[clang] [llvm] [PAC][ELF][AArch64] Encode signed GOT flag in PAuth core info (PR #96159)

[James Henderson via cfe-commits]

jh7370 wrote:

> > I'm not at all familiar with this PAuth stuff, but don't you need a test case for where the new value is set (currently they all seem to be unset, if I'm interpreting things correctly)?
> 
> @jh7370 I'm not sure if I understood your question correctly - particularly, I'm not sure what does the phrase "the new value is set" mean. Could you please add a bit more details in your question?
> 
> If you are talking about llvm/test/tools/llvm-readobj/ELF/AArch64/aarch64-feature-pauth.s and llvm/test/CodeGen/AArch64/note-gnu-property-elf-pauthabi.ll tests checking version value 0x55 which does not imply signed GOT enabled, we just can't test 2^8=256 combinations of flags, so we test values which look like 0b10101... But I can add a test for version value 0xAA which would set opposite flags compared to 0x55.

I was referring to this line from the description:

> llvm-readobj: print `PointerAuthELFGOT` or `!PointerAuthELFGOT` in version description of llvm_linux platform depending on whether the flag is set.

In my opinion, if you don't test the first of those two cases, you might as well not have implemented behaviour for it. I'd always test "all flags set" and "no flags set" cases (or some variant that effectively tests this, e.g. 0xff and ~0xff). Of course, if it's not practical, that's fine.

https://github.com/llvm/llvm-project/pull/96159