Re: Strange C developments

From	gordonb.5rhpu@burditt.org (Gordon Burditt)
Subject	Re: Strange C developments
Newsgroups	comp.lang.c
References	(1 earlier) <judtk6$uen$1@speranza.aioe.org> <judvvo$3r7$1@speranza.aioe.org> <jue270$9aj$1@speranza.aioe.org> <XqydnXsdeJjVKJfNnZ2dnUVZ_uKdnZ2d@posted.internetamerica> <juench$rca$1@speranza.aioe.org>
Message-ID	<5OSdnepZ1ceeOpbNnZ2dnUVZ_jSdnZ2d@posted.internetamerica> (permalink)
Date	2012-07-22 02:08 -0500

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>> Jacob, what rules would have to be added for application writers
>> to use the GC in lcc-win besides the C standard and "don't invoke
>> undefined behavior"?  Hint:  the answer is not "none".  And that's
>> not intended as a put-down of lcc's GC or GC in general.
> 
> 1) Do not hide pointers to the collector, i.e. the collector will NOT 
> search the window extra bytes (for instance) for pointers, or the hard
> disk. If you need to XOR pointers to hide them do not use the collector
> either.

Can I count on (unmangled, unencrypted) pointers in auto variables,
even if the compiler puts them in registers, to be found?  How about
register variables?  Function arguments?  If I can't count on those, I
see lots of trouble ahead for programs heavy on linked lists, which
may be in serious need of garbage collection.

How about the return value of a function in code like:
	NODE	*nptr;	/* auto variable */
	...
	nptr = allocatenewnode(....);
if garbage collection happens to be activated (say, by another
thread) just before the return value of allocatenewnode() is stored
in nptr?  Here, allocatenewnode()'s function is to gc_alloc()
something, fill it in with data, and return a pointer to that data.


> 2) In modern machines a collector slows down the program for at most
> a milisecond in normal situations, that could be bigger but not much
> bigger since the collector tries to spread out the GC time in each
> allocation.

The 1,000,000% slowdown I was thinking of could be the result of
scanning huge disk files (if it attempts such a thing, which is
probably hopeless) or, large amounts of compressed, say, video data
in memory.  This assumes the program wasn't modified to be GC-aware
and it just uses gc_alloc() for everything including huge quantities
of data.

Thread

Strange C developments Jase Schick <nospam@nospam.com> - 2012-07-20 21:14 +0000
  Re: Strange C developments Les Cargill <lcargill99@comcast.com> - 2012-07-20 18:03 -0500
  Re: Strange C developments "christian.bau" <christian.bau@cbau.wanadoo.co.uk> - 2012-07-20 16:03 -0700
    Re: Strange C developments Tim Rentsch <txr@alumni.caltech.edu> - 2012-07-21 15:11 -0700
    Re: Strange C developments tom st denis <tom@iahu.ca> - 2012-08-02 06:08 -0700
      Re: Strange C developments Jens Gustedt <jens.gustedt@loria.fr> - 2012-08-02 21:23 +0200
        Re: Strange C developments tom st denis <tom@iahu.ca> - 2012-08-03 04:13 -0700
          Re: Strange C developments Noob <root@127.0.0.1> - 2012-08-03 13:19 +0200
          Re: Strange C developments Anders Wegge Keller <wegge@wegge.dk> - 2012-08-03 13:31 +0200
          Re: Strange C developments Jens Gustedt <jens.gustedt@loria.fr> - 2012-08-03 23:47 +0200
      Re: Strange C developments gwowen <gwowen@gmail.com> - 2012-08-03 02:20 -0700
  Re: Strange C developments Rui Maciel <rui.maciel@gmail.com> - 2012-07-21 01:25 +0100
  Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-07-20 19:38 -0500
  Re: Strange C developments Nobody <nobody@nowhere.com> - 2012-07-21 10:32 +0100
    Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-07-21 09:31 -0500
      Re: Strange C developments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-07-21 17:38 +0100
        Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-07-21 12:58 -0500
        Re: Strange C developments Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-07-21 11:42 -0700
          Re: Strange C developments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-07-21 20:13 +0100
            Re: Strange C developments Nobody <nobody@nowhere.com> - 2012-07-21 20:48 +0100
              Re: Strange C developments Ben Bacarisse <ben.usenet@bsb.me.uk> - 2012-07-21 23:32 +0100
  Re: Strange C developments jacob navia <jacob@spamsink.net> - 2012-07-21 11:43 +0200
    Re: Strange C developments Quentin Pope <qp19433@hotmail.NOSPAM.com> - 2012-07-21 10:23 +0000
      Re: Strange C developments jacob navia <jacob@spamsink.net> - 2012-07-21 13:01 +0200
        Re: Strange C developments gordonb.y4pdz@burditt.org (Gordon Burditt) - 2012-07-21 08:57 -0500
          Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-07-21 10:40 -0500
          Re: Strange C developments jacob navia <jacob@spamsink.net> - 2012-07-21 19:03 +0200
            Re: Strange C developments gordonb.5rhpu@burditt.org (Gordon Burditt) - 2012-07-22 02:08 -0500
              Re: Strange C developments jacob navia <jacob@spamsink.net> - 2012-07-22 12:32 +0200
                Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-07-22 08:26 -0500
            Re: Strange C developments Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-07-24 01:23 -0700
              Re: Strange C developments Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-07-24 05:36 -0700
                Re: Strange C developments Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-07-30 02:04 -0700
              Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-07-24 09:55 -0500
                Re: Strange C developments 88888 Dihedral <dihedral88888@googlemail.com> - 2012-08-02 06:44 -0700
                Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-08-03 08:48 -0500
          Re: Strange C developments jacob navia <jacob@spamsink.net> - 2012-07-21 19:06 +0200
            Re: Strange C developments gordonb.ibds9@burditt.org (Gordon Burditt) - 2012-07-22 02:28 -0500
              Re: Strange C developments jacob navia <jacob@spamsink.net> - 2012-07-22 12:30 +0200
              Re: Strange C developments Philip Lantz <prl@canterey.us> - 2012-07-24 00:58 -0700
        Re: Strange C developments Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-07-24 01:13 -0700
      Re: Strange C developments Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-07-21 05:44 -0700
        Re: Strange C developments Tim Rentsch <txr@alumni.caltech.edu> - 2012-07-21 15:31 -0700
          Re: Strange C developments Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-07-21 16:59 -0700
            Re: Strange C developments Tim Rentsch <txr@alumni.caltech.edu> - 2012-07-21 23:46 -0700
              Re: Strange C developments "io_x" <a@b.c.invalid> - 2012-07-22 10:37 +0200
                Re: Strange C developments Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-07-22 03:28 -0700
                Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-07-22 09:05 -0500
                Re: Strange C developments Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-07-24 02:10 -0700
                Re: Strange C developments "io_x" <a@b.c.invalid> - 2012-07-27 20:47 +0200
                Re: Strange C developments Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-07-30 02:09 -0700
                Re: Strange C developments "BartC" <bc@freeuk.com> - 2012-07-30 13:05 +0100
                Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-08-03 10:45 -0500
                Re: Strange C developments "io_x" <a@b.c.invalid> - 2012-07-30 16:52 +0200
                Re: Strange C developments "io_x" <a@b.c.invalid> - 2012-07-30 18:26 +0200
                Re: Strange C developments Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-08-03 12:12 -0700
                Re: Strange C developments "BartC" <bc@freeuk.com> - 2012-08-04 12:18 +0100
                Re: Strange C developments Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-08-10 09:50 +0300
                Re: Strange C developments Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 11:19 -0700
                Re: Strange C developments "io_x" <a@b.c.invalid> - 2012-09-09 12:06 +0200
                Re: Strange C developments Kaz Kylheku <kaz@kylheku.com> - 2012-09-09 05:25 +0000
          Re: Strange C developments Melzzzzz <mel@zzzzz.com> - 2012-07-22 02:48 +0200
          Re: Strange C developments William Ahern <william@wilbur.25thandClement.com> - 2012-07-21 21:45 -0700
            Re: Strange C developments Tim Rentsch <txr@alumni.caltech.edu> - 2012-07-22 02:40 -0700
              Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-07-22 10:38 -0500
          Re: Strange C developments William Ahern <william@wilbur.25thandClement.com> - 2012-07-21 22:38 -0700
            Re: Strange C developments jacob navia <jacob@spamsink.net> - 2012-07-22 08:43 +0200
            Re: Strange C developments "BartC" <bc@freeuk.com> - 2012-07-22 11:24 +0100
              Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-08-03 09:09 -0500
                Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-08-03 16:54 -0500
          Re: Strange C developments Tim Rentsch <txr@alumni.caltech.edu> - 2012-07-21 23:16 -0700
            Re: Strange C developments Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2012-07-22 17:50 +0300
              Re: Strange C developments BGB <cr88192@hotmail.com> - 2012-07-22 11:27 -0500
                Re: Strange C developments Ike Naar <ike@iceland.freeshell.org> - 2012-07-22 20:55 +0000
                Re: Strange C developments Philip Lantz <prl@canterey.us> - 2012-07-24 00:56 -0700
                Re: Strange C developments Nick Keighley <nick_keighley_nospam@hotmail.com> - 2012-07-24 01:57 -0700
              Re: Strange C developments Tim Rentsch <txr@alumni.caltech.edu> - 2012-09-07 11:20 -0700
      Re: Strange C developments Tim Rentsch <txr@alumni.caltech.edu> - 2012-07-21 15:13 -0700
  Re: Strange C developments John Bode <jfbode1029@gmail.com> - 2012-07-23 14:59 -0700

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