Building GMP 6.0 for Ivy Bridge

[Marc Glisse]

On Fri, 2 Oct 2015, Victor Shoup wrote:

> Thanks.  Compiled and ran.
> Output is "ivybridge".
>
> But ./config.guess outputs x86_64 and that's what is is
> in ./config.log, too.

Uh. Weird. Maybe config.guess is using a different compiler or something. 
bash -x ./config.guess would help locate the issue (if there is no line 
"/bin/sh -c /tmp/.../dummy" then it probably failed to compile), and 
further debugging (print the command that fails so it can be reproduced 
outside of config.guess) would likely identify the issue.


On Fri, 2 Oct 2015, Victor Shoup wrote:

> I tried --build=ivybridge...
> On the latest snapshot, that works...the only difference I
> can really discern between the two is that --march and --mtune
> resolve to ivybridge, rather than corei7, which is what I get
> when I build with coreisbr.
>
> My understanding is that there should be little difference between the
> two microarchitectures.  It looks like the same assembly codes are pulled
> in --- actually, it looks like GMP lumps ive/sandy bridge together...

Yes, that's what configure.ac says.

> Another note: on the official 6.0.0 release.
> --build=ivybridge doesn't work at all...it doesn't even
> pull x86 assembly codes at all.

That release is getting old...

> So maybe it is just a bug somewhere else in the configure script??

Well the problem is clearly with config.guess, it is just hard to guess 
what it may be.

-- 
Marc Glisse