To: "Gerrit @ cygwin" <[EMAIL PROTECTED]>
cc: Mathias Wagner/HBG/SC/[EMAIL PROTECTED]
Subject: Re: GCC 3.3.1 problem with printf %Lg %Lg and
-m128bit-long-double compile
option
Classification:
> On Thu, 27 May 2004, Gerrit P. Haase wrote:
>
> > Hallo mathias,
> >
> > > GCC 3.3.1 has a problem when printing multiple long double variables
using
> > > printf and the -m128bit-long-double compile option on a
Pentium-based
> > > machine.
> >
> > Seems to be a bug in gcc, for bug reporting instructions, please see:
> > http://gcc.gnu.org/bugs.html.
>
> No disrespect intended Mr. GCC maintainer, but I'm pretty sure that is
> expected behavior. See "info gcc" in the -m128bit-long-double section:
>
> *Warning:* if you override the default value for your target ABI,
> the structures and arrays containing `long double' will change
> their size as well as function calling convention for function
> taking `long double' will be modified. Hence they will not be
> binary compatible with arrays or structures in code compiled
> without that switch.
>
> Cygwin/newlib would need to be recompiled with this switch for proper
> printf operation. Why are you trying to use this switch, Mathias?
Thanks for these infos to both of you!
Meanwhile I have had some help from another colleague here at Philips and
he found out that the -m96bit-long-double compile option works fine. Note
that 96 bit is what a long double takes. This makes sense in conjunction
with what Brian said: The alignment of the parameters handed over to a
function is changed when using -m128bit-long-double, and hence all
functions affected must be recompiled - so presumably cygwin itself.
There was no particular reason for using -m128bit-long-double other than
that I have always used it, and I will switch to -m96bit-long-double. But
perhaps one could insert somewhere in gcc a warning when using such a
combination of compile options. I know it is in the documentation
somewhere, but compiler warnings are much more visible... :-)
Cheers
Mathias
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