Re: Makefile or IDE?

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From	Stefan Reuther <stefan.news@arcor.de>
Newsgroups	comp.arch.embedded
Subject	Re: Makefile or IDE?
Date	Sun, 5 Dec 2021 11:11:36 +0100
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Am 04.12.2021 um 16:23 schrieb pozz:
> Il 04/12/2021 10:31, Stefan Reuther ha scritto:
>> I'm not sure what you need order-only dependencies for. For a project
>> like this, with GNU make I'd most likely just do something like
>>
>>      OBJ = file1.o module1/file2.o module2/file3.o
>>      main: $(OBJ)
>>           $(CC) -o $@ $(OBJ)
>>      $(OBJ): %.o: $(SRCDIR)/%.c
>>           mkdir $(dir $@)
>>           $(CC) $(CFLAGS) -c $< -o $@
> 
> This is suboptimal. Every time one object file is created (because it is
> not present or because prerequisites aren't satisfied), mkdir command is
> executed, even if $(dir $@) is already created.

(did I really forget the '-p'?)

The idea was that creating a directory and checking for its existence
both require a path lookup, which is the expensive operation here.

When generating the Makefile with a script, it's easy to sneak a 100%
matching directory creation dependency into any rule that needs it

     foo/bar.o: bar.c foo/.mark
          ...
     foo/.mark:
          mkdir foo

>>> Dependencies must be created as a side effect of compilation with
>>> esoteric -M options for gcc.
>>
>> It's not too bad with sufficiently current versions.
>>
>>      CFLAGS += -MMD -MP
>>      -include $(OBJ:.o=.d)
> 
> Are you sure you don't need -MT too, to specify exactly the target rule?

Documentation says you are right, but '-MMD -MP' works fine for me so far...


  Stefan

Thread

Makefile or IDE? pozz <pozzugno@gmail.com> - 2021-12-02 12:46 +0100
  Re: Makefile or IDE? Grant Edwards <invalid@invalid.invalid> - 2021-12-02 15:22 +0000
    Re: Makefile or IDE? pozz <pozzugno@gmail.com> - 2021-12-02 17:34 +0100
      Re: Makefile or IDE? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2021-12-03 13:15 +0200
  Re: Makefile or IDE? Don Y <blockedofcourse@foo.invalid> - 2021-12-02 09:48 -0700
  Re: Makefile or IDE? Stefan Reuther <stefan.news@arcor.de> - 2021-12-02 17:34 +0100
    Re: Makefile or IDE? pozz <pozzugno@gmail.com> - 2021-12-03 11:49 +0100
      Re: Makefile or IDE? Stefan Reuther <stefan.news@arcor.de> - 2021-12-03 18:27 +0100
    Re: Makefile or IDE? George Neuner <gneuner2@comcast.net> - 2021-12-04 14:37 -0500
  Re: Makefile or IDE? Theo <theom+news@chiark.greenend.org.uk> - 2021-12-03 20:51 +0000
    Re: Makefile or IDE? Grant Edwards <invalid@invalid.invalid> - 2021-12-03 21:28 +0000
      Re: Makefile or IDE? George Neuner <gneuner2@comcast.net> - 2021-12-04 14:53 -0500
        Re: Makefile or IDE? David Brown <david.brown@hesbynett.no> - 2021-12-04 22:17 +0100
          Re: Makefile or IDE? Stefan Reuther <stefan.news@arcor.de> - 2021-12-05 11:02 +0100
            Re: Makefile or IDE? David Brown <david.brown@hesbynett.no> - 2021-12-05 13:16 +0100
        Re: Makefile or IDE? Grant Edwards <invalid@invalid.invalid> - 2021-12-06 13:52 +0000
          Re: Makefile or IDE? chris <chris-nospam@tridac.net> - 2021-12-17 17:19 +0000
  Re: Makefile or IDE? pozz <pozzugno@gmail.com> - 2021-12-03 23:48 +0100
    Re: Makefile or IDE? Stefan Reuther <stefan.news@arcor.de> - 2021-12-04 10:31 +0100
      Re: Makefile or IDE? pozz <pozzugno@gmail.com> - 2021-12-04 16:23 +0100
        Re: Makefile or IDE? David Brown <david.brown@hesbynett.no> - 2021-12-04 17:41 +0100
          Re: Makefile or IDE? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2021-12-04 18:49 +0200
            Re: Makefile or IDE? David Brown <david.brown@hesbynett.no> - 2021-12-04 18:23 +0100
              Re: Makefile or IDE? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2021-12-04 21:25 +0200
                Re: Makefile or IDE? David Brown <david.brown@hesbynett.no> - 2021-12-04 22:20 +0100
                Re: Makefile or IDE? Grant Edwards <invalid@invalid.invalid> - 2021-12-06 13:51 +0000
                Re: Makefile or IDE? David Brown <david.brown@hesbynett.no> - 2021-12-06 16:33 +0100
                Re: Makefile or IDE? Grant Edwards <invalid@invalid.invalid> - 2021-12-06 16:02 +0000
          Re: Makefile or IDE? pozz <pozzugno@gmail.com> - 2021-12-09 11:54 +0100
            Re: Makefile or IDE? Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2021-12-10 18:35 +0100
              Re: Makefile or IDE? David Brown <david.brown@hesbynett.no> - 2021-12-10 19:44 +0100
                Re: Makefile or IDE? pozz <pozzugno@gmail.com> - 2021-12-11 16:18 +0100
                Re: Makefile or IDE? David Brown <david.brown@hesbynett.no> - 2021-12-11 17:06 +0100
                Re: Makefile or IDE? Grant Edwards <invalid@invalid.invalid> - 2021-12-11 16:57 +0000
                Re: Makefile or IDE? Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2021-12-11 18:53 +0100
                Re: Makefile or IDE? David Brown <david.brown@hesbynett.no> - 2021-12-12 14:15 +0100
              Re: Makefile or IDE? Stefan Reuther <stefan.news@arcor.de> - 2021-12-11 10:01 +0100
                Re: Makefile or IDE? Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2021-12-11 18:47 +0100
                Re: Makefile or IDE? Stefan Reuther <stefan.news@arcor.de> - 2021-12-12 11:27 +0100
        Re: Makefile or IDE? Stefan Reuther <stefan.news@arcor.de> - 2021-12-05 11:11 +0100
          Re: Makefile or IDE? David Brown <david.brown@hesbynett.no> - 2021-12-05 13:21 +0100
  Re: Makefile or IDE? Dave Nadler <drn@nadler.com> - 2021-12-06 15:45 -0500
  Re: Makefile or IDE? pozz <pozzugno@gmail.com> - 2021-12-09 10:43 +0100
  Re: Makefile or IDE? Johann Klammer <klammerj@NOSPAM.a1.net> - 2021-12-10 09:30 +0100
  Re: Makefile or IDE? chris <chris-nospam@tridac.net> - 2021-12-17 17:27 +0000
    Re: Makefile or IDE? StateMachineCOM <statemachineguru@gmail.com> - 2021-12-20 17:18 -0800
      Re: Makefile or IDE? chris <chris-nospam@tridac.net> - 2021-12-21 16:45 +0000
      Re: Makefile or IDE? Jim Jackson <jj@franjam.org.uk> - 2021-12-21 17:40 +0000
        Re: Makefile or IDE? StateMachineCOM <statemachineguru@gmail.com> - 2021-12-21 10:55 -0800

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