[Issue 13784] New: Wrong code with modulo operation and optimisations enabled

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13784

          Issue ID: 13784
           Summary: Wrong code with modulo operation and optimisations
                    enabled
           Product: D
           Version: D1 & D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P1
         Component: DMD
          Assignee: nobody at puremagic.com
          Reporter: public at dicebot.lv

assertions passes when compiled with no flags and fails when compiled with -O

```
long modulo24 (long ticks)
{
    const TicksPerDay = 864000000000;
    ticks %= TicksPerDay;
    if (ticks < 0)
        ticks += TicksPerDay;
    return ticks;
}

unittest
{
    assert (modulo24(-141600000000) == 722400000000);
}
```

Checking assembly reveals wrong optimisation via replacing modulo with
multiplication.

Issue present in both D1 and D2 compilers. Workaround is to avoid modulo
operation with negative numbers.

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