[cfarm-users] Enable one ISA for my code, and another ISA for GCC code?

[Jonathan Wakely]

On Wed, 15 Aug 2018 at 11:33, Jeffrey Walton via cfarm-users
<cfarm-users at lists.tetaneutral.net> wrote:
>
> I'm catching a SIGILL on POWER7 ppc64-le machine. I compiled the
> source with -mcpu=power8 so I could enable some builtins I may need.
> Use of the builtins is guarded at runtime. (This is the classic distro
> model, where most source code is compiled for a minimum machine but
> higher ISAs are guarded at runtime).
>
> GCC converted some C code into POWER8 code. The SIGILL is happening in
> the function prologue due to use of mtfprwz. Apparently mtfprwz is a
> ISA 2.07B/POWER8 instruction.
>
> My question is, how do I tell GCC to use a different ISA than I am using?

Doesn't this belong on gcc-help at gcc.gnu.org not the cfarm users list?