[Bug tree-optimization/127168] New: [17 Regression] vectorization of ctz for small BitInt is wrong

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127168

            Bug ID: 127168
           Summary: [17 Regression] vectorization of ctz for small BitInt
                    is wrong
           Product: gcc
           Version: 17.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---
            Target: aarch64

Created attachment 65465
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=65465&action=edit
testcase

A modified testcase from PR 127149 but for ctz rather than popcount.
And this shows that this case is a regression.