[dmd-internals] non-PODs again

[Maxim Fomin]

2013/3/8 Walter Bright <walter at digitalmars.com>

>
> On 3/7/2013 12:19 PM, Johannes Pfau wrote:
>
>> Am 07.03.2013 20:45, schrieb Walter Bright:
>>
>>>
>>> On 3/7/2013 9:36 AM, Johannes Pfau wrote:
>>>
>>>> I'm sorry I have to pester you with this again, but I still have some
>>>> questions regarding POD types and I'd like to fix this in GDC.
>>>>
>>>> So from last discussion:
>>>> >> Wouldn't it be legal to still pass non-PODs in registers when
>>>> calling functions and only copying them back to
>>>> >> the stack if the address is needed? As we pass structs by value
>>>> anyway, how could this be problematic?
>>>> >
>>>> > No, not allowed. Consider why there are copy constructors, and what
>>>> they do.
>>>>
>>>> I compiled some test programs with dmd and dmd _does_ pass non-POD
>>>> values in registers as I suggested above.
>>>> See this example:
>>>> https://gist.github.com/jpf91/**5064703<https://gist.github.com/jpf91/5064703>(D)
>>>> https://gist.github.com/jpf91/**5064764<https://gist.github.com/jpf91/5064764>(ASM)
>>>>
>>>
>>> That's because objects with constructors are now regarded as POD.
>>>
>>
>> This example uses a postblit to make sure the type is not a POD. It's
>> obvious in the ASM that the copy ctor is called,
>>
>
> Oops, I missed that. It's a bug in dmd.
>

Isn't there another bug with struct parameter which is copied twice - on
caller and callee side?

function  D main
Date d = _D1e4Date6__initZ;
setDate((Date __cpcttmp7 = __cpcttmp7.__cpctor(d); , __cpcttmp7))

function  e.setDate
x.opAssign((Date __cpcttmp6 = __cpcttmp6.__cpctor(d); , __cpcttmp6))
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