Re: Bit field usage

From	jacobnavia <jacob@jacob.remcomp.fr>
Newsgroups	comp.lang.c
Subject	Re: Bit field usage
Date	2019-10-24 22:15 +0200
Organization	A noiseless patient Spider
Message-ID	<qot0oj$ih5$1@dont-email.me> (permalink)
References	(1 earlier) <1bo8y6azlw.fsf@pfeifferfamily.net> <k5lsF.44703$xZ1.38649@fx30.iad> <qosojo$i3v$1@dont-email.me> <d0179f01-b35e-4e2e-bb49-f24237e45b78@googlegroups.com> <Z6nsF.77310$iA2.26162@fx06.iad>

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Le 24/10/2019 à 21:40, Scott Lurndal a écrit :
> I'll have to check our version of gcc for ARM64 to see if it generates them.

Of course it does. If I change the length of the bit field to 3 bits, it 
will generate:
  18     bfi w3, w4, 2, 3

i.e. bit field insert w4 (contains 1) from bit 2 with length 3 bits and 
put the result in w3. The overhead remains the same as before, it is 
just that it doesn't a simple OR instruction but a bit field insert... 
Still one instruction more

Thread

Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-24 08:03 +0200
  Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-24 10:15 -0600
    Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-24 18:55 +0200
      Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-24 21:28 -0600
    Re: Bit field usage scott@slp53.sl.home (Scott Lurndal) - 2019-10-24 17:22 +0000
      Re: Bit field usage Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-24 19:45 +0200
        Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-24 19:59 +0200
          Re: Bit field usage Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-24 20:02 +0200
            Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-24 21:29 -0600
              Re: Bit field usage Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-25 07:51 +0200
                Re: Bit field usage scott@slp53.sl.home (Scott Lurndal) - 2019-10-25 15:05 +0000
        Re: Bit field usage Bart <bc@freeuk.com> - 2019-10-24 19:13 +0100
          Re: Bit field usage Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-24 20:54 +0200
            Re: Bit field usage Bart <bc@freeuk.com> - 2019-10-24 20:12 +0100
              Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-10-24 23:03 +0200
                Re: Bit field usage Ben Bacarisse <ben.usenet@bsb.me.uk> - 2019-10-24 22:50 +0100
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-10-25 09:18 +0200
                Re: Bit field usage Reinhardt Behm <rbehm@hushmail.com> - 2019-10-25 15:46 +0800
                Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-26 12:36 -0500
                Re: Bit field usage scott@slp53.sl.home (Scott Lurndal) - 2019-10-25 15:04 +0000
                Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-26 12:40 -0500
                Re: Bit field usage Philipp Klaus Krause <pkk@spth.de> - 2019-10-26 21:12 +0200
              Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-25 09:25 -0600
                Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-26 12:52 -0500
      Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-24 19:56 +0200
        Re: Bit field usage already5chosen@yahoo.com - 2019-10-24 12:03 -0700
          Re: Bit field usage scott@slp53.sl.home (Scott Lurndal) - 2019-10-24 19:40 +0000
            Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-24 22:15 +0200
            Re: Bit field usage already5chosen@yahoo.com - 2019-10-24 14:16 -0700
    Re: Bit field usage Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-10-24 17:50 -0700
      Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-25 09:36 -0600
        Re: Bit field usage Tim Rentsch <tr.17687@z991.linuxsc.com> - 2019-10-27 04:54 -0700
          Re: Bit field usage Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-27 10:05 -0600
  Re: Bit field usage Philipp Klaus Krause <pkk@spth.de> - 2019-10-26 20:15 +0200
    Re: Bit field usage Philipp Klaus Krause <pkk@spth.de> - 2019-10-26 20:16 +0200
      Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-26 20:37 +0200
        Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-26 13:41 -0500
          Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-26 21:54 +0200
            Re: Bit field usage already5chosen@yahoo.com - 2019-10-27 03:46 -0700
              Re: Bit field usage jacobnavia <jacob@jacob.remcomp.fr> - 2019-10-27 12:50 +0100
                Re: Bit field usage already5chosen@yahoo.com - 2019-10-27 06:37 -0700
              Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-10-27 13:00 +0100
                Re: Bit field usage already5chosen@yahoo.com - 2019-10-27 07:19 -0700
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-10-27 22:30 +0100
                Re: Bit field usage Christopher Collins <ccollins476ad@gmail.com> - 2019-11-07 12:36 -0800
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-11-08 08:18 +0100
                Re: Bit field usage Christopher Collins <ccollins476ad@gmail.com> - 2019-11-08 10:19 -0800
                Re: Bit field usage Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-11-08 21:47 +0000
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-11-10 14:08 +0100
                Re: Bit field usage Christopher Collins <ccollins476ad@gmail.com> - 2019-11-11 09:26 -0800
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-11-11 20:31 +0100
                Re: Bit field usage Christopher Collins <ccollins476ad@gmail.com> - 2019-11-11 23:01 -0800
                Re: Bit field usage Christopher Collins <ccollins476ad@gmail.com> - 2019-11-11 23:25 -0800
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-11-12 10:54 +0100
                Re: Bit field usage Jorgen Grahn <grahn+nntp@snipabacken.se> - 2019-11-12 14:43 +0000
                Re: Bit field usage James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-11-12 10:54 -0500
                Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-11-12 19:37 +0100
              Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-27 08:36 -0500
                Re: Bit field usage already5chosen@yahoo.com - 2019-10-27 06:49 -0700
            Re: Bit field usage Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-27 14:23 +0100
            Re: Bit field usage Robert Wessel <robertwessel2@yahoo.com> - 2019-10-27 08:42 -0500
        Re: Bit field usage Philipp Klaus Krause <pkk@spth.de> - 2019-10-26 21:06 +0200
        Re: Bit field usage Bart <bc@freeuk.com> - 2019-10-26 20:41 +0100
          Re: Bit field usage Philipp Klaus Krause <pkk@spth.de> - 2019-10-27 08:29 +0100
            Re: Bit field usage David Brown <david.brown@hesbynett.no> - 2019-10-27 13:05 +0100

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