[llvm-bugs] [Bug 31802] New: Count Leading Ones does not work properly on ARMv8 (should lower to CLS) ?

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=31802

            Bug ID: 31802
           Summary: Count Leading Ones does not work properly on ARMv8
                    (should lower to CLS) ?
           Product: clang
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: LLVM Codegen
          Assignee: unassignedclangbugs at nondot.org
          Reporter: gonzalobg88 at gmail.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

One can implement count leading ones (or count leading significant bits) as
follows:

unsigned cls(unsigned i) {
  return __builtint_clz(!i);
}

I would expect this code to generate the cls instruction on aarch64 but i don't
seem to be able to generate this instruction at all.

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20170130/b5674d08/attachment.html>