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Re: Generally, are the programs written by C++ slower than written by C 10% ?

From Miles Bader <miles@gnu.org>
Newsgroups comp.lang.c++
Subject Re: Generally, are the programs written by C++ slower than written by C 10% ?
Date 2011-09-12 18:06 +0900
Organization NEC Electronics
Message-ID <buobouq2kpj.fsf@dhlpc061.dev.necel.com> (permalink)
References (13 earlier) <j4g5oo$mae$1@news.albasani.net> <a5bc5b64-82a8-49ba-b01e-49a89a0348b3@b9g2000prd.googlegroups.com> <j4gkq9$o32$1@news.albasani.net> <87wrdfkb91.fsf@catnip.gol.com> <4fa2fdfc-caa8-49c2-bffd-90841d4dfc98@t29g2000vby.googlegroups.com>

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Joshua Maurice <joshuamaurice@gmail.com> writes:
>> Shared libraries in linux have dependencies, just like programs, so
>> the end program only needs to link with the libraries it uses
>> directly; any "transitive" dependencies are pulled in automatically.
>
> This isn't true for my experience of Linux with gcc. However, I have
> seen this on one other platform where the linker would complain if you
> didn't give it all transitive shared-obj (aka shared-lib aka dlls) on
> the command line for some cases. HP-UX maybe?

Here's an example:

# A very silly program (on Debian):

   $ cat > lt.cc <<EOF
   #include <ImfRgbaFile.h>
   int main () { Imf::RgbaInputFile inf ("oink", Imf::WRITE_RGBA); }
   EOF

# We only specify a single library at link-time, "libIlmImf":

   $ g++ -o lt -I/usr/include/OpenEXR lt.cc -lIlmImf

# Here's the dependencies in the resulting ELF file:

   $ readelf --dynamic lt | grep NEEDED
    0x0000000000000001 (NEEDED)             Shared library: [libIlmImf.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libstdc++.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libm.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libgcc_s.so.1]
    0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]

# But if we look at the actual libraries actualy _used_ at runtime:

   $ ldd lt
	linux-vdso.so.1 =>  (0x00007fff66a8d000)
	libIlmImf.so.6 => /usr/lib/libIlmImf.so.6 (0x00007f063b738000)
	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f063b42e000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f063b1ab000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f063af95000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f063ac11000)
	libz.so.1 => /usr/lib/libz.so.1 (0x00007f063a9f8000)
	libImath.so.6 => /usr/lib/libImath.so.6 (0x00007f063a7f3000)
	libHalf.so.6 => /usr/lib/libHalf.so.6 (0x00007f063a5b1000)
	libIex.so.6 => /usr/lib/libIex.so.6 (0x00007f063a392000)
	libIlmThread.so.6 => /usr/lib/libIlmThread.so.6 (0x00007f063a18b000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f0639f6f000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f063ba20000)

# ... note there are a bunch of additional libraries!
#
# They are transitive dependencies, which came from the dependencies
# of "libIlmImf", the single library we linked with:

   $ readelf --dynamic /usr/lib/libIlmImf.so | grep NEEDED
    0x0000000000000001 (NEEDED)             Shared library: [libz.so.1]
    0x0000000000000001 (NEEDED)             Shared library: [libImath.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libHalf.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libIex.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libIlmThread.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libpthread.so.0]
    0x0000000000000001 (NEEDED)             Shared library: [libstdc++.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libm.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libc.so.6]
    0x0000000000000001 (NEEDED)             Shared library: [libgcc_s.so.1]

-Miles

-- 
Acquaintance, n. A person whom we know well enough to borrow from, but not
well enough to lend to.

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Generally, are the programs written by C++ slower than written by C 10% ? KaiWen <wenkai1987@gmail.com> - 2011-09-01 01:41 -0700
  Re: Generally, are the programs written by C++ slower than written by C   10% ? Ian Collins <ian-news@hotmail.com> - 2011-09-01 21:15 +1200
  Re: Generally, are the programs written by C++ slower than written by C 10% ? "Fred Zwarts \(KVI\)" <F.Zwarts@KVI.nl> - 2011-09-01 11:48 +0200
    Re: Generally, are the programs written by C++ slower than written by C 10% ? Joshua Maurice <joshuamaurice@gmail.com> - 2011-09-01 15:34 -0700
      Re: Generally, are the programs written by C++ slower than written by C 10% ? KaiWen <wenkai1987@gmail.com> - 2011-09-01 19:09 -0700
        Re: Generally, are the programs written by C++ slower than written by   C 10% ? Ian Collins <ian-news@hotmail.com> - 2011-09-02 14:39 +1200
        Re: Generally, are the programs written by C++ slower than written by C 10% ? Krice <paulkp@mbnet.fi> - 2011-09-01 22:33 -0700
        Re: Generally, are the programs written by C++ slower than written by C 10% ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-02 01:12 -0500
          Re: Generally, are the programs written by C++ slower than written by C 10% ? James Kanze <james.kanze@gmail.com> - 2011-09-03 15:25 -0700
            Re: Generally, are the programs written by C++ slower than written by C 10% ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-04 01:34 -0500
              Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-04 02:33 -0700
              Re: Generally, are the programs written by C++ slower than written by C 10% ? James Kanze <james.kanze@gmail.com> - 2011-09-04 11:00 -0700
        Re: Generally, are the programs written by C++ slower than written by C 10% ? Goran <goran.pusic@gmail.com> - 2011-09-01 23:23 -0700
          Re: Generally, are the programs written by C++ slower than written by C 10% ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-02 03:00 -0700
            Re: Generally, are the programs written by C++ slower than written by C 10% ? Goran <goran.pusic@gmail.com> - 2011-09-02 09:39 -0700
          Re: Generally, are the programs written by C++ slower than written by C 10% ? Rui Maciel <rui.maciel@gmail.com> - 2011-09-02 12:44 +0100
        Re: Generally, are the programs written by C++ slower than written by C 10% ? Rui Maciel <rui.maciel@gmail.com> - 2011-09-02 09:59 +0100
          Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-02 11:25 -0700
        Re: Generally, are the programs written by C++ slower than written by C 10% ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-03 05:51 +0000
          Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-03 01:45 -0700
            Re: Generally, are the programs written by C++ slower than written   by C 10% ? Ian Collins <ian-news@hotmail.com> - 2011-09-03 20:53 +1200
              Re: Generally, are the programs written by C++ slower than written   by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-03 10:49 -0700
                Re: Generally, are the programs written by C++ slower than written     by C 10% ? Ian Collins <ian-news@hotmail.com> - 2011-09-04 08:15 +1200
                Re: Generally, are the programs written by C++ slower than written     by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-03 17:50 -0700
            Re: Generally, are the programs written by C++ slower than written by C 10% ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-03 16:28 +0000
              Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-03 10:42 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? "Bo Persson" <bop@gmb.dk> - 2011-09-04 11:34 +0200
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-04 09:04 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-04 18:04 +0000
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Keith H Duggar <duggar@alum.mit.edu> - 2011-09-04 18:44 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-04 23:26 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-05 08:01 +0000
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-05 11:45 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-06 06:30 +0000
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-06 07:22 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Miles Bader <miles@gnu.org> - 2011-09-06 16:25 +0900
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-06 07:14 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Miles Bader <miles@gnu.org> - 2011-09-07 12:28 +0900
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-07 16:49 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Noah Roberts <roberts.noah@gmail.com> - 2011-09-07 18:45 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-08 15:56 -0700
            Re: Generally, are the programs written by C++ slower than written by C 10% ? James Kanze <james.kanze@gmail.com> - 2011-09-03 15:32 -0700
              Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-03 19:16 -0700
            Re: Generally, are the programs written by C++ slower than written by C 10% ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-05 00:28 -0700
              Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-05 12:34 -0700
                Re: Generally, are the programs written by C++ slower than written   by C 10% ? Ian Collins <ian-news@hotmail.com> - 2011-09-06 07:51 +1200
                Re: Generally, are the programs written by C++ slower than written   by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-05 14:06 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-06 00:32 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-06 07:33 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-07 02:52 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-08 16:24 -0700
                Re: Generally, are the programs written by C++ slower than written   by C 10% ? Ian Collins <ian-news@hotmail.com> - 2011-09-09 11:38 +1200
                Re: Generally, are the programs written by C++ slower than written   by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-08 21:39 -0700
                Re: Generally, are the programs written by C++ slower than written     by C 10% ? Ian Collins <ian-news@hotmail.com> - 2011-09-09 19:01 +1200
                Re: Generally, are the programs written by C++ slower than written     by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-09 02:45 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-09 03:23 -0700
                Re: Generally, are the programs written by C++ slower than written     by C 10% ? Jorgen Grahn <grahn+nntp@snipabacken.se> - 2011-09-14 23:12 +0000
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-09 02:40 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-09 11:19 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-09 15:42 -0500
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-09 14:24 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Noah Roberts <roberts.noah@gmail.com> - 2011-09-09 18:22 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-10 10:11 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Noah Roberts <roberts.noah@gmail.com> - 2011-09-10 10:54 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-10 14:28 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Miles Bader <miles@gnu.org> - 2011-09-11 12:29 +0900
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-11 00:45 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Joshua Maurice <joshuamaurice@gmail.com> - 2011-09-12 00:39 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Miles Bader <miles@gnu.org> - 2011-09-12 18:06 +0900
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Joshua Maurice <joshuamaurice@gmail.com> - 2011-09-12 16:46 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Miles Bader <miles@gnu.org> - 2011-09-13 10:20 +0900
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Joshua Maurice <joshuamaurice@gmail.com> - 2011-09-13 13:16 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Nobody <nobody@nowhere.com> - 2011-09-11 04:53 +0100
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Miles Bader <miles@gnu.org> - 2011-09-11 14:51 +0900
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-10 07:46 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? KaiWen <wenkai1987@gmail.com> - 2011-09-06 03:10 -0700
                Re: Generally, are the programs written by C++ slower than written by   C 10% ? Ian Collins <ian-news@hotmail.com> - 2011-09-06 22:50 +1200
                Re: Generally, are the programs written by C++ slower than written by C 10% ? KaiWen <wenkai1987@gmail.com> - 2011-09-06 04:48 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? yatremblay@bel1lin202.(none) (Yannick Tremblay) - 2011-09-07 09:45 +0000
                Re: Generally, are the programs written by C++ slower than written by   C 10% ? Ian Collins <ian-news@hotmail.com> - 2011-09-07 21:51 +1200
                Re: Generally, are the programs written by C++ slower than written by C 10% ? KaiWen <wenkai1987@gmail.com> - 2011-09-08 00:15 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? yatremblay@bel1lin202.(none) (Yannick Tremblay) - 2011-09-08 12:14 +0000
                Re: Generally, are the programs written by C++ slower than written by C 10% ? KaiWen <wenkai1987@gmail.com> - 2011-09-08 07:14 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Asger-P <junk@asger-p.dk> - 2011-09-06 13:52 +0200
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-06 11:47 -0500
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-06 11:50 -0500
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Asger-P <junk@asger-p.dk> - 2011-09-06 21:04 +0200
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Leigh Johnston <leigh@i42.co.uk> - 2011-09-06 20:37 +0100
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-06 15:10 -0500
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Leigh Johnston <leigh@i42.co.uk> - 2011-09-06 21:14 +0100
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Asger-P <junk@asger-p.dk> - 2011-09-07 00:40 +0200
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Leigh Johnston <leigh@i42.co.uk> - 2011-09-06 23:59 +0100
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Noah Roberts <roberts.noah@gmail.com> - 2011-09-06 16:26 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-06 14:55 -0500
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Asger-P <junk@asger-p.dk> - 2011-09-07 00:51 +0200
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-09-06 23:29 -0500
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Asger-P <junk@asger-p.dk> - 2011-09-07 09:06 +0200
                Re: Generally, are the programs written by C++ slower than written by   C 10% ? Ian Collins <ian-news@hotmail.com> - 2011-09-07 19:09 +1200
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Nobody <nobody@nowhere.com> - 2011-09-07 13:19 +0100
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Juha Nieminen <nospam@thanks.invalid> - 2011-09-07 13:01 +0000
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Rui Maciel <rui.maciel@gmail.com> - 2011-09-07 14:26 +0100
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Asger-P <junk@asger-p.dk> - 2011-09-07 15:49 +0200
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-08 22:49 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Miles Bader <miles@gnu.org> - 2011-09-09 15:25 +0900
                Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-09 02:50 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-09 03:26 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-09 03:25 -0700
                Re: Generally, are the programs written by C++ slower than written by C 10% ? Nick Keighley <nick_keighley_nospam@hotmail.com> - 2011-09-06 00:24 -0700
            Re: Generally, are the programs written by C++ slower than written by C 10% ? yatremblay@bel1lin202.(none) (Yannick Tremblay) - 2011-09-06 13:57 +0000
              Re: Generally, are the programs written by C++ slower than written by C 10% ? BGB <cr88192@hotmail.com> - 2011-09-06 08:18 -0700
        Re: Generally, are the programs written by C++ slower than written by C 10% ? Nobody <nobody@nowhere.com> - 2011-09-03 08:34 +0100
  Re: Generally, are the programs written by C++ slower than written by C 10% ? "A" <a@a.a> - 2011-09-01 11:50 +0200
  Re: Generally, are the programs written by C++ slower than written by C 10% ? Rui Maciel <rui.maciel@gmail.com> - 2011-09-01 10:53 +0100
  Re: Generally, are the programs written by C++ slower than written by C 10% ? James Kanze <james.kanze@gmail.com> - 2011-09-03 15:11 -0700

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