CTZ instruction implemented as optional operator.

src/ia32/assembler-ia32.cc

Index: src/ia32/assembler-ia32.cc
diff --git a/src/ia32/assembler-ia32.cc b/src/ia32/assembler-ia32.cc
index 9f64a6005fdcba1887dcfd346b9ac43f378e4f38..59d00259396db5f2091dbf53692aba82528af4c4 100644
--- a/src/ia32/assembler-ia32.cc
+++ b/src/ia32/assembler-ia32.cc
@@ -1307,6 +1307,14 @@ void Assembler::bsr(Register dst, const Operand& src) {
 }
 
 
+void Assembler::bsf(Register dst, const Operand& src) {
+  EnsureSpace ensure_space(this);
+  EMIT(0x0F);
+  EMIT(0xBC);
+  emit_operand(dst, src);
+}
+
+
 void Assembler::hlt() {
   EnsureSpace ensure_space(this);
   EMIT(0xF4);