1 #! /usr/bin/env python 2 # 3 # Copyright (C) 2016 Intel Corporation 4 # 5 # Permission is hereby granted, free of charge, to any person obtaining a 6 # copy of this software and associated documentation files (the "Software"), 7 # to deal in the Software without restriction, including without limitation 8 # the rights to use, copy, modify, merge, publish, distribute, sublicense, 9 # and/or sell copies of the Software, and to permit persons to whom the 10 # Software is furnished to do so, subject to the following conditions: 11 # 12 # The above copyright notice and this permission notice (including the next 13 # paragraph) shall be included in all copies or substantial portions of the 14 # Software. 15 # 16 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 17 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 18 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 19 # THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 20 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 21 # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 22 # IN THE SOFTWARE. 23 24 import nir_algebraic 25 26 # Prior to Kaby Lake, The SIN and COS instructions on Intel hardware can 27 # produce values slightly outside of the [-1.0, 1.0] range for a small set of 28 # values. Obviously, this can break everyone's expectations about trig 29 # functions. This appears to be fixed in Kaby Lake. 30 # 31 # According to an internal presentation, the COS instruction can produce 32 # a value up to 1.000027 for inputs in the range (0.08296, 0.09888). One 33 # suggested workaround is to multiply by 0.99997, scaling down the 34 # amplitude slightly. Apparently this also minimizes the error function, 35 # reducing the maximum error from 0.00006 to about 0.00003. 36 37 trig_workarounds = [ 38 (('fsin', 'x'), ('fmul', ('fsin', 'x'), 0.99997)), 39 (('fcos', 'x'), ('fmul', ('fcos', 'x'), 0.99997)), 40 ] 41 42 print '#include "brw_nir.h"' 43 print nir_algebraic.AlgebraicPass("brw_nir_apply_trig_workarounds", 44 trig_workarounds).render() 45
