x86-64 GCC CPU target options

[Torbjorn Granlund]

Cameron Gutman <aicommander at gmail.com> writes:

  I noticed that GMP 5.1.2 doesn't use the newer GCC -march and -mtune
  targets for Sandy Bridge (corei7-avx) and Haswell (core-avx2). Is this
  because configure.ac just hasn't been updated or is there another reason?
  
We add such options now and then, but we don't do it very eagerly.

  Also, would it be worth splitting Ivy Bridge out of the coreisbr group so
  we can use the core-avx-i GCC target?
  
  I've tested a modified configure.ac that uses corei7-avx on an Ivy Bridge
  system (recognized as coreisbr). It passes all the tests in make check. I
  haven't done any major performance tests yet though.
  
GMP depends on its assembly code for most operations and hosts.
Therefore, we shouldn't expect any general and significant speedup by
adding a few new configure.ac options.

-- 
Torbjörn