[clang] [llvm] [ARM] musttail fixes (PR #102896)

[Eli Friedman via cfe-commits]

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@@ -67,33 +327,85 @@ declare i32 @e3(ptr nocapture byval(%struct.LargeStruct) align 16 %in) nounwind
 ; We can't do tail call since address of s is passed to the callee and part of
 ; s is in caller's local frame.
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efriedma-quic wrote:

Pretty sure this comment is still correct... we can't tail-call here.  r0 points below the bottom of the stack.

https://github.com/llvm/llvm-project/pull/102896