• via Digitalmars-d-bugs (33/33) Sep 23 2016 https://issues.dlang.org/show_bug.cgi?id=16530

via Digitalmars-d-bugs <digitalmars-d-bugs puremagic.com> writes:

https://issues.dlang.org/show_bug.cgi?id=16530

          Issue ID: 16530
           Summary: -O -cov interaction leads to wrong codegen
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: critical
          Priority: P1
         Component: dmd
          Assignee: nobody puremagic.com
          Reporter: andrei erdani.com

Code:

double entropy(double[] probs)
{
    double result = 0;
    // BUG: remove the "ref" below to expose codegen bug in dmd
    foreach (p; probs)
    {
        if (!p) continue;
        import std.math : log2;
        result -= p * log2(p);
    }
    return result;
}

void main()
{
    import std.stdio;
    writeln(entropy([1.0, 0, 0]));
}

To repro, build with -O -cov. It will print -nan. Should print 0.

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