[PATCH] D22254: [ARM, AArch64] Adds builtins to get current SP and PC

[Tim Northover via cfe-commits]

t.p.northover added a comment.

I agree with Renato too.

It seems like, as a compiler, we can provide virtually no guarantees about the value of `__builtin_arm_current_pc`: it's not necessarily in the PC-range of the dynamically innermost frame (inlining); it's not necessarily even in the callstack at all (you actually get PC+8 or PC+4).

About the only feasible use-case is a some kind of panic/abort implementation best-effort. And at that point you'll want r0-r14 as well.

Tim.


http://reviews.llvm.org/D22254