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Re: Correct way to build .deb with -mieee

Christopher C. Chimelis wrote:

On Tue, 19 Jun 2001, Adam C Powell IV wrote:

I have a program (petscgraphics) which, when built without -mieee, fails with SIGFPE (division by zero); with -mieee, works perfectly (still divides by zero, but works anyway).

So, should -mieee go in debian/rules, something like "CFLAGS=-mieee ./configure --prefix=/usr"? Or is there a more intelligent way for upstream (me) to put it in, such that it is only used for one source file (petscgraphics.c)?

It's usually ideal to make such changes in the autoconf scripts, unless
the software doesn't use autoconf.  If it doesn't, then the best way may
be to handle it via debian/rules.  Since it's only needed for one file,
though, doing a "blanket" -mieee compilation would probably be overkill...

Indeed. I took this approach (autoconf scripts), and now PETScGraphics works on alpha.

Just "for the record", here's what I did: in configure.in

AC_CHECKING([whether -mieee is needed to avoid SIGFPE on divide by zero])
case $build/$CC in
   alpha*/gcc* )
   AC_MSG_RESULT([yes, will be used for libpetscgraphics])
   * )
   AC_MSG_RESULT([not needed])
AM_CONDITIONAL(GCC_ALPHA, test x$build_gcc_alpha != xno)

Then in Makefile.am, I copied the %.lo:%.c target from Makefile.in but added -mieee for this particular file:

# This is to get -mieee in for gcc on Alpha
petscgraphics.lo: petscgraphics.c
   @echo '$(LTCOMPILE) -mieee -c $<'; \
   $(LTCOMPILE) -mieee -Wp,-MD,.deps/$(*F).pp -c $<
   @-sed -e 's/^\([^:]*\)\.o[     ]*:/\1.lo \1.o :/' \
     < .deps/$(*F).pp > .deps/$(*F).P; \
   tr ' ' '\012' < .deps/$(*F).pp \
     | sed -e 's/^\\$$//' -e '/^$$/ d' -e '/:$$/ d' -e 's/$$/ :/' \
       >> .deps/$(*F).P; \
   rm -f .deps/$(*F).pp
endif # GCC_ALPHA

I really don't know what all the obscure sed and tr stuff does (except that it helps set up build dependencies properly), and it may break on automake upgrade, but at least for now it works. :-)

HTH, share and enjoy, etc.

-Adam P.

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