On 21.02.2022 12:35, Richard Sandiford via Gcc-help wrote:
Christer Solskogen via Gcc-help <gcc-help@xxxxxxxxxxx> writes:
On https://gcc.gnu.org/onlinedocs/gcc/AArch64-Options.html there's a
list of feature modifiers to -march and -mcpu. Is there a way to check
or detect what features are available on a particular CPU?
If you want to compile for a specific CPU then it's better to use
-mcpu=<that-cpu> with no feature modifiers, and leave out -march.
GCC will then make full use of the available features.
E.g. -mcpu=neoverse-n1 (on its own) will enable all features
available on Neoverse N1 and optimise code for Neoverse N1.
If you're just curious which features a given CPU implements,
you can find that out by compiling a dummy file with -mcpu. E.g.:
echo | gcc -mcpu=neoverse-n1 -xc - -o - -S | grep '\.arch'
will print out:
.arch armv8.2-a+crc+fp16+rcpc+dotprod+profile
I see. Thank you.
Does that mean that the cortex-a72 doesn't really support the +crypto or
+simd? Or does that depend on what is built?
--
chs
