[llvm] [RISCV] improve `musttail` support (PR #170547)

[via llvm-commits]

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@@ -9,12 +9,13 @@
 ; RUN: not --crash llc -mtriple riscv64-unknown-elf -o - %s \
 ; RUN: 2>&1 | FileCheck %s
 
-%struct.A = type { i32 }
+declare void @callee_musttail()
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heiher wrote:

The test cases for `sret` are still covered; they have been placed in
https://github.com/llvm/llvm-project/pull/170547/changes#diff-f387543c8007fbf1aba84d8230a49697210b588a1aca5fb81feba42680632de8R351-R379

https://github.com/llvm/llvm-project/pull/170547