Optimize the emitted instruction of random function for X64

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
===================================================================
--- src/x64/assembler-x64.h	(revision 13335)
+++ src/x64/assembler-x64.h	(working copy)
@@ -419,6 +419,8 @@
   int operand_size() const { return len_; }
 
  private:
+  explicit Operand(Register reg);

[Jakob Kummerow, 2013/01/11 17:43:38]

On x64 so far, an Operand always means a memory access, and I'd like to keep
that consistency. So please don't add this constructor. Instead, please
implement an overloaded version of movzxwl that takes two registers as input
(similar to how we have two versions of movsxlq).

+
   byte rex_;
   byte buf_[6];
   // The number of bytes of buf_ in use.
@@ -732,6 +734,7 @@
   void movzxbl(Register dst, const Operand& src);
   void movzxwq(Register dst, const Operand& src);
   void movzxwl(Register dst, const Operand& src);
+  void movzxwl(Register dst, Register src) { movzxwl(dst, Operand(src)); }
 
   // Repeated moves.