[webkit-dev] Fix for Vector::m_inlineBuffer alignment?

[Maciej Stachowiak]

On Sep 4, 2008, at 1:20 AM, Paul Pedriana wrote:

> Well the proposed solution in
> <https://bugs.webkit.org/show_bug.cgi?id=16925> doesn't work, as VC++
> doesn't accept that syntax. And the solutions in
> <https://bugs.webkit.org/show_bug.cgi?id=19775> whereby a uint32_t or
> uint64_t buffer are made don't work for larger types and use more  
> memory
> than necessary. They might be useful as a fallback for compilers that
> don't support alignment directives, though the primary implementations
> of every compiler that I work with (GCC, VC++, CodeWarrior, EDG, SN,
> IBM) support it.

The buffer should definitely remain char to avoid strict aliasing  
problems. However, I think the most portable way to ensure alignment  
is to union the buffer with a one-element array of the template  
parameter type T.

  - Maciej


>
>
> I'll make a patch and attach it to
> <https://bugs.webkit.org/show_bug.cgi?id=16925>, if that's OK.


>
>
> Paul
>
>
>
>>
>> On Sep 4, 2008, at 2:05 AM, Paul Pedriana wrote:
>>
>>> I see that JavaScriptCore/wtf/Vector.h has this:
>>>
>>>   // FIXME: Nothing guarantees this buffer is appropriately  
>>> aligned to
>>> hold objects of type T.
>>>   char m_inlineBuffer[m_inlineBufferSize];
>>
>>
>> We have a bug for this:
>> <https://bugs.webkit.org/show_bug.cgi?id=16925>. Also,
>> <https://bugs.webkit.org/show_bug.cgi?id=19775>.
>>
>> There are several patches and suggestions in these bugs, which wait
>> for someone to submit them as clean patches.
>>
>> - WBR, Alexey Proskuryakov
>>
>>
>>
>
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