[Python-Dev] Python-acceleration instructions on ARM
"Martin v. Löwis"
martin at v.loewis.de
Wed Feb 11 20:10:24 CET 2009
Antoine Pitrou wrote:
> Martin v. Löwis <martin <at> v.loewis.de> writes:
>> - efficient array indexing: they give shift-and-index back to
>> Thumb mode, for a shift by 2, allowing to index arrays with
>> 4-byte elements in a single instruction (rather than requiring
>> a separate multipy-by-four). Again useful for JIT of array
>> access instructions, not applicable to Python - although it
>> would be nice if the C compiler knew how to emit that.
>
> This could be used in PyTuple_GetItem and PyList_GetItem, no?
> (assuming Thumb has 4-byte pointers)
Yes - but it would require an assembly version of these functions;
I'm skeptical that the savings would be measurable (given that there
is also the type check and the range check).
OTOH, PyTuple_GET_ITEM could probably be implemented as
inline assembly.
Regards,
Martin
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