[clang] [llvm] [clang][ARM] Add -fstack-limit-variable to trap before stack overflow (PR #208076)

[Peter Smith via llvm-commits]

smithp35 wrote:

Thanks for the RFC. Hopefully will be able to discuss in the next embedded toolchains call.

I expect that the only way we'll know whether reloading a variable or reserving a register is better is to benchmark for code-size and performance. It will be useful to have some code-size and performance figures anyway as many embedded developers will want to know before they attempt to use an option.

https://github.com/llvm/llvm-project/pull/208076