[PATCH] D26413: [XRay] Support AArch64 in compiler-rt

[Serge Rogatch via llvm-commits]

rSerge added a comment.

We require from the handler function that it handles well spurious calls (after it is removed or changed to another handler). Perhaps this is not documented anywhere except our discussions on the mailing list, but it is so for all the currently supported CPUs.
`_ZN6__xray19XRayPatchedFunctionE` is a global variable, so it should always be there. Its definition and setting are in `xray_interface.cc` file (not touched by my current changes).
Definition:

  // This is the function to call when we encounter the entry or exit sleds.
  std::atomic<void (*)(int32_t, XRayEntryType)> XRayPatchedFunction{nullptr};

Setting:

  __xray::XRayPatchedFunction.store(entry, std::memory_order_release);


https://reviews.llvm.org/D26413