[arm][arm64] Improve CountTrailingZero implementation.

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

Index: src/compiler/ppc/instruction-selector-ppc.cc
diff --git a/src/compiler/ppc/instruction-selector-ppc.cc b/src/compiler/ppc/instruction-selector-ppc.cc
index d3de14bf55d76c7fec6b9b3e0eaf7a6cfc10a1e5..7519c9883de99fdabb1c1bd907af9498b5c5a028 100644
--- a/src/compiler/ppc/instruction-selector-ppc.cc
+++ b/src/compiler/ppc/instruction-selector-ppc.cc
@@ -825,6 +825,14 @@ void InstructionSelector::VisitWord64Ctz(Node* node) { UNREACHABLE(); }
 #endif
 
 
+void InstructionSelector::VisitWord32ReverseBits(Node* node) { UNREACHABLE(); }
+
+
+#if V8_TARGET_ARCH_PPC64
+void InstructionSelector::VisitWord64ReverseBits(Node* node) { UNREACHABLE(); }
+#endif
+
+
 void InstructionSelector::VisitInt32Add(Node* node) {
   VisitBinop<Int32BinopMatcher>(this, node, kPPC_Add, kInt16Imm);
 }