[arm][arm64] Improve CountTrailingZero implementation.

test/cctest/test-disasm-arm.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 344 matching lines @@
           "32314201       eorccs r4, r1, #268435456");
 
   VERIFY_RUN();
 }
 
 
 TEST(Type3) {
   SET_UP();
 
   if (CpuFeatures::IsSupported(ARMv7)) {
+    CpuFeatureScope scope(&assm, ARMv7);
     COMPARE(ubfx(r0, r1, 5, 10),
             "e7e902d1       ubfx r0, r1, #5, #10");
     COMPARE(ubfx(r1, r0, 5, 10),
             "e7e912d0       ubfx r1, r0, #5, #10");
     COMPARE(ubfx(r0, r1, 31, 1),
             "e7e00fd1       ubfx r0, r1, #31, #1");
     COMPARE(ubfx(r1, r0, 31, 1),
             "e7e01fd0       ubfx r1, r0, #31, #1");
 
     COMPARE(sbfx(r0, r1, 5, 10),
@@ skipping 55 matching lines @@
     COMPARE(uxtb(r3, r4, 8), "e6ef3474       uxtb r3, r4, ror #8");
 
     COMPARE(uxtab(r3, r4, r5, 8), "e6e43475       uxtab r3, r4, r5, ror #8");
 
     COMPARE(uxtb16(r3, r4, 8), "e6cf3474       uxtb16 r3, r4, ror #8");
 
     COMPARE(uxth(r9, r10), "e6ff907a       uxth r9, r10");
     COMPARE(uxth(r3, r4, 8), "e6ff3474       uxth r3, r4, ror #8");
 
     COMPARE(uxtah(r3, r4, r5, 24), "e6f43c75       uxtah r3, r4, r5, ror #24");
+
+    COMPARE(rbit(r1, r2), "e6ff1f32       rbit r1, r2");
+    COMPARE(rbit(r10, ip), "e6ffaf3c       rbit r10, ip");
   }
 
   COMPARE(smmla(r0, r1, r2, r3), "e7503211       smmla r0, r1, r2, r3");
   COMPARE(smmla(r10, r9, r8, r7), "e75a7819       smmla r10, r9, r8, r7");
 
   COMPARE(smmul(r0, r1, r2), "e750f211       smmul r0, r1, r2");
   COMPARE(smmul(r8, r9, r10), "e758fa19       smmul r8, r9, r10");
 
   VERIFY_RUN();
 }
@@ skipping 570 matching lines @@
             "e16dc7ff       strd ip, [sp, #-127]!");
 
     COMPARE(pld(MemOperand(r1, 0)),
             "f5d1f000       pld [r1]");
     COMPARE(pld(MemOperand(r2, 128)),
             "f5d2f080       pld [r2, #+128]");
   }
 
   VERIFY_RUN();
 }