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Re: m4-1.4.9b on HP-UX 11
From: |
Albert Chin-A-Young |
Subject: |
Re: m4-1.4.9b on HP-UX 11 |
Date: |
Sun, 3 Jun 2007 08:59:49 -0500 |
User-agent: |
Mutt/1.5.6i |
On Sun, Jun 03, 2007 at 02:53:22PM +0100, Gary V. Vaughan wrote:
> [[Cc:ing Albert Chin: Albert, why do we need +Onofltacc in the
> standard hpux11.23
> flags, when it clearly causes NaN regressions?]]
>From the cc(1) man page:
+O[no]fltacc Disable [enable] floating-point optimizations that
can result in numerical differences.
+Ofltacc is the same as +Ofltacc=strict.
+Onofltacc is the same as +Ofltacc=relaxed.
So, +Onofltacc disables floating-point optimizations. Seems like the
correct decision to me.
I'm fine leaving it off if it fixes something but it seems odd.
> 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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--
albert chin (address@hidden)