Re: shifts and rotates by 1 on ix86

[Jeffrey A Law <law at cygnus dot com>]

  In message <Pine.LNX.4.10.10005101022080.12070-100000@ns.netlink.ru>you write
:
  > It seems that gas (2.9.5.0.41) always uses the form with immediate for 
  > encoding shifts and rotates by immediate count, even if the count is 1
  > where special form of encoding could be used which is 1 byte shorter
  > (e.g. shll $1,%eax could be encoded as D1 E0, but gas outputs C1 E0 01).
  > I think gas should always produce the shortest possible encodings.
This was discussed recently, and what you propose might still make
sense.

However, what I think makes sense regardless of what we do with gas is to
have gcc emit the short form (no shift count when we want shift-by-1).  A
patch to do this would be greatly appreciated.

jeffv