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 But it should never be necessary to convert that back into an -march option. Using -mcpu with no feature modifiers is better. -march is really for the case in which you don't know which CPU the code will run on, but you instead have a baseline set of requirements. Thanks, Richard
