tree 2fb62bcd8f615cba777ca1d12eef7f1dc8cac8aa
parent eed2b2f87d7712117c9fc8bc3f55725b92c6aa17
author Alex Richardson <Alexander.Richardson@cl.cam.ac.uk> 1655715432 +0000
committer Copybara-Service <copybara-worker@google.com> 1655716216 -0700

[libunwind] Ensure test/libunwind_01.pass is not completely inlined

By adding noinline and calling fprintf before returning we ensure that
every function will have a distinct call frame and that the return address
will always be saved instead of saving the target in main as the result.

Before this change all backtraces were always backtrace -> main -> _start,
i.e. always exactly three entries. This happenend because all calls were
inlined in main() and the test just happenend to pass because there is at
least _start before main.

I found this while fixing some bugs in libunwind for CHERI and noticed that
the test was passing even though the code was completely broken.

Obtained from: https://github.com/CTSRD-CHERI/llvm-project

Reviewed By: #libunwind, ldionne, MaskRay

Differential Revision: https://reviews.llvm.org/D126611

GitOrigin-RevId: 8df257a6d0b0b32e05e89874eff4c8ddd2a2a2a9