[Python-Dev] mingw32 and gc-header weirdness

Christian Tismer tismer at stackless.com
Mon Jul 27 09:00:19 CEST 2009


On 7/25/09 7:11 AM, Neil Hodgson wrote:
> Martin v. Löwis:
>
>> I propose to add another (regular) double into the union.
>
>     Adding a regular double as a second dummy gives the same sizes and
> alignments with Mingw or MSVC as the original definition with MSVC:

Great (checked that, too)

This makes pretty much sense, also given that this waste
happens under Windows, already.

>     In regard to alignment penalties, a simple copy loop for doubles
> runs about 20% slower when misaligned on an my AMD processor. Other
> x86 processors can be much worse. As much as 2 to 3.25 times according
> to

I am still unhappy with this waste of memory, just because the
GC header has to be rounded up, regardlwss wether that is needed
or not.
We should keep Martin's hint in mind, that Python 4 could place
the gc header at the end of structures, instead.

cheers - chris
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