[MacPorts] #54771: gcc7 -march=native fails on compile for corei7

[MacPorts]

#54771: gcc7 -march=native fails on compile for corei7
----------------------+-------------------
  Reporter:  bdmckay  |      Owner:
      Type:  defect   |     Status:  new
  Priority:  Normal   |  Milestone:
 Component:  ports    |    Version:  2.4.1
Resolution:           |   Keywords:
      Port:  gcc7     |
----------------------+-------------------

Comment (by colinhowell):

 This same problem is also the cause of tickets #36389 and #51642.

 Incidentally, bdmckay, I think "vcvtsi2sdq %rax, %xmm0,%xmm0" (which is
 AT&T assembler syntax; in Intel syntax it would be "vcvtsi2sd xmm0, xmm0,
 rax") is actually in AVX, not AVX2. So it's legal for GCC, when run with
 -march=native, to generate it for your processor, which, for your MacBook
 Pro model, is an "Ivy Bridge", a somewhat later "Core i7" variant. "Core
 i7" is an Intel brand name for an entire family of processors, not all of
 which are the same; while the earliest Core i7s did not support AVX, all
 later ones do. GCC performs a detailed feature check to see what features
 are available.

 Anyway, the problem is not that GCC generates the instruction, but that
 the assembler doesn't know what to do with it.

--
Ticket URL: <https://trac.macports.org/ticket/54771#comment:6>
MacPorts <https://www.macports.org/>
Ports system for macOS