[llvm-bugs] [Bug 47064] New: Failure to optimize multiplication by copysign to abs

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=47064

            Bug ID: 47064
           Summary: Failure to optimize multiplication by copysign to abs
           Product: libraries
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: Scalar Optimizations
          Assignee: unassignedbugs at nondot.org
          Reporter: gabravier at gmail.com
                CC: llvm-bugs at lists.llvm.org

float f(float x)
{
    return x * copysignf(1.0f, x);
}

This can be optimized to `fabsf(x);`. This transformation is done by GCC, but
not by LLVM. Similar transformations can also be done, such as `x *
copysignf(1.0f, -x)` -> `-fabsf(x)`, and are done by GCC, but not by LLVM.

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