[clang] [compiler-rt] [llvm] [Hexagon] Add ShadowCallStack support (PR #200508)

[Brian Cain via cfe-commits]

androm3da wrote:

> Looks good (though haven't touched CFI much). Is there a directed EH test that checks unwind fires N times and R19 matches original value? In the epilogue CHECK-DAG, can the memw/add ever get reordered?

I have added tighter checks in a73b1c8d16552809936a9d5e0fc3744d570141c5 to verify the memw/add packetization.

Directed tests - not sure, but I will at least run the `llvm-test-suite` and if there's no specific tests like this to stress the call stack I can add one.

https://github.com/llvm/llvm-project/pull/200508