[lldb-dev] compile failure with VS 2015 Update 3

[Zachary Turner via lldb-dev]

So without declspec(align(8)) was this a silent codegen bug in update 2?

Despite the error message, I don't think this happens on a pass by value,
as std atomic is not copyable
On Thu, Jun 30, 2016 at 3:49 PM Reid Kleckner via lldb-dev <
lldb-dev at lists.llvm.org> wrote:

> Right, the x86_32 calling convention that MSVC uses fails to align such
> objects, and this is the error you get if you try. VS 2015 update 3
> probably added __declspec(align(8)) to std::atomic<__int64>, triggering
> this error if you pass one or an object that contains one by value.
>
> On Thu, Jun 30, 2016 at 3:16 PM, Adrian McCarthy via lldb-dev <
> lldb-dev at lists.llvm.org> wrote:
>
>> I left out some words.  I meant:
>>
>> The answers on that StackOverflow question claim that 32-bit MSVC never
>> does more than 32-byte alignment *for parameters*.
>>
>> On Thu, Jun 30, 2016 at 3:12 PM, Adrian McCarthy <amccarth at google.com>
>> wrote:
>>
>>> `default_stop_addr` is an `Address` which contains a
>>> `std::atomic<lldb::addr_t>`.  The `addr_t` is a 64-bit value, so I assume
>>> it needs 64-bit alignment.  The answers on that StackOverflow question
>>> claim that 32-bit MSVC never does more than 32-byte alignment. So my guess
>>> is that this has always been a problem, and the newer compiler is just
>>> better at reporting it.
>>>
>>> On Thu, Jun 30, 2016 at 2:56 PM, Philippe Lavoie <
>>> philippe.lavoie at octasic.com> wrote:
>>>
>>>> 32-bit.
>>>> ------------------------------
>>>> *From:* Adrian McCarthy [amccarth at google.com]
>>>> *Sent:* Thursday, June 30, 2016 5:36 PM
>>>> *To:* Philippe Lavoie
>>>> *Cc:* lldb-dev at lists.llvm.org
>>>> *Subject:* Re: [lldb-dev] compile failure with VS 2015 Update 3
>>>>
>>>> Compiling for 32-bit or 64-bit?
>>>>
>>>> This question looks relevant:
>>>> http://stackoverflow.com/questions/21743144/using-stdatomic-with-aligned-classes
>>>>
>>>> On Thu, Jun 30, 2016 at 1:19 PM, Philippe Lavoie via lldb-dev <
>>>> lldb-dev at lists.llvm.org> wrote:
>>>>
>>>>> Hello,
>>>>>
>>>>> has anyone tried to compile LLDB with Visual Studio 2015 Update 3 ?
>>>>>
>>>>> It compiles fine with Update 2, but with Update 3 we get error
>>>>> messages like:
>>>>>
>>>>>     D:\dev\llvm\tools\lldb\include\lldb/Target/Process.h(3194): error
>>>>> C2719:
>>>>>     'default_stop_addr': formal parameter with requested alignment of
>>>>> 8 won't be aligned
>>>>>     (compiling source file
>>>>> D:\dev\llvm\tools\lldb\source\Expression\FunctionCaller.cpp)
>>>>>
>>>>> although there is no __declspec(align) on that parameter.
>>>>> We reported the issue to Microsoft here:
>>>>>
>>>>> https://connect.microsoft.com/VisualStudio/feedback/details/2870567/lldb-no-longer-compiles
>>>>>
>>>>> -Philippe
>>>>>
>>>>> _______________________________________________
>>>>> lldb-dev mailing list
>>>>> lldb-dev at lists.llvm.org
>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev
>>>>>
>>>>>
>>>>
>>>
>>
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