CTZ instruction implemented as optional operator.

src/compiler/ia32/code-generator-ia32.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/code-generator.h"
 
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/osr.h"
@@ skipping 491 matching lines @@
     case kIA32Ror:
       if (HasImmediateInput(instr, 1)) {
         __ ror(i.OutputOperand(), i.InputInt5(1));
       } else {
         __ ror_cl(i.OutputOperand());
       }
       break;
     case kIA32Lzcnt:
       __ Lzcnt(i.OutputRegister(), i.InputOperand(0));
       break;
+    case kIA32Tzcnt:
+      __ Tzcnt(i.OutputRegister(), i.InputOperand(0));
+      break;
     case kSSEFloat32Cmp:
       __ ucomiss(i.InputDoubleRegister(0), i.InputOperand(1));
       break;
     case kSSEFloat32Add:
       __ addss(i.InputDoubleRegister(0), i.InputOperand(1));
       break;
     case kSSEFloat32Sub:
       __ subss(i.InputDoubleRegister(0), i.InputOperand(1));
       break;
     case kSSEFloat32Mul:
@@ skipping 1033 matching lines @@
     int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     __ Nop(padding_size);
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8