Aarch64 gcc does not optimize function when applied as function attribute

Greetings,

I’m trying to have the Aarch64 gcc optimize a single function using the O3 optimization in this manner:

void __attribute__ ((optimize ("-O3", "-ftree-vectorize" ))) However, when examining the assembler code, there is no trace of any optimization beyond the project default. The only way to successfully enforce the optimization is using -O3 in the gcc command line. Then the compiler produces ARM neon instructions.

Do you know any issues regarding function level optimizations and the Aarch64 gcc?

Regards