GMP doesn't honor march flag

[Torbjörn Granlund]

Paul Jähne <paul.jaehne at gmx.de> writes:

  I encountered a problem with GMP when using the march flag.
  
  I build GMP 6.1.1 with march=corei7 or march=westmere with GCC 5.4.0
  on a server with a Haswell processor (E5-2630 v3). When executing curl
  (version 7.47.0 on Ubuntu 16.04) which uses GMP to retrieve a https
  website on a system with a Westmere Processor (Intel Xeon E5645) it
  crashes with the error: Illegal instruction (core dumped).
  
No GMP bug.  You're not following the doumented procedures.  Don't
override CFLAGS like that, it is ineffective and as you omitted any -O
also a disaster for performance.

You might find it helpful to read the GMP manual's chapter "Installing
GMP".  There are many good suggestions there!


-- 
Torbjörn
Please encrypt, key id 0xC8601622