[PATCH] Support powerpc64le-linux platform

Ulrich Weigand Ulrich.Weigand at de.ibm.com
Fri Dec 6 17:20:37 UTC 2013

Torbjorn Granlund <tg at gmplib.org> wrote:

> Testing cpp symbols for ABI version makes me a bit nervous.  Such things
> can easily get out-of-synch.  It might be more resilient to check a
> generated object.

Well, the _CALL_ELF check is what we use for all other packages that
needed ELFv2 changes, starting from glibc ...  So if that ever gets
out of sync, we'll have bigger problems anyway.

> Is the setting of of a TOC pointer unconditionally really needed
> (presumably for a call from another shlib including the main program)
> even for leaf functions which also don't use the TOC?

If a function does not use the TOC (either explicitly or implicitly
e.g. because it performs a function call), then we do not need to
set it up in the prolog.  However, since there was just a single
PROLOGUE macro, it seemed the safe course to set it always.

Now, if we know for sure that none of the functions needs a TOC,
we can omit it completely.  Or else, we could introduce two versions
of the PROLOGUE macro, and let each function choose the right one.

I'm not sure if this is really worth the effort though: it makes
a difference only if the function is called externally (from another
shared library or via function pointer).  Aren't those routines
mostly called locally anyway?  Local calls will bypass the TOC
setup automatically anyway.

> Is there a way we could test powerpc64le-linux or the new abi?  We try
> to have (automated) tests for every ABI which we claim to be supporting.

Right now there is no base OS for powerpc64le-linux that you could
install readily, and there's also no easy way to get a machine to
run this on.  I'm sure once we're a bit farther along, we'll try
to make a powerpc64le-linux test machine available, e.g. in the
GCC compile farm.


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