[arm][arm64] Improve CountTrailingZero implementation.

src/compiler/instruction-selector.cc

Index: src/compiler/instruction-selector.cc
diff --git a/src/compiler/instruction-selector.cc b/src/compiler/instruction-selector.cc
index aea29eb24eec6cfed91499074a58a15fc79b100c..00885f02d1695aeadee651cdff7232d36524f90f 100644
--- a/src/compiler/instruction-selector.cc
+++ b/src/compiler/instruction-selector.cc
@@ -867,6 +867,8 @@ void InstructionSelector::VisitNode(Node* node) {
       return MarkAsWord32(node), VisitWord32Clz(node);
     case IrOpcode::kWord32Ctz:
       return MarkAsWord32(node), VisitWord32Ctz(node);
+    case IrOpcode::kWord32ReverseBits:
+      return MarkAsWord32(node), VisitWord32ReverseBits(node);
     case IrOpcode::kWord32Popcnt:
       return MarkAsWord32(node), VisitWord32Popcnt(node);
     case IrOpcode::kWord64Popcnt:
@@ -889,6 +891,8 @@ void InstructionSelector::VisitNode(Node* node) {
       return MarkAsWord64(node), VisitWord64Clz(node);
     case IrOpcode::kWord64Ctz:
       return MarkAsWord64(node), VisitWord64Ctz(node);
+    case IrOpcode::kWord64ReverseBits:
+      return MarkAsWord64(node), VisitWord64ReverseBits(node);
     case IrOpcode::kWord64Equal:
       return VisitWord64Equal(node);
     case IrOpcode::kInt32Add:
@@ -1179,6 +1183,11 @@ void InstructionSelector::VisitWord64Clz(Node* node) { UNIMPLEMENTED(); }
 void InstructionSelector::VisitWord64Ctz(Node* node) { UNIMPLEMENTED(); }
 
 
+void InstructionSelector::VisitWord64ReverseBits(Node* node) {
+  UNIMPLEMENTED();
+}
+
+
 void InstructionSelector::VisitWord64Popcnt(Node* node) { UNIMPLEMENTED(); }