PPC/s390:[turbofan][64][ptr-compr] Optimize Smi Tagging for 31 bit smis

Port edd50ad2

Change-Id: Ibad74933a6f70c6cbd2fb06f5d1a824f0a199609
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1935256Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Junliang Yan <jyan@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#65187}

src/compiler/backend/ppc/instruction-selector-ppc.cc

@@ -1137,6 +1137,12 @@ void InstructionSelector::VisitTryTruncateFloat64ToUint64(Node* node) {
   VisitTryTruncateDouble(this, kPPC_DoubleToUint64, node);
 }
 
+void InstructionSelector::VisitBitcastWord32ToWord64(Node* node) {
+  DCHECK(SmiValuesAre31Bits());
+  DCHECK(COMPRESS_POINTERS_BOOL);
+  EmitIdentity(node);
+}
+
 void InstructionSelector::VisitChangeInt32ToInt64(Node* node) {
   // TODO(mbrandy): inspect input to see if nop is appropriate.
   VisitRR(this, kPPC_ExtendSignWord32, node);

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

@@ -1613,6 +1613,12 @@ void InstructionSelector::VisitTryTruncateFloat64ToUint64(Node* node) {
 
 #endif
 
+void InstructionSelector::VisitBitcastWord32ToWord64(Node* node) {
+  DCHECK(SmiValuesAre31Bits());
+  DCHECK(COMPRESS_POINTERS_BOOL);
+  EmitIdentity(node);
+}
+
 void InstructionSelector::VisitFloat64Mod(Node* node) {
   S390OperandGenerator g(this);
   Emit(kS390_ModDouble, g.DefineAsFixed(node, d1),