[llvm] [BOLT][AArch64] Skip gadget pacret test on RHEL8 (PR #145527)

[Paschalis Mpeis via llvm-commits]

paschalis-mpeis wrote:

Hey @atrosinenko,

Thanks a lot for your comment. Reading this back to see if I got it right.
**(1)** you are saying the following should (probably) work on RHEL8:

```diff
// CHECK-LABEL: GS-PAUTH: non-protected ret found in function f1, basic block {{[0-9a-zA-Z.]+}}, at address
// CHECK-NEXT:    The instruction is     {{[0-9a-f]+}}:       ret
// CHECK-NEXT:    The 1 instructions that write to the affected registers after any authentication are:
// CHECK-NEXT:    1. {{[0-9a-f]+}}: ldp     x29, x30, [sp], #0x10
// CHECK-NEXT:  This happens in the following basic block:
// CHECK-NEXT: {{[0-9a-f]+}}:   paciasp
+ // CHECK-NEXT: {{[0-9a-f]+}}:   stp     x29, x30, [sp, #-16]!
+ // CHECK-NEXT: {{[0-9a-f]+}}:   mov     x29, sp
+ // CHECK-NEXT: {{[0-9a-f]+}}:   bl      g
// CHECK-NEXT: {{[0-9a-f]+}}:   add     x0, x0, #0x3
// CHECK-NEXT: {{[0-9a-f]+}}:   ldp     x29, x30, [sp], #0x10
// CHECK-NEXT: {{[0-9a-f]+}}:   ret
        ret
```


**(2)** you're asking why on other platforms (non-RHEL8) a `bl` call splits the basic block?

So we should expect BOLT IR to produce a single block for `f1`. Given we achieve this consistently, we could add the above extra 3 lines to the test?


I can confirm that on my platform (a non-RHEL8 linux) I get two basic blocks in `f1`, where the `g` symbol is undefined. If replace the call target with something that exists (ie `f_intermediate_overwrite1`), I get a single block.


https://github.com/llvm/llvm-project/pull/145527