Help with New Port - M2VDownsizer

[Robert Kennedy]

I have been playing around with CFLAGS += -Xarch_ppc -faltivec in my Makefile, as suggested by Josh.

I noticed that if I include CFLAGS += -Xarch_ppc -faltivec in my Makefile, the output from the clang compiler gets garbled but the M2VDownsizer binary appears to build fine.
E,g,
/opt/local/var/macports/build/_Users_grinch_Macports_ports_multimedia_M2VDownsizer/M2VDownsizer/work/compwrap/cc/usr/bin/clang -Os -arch x86_64 -Wall -g -Xarch_ppc -faltivec -Xarch_ppc64 -faltivec -I./ -Iutils -Iutils/altivec -Impeg2dec -Impeg2enc -I/System/Library/Frameworks/CoreServices.framework/Headers  -c utils/mpegconsts.c -o obj/utils/mpegconsts.o

clang: clang: clang: clang: warning: warning: warning: warning: argument unusedargument unusargument dured dur unused dinig ng compilation:uring '- coacompilXarchatmpilio_ppatiornn: gu:c  -m''--faXXarletntciav rhch_ec_ppu'n
usppc clang: warning: ar-faltedc guiv d-fmeecuralnt'
ing compilatclang: warning: ioti uarn: '-Xarch_ppc -faltivec'
clang: warning: argument unused during compilation: '-Xarch_ppc6nguvs4 uemece'
d-faltivclang: nt decu'
 unriwarning: argument unused during compilation: '-Xarch_ppc64 -faltivec'
ng compilation: '-Xarch_ppc64 -faltivec'
used during compilation: '-Xarch_ppc64 -faltivec'

I can avoid this garbled output if I turn off parallel builds by including the following in the Portfile:

use_parallel_build            no

What is recommended in these circumstances considering that the garbled output does not appear to affect building the final binary?  Should I turn off parallel builds in the Portfile?

Rob
________________________________
From: Robert Kennedy <amtor at hotmail.com>
Sent: August 1, 2022 10:54 AM
To: Joshua Root <jmr at macports.org>
Cc: MacPorts Development <macports-dev at lists.macports.org>
Subject: Re: Help with New Port - M2VDownsizer

Joshua,

I can confirm that your elegant solution using CFLAGS += -Xarch_ppc -faltivec does work.  The compile succeeds.  But clang does throw this warning message:

clang: warning: argument unused during compilation: '-Xarch_ppc -faltivec'

P.S.  To cover the ppc64 arch, I also added the following to the Makefile:

CFLAGS += -Xarch_ppc64 -faltivec

Thanks again,

Rob



________________________________
From: macports-dev <macports-dev-bounces at lists.macports.org> on behalf of Robert Kennedy <amtor at hotmail.com>
Sent: July 31, 2022 10:16 PM
To: Joshua Root <jmr at macports.org>
Cc: MacPorts Development <macports-dev at lists.macports.org>
Subject: Re: Help with New Port - M2VDownsizer

Thanks Joshua.

I have never seen "-Xarch" before in a Makefile.  That looks like very simple and elegant way to address the issue.  I will give it a shot.  I will be able to easily verify that it works because Intel builds will fail with following error if CFLAGS contains the -faltivec flag:


clang: error: invalid argument '-faltivec' only allowed with 'ppc/ppc64'

I am glad to hear that I can use conditional expressions in my Portfiles, if need be.  It looks like I will need to brush up on my Tcl.

Thanks again,

Rob
________________________________
From: Joshua Root <jmr at macports.org>
Sent: July 31, 2022 9:38 PM
To: Robert Kennedy <amtor at hotmail.com>
Cc: MacPorts Development <macports-dev at lists.macports.org>
Subject: Re: Help with New Port - M2VDownsizer

On 2022-8-1 10:11 , Robert Kennedy wrote:
> Hello everyone!
>
> I am working on a new port, M2VDownzsizer, which is a sister port to the
> recent existing port, M2VRequantiser.  Both ports are command line
> programs that shrink MPEG-2 video and are commonly used when shrinking
> a DVD-9 video disc to fit onto a much more affordable DVD-5 writable disc.
>
> M2VDownsizer was released as an open source project many years ago and
> was developed as an old XCode project for Macs running PowerPC and Intel
> 32 bit.  The code is quite old.
>
> I have converted the project from an XCode project to a much simpler
> project using a Makefile.  I have also hacked and updated the code so it
> will run on modern compilers.  I also eliminated the need to compile the
> very old libraries in the source code by linking to much more up to date
> libraries available in Macports.  I have even written a man page!
> M2VDownsizer appears to run just fine on more modern Macs!
>
> Now my challenge is creating a Portfile!  I have a couple of questions:
>
>  1.   How do I tell Macports to copy my Makefile (which I will place in
>     the Files directory along with my source code patches) into my
>     working directory before building?  (The original source never had a
>     Makefile so there is nothing to patch).  P.S.  I could always create
>     my own GitHub project and download the source (with the Makefile)
>     from there.

post-extract {
     copy ${filespath}/Makefile ${worksrcpath}
}

>  2. How do I tell Macports to include the -faltivec flag in CFLAGS but
>     only when a ppc build is being done?  I have the following in my
>     Makefile but I suspect it would be much better to address this issue
>     in the Portfile in case an Intel Mac is trying to build a ppc/x86
>     FAT binary:
>
>         ifeq ($(findstring ppc, $(UNAME_P)), ppc)
>               CFLAGS += -faltivec
>               CXXFLAGS += -flativec
>         endif

You could instead do:
CFLAGS += -Xarch_ppc -faltivec
CXXFLAGS += -Xarch_ppc -faltivec

That will apply -faltivec only when building for ppc.

>       3. Is there anything like an "if-then-else" statement in Portfiles?

Yes, Portfiles are written in Tcl and can use all Tcl's control flow
mechanisms.

- Josh
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