Re: Compiler/Linker flags

[Christopher Hulbert]

On 1/18/07, Ralf Wildenhues <address@hidden> wrote:
> * Christopher Hulbert wrote on Thu, Jan 18, 2007 at 01:18:07PM CET:
> > On 1/17/07, Bob Friesenhahn <address@hidden> wrote:
> > >On Wed, 17 Jan 2007, Christopher Hulbert wrote:
> > >
> > >> It seems that libtool is set up to strip unrecognized flags unless
> > >> using something like -Wc,flag.  Can anyone give me a brief answer as
> > >> to why? I often find myself going through hoops to get flags past
> > >
> > >The reason for the odd behavior is that libtool needs to know which
> > >options should be applied to the compiler, and which should be applied
> > >to the linker. [...]
>
> > Makes sense. Now if the compiler is used for linking (which is
> > generally the case for my compilations), would it make sense to allow
> > unrecognized flags through?
>
> As in, for example, `-MF foo.Tpo', erroneously passed by the
> (non-Automake-using) innocent user in $(CFLAGS)?  Or, FWIW, -Bstatic,
> which will let libtool make the completely wrong choices of libraries
> (at the moment) if allowed through?

I can't say I've ever tried -Bstatic, so I have no idea what libtool
would do with it. I still lack the details of libtool's guts :)!

 -Bstatic_pgi may very well also
> be in the category that libtool needs to know about it; I cannot know,
> you haven't told us what semantics it has, and the GNU/Linux PGI I have
> access to doesn't know about it either.

Well, -Bstatic_pgi was just the latest flag I was trying to get
through. There are a lot of others that are useful at link time for
the pgi compilers. These flags deal with optimization flags like IPA,
vectorization, etc.

Sometimes, I just end up defining a variable like LDFLAGS_LT which I
put in AM_LDFLAGS in the automake files so that they do not get used
in autoconf testing, but still make it into the package compiling.
Then I can use -Wc,-Bstatic_pgi -Wc,"-Mipa=fast,libinline", etc....

> Cheers,
> Ralf