llvm dev - Apr 2009 - [LLVMdev] advice on default options for building LLVM-GCC on Ubuntu Linux

On Apr 5, 2009, at 7:13 AM, Duncan Sands wrote:
> On Saturday 04 April 2009 19:12:55 Mike Stump wrote:
>> On Apr 4, 2009, at 6:17 AM, Duncan Sands wrote:
>>> you need to use a separate objects directory and not build directly
>>> in the llvm-gcc tree.  For some reason the Apple people placed a  
>>> file
>>> GNUmakefile in the tree which "make" chooses in
preference to the
>>> Makefile
>>> produced by configuring.  Personally I would like to see
GNUmakefile
>>> deleted.
>>
>> My take, you can test an environment variable called RC_RELEASE in  
>> the
>> GNUmakefile and use it, if set, and if it isn't set, include
Makefile
>> and use it in preference.  Oh course, this is untested, someone would
>> have to test it in all three environments.
>
> Non-apple people build from svn too, not just releases.  My take is  
> that
> Apple should have their own build script which passes "make"  
> whichever file
> they want to use as the makefile, so then it doesn't need a special  
> name
> like GNUmakefile.  Actually, doesn't Apple use a build script already?
>
We use GNUmakefile to trigger using the build_gcc script. It's not  
ideal, but it's all we have at the moment. For LLVM, we placed those  
files in a subdirectory. This isn't ideal because of our build  
processes, but was better than the alternative. We would *really*  
prefer not doing the same thing to LLVM-GCC. Because we've been  
building LLVM-GCC with srcdir != objdir for years now, it shouldn't be  
too much of a burden. . .

 From what I understand, FSF GCC doesn't recommend building with  
srcdir == objdir. Not that this necessarily means much to us, but  
should indicate that it's not entirely out of the ordinary that we  
require srcdir != objdir for LLVM-GCC. :-)

-bw

Hi Bill,
> We use GNUmakefile to trigger using the build_gcc script.
thanks for the explanation, but I still don't understand why
it is done this way.  Why not just get Apple people to run some
script, rather than trying to have "make" automagically do an
Apple build?
> It's not  
> ideal, but it's all we have at the moment. For LLVM, we placed those  
> files in a subdirectory. This isn't ideal because of our build  
> processes, but was better than the alternative. We would *really*  
> prefer not doing the same thing to LLVM-GCC. Because we've been  
> building LLVM-GCC with srcdir != objdir for years now, it shouldn't be
> too much of a burden. . .
> 
>  From what I understand, FSF GCC doesn't recommend building with  
> srcdir == objdir. Not that this necessarily means much to us, but  
> should indicate that it's not entirely out of the ordinary that we  
> require srcdir != objdir for LLVM-GCC. :-)
Newcomers to llvm-gcc regularly try to build with srcdir == objdir.
Some of them come on irc and ask about why it fails, but probably
most of them just give up on llvm-gcc.

Ciao,

Duncan.

On Tue, Apr 7, 2009 at 12:38 AM, Duncan Sands <baldrick at free.fr>
wrote:
> Hi Bill,
>
>> We use GNUmakefile to trigger using the build_gcc script.
>
> thanks for the explanation, but I still don't understand why
> it is done this way.  Why not just get Apple people to run some
> script, rather than trying to have "make" automagically do an
> Apple build?
>
It's more complicated than that. Suffice it to say that we wouldn't be
able to get the people who need to use GNUmakefile/build_gcc to change
just for our team (it's more than just our team that is required to do
this). In truth, they do have this. It's called "xcodebuild". But
llvm-gcc is very incompatible with this method of building.
>> It's not
>> ideal, but it's all we have at the moment. For LLVM, we placed
those
>> files in a subdirectory. This isn't ideal because of our build
>> processes, but was better than the alternative. We would *really*
>> prefer not doing the same thing to LLVM-GCC. Because we've been
>> building LLVM-GCC with srcdir != objdir for years now, it shouldn't
be
>> too much of a burden. . .
>>
>>  From what I understand, FSF GCC doesn't recommend building with
>> srcdir == objdir. Not that this necessarily means much to us, but
>> should indicate that it's not entirely out of the ordinary that we
>> require srcdir != objdir for LLVM-GCC. :-)
>
> Newcomers to llvm-gcc regularly try to build with srcdir == objdir.
> Some of them come on irc and ask about why it fails, but probably
> most of them just give up on llvm-gcc.
>
I understand. Believe me, I'm not a big fan of this method of building
llvm-gcc either. But I'm not a Makefile guru, so I don't know how to
make the two systems of building llvm-gcc compatible. Is there a FAQ
entry on this? If not, I'll add one.

-bw