How to provide some compiler flags?

[tricarte]

I want to do some benchmarks with compiler optimizations such as -O2 -march=native -pipe.

Is it possible to customize these flags? If it's possible, will it apply to all static extensions or just the final php binary?

Also, can we use Intel Profile Guided Optimization? The generated Makefile for PHP source code has PGO targets but I think spc does (can) not use it in any way.

Thanks in advance.