[arm][arm64] Improve CountTrailingZero implementation.

src/compiler/machine-operator.cc

Index: src/compiler/machine-operator.cc
diff --git a/src/compiler/machine-operator.cc b/src/compiler/machine-operator.cc
index c0791c0e58722243343cb6c9327642d5b2173ac1..690725ef53dd761a6fe9df60003b1b6caa3e33f8 100644
--- a/src/compiler/machine-operator.cc
+++ b/src/compiler/machine-operator.cc
@@ -199,6 +199,8 @@ MachineRepresentation StackSlotRepresentationOf(Operator const* op) {
 #define PURE_OPTIONAL_OP_LIST(V)                            \
   V(Word32Ctz, Operator::kNoProperties, 1, 0, 1)            \
   V(Word64Ctz, Operator::kNoProperties, 1, 0, 1)            \
+  V(Word32ReverseBits, Operator::kNoProperties, 1, 0, 1)    \
+  V(Word64ReverseBits, Operator::kNoProperties, 1, 0, 1)    \
   V(Word32Popcnt, Operator::kNoProperties, 1, 0, 1)         \
   V(Word64Popcnt, Operator::kNoProperties, 1, 0, 1)         \
   V(Float32Max, Operator::kNoProperties, 2, 0, 1)           \
@@ -215,7 +217,6 @@ MachineRepresentation StackSlotRepresentationOf(Operator const* op) {
   V(Float32RoundTiesEven, Operator::kNoProperties, 1, 0, 1) \
   V(Float64RoundTiesEven, Operator::kNoProperties, 1, 0, 1)
 
-
 #define MACHINE_TYPE_LIST(V) \
   V(Float32)                 \
   V(Float64)                 \