A question about integer promotion in GCC

[Jie Zhang]

For this simple case:

   int
   foo (unsigned short x)
   {
     return (x << 8) | (x >> 8);
   }

its t03.original dump is:

   ;; Function foo (foo)
   ;; enabled by -tree-original


   {
     return (int)x << 8 | (int)(x >> 8);
   }

My question is why GCC treat two bitwise shift operators differently. 
C99 reads:

   (6.5.7.3) The integer promotions are performed on each of the
   operands. The type of the result is that of the promoted left
   operand. [snip]

According to this, shouldn't it be:

     return (int)x << 8 | (int)x >> 8;

Maybe it has no performance benefit. But it make the tree dump result 
conforming to the standard and improve the readability of the final 
assembly output when being compiled using -O2 option. How about your 
thoughts?


regards
-- 
Jie