Tweak to shorten generated code in Math.pow.

src/x64/code-stubs-x64.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 2163 matching lines @@
 
   // Calculate power with integer exponent.
   __ bind(&int_exponent);
   const XMMRegister double_scratch2 = double_exponent;
   // Back up exponent as we need to check if exponent is negative later.
   __ movq(scratch, exponent);  // Back up exponent.
   __ movsd(double_scratch, double_base);  // Back up base.
   __ movsd(double_scratch2, double_result);  // Load double_exponent with 1.
 
   // Get absolute value of exponent.
-  Label no_neg, while_true, no_multiply;
-  __ cmpl(scratch, Immediate(0));
-  __ j(positive, &no_neg, Label::kNear);
-  __ negl(scratch);
-  __ bind(&no_neg);
+  Label while_true, no_multiply;
+  const uint32_t kClearSignBitMask = 0x7FFFFFFF;
+  __ andl(scratch, Immediate(kClearSignBitMask));
 
   __ bind(&while_true);
   __ shrl(scratch, Immediate(1));
   __ j(not_carry, &no_multiply, Label::kNear);
   __ mulsd(double_result, double_scratch);
   __ bind(&no_multiply);
 
   __ mulsd(double_scratch, double_scratch);
   __ j(not_zero, &while_true);
 
@@ skipping 4016 matching lines @@
                                  xmm0,
                                  &slow_elements);
   __ ret(0);
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64