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Re: [PATCH] Fix underflow and inexact signalling in soft-fp whenpacking.
On Fri, 25 May 2012, David Miller wrote:
> Did I ever tell you how extremely unfortunate it is that we have three
> copies of this soft-fp code base and no real synchronization between
> them?
>
> I warned way back when libgcc got a copy of the soft-fp code that this
> would happen, and those warnings fell on deaf ears.
glibc and libgcc are kept in sync; local changes are not made to the
libgcc copy (by GNU project policy) but instead updated files are imported
verbatim from glibc.
> Longer term we need to rectify the situation that we have three
> copies of the soft-fp code base, each has different bugs fixed
> and different performance improvements.
It's effectively two copies, not three. It was noted by RTH in
<http://sourceware.org/ml/libc-alpha/2006-02/msg00075.html> that the
changes should be merged into the kernel; I don't know if any kernel
people ever actually tried doing that (I only follow kernel development to
a very limited extent; if it's not on the linux-api list, which *should*
get all things relevant to the kernel/userspace interface but doesn't
always, I'm likely to miss it).
I've just followed up on an item that's been on my glibc todo list for a
while, to check if GCC bug 44631 - a bug in the Linux kernel's copy of
soft-fp - was applicable to the glibc version. It's not; it's the same
off-by-one error I mentioned as the fourth bullet point in
<http://sourceware.org/ml/libc-alpha/2006-02/msg00028.html>, so fixed by
my 2005-6 changes.
--
Joseph S. Myers
joseph@codesourcery.com