[llvm] [llvm-exegesis][AArch64] Check for PAC keys before disabling them (PR #138643)

[Tulio Magno Quites Machado Filho via llvm-commits]

tuliom wrote:

@abhilash1910  I applied the following change on top of this PR in order to test with `--aarch64-disable-pac-control`:

```
diff --git i/llvm/test/tools/llvm-exegesis/AArch64/all-opcodes.test w/llvm/test/tools/llvm-exegesis/AArch64/all-opcodes.test
index 4644b48bef1a..c35f5e143493 100644
--- i/llvm/test/tools/llvm-exegesis/AArch64/all-opcodes.test
+++ w/llvm/test/tools/llvm-exegesis/AArch64/all-opcodes.test
@@ -1,6 +1,8 @@
 # Test that we can just use --opcode-index=-1 to generate snippets for
 # all supported opcodes and gracefully handle unsupported ones.
 
+# RUN: llvm-exegesis --mtriple=aarch64-linux-gnu --mcpu=cortex-a55 --benchmark-phase=prepare-and-assemble-snippet \
+# RUN:               --mode=latency --opcode-index=-1 --aarch64-disable-pac-control | FileCheck %s
 # RUN: llvm-exegesis --mtriple=aarch64-linux-gnu --mcpu=cortex-a55 --benchmark-phase=prepare-and-assemble-snippet \
 # RUN:               --mode=latency --opcode-index=-1 | FileCheck %s
 # RUN: llvm-exegesis --mtriple=aarch64-linux-gnu --mcpu=cortex-a55 --benchmark-phase=prepare-and-assemble-snippet \
```

The first execution (line 4) completed successfully.
The second execution (line 6) crashed with a similar output as in my previous test/message.

The full log is available at: https://download.copr.fedorainfracloud.org/results/tuliom/llvm-snapshots-big-merge-20250604-pac/fedora-rawhide-aarch64/09136603-llvm/builder-live.log.gz

https://github.com/llvm/llvm-project/pull/138643