• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1#
2# Copyright (C) 2016 Intel Corporation
3#
4# Permission is hereby granted, free of charge, to any person obtaining a
5# copy of this software and associated documentation files (the "Software"),
6# to deal in the Software without restriction, including without limitation
7# the rights to use, copy, modify, merge, publish, distribute, sublicense,
8# and/or sell copies of the Software, and to permit persons to whom the
9# Software is furnished to do so, subject to the following conditions:
10#
11# The above copyright notice and this permission notice (including the next
12# paragraph) shall be included in all copies or substantial portions of the
13# Software.
14#
15# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21# IN THE SOFTWARE.
22
23# Prior to Kaby Lake, The SIN and COS instructions on Intel hardware can
24# produce values slightly outside of the [-1.0, 1.0] range for a small set of
25# values.  Obviously, this can break everyone's expectations about trig
26# functions.  This appears to be fixed in Kaby Lake.
27#
28# According to an internal presentation, the COS instruction can produce
29# a value up to 1.000027 for inputs in the range (0.08296, 0.09888).  One
30# suggested workaround is to multiply by 0.99997, scaling down the
31# amplitude slightly.  Apparently this also minimizes the error function,
32# reducing the maximum error from 0.00006 to about 0.00003.
33
34import argparse
35import sys
36
37TRIG_WORKAROUNDS = [
38    (('fsin', 'x'), ('fmul', ('fsin', 'x'), 0.99997)),
39    (('fcos', 'x'), ('fmul', ('fcos', 'x'), 0.99997)),
40]
41
42
43def main():
44    parser = argparse.ArgumentParser()
45    parser.add_argument('-p', '--import-path', required=True)
46    args = parser.parse_args()
47    sys.path.insert(0, args.import_path)
48    run()
49
50
51def run():
52    import nir_algebraic  # pylint: disable=import-error
53
54    print '#include "brw_nir.h"'
55    print nir_algebraic.AlgebraicPass("brw_nir_apply_trig_workarounds",
56                                      TRIG_WORKAROUNDS).render()
57
58
59if __name__ == '__main__':
60    main()
61