This option lets you enable branch authentication instructions on AArch64.
This option is ignored for non-AArch64 architectures.
It takes some combination of the following values, separated by a
pac-ret- Enable pointer authentication for non-leaf functions.
leaf- Enable pointer authentication for all functions, including leaf functions.
b-key- Sign return addresses with key B, instead of the default key A.
bti- Enable branch target identification.
b-key are only valid if
pac-ret was previously specified.
-Z branch-protection=bti,pac-ret,leaf is valid, but
-Z branch-protection=bti,leaf,pac-ret is not.
Rust's standard library does not ship with BTI or pointer authentication enabled by default. In Cargo projects the standard library can be recompiled with pointer authentication using the nightly build-std feature.