C is a crappy

Article: MAQSIP-RT: An HPC Benchmark
By: rwessel (robertwessel.delete@this.yahoo.com), July 2, 2010 3:32 pm
Room: Moderated Discussions
Max (max@a.com) on 7/2/10 wrote:
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>Max (max@a.com) on 7/2/10 wrote:
>---------------------------
>>rwessel (robertwessel@yahoo.com) on 7/2/10 wrote:
>>---------------------------
>>>In any event, LTCG is the solution to the optimization issue.
>>
>>If you don't care about compile speed, you can just compile everything at once.
>>That's simpler and more effective than duplicating parts of the compiler in the linker.
>
>On second thought, compile everything at once (starting from the intermediate language,
>not source) is probably exactly what you meant by LTCG. That is, LTCG is not enhanced
>traditional linking, it's a full blown compile with link semantics. Right?

Typically Link Time Code Generation works by having the compiler store the intermediate representation (usually something along the lines of the parse tree) in the "object" file, rather than passing it to the back end of the compiler for turning into object code. Usually the object file contains the name of the required back end (MSVC, for example, stores the full directory and file name of the compiler back end DLL).

The linker then collects all the intermediate "code" objects destined for a given back end, and passes then to that (actual) compiler back end, which then (typically) generates a "real" object file, which the linker then handles as usual. Other “real” object files are handled in the traditional way.

This usually has minimal impact on either the linker or compiler. The compiler back end has to handle names a bit differently (basically static names now need additional qualification), but not too much. The linker obviously has to recognize the new format, and deal with that, but usually then just has to deal with a normal object file.

I'm not sure what you mean by "compile all at once." Typically invoking the compiler with the command line specifying several source modules does *not* provide for any sort of inter-translation unit optimization, it just automatically compiles each source module as if you had invoked the compiler several times. It would, however, not be at all unreasonable for the compiler to invoke LTCG in such a case, but I don’t know of anyone who does that.


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TopicPosted ByDate
New article online: MAQSIP RTDavid Kanter2010/06/21 11:57 AM
  Why no GCC?Rohit2010/06/22 09:25 PM
    Why no GCC?David Kanter2010/06/23 12:45 AM
      sun 's cc better than GCC?Rohit2010/06/23 05:04 AM
        sun 's cc better than GCC?anon2010/06/23 07:49 AM
          Where is the GCC optimization effort directed?Mark Roulo2010/06/23 10:42 AM
            GCC is very ugly bad everywhere in 64 bitsVincent Diepeveen2010/06/23 02:49 PM
              even for 64-bit arch?anon2010/06/23 02:59 PM
              GCC is very ugly bad everywhere in 64 bitsajensen2010/06/23 11:03 PM
                GCC is very ugly bad everywhere in 64 bitsGabriele Svelto2010/06/24 02:33 AM
                  GCC is very ugly bad everywhere in 64 bitsajensen2010/06/24 05:32 AM
                    GCC is very ugly bad everywhere in 64 bitsGabriele Svelto2010/06/24 07:18 AM
                      GCC is very ugly bad everywhere in 64 bitsajensen2010/06/24 09:50 AM
                        Why GCC is big and complicated (my guess)Mark Roulo2010/06/24 12:17 PM
                          Why GCC is big and complicated (my guess)Gabriele Svelto2010/06/28 04:00 AM
                GCC is very ugly bad everywhere in 64 bitsBernd Schmidt2010/06/24 05:46 AM
                  GCC is very ugly bad everywhere in 64 bitsajensen2010/06/24 09:43 AM
                  GCC is very ugly bad everywhere in 64 bitsVincent Diepeveen2010/06/26 02:12 PM
                GCC is very ugly bad everywhere in 64 bitsRob Thorpe2010/06/24 07:47 AM
                  GCC is very ugly bad everywhere in 64 bitsAnon2010/06/24 05:23 PM
            Where is the GCC optimization effort directed?Gabriele Svelto2010/06/23 10:45 PM
              Where is the GCC optimization effort directed??2010/06/24 01:48 AM
                Where is the GCC optimization effort directed?Gabriele Svelto2010/06/24 02:29 AM
                  Where is the GCC optimization effort directed??2010/06/24 03:13 AM
                    Where is the GCC optimization effort directed?Andi Kleen2010/06/24 03:15 AM
                      Where is the GCC optimization effort directed??2010/06/24 04:08 AM
                    Where is the GCC optimization effort directed?Gabriele Svelto2010/06/24 03:54 AM
                      Where is the GCC optimization effort directed??2010/06/24 04:15 AM
                        Where is the GCC optimization effort directed?Gabriele Svelto2010/06/24 07:22 AM
                Where is the GCC optimization effort directed?Rohit2010/06/24 03:04 AM
                  Placebo effect?2010/06/24 06:37 AM
                    Placebo effectRohit2010/06/24 08:45 AM
                    Placebo effectVincent Diepeveen2010/06/26 02:50 PM
                      Compile timeMark Roulo2010/06/26 05:28 PM
                        Compile timeRichard Cownie2010/06/27 04:44 AM
                          Compile timeMark Roulo2010/06/27 10:12 AM
                          Compile timeMark Roulo2010/06/27 10:21 AM
                            Compile timeEduardoS2010/06/27 11:37 AM
                            Compile timeRichard Cownie2010/06/27 04:07 PM
                              Compile time & efficiency?2010/06/28 12:03 AM
                                Compile time & efficiencyMark Christiansen2010/06/28 06:08 AM
                                Compile time & efficiencyLinus Torvalds2010/06/28 07:48 AM
                                  kernel programming languageJohn Simon2010/06/29 06:46 PM
                                Compile time & efficiencyRichard Cownie2010/06/28 09:29 AM
                                  Compile time & efficiencyLinus Torvalds2010/06/28 11:17 AM
                                    Compile time & efficiencyRichard Cownie2010/06/28 02:16 PM
                                      Compile time & efficiencyRichard Cownie2010/06/28 06:23 PM
                                        Compile time & efficiencyMark Roulo2010/06/29 08:31 AM
                                          Compile time & efficiencyRichard Cownie2010/06/29 11:48 AM
                                          Compile time & efficiencyrwessel2010/06/29 12:28 PM
                                            C is a crappydev2010/06/29 07:12 PM
                                              C is a crappy, but only when you push it out of it's nicheRohit2010/06/30 02:11 AM
                                              C is a crappyanon2010/06/30 02:17 AM
                                                C is a crappydev2010/06/30 07:59 AM
                                                  C is a crappyMax2010/07/01 04:30 AM
                                                    C is a crappyMichael S2010/07/01 07:00 AM
                                                      C is a crappyKonrad Schwarz2010/07/01 08:02 AM
                                                        C is a crappyMichael S2010/07/01 08:50 AM
                                                          C isn't so crappyanon2010/07/01 10:11 AM
                                                            C isn't so crappyMikael Tillenius2010/07/01 11:39 AM
                                                          C is a crappyKonrad Schwarz2010/07/01 11:22 AM
                                                          C is a crappyMax2010/07/02 08:44 AM
                                                            C is a crappyrwessel2010/07/02 12:33 PM
                                                              C is a crappyanon2010/07/02 01:17 PM
                                                              C is a crappyMax2010/07/02 02:56 PM
                                                                C is a crappyMax2010/07/02 03:13 PM
                                                                  C is a crappyrwessel2010/07/02 03:32 PM
                                                                    C is a crappyMax2010/07/02 04:19 PM
                                                                    C is a crappyGabriele Svelto2010/07/05 05:25 AM
                                                      C is a crappygallier22010/07/02 12:14 AM
                                                    C is a crappyIan Ollmann2010/07/06 03:07 PM
                                                      PortabilityMax2010/07/06 03:37 PM
                                                      C is a crappyhobold2010/07/07 02:31 AM
                                                        C is a crappyIan Ollmann2010/07/07 05:18 PM
                                                      failure to standardize typesCarlie Coats2010/07/07 04:11 AM
                                                      C is a crappyKonrad Schwarz2010/07/07 08:34 AM
                                                        C is a crappyIan Ollmann2010/07/07 05:29 PM
                                                          C is a crappy NOTKonrad Schwarz2010/07/08 12:29 AM
                                                  C is a crappyanon2010/07/01 10:40 PM
                                                    C type safety?2010/07/02 01:10 AM
                                                      C type safetyanon2010/07/02 11:02 PM
                                                    C is a crappydev2010/07/03 04:51 PM
                                                      C is a crappyanon2010/07/03 07:02 PM
                                                        C is a crappydev2010/07/05 07:27 AM
                                                          C is a crappy?2010/07/05 09:05 AM
                                                            C is a crappyanonymous2010/07/07 08:32 AM
                                                              C is a crappy?2010/07/07 10:48 PM
                                                              C is a crappyAnon2010/07/08 12:53 AM
                                                      C is a crappy and a crappie is a fishanonymous2010/07/03 07:24 PM
                                      Compile time & efficiencyMichael S2010/06/29 03:18 AM
                                        Compile time & efficiencyrwessel2010/06/29 12:20 PM
                                        Compile time & efficiencysomeone2010/06/30 11:03 AM
                                        Compile time & efficiencyJouni Osmala2010/07/02 05:29 AM
                                  Compile time & efficiencyMax2010/06/28 05:05 PM
                                    Compile time & efficiencyEduardoS2010/06/28 05:11 PM
                                    Compile time & efficiencyMichael S2010/06/29 03:33 AM
                              Compile timeFoo_2010/06/28 09:03 AM
          sun 's cc better than GCC?Silent2010/06/23 06:19 PM
            sun 's cc better than GCC?Foo_2010/06/23 07:06 PM
          sun 's cc better than GCC?Andi Kleen2010/06/24 02:49 AM
        sun 's versus gccVincent Diepeveen2010/06/23 03:07 PM
    Why no GCC?Carlie Coats2010/06/23 05:11 AM
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