[Mesa-dev] LLVM_CFLAGS

[José Fonseca]

On Mon, 2010-12-06 at 10:58 -0800, Brian Paul wrote:
> I'd like to simply try --cppflags for now and see if that fixes the 
> problem for us.  There's a few -D flags that we also need; it's not 
> just the -I path.

I agree.

The scons build has been using --cppflags since the very beginning. I
don't recall any problem.

> On 12/06/2010 11:27 AM, Bob Gleitsmann wrote:
> > There is an option --includefiles that returns the directory with the include
> > files. It isn't prefixed by -I so that would have to be worked out. Is that all
> > that is needed? Seems like it should be.
> >
> > BG
> > On Monday, December 06, 2010 12:58:11 pm Corbin Simpson wrote:
> >> Isn't there a --cflags-only-I or something along those lines?
> >>
> >> Sending from a mobile, pardon the brevity. ~ C.
> >>
> >> On Dec 6, 2010 9:42 AM, "Dan Nicholson"<dbn.lists at gmail.com>  wrote:
> >>> On Mon, Dec 6, 2010 at 9:15 AM, Brian Paul<brianp at vmware.com>  wrote:
> >>>> On 12/05/2010 02:06 AM, Bob Gleitsmann wrote:
> >>>>> Hello,
> >>>>>
> >>>>> Can someone explain the value of including this in
> >>>>> mesa/src/gallium/Makefile.template:
> >>>>>
> >>>>> ifeq ($(MESA_LLVM),1)
> >>>>> LIBRARY_DEFINES += $(LLVM_CFLAGS)
> >>>>> endif
> >>>>>
> >>>>> ?
> >>>>> This effectively adds the LLVM cflags to gcc compiles if LLVM is
> >>
> >> enabled.
> >>
> >>>>> One
> >>>>> side-effect of this is to include -O3 optimization no matter what,
> >>
> >> making
> >>
> >>>>> debugging very difficult. Removing it seems to have no catastrophic
> >>>>> effects (or
> >>>>> even detectable ones).
> >>>>> But maybe I am missing something.
> >>>>
> >>>> We need some of the LLVM C flags to get the -I path for headers, for
> >>>> example.
> >>>>
> >>>> I think we should use llvm-config --cppflags instead of --cflags.
> >>>>
> >>>> If you're using autoconf, try changing this line:
> >>>>         LLVM_CFLAGS=`$LLVM_CONFIG --cflags`
> >>>>
> >>>> in configure.ac to use --cppflags instead.  Does that help?
> >>>
> >>> I think the question is, what else is in llvm-config --cflags? If all
> >>> that's needed is the include paths, then --cppflags would be
> >>> sufficient. However, if there are macro definitions or compiler flags
> >>> (e.g. -fomit-frame-pointer) in --cflags that are needed to properly
> >>> use llvm, then I guess you need --cflags. 

-fomit-frame-pointer doesn't cause ABI changes. It's fine to mix code
built with/without it.

> This is really a bug in
> >>> llvm, but the last time someone here tried to bring it up to the llvm
> >>> people, it was dismissed. Here's that bug:
> >>>
> >>> http://llvm.org/bugs/show_bug.cgi?id=8220
> >>>
> >>> There's some more in the mesa archives, but I can't find the thread
> >>> now. Sadly, that bug became a discussion about pkg-config which was
> >>> not what was intended.

Jose