[llvm] [VectorCombine] fold nested bitreverse and bswap (PR #202236)

[Kenny Lau via llvm-commits]

lauk20 wrote:

Looks like the `Build and Test Linux` workflow failed due to permissions on the runner? This was not an issue in past runs, perhaps this specific runner does not have `kernel.yama.ptrace_scope` configured? Or is this some other issue I am missing?

https://github.com/llvm/llvm-project/actions/runs/28049428679/job/83442952648?pr=202236#step:3:17535:

```
Thu, 25 Jun 2026 13:37:03 GMT
  ======================================================================
Thu, 25 Jun 2026 13:37:03 GMT
  FAIL: test_attach_to_process_by_id_correct_executable_offset (TestProcessAttach.ProcessAttachTestCase.test_attach_to_process_by_id_correct_executable_offset)
Thu, 25 Jun 2026 13:37:03 GMT
     Test that after attaching to a process the executable offset
Thu, 25 Jun 2026 13:37:03 GMT
  ----------------------------------------------------------------------
Thu, 25 Jun 2026 13:37:03 GMT
  Traceback (most recent call last):
Thu, 25 Jun 2026 13:37:03 GMT
    File "/home/gha/actions-runner/_work/llvm-project/llvm-project/lldb/test/API/commands/process/attach/TestProcessAttach.py", line 137, in test_attach_to_process_by_id_correct_executable_offset
Thu, 25 Jun 2026 13:37:03 GMT
      self.runCmd("process attach -p " + str(popen.pid))
Thu, 25 Jun 2026 13:37:03 GMT
    File "/home/gha/actions-runner/_work/llvm-project/llvm-project/lldb/packages/Python/lldbsuite/test/lldbtest.py", line 1092, in runCmd
Thu, 25 Jun 2026 13:37:03 GMT
      self.assertTrue(self.res.Succeeded(), msg + output)
Thu, 25 Jun 2026 13:37:03 GMT
  AssertionError: False is not true : Command 'process attach -p 1637945' did not return successfully
Thu, 25 Jun 2026 13:37:03 GMT
  Error output:
Thu, 25 Jun 2026 13:37:03 GMT
  error: attach failed: The current value of ptrace_scope is 1, which can cause ptrace to fail to attach to a running process. To fix this, run:
Thu, 25 Jun 2026 13:37:03 GMT
  	sudo sysctl -w kernel.yama.ptrace_scope=0
Thu, 25 Jun 2026 13:37:03 GMT
  For more information, see: https://www.kernel.org/doc/Documentation/security/Yama.txt.
Thu, 25 Jun 2026 13:37:03 GMT
  
Thu, 25 Jun 2026 13:37:03 GMT
  Config=x86_64-/home/gha/actions-runner/_work/llvm-project/llvm-project/build/bin/clang
Thu, 25 Jun 2026 13:37:03 GMT
  ----------------------------------------------------------------------
  ```

https://github.com/llvm/llvm-project/pull/202236