[PATCH] Implement __builtin_stack_pointer

[Renato Golin]

================
Comment at: docs/LangRef.rst:6802-6803
@@ +6801,4 @@
+
+The '``llvm.stackpointer``' intrinsic returns the current value of the
+stack pointer register.
+
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Tim Northover wrote:
> Isn't that a bit strong? I think things like VLAs can cause sp to change in the middle of a function and I dread to think what it'll return in those cases.
That's a good point. Also, if the target has no reserved stack-pointer, LLVM will bail on "unimplemented", which would be good to have it documented.


http://llvm-reviews.chandlerc.com/D3184