ARM: clean up code now that ARMv6 is the baseline.

src/arm/code-stubs-arm.cc

 // Copyright 2012 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 463 matching lines @@
 
   // For 1 or -1 we need to or in the 0 exponent (biased to 1023).
   const uint32_t exponent_word_for_1 =
       HeapNumber::kExponentBias << HeapNumber::kExponentShift;
   __ orr(exponent, exponent, Operand(exponent_word_for_1), LeaveCC, eq);
   // 1, 0 and -1 all have 0 for the second word.
   __ mov(mantissa, Operand::Zero());
   __ Ret();
 
   __ bind(&not_special);
-  // Count leading zeros.  Uses mantissa for a scratch register on pre-ARM5.
-  // Gets the wrong answer for 0, but we already checked for that case above.
-  __ CountLeadingZeros(zeros_, source_, mantissa);
+  __ clz(zeros_, source_);
   // Compute exponent and or it into the exponent register.
   // We use mantissa as a scratch register here.  Use a fudge factor to
   // divide the constant 31 + HeapNumber::kExponentBias, 0x41d, into two parts
   // that fit in the ARM's constant field.
   int fudge = 0x400;
   __ rsb(mantissa, zeros_, Operand(31 + HeapNumber::kExponentBias - fudge));
   __ add(mantissa, mantissa, Operand(fudge));
   __ orr(exponent,
          exponent,
          Operand(mantissa, LSL, HeapNumber::kExponentShift));
@@ skipping 1527 matching lines @@
         __ b(mi, &div_with_sdiv);
       } else {
         __ b(ne, &not_smi_result);
         // Check for positive and no remainder.
         __ orr(scratch2, scratch1, Operand(0x80000000u));
         __ tst(left, scratch2);
         __ b(ne, &not_smi_result);
       }
 
       // Perform division by shifting.
-      __ CountLeadingZeros(scratch1, scratch1, scratch2);
+      __ clz(scratch1, scratch1);
       __ rsb(scratch1, scratch1, Operand(31));
       __ mov(right, Operand(left, LSR, scratch1));
       __ Ret();
 
       if (CpuFeatures::IsSupported(SUDIV)) {
         Label result_not_zero;
 
         __ bind(&div_with_sdiv);
         // Do division.
         __ sdiv(scratch1, left, right);
@@ skipping 5483 matching lines @@
 
   __ Pop(lr, r5, r1);
   __ Ret();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM