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Thanks for your changes. About j: no sense to treat it as signed. Here is updated algorithm with table of 2^(j/K) for j=[0;K-1]. Please, see new attached patch. About the benchmark: this is just perfomance in cycles for main interval [-87.0; 87.0]. Results: Istanbul/Atom/Nehalem/AVX Attached version: 51.63 97.23 31.12 25.34 (__AVX__ enabling gives 24.98 cycles on AVX.) About stability: We used "make check". Also we used proprietary test system that tests on many intervals with different steps, checks for special values (from ISO C) and corner cases. -- Liubov Dmitrieva Intel Corporation 2012/2/22 Ulrich Drepper <drepper@gmail.com>: > This time with attachment. > > On Wed, Feb 22, 2012 at 10:14, Ulrich Drepper <drepper@gmail.com> wrote: >> On Tue, Feb 21, 2012 at 15:32, Dmitrieva Liubov >> <liubov.dmitrieva@gmail.com> wrote: >>> The updated attached version is significantly hand-tuned assembler code. >>> We are looking forward to accepting and releasing this change. >> >> At least the changes made to the attached version should be made. >> They are small but save another cycle or two. >> >> I don't see why the computation of j has to be that complicated. ?6 >> bits are taken from the mantissa. ?These are then interpreted as a >> signed value. ?Why? ?I know it works but is there really a reason? >> >> If the bits are considered are unsigned that computation for the >> access of the array DP_T as well as the computation of ?n*k are >> simpler (only AND, no shifting and subtracting). ?The algo has to be >> adapted but this should be possible. ?I think nobody really paid >> attention to that since the DP_T table was too large (it had 65 >> entries!).
Attachment:
exp.patch
Description: Binary data
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