Re: m4-1.4.9b on HP-UX 11

[Gary V. Vaughan]

Hi Bruno,

[[Cc:ing Albert Chin:  Albert, why do we need +Onofltacc in the  
standard hpux11.23
  flags, when it clearly causes NaN regressions?]]

On 3 Jun 2007, at 01:48, Bruno Haible wrote:

> Gary V. Vaughan wrote in
>   http://lists.gnu.org/archive/html/bug-gnulib/2007-06/msg00005.html
> [For some reason, I can see your last 3 mails on gmane and on  
> lists.gnu.org,
> but they don't came into my mailbox. And I have no spam filter.]
>
> > With CC=cc CFLAGS="-z +O2 +Onofltacc +Olit=all +Oentrysched  
> > +Odataprefetch \
> > +Onolimit" LDFLAGS="-Wl,+nodefaultrpath":
> >
> > 1.000000 33
> > test-vasprintf-posix.c:1239: assertion failed
> > /opt/fsw/bash30/bin/bash: line 1: 12683 ABORT instruction (core  
> > dumped) EXEEXT='' EXEEXT='' EXEEXT='' srcdir='.' EXEEXT=''  
> > srcdir='.' EXEEXT='' srcdir='.' ${dir}$tst
> > FAIL: test-vasprintf-posix
> >
> > With CC=cc CFLAGS="-z +O2 +Olit=all +Oentrysched +Odataprefetch  
> > +Onolimit" \
> > LDFLAGS="-Wl,+nodefaultrpath":
> >
> >   -nan 33
> >   -nan 33
> >   PASS: test-vasprintf-posix
>
> This makes it pretty clear that +Onofltacc is the culprit.
>
> > Do you think the test is at fault here?
>
> No; dividing zero by zero *must* give a NaN according to IEEE 754.  
> This is
> not the kind of "undefined behaviour" that may be optimized  
> randomly by
> the compilers.
>
> > Or is it an hpux compiler bug?
>
> Whether it's an HP-UX compiler bug or whether it's you who are  
> willfully
> choosing a non-IEEE-754-compliant compiler by using the option  
> +Onofltacc,
> depends on the HP compiler's documentation. I can not judge it by  
> the small
> snippet you posted.

The fact that it breaks this test only on hpux11.23 when the same  
flags do
not break it on hpux11.11 and hpux11.00 makes me think it is a  
compiler bug.

> > we've made it a standard flag for compilations on hpux in order for
> > other FLOSS projects to build correctly
>
> It sounds surprising that some projects _require_ a particular  
> optimization
> in order to build correctly?! But it any case, I'm more inclined to  
> adapt
> source code so that it compiles with default flags, more than for some
> pretty aggressive vendor-specific optimization flags. (Here for HP- 
> UX cc
> I consider "cc -Ae" the default.)

ACK.  Thanks for your input.

Cheers,
        Gary
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