This commit adds a new ABI to be selected via `extern "C-cmse-nonsecure-call"` on function pointers in order for the compiler to apply the corresponding cmse_nonsecure_call callsite attribute. For Armv8-M targets supporting TrustZone-M, this will perform a non-secure function call by saving, clearing and calling a non-secure function pointer using the BLXNS instruction. See the page on the unstable book for details. Signed-off-by: Hugues de Valon <hugues.devalon@arm.com>
The codegen
crate contains the code to convert from MIR into LLVM IR,
and then from LLVM IR into machine code. In general it contains code
that runs towards the end of the compilation process.
For more information about how codegen works, see the rustc dev guide.