[compiler-rt] [flang] [llvm] [AArch64] fix trampoline implementation: use X15 (PR #126743)

[Jameson Nash via llvm-commits]

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@@ -1,35 +1,26 @@
-; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+;; Testing that nest uses x15 on all calling conventions (except Arm64EC)
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vtjnash wrote:

I think `init.trampoline` should be okay, since it generates code on aarch64 to run on aarch64. I don't really know why the td claimed the nest pointer should be X4 (since external / x86-64 code cannot access the nest pointer as it is entirely hidden inside the ABI of the calling convention, so there is not really any compatibility to care about). I also don't have a machine to test it on, but it is implemented here for both the init and the prologue, so it should work as the comments described.

https://github.com/llvm/llvm-project/pull/126743