[PATCH] D77852: Outline CFI Instructions in Tail Calls

[Jessica Paquette via Phabricator via llvm-commits]

paquette added a reviewer: thegameg.
paquette added a comment.

Francis, you had some concerns about unwinding here. Can you take a look as well?



================
Comment at: llvm/lib/CodeGen/MachineOutliner.cpp:1170-1171
+        OriginalMF->getFrameInstructions();
+      for(MCCFIInstruction CFI : Instrs)
+        (void)MF.addFrameInst(CFI);
+    }
----------------
It looks like you copy over every CFI from the (first) original function into the outlined function here.

However, I don't think that there are any guarantees that *every* CFI instruction from the original function is actually present in the outlined sequence right now.



================
Comment at: llvm/lib/Target/AArch64/AArch64InstrInfo.cpp:5865
 
+  bool HasCFI = any_of(RepeatedSequenceLocs, [](outliner::Candidate &C) {
+    for (MachineBasicBlock::iterator mit : *(C.getMBB())) {
----------------
I don't think you have to check `any_of`. They should all contain the same instructions.


================
Comment at: llvm/lib/Target/AArch64/AArch64InstrInfo.cpp:6049-6050
 
+  if (FrameID != MachineOutlinerTailCall && HasCFI)
+    return outliner::OutlinedFunction();
+
----------------
We probably also want to check that the candidate has all of the original function's CFI instructions


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D77852/new/

https://reviews.llvm.org/D77852