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

Paul Pedriana ppedriana at gmail.com
Thu Sep 4 02:24:10 PDT 2008

This is a hardware issue and can vary between different versions. Some 
hardware of course generates an unhandled exception on unaligned access; 
some hardware generates an internally handled exception and restarts the 
access with a different and more expensive pathway or with microcode; 
some hardware efficiently handles it as it goes and has minimal impact. 
Sometimes this behavior is different depending on whether the hardware 
is in big endian vs. little endian mode. A new generation of the same 
processor family or a version by a different company may act differently 
than another. Finally, if that memory is accessed by a different means 
than the CPU (e.g. via DMA or the video bus), then it may require 
alignment where it doesn't otherwise.

What I'm getting at here is that I think we would need to be careful 
about disabling it for any hardware, including even forgiving hardware 
like x86.

> On Sep 4, 2008, at 12:20 PM, Paul Pedriana wrote:
>> I'll make a patch and attach it to 
>> <https://bugs.webkit.org/show_bug.cgi?id=16925>, if that's OK.
> That would be great!
> One thing I'm not sure about is whether we want to enforce alignment 
> on platforms that don't require it - performance testing should answer 
> this.
> - WBR, Alexey Proskuryakov

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