[llvm-bugs] [Bug 36518] New: cbrt() function cannot be vectorized through OpenMP

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=36518

            Bug ID: 36518
           Summary: cbrt() function cannot be vectorized through OpenMP
           Product: OpenMP
           Version: unspecified
          Hardware: PC
                OS: FreeBSD
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Clang Compiler Support
          Assignee: unassignedclangbugs at nondot.org
          Reporter: jmd at freebsd.org
                CC: llvm-bugs at lists.llvm.org

Created attachment 19962
  --> https://bugs.llvm.org/attachment.cgi?id=19962&action=edit
reproduction of issue

A trivial loop using cbrt() from cmath in its body cannot be vectorized.
Compiling attached gives the following (on FreeBSD with LLVM devel as of
beginning of February):

$ clang++-devel -O3 -Rpass=loop-vectorize -Rpass-missed=loop-vectorize
-Rpass-analysis=loop-vectorize -fsave-optimization-record -fopenmp -o cbrt
cbrt.cpp 
cbrt.cpp:13:12: remark: loop not vectorized: call instruction cannot be
      vectorized [-Rpass-analysis]
                res[x] = cbrt((double) x);
                         ^
cbrt.cpp:11:10: remark: loop not vectorized (Force=true)
      [-Rpass-missed=loop-vectorize]
        #pragma omp simd
                ^
cbrt.cpp:11:10: warning: loop not vectorized: failed explicitly specified loop
      vectorization [-Wpass-failed=loop-vectorize]
1 warning generated.

What is necessary to have cbrt() vectorizable? This works with recent Intel
compilers on Linux and GCC seems to also be capable to do this properly.

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