[XRay][compiler-rt+llvm] Update XRay register stashing semantics

Summary:
This change expands the amount of registers stashed by the entry and
`__xray_CustomEvent` trampolines.

We've found that since the `__xray_CustomEvent` trampoline calls can show up in
situations where the scratch registers are being used, and since we don't
typically want to affect the code-gen around the disabled
`__xray_customevent(...)` intrinsic calls, that we need to save and restore the
state of even the scratch registers in the handling of these custom events.

Reviewers: pcc, pelikan, dblaikie, eizan, kpw, echristo, chandlerc

Reviewed By: echristo

Subscribers: chandlerc, echristo, hiraditya, davide, dblaikie, llvm-commits

Differential Revision: https://reviews.llvm.org/D40894

llvm-svn: 323940

1 files changed, 1 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index 3c856914053..bc961386e6d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -874,6 +874,7 @@ bool FastISel::selectXRayCustomEvent(const CallInst *I) {
               TII.get(TargetOpcode::PATCHABLE_EVENT_CALL));
   for (auto &MO : Ops)
     MIB.add(MO);
+
   // Insert the Patchable Event Call instruction, that gets lowered properly.
   return true;
 }