[llvm] [PowerPC] Support PIC Secure PLT for CALL_RM (PR #121281)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> #72758
> 
> There was also a PR for the same fix. But for some reason George stopped responding.

Thanks for bringing up the old thread. I did not know similar code change was brought up before. I do prefer the tests in this patch, tho...

https://github.com/llvm/llvm-project/pull/121281