[llvm-bugs] [Bug 51722] New: LoopIdiom regression: ctlz no longer recognized

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51722

            Bug ID: 51722
           Summary: LoopIdiom regression: ctlz no longer recognized
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: david.bolvansky at gmail.com
                CC: llvm-bugs at lists.llvm.org

unsigned long long FIO_highbit64(unsigned long long v)
{
    unsigned  count = 0;
    v >>= 1;
    while (v) { v >>= 1; count++; }
    return count;
}

Since LLVM 13, we lost recognized "@llvm.ctlz.i64".

https://godbolt.org/z/nodKdfab4

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