Antoine Pitrou <solip...@pitrou.net> 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?
Yes, but it's a compiler (Thumb-EE specific back-end) burden. Otherwise, we can introduce Thumb-EE assembly code were needed, but the same can happen for a wide range of ISAs. At least IA32 and AMD64 have specific addressing modes where it's possibile to use a multiplying factor of 1, 2, 4 or 8 for the index register. I hope that compilers were smart enough to already used them. > (assuming Thumb has 4-byte pointers) Yes, it does. Cesare _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
