On Tue, 24 Jul 2018, Andrew Janke wrote:
I am having difficulty compiling GCC for a different generation of x86 CPU. I
would like to produce a portable/redistributable build of GCC to be
distributed along with a packaging of GNU Octave. So I would like to build it
for the Core2 architecture, even though my build box has a Skylake CPU.
This is for GCC 8.1.0 on macOS.
It seems like setting "-march=core2" in CFLAGS, BOOT_CFLAGS, and
CFLAGS_FOR_TARGET is the way to do this, but it doesn't seem to be working.
When I do the build, and then copy the built GCC to an older Ivy Bridge Mac,
and attempt to use gfortran to compile a program, it errors out with an
"internal compiler error: Illegal instruction: 4" error message.
Here you are supposed to use a debugger to find out what instruction this
is and where it is (could be in libgmp for instance).
--
Marc Glisse
