeOf(node->op())) {
-    case TruncationMode::kJavaScript:
-      return VisitRR(this, kArchTruncateDoubleToI, node);
-    case TruncationMode::kRoundToZero:
-      return VisitRR(this, kS390_DoubleToInt32, node);
-  }
-  UNREACHABLE();
+  VisitRR(this, kArchTruncateDoubleToI, node);
+}
+
+void InstructionSelector::VisitRoundFloat64ToInt32(Node* node) {
+  VisitRR(this, kS390_DoubleToInt32, node);
 }
 
 void InstructionSelector::VisitTruncateFloat32ToInt32(Node* node) {