[arm][arm64] Improve CountTrailingZero implementation.

src/compiler/mips64/instruction-selector-mips64.cc

Index: src/compiler/mips64/instruction-selector-mips64.cc
diff --git a/src/compiler/mips64/instruction-selector-mips64.cc b/src/compiler/mips64/instruction-selector-mips64.cc
index c539600506d9ec1aed30eabb4b941c14681806ee..9f3aff602ce09d133467b9a4ec8ddad96a98b294 100644
--- a/src/compiler/mips64/instruction-selector-mips64.cc
+++ b/src/compiler/mips64/instruction-selector-mips64.cc
@@ -562,6 +562,12 @@ void InstructionSelector::VisitWord32Clz(Node* node) {
 }
 
 
+void InstructionSelector::VisitWord32ReverseBits(Node* node) { UNREACHABLE(); }
+
+
+void InstructionSelector::VisitWord64ReverseBits(Node* node) { UNREACHABLE(); }
+
+
 void InstructionSelector::VisitWord32Ctz(Node* node) {
   Mips64OperandGenerator g(this);
   Emit(kMips64Ctz, g.DefineAsRegister(node), g.UseRegister(node->InputAt(0)));