nir: rename lower_flrp to lower_flrp32
[mesa.git] / src / compiler / nir / nir_opt_algebraic.py
1 #! /usr/bin/env python
2 #
3 # Copyright (C) 2014 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 # Authors:
25 # Jason Ekstrand (jason@jlekstrand.net)
26
27 import nir_algebraic
28
29 # Convenience variables
30 a = 'a'
31 b = 'b'
32 c = 'c'
33 d = 'd'
34
35 # Written in the form (<search>, <replace>) where <search> is an expression
36 # and <replace> is either an expression or a value. An expression is
37 # defined as a tuple of the form ([~]<op>, <src0>, <src1>, <src2>, <src3>)
38 # where each source is either an expression or a value. A value can be
39 # either a numeric constant or a string representing a variable name.
40 #
41 # If the opcode in a search expression is prefixed by a '~' character, this
42 # indicates that the operation is inexact. Such operations will only get
43 # applied to SSA values that do not have the exact bit set. This should be
44 # used by by any optimizations that are not bit-for-bit exact. It should not,
45 # however, be used for backend-requested lowering operations as those need to
46 # happen regardless of precision.
47 #
48 # Variable names are specified as "[#]name[@type]" where "#" inicates that
49 # the given variable will only match constants and the type indicates that
50 # the given variable will only match values from ALU instructions with the
51 # given output type.
52 #
53 # For constants, you have to be careful to make sure that it is the right
54 # type because python is unaware of the source and destination types of the
55 # opcodes.
56 #
57 # All expression types can have a bit-size specified. For opcodes, this
58 # looks like "op@32", for variables it is "a@32" or "a@uint32" to specify a
59 # type and size, and for literals, you can write "2.0@32". In the search half
60 # of the expression this indicates that it should only match that particular
61 # bit-size. In the replace half of the expression this indicates that the
62 # constructed value should have that bit-size.
63
64 optimizations = [
65 (('fneg', ('fneg', a)), a),
66 (('ineg', ('ineg', a)), a),
67 (('fabs', ('fabs', a)), ('fabs', a)),
68 (('fabs', ('fneg', a)), ('fabs', a)),
69 (('iabs', ('iabs', a)), ('iabs', a)),
70 (('iabs', ('ineg', a)), ('iabs', a)),
71 (('~fadd', a, 0.0), a),
72 (('iadd', a, 0), a),
73 (('usadd_4x8', a, 0), a),
74 (('usadd_4x8', a, ~0), ~0),
75 (('~fadd', ('fmul', a, b), ('fmul', a, c)), ('fmul', a, ('fadd', b, c))),
76 (('iadd', ('imul', a, b), ('imul', a, c)), ('imul', a, ('iadd', b, c))),
77 (('~fadd', ('fneg', a), a), 0.0),
78 (('iadd', ('ineg', a), a), 0),
79 (('iadd', ('ineg', a), ('iadd', a, b)), b),
80 (('iadd', a, ('iadd', ('ineg', a), b)), b),
81 (('~fadd', ('fneg', a), ('fadd', a, b)), b),
82 (('~fadd', a, ('fadd', ('fneg', a), b)), b),
83 (('~fmul', a, 0.0), 0.0),
84 (('imul', a, 0), 0),
85 (('umul_unorm_4x8', a, 0), 0),
86 (('umul_unorm_4x8', a, ~0), a),
87 (('fmul', a, 1.0), a),
88 (('imul', a, 1), a),
89 (('fmul', a, -1.0), ('fneg', a)),
90 (('imul', a, -1), ('ineg', a)),
91 (('~ffma', 0.0, a, b), b),
92 (('~ffma', a, 0.0, b), b),
93 (('~ffma', a, b, 0.0), ('fmul', a, b)),
94 (('ffma', a, 1.0, b), ('fadd', a, b)),
95 (('ffma', 1.0, a, b), ('fadd', a, b)),
96 (('~flrp', a, b, 0.0), a),
97 (('~flrp', a, b, 1.0), b),
98 (('~flrp', a, a, b), a),
99 (('~flrp', 0.0, a, b), ('fmul', a, b)),
100 (('~flrp', a, b, ('b2f', c)), ('bcsel', c, b, a), 'options->lower_flrp32'),
101 (('flrp', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp32'),
102 (('ffract', a), ('fsub', a, ('ffloor', a)), 'options->lower_ffract'),
103 (('~fadd', ('fmul', a, ('fadd', 1.0, ('fneg', ('b2f', c)))), ('fmul', b, ('b2f', c))), ('bcsel', c, b, a), 'options->lower_flrp32'),
104 (('~fadd', ('fmul', a, ('fadd', 1.0, ('fneg', c ))), ('fmul', b, c )), ('flrp', a, b, c), '!options->lower_flrp32'),
105 (('~fadd', a, ('fmul', ('b2f', c), ('fadd', b, ('fneg', a)))), ('bcsel', c, b, a), 'options->lower_flrp32'),
106 (('~fadd', a, ('fmul', c , ('fadd', b, ('fneg', a)))), ('flrp', a, b, c), '!options->lower_flrp32'),
107 (('ffma', a, b, c), ('fadd', ('fmul', a, b), c), 'options->lower_ffma'),
108 (('~fadd', ('fmul', a, b), c), ('ffma', a, b, c), '!options->lower_ffma'),
109 # Comparison simplifications
110 (('~inot', ('flt', a, b)), ('fge', a, b)),
111 (('~inot', ('fge', a, b)), ('flt', a, b)),
112 (('~inot', ('feq', a, b)), ('fne', a, b)),
113 (('~inot', ('fne', a, b)), ('feq', a, b)),
114 (('inot', ('ilt', a, b)), ('ige', a, b)),
115 (('inot', ('ige', a, b)), ('ilt', a, b)),
116 (('inot', ('ieq', a, b)), ('ine', a, b)),
117 (('inot', ('ine', a, b)), ('ieq', a, b)),
118
119 # 0.0 >= b2f(a)
120 # b2f(a) <= 0.0
121 # b2f(a) == 0.0 because b2f(a) can only be 0 or 1
122 # inot(a)
123 (('fge', 0.0, ('b2f', a)), ('inot', a)),
124
125 # 0.0 < fabs(a)
126 # fabs(a) > 0.0
127 # fabs(a) != 0.0 because fabs(a) must be >= 0
128 # a != 0.0
129 (('flt', 0.0, ('fabs', a)), ('fne', a, 0.0)),
130
131 (('fge', ('fneg', ('fabs', a)), 0.0), ('feq', a, 0.0)),
132 (('bcsel', ('flt', b, a), b, a), ('fmin', a, b)),
133 (('bcsel', ('flt', a, b), b, a), ('fmax', a, b)),
134 (('bcsel', ('inot', 'a@bool'), b, c), ('bcsel', a, c, b)),
135 (('bcsel', a, ('bcsel', a, b, c), d), ('bcsel', a, b, d)),
136 (('bcsel', a, True, 'b@bool'), ('ior', a, b)),
137 (('fmin', a, a), a),
138 (('fmax', a, a), a),
139 (('imin', a, a), a),
140 (('imax', a, a), a),
141 (('umin', a, a), a),
142 (('umax', a, a), a),
143 (('~fmin', ('fmax', a, 0.0), 1.0), ('fsat', a), '!options->lower_fsat'),
144 (('~fmax', ('fmin', a, 1.0), 0.0), ('fsat', a), '!options->lower_fsat'),
145 (('fsat', a), ('fmin', ('fmax', a, 0.0), 1.0), 'options->lower_fsat'),
146 (('fsat', ('fsat', a)), ('fsat', a)),
147 (('fmin', ('fmax', ('fmin', ('fmax', a, b), c), b), c), ('fmin', ('fmax', a, b), c)),
148 (('imin', ('imax', ('imin', ('imax', a, b), c), b), c), ('imin', ('imax', a, b), c)),
149 (('umin', ('umax', ('umin', ('umax', a, b), c), b), c), ('umin', ('umax', a, b), c)),
150 (('extract_u8', ('imin', ('imax', a, 0), 0xff), 0), ('imin', ('imax', a, 0), 0xff)),
151 (('~ior', ('flt', a, b), ('flt', a, c)), ('flt', a, ('fmax', b, c))),
152 (('~ior', ('flt', a, c), ('flt', b, c)), ('flt', ('fmin', a, b), c)),
153 (('~ior', ('fge', a, b), ('fge', a, c)), ('fge', a, ('fmin', b, c))),
154 (('~ior', ('fge', a, c), ('fge', b, c)), ('fge', ('fmax', a, b), c)),
155 (('fabs', ('slt', a, b)), ('slt', a, b)),
156 (('fabs', ('sge', a, b)), ('sge', a, b)),
157 (('fabs', ('seq', a, b)), ('seq', a, b)),
158 (('fabs', ('sne', a, b)), ('sne', a, b)),
159 (('slt', a, b), ('b2f', ('flt', a, b)), 'options->lower_scmp'),
160 (('sge', a, b), ('b2f', ('fge', a, b)), 'options->lower_scmp'),
161 (('seq', a, b), ('b2f', ('feq', a, b)), 'options->lower_scmp'),
162 (('sne', a, b), ('b2f', ('fne', a, b)), 'options->lower_scmp'),
163 (('fne', ('fneg', a), a), ('fne', a, 0.0)),
164 (('feq', ('fneg', a), a), ('feq', a, 0.0)),
165 # Emulating booleans
166 (('imul', ('b2i', a), ('b2i', b)), ('b2i', ('iand', a, b))),
167 (('fmul', ('b2f', a), ('b2f', b)), ('b2f', ('iand', a, b))),
168 (('fsat', ('fadd', ('b2f', a), ('b2f', b))), ('b2f', ('ior', a, b))),
169 (('iand', 'a@bool', 1.0), ('b2f', a)),
170 (('flt', ('fneg', ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
171 (('flt', ('fsub', 0.0, ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
172 # Comparison with the same args. Note that these are not done for
173 # the float versions because NaN always returns false on float
174 # inequalities.
175 (('ilt', a, a), False),
176 (('ige', a, a), True),
177 (('ieq', a, a), True),
178 (('ine', a, a), False),
179 (('ult', a, a), False),
180 (('uge', a, a), True),
181 # Logical and bit operations
182 (('fand', a, 0.0), 0.0),
183 (('iand', a, a), a),
184 (('iand', a, ~0), a),
185 (('iand', a, 0), 0),
186 (('ior', a, a), a),
187 (('ior', a, 0), a),
188 (('fxor', a, a), 0.0),
189 (('ixor', a, a), 0),
190 (('ixor', a, 0), a),
191 (('inot', ('inot', a)), a),
192 # DeMorgan's Laws
193 (('iand', ('inot', a), ('inot', b)), ('inot', ('ior', a, b))),
194 (('ior', ('inot', a), ('inot', b)), ('inot', ('iand', a, b))),
195 # Shift optimizations
196 (('ishl', 0, a), 0),
197 (('ishl', a, 0), a),
198 (('ishr', 0, a), 0),
199 (('ishr', a, 0), a),
200 (('ushr', 0, a), 0),
201 (('ushr', a, 0), a),
202 (('iand', 0xff, ('ushr', a, 24)), ('ushr', a, 24)),
203 (('iand', 0xffff, ('ushr', a, 16)), ('ushr', a, 16)),
204 # Exponential/logarithmic identities
205 (('~fexp2', ('flog2', a)), a), # 2^lg2(a) = a
206 (('~flog2', ('fexp2', a)), a), # lg2(2^a) = a
207 (('fpow', a, b), ('fexp2', ('fmul', ('flog2', a), b)), 'options->lower_fpow'), # a^b = 2^(lg2(a)*b)
208 (('~fexp2', ('fmul', ('flog2', a), b)), ('fpow', a, b), '!options->lower_fpow'), # 2^(lg2(a)*b) = a^b
209 (('~fexp2', ('fadd', ('fmul', ('flog2', a), b), ('fmul', ('flog2', c), d))),
210 ('~fmul', ('fpow', a, b), ('fpow', c, d)), '!options->lower_fpow'), # 2^(lg2(a) * b + lg2(c) + d) = a^b * c^d
211 (('~fpow', a, 1.0), a),
212 (('~fpow', a, 2.0), ('fmul', a, a)),
213 (('~fpow', a, 4.0), ('fmul', ('fmul', a, a), ('fmul', a, a))),
214 (('~fpow', 2.0, a), ('fexp2', a)),
215 (('~fpow', ('fpow', a, 2.2), 0.454545), a),
216 (('~fpow', ('fabs', ('fpow', a, 2.2)), 0.454545), ('fabs', a)),
217 (('~fsqrt', ('fexp2', a)), ('fexp2', ('fmul', 0.5, a))),
218 (('~frcp', ('fexp2', a)), ('fexp2', ('fneg', a))),
219 (('~frsq', ('fexp2', a)), ('fexp2', ('fmul', -0.5, a))),
220 (('~flog2', ('fsqrt', a)), ('fmul', 0.5, ('flog2', a))),
221 (('~flog2', ('frcp', a)), ('fneg', ('flog2', a))),
222 (('~flog2', ('frsq', a)), ('fmul', -0.5, ('flog2', a))),
223 (('~flog2', ('fpow', a, b)), ('fmul', b, ('flog2', a))),
224 (('~fadd', ('flog2', a), ('flog2', b)), ('flog2', ('fmul', a, b))),
225 (('~fadd', ('flog2', a), ('fneg', ('flog2', b))), ('flog2', ('fdiv', a, b))),
226 (('~fmul', ('fexp2', a), ('fexp2', b)), ('fexp2', ('fadd', a, b))),
227 # Division and reciprocal
228 (('~fdiv', 1.0, a), ('frcp', a)),
229 (('fdiv', a, b), ('fmul', a, ('frcp', b)), 'options->lower_fdiv'),
230 (('~frcp', ('frcp', a)), a),
231 (('~frcp', ('fsqrt', a)), ('frsq', a)),
232 (('fsqrt', a), ('frcp', ('frsq', a)), 'options->lower_fsqrt'),
233 (('~frcp', ('frsq', a)), ('fsqrt', a), '!options->lower_fsqrt'),
234 # Boolean simplifications
235 (('ieq', 'a@bool', True), a),
236 (('ine', 'a@bool', True), ('inot', a)),
237 (('ine', 'a@bool', False), a),
238 (('ieq', 'a@bool', False), ('inot', 'a')),
239 (('bcsel', a, True, False), ('ine', a, 0)),
240 (('bcsel', a, False, True), ('ieq', a, 0)),
241 (('bcsel', True, b, c), b),
242 (('bcsel', False, b, c), c),
243 # The result of this should be hit by constant propagation and, in the
244 # next round of opt_algebraic, get picked up by one of the above two.
245 (('bcsel', '#a', b, c), ('bcsel', ('ine', 'a', 0), b, c)),
246
247 (('bcsel', a, b, b), b),
248 (('fcsel', a, b, b), b),
249
250 # Conversions
251 (('i2b', ('b2i', a)), a),
252 (('f2i', ('ftrunc', a)), ('f2i', a)),
253 (('f2u', ('ftrunc', a)), ('f2u', a)),
254 (('i2b', ('ineg', a)), ('i2b', a)),
255 (('i2b', ('iabs', a)), ('i2b', a)),
256 (('fabs', ('b2f', a)), ('b2f', a)),
257 (('iabs', ('b2i', a)), ('b2i', a)),
258
259 # Byte extraction
260 (('ushr', a, 24), ('extract_u8', a, 3), '!options->lower_extract_byte'),
261 (('iand', 0xff, ('ushr', a, 16)), ('extract_u8', a, 2), '!options->lower_extract_byte'),
262 (('iand', 0xff, ('ushr', a, 8)), ('extract_u8', a, 1), '!options->lower_extract_byte'),
263 (('iand', 0xff, a), ('extract_u8', a, 0), '!options->lower_extract_byte'),
264
265 # Word extraction
266 (('ushr', a, 16), ('extract_u16', a, 1), '!options->lower_extract_word'),
267 (('iand', 0xffff, a), ('extract_u16', a, 0), '!options->lower_extract_word'),
268
269 # Subtracts
270 (('~fsub', a, ('fsub', 0.0, b)), ('fadd', a, b)),
271 (('isub', a, ('isub', 0, b)), ('iadd', a, b)),
272 (('ussub_4x8', a, 0), a),
273 (('ussub_4x8', a, ~0), 0),
274 (('fsub', a, b), ('fadd', a, ('fneg', b)), 'options->lower_sub'),
275 (('isub', a, b), ('iadd', a, ('ineg', b)), 'options->lower_sub'),
276 (('fneg', a), ('fsub', 0.0, a), 'options->lower_negate'),
277 (('ineg', a), ('isub', 0, a), 'options->lower_negate'),
278 (('~fadd', a, ('fsub', 0.0, b)), ('fsub', a, b)),
279 (('iadd', a, ('isub', 0, b)), ('isub', a, b)),
280 (('fabs', ('fsub', 0.0, a)), ('fabs', a)),
281 (('iabs', ('isub', 0, a)), ('iabs', a)),
282
283 # Propagate negation up multiplication chains
284 (('fmul', ('fneg', a), b), ('fneg', ('fmul', a, b))),
285 (('imul', ('ineg', a), b), ('ineg', ('imul', a, b))),
286
287 # Reassociate constants in add/mul chains so they can be folded together.
288 # For now, we only handle cases where the constants are separated by
289 # a single non-constant. We could do better eventually.
290 (('~fmul', '#a', ('fmul', b, '#c')), ('fmul', ('fmul', a, c), b)),
291 (('imul', '#a', ('imul', b, '#c')), ('imul', ('imul', a, c), b)),
292 (('~fadd', '#a', ('fadd', b, '#c')), ('fadd', ('fadd', a, c), b)),
293 (('iadd', '#a', ('iadd', b, '#c')), ('iadd', ('iadd', a, c), b)),
294
295 # Misc. lowering
296 (('fmod', a, b), ('fsub', a, ('fmul', b, ('ffloor', ('fdiv', a, b)))), 'options->lower_fmod'),
297 (('frem', a, b), ('fsub', a, ('fmul', b, ('ftrunc', ('fdiv', a, b)))), 'options->lower_fmod'),
298 (('uadd_carry@32', a, b), ('b2i', ('ult', ('iadd', a, b), a)), 'options->lower_uadd_carry'),
299 (('usub_borrow@32', a, b), ('b2i', ('ult', a, b)), 'options->lower_usub_borrow'),
300
301 (('bitfield_insert', 'base', 'insert', 'offset', 'bits'),
302 ('bcsel', ('ilt', 31, 'bits'), 'insert',
303 ('bfi', ('bfm', 'bits', 'offset'), 'insert', 'base')),
304 'options->lower_bitfield_insert'),
305
306 (('ibitfield_extract', 'value', 'offset', 'bits'),
307 ('bcsel', ('ilt', 31, 'bits'), 'value',
308 ('ibfe', 'value', 'offset', 'bits')),
309 'options->lower_bitfield_extract'),
310
311 (('ubitfield_extract', 'value', 'offset', 'bits'),
312 ('bcsel', ('ult', 31, 'bits'), 'value',
313 ('ubfe', 'value', 'offset', 'bits')),
314 'options->lower_bitfield_extract'),
315
316 (('extract_i8', a, b),
317 ('ishr', ('ishl', a, ('imul', ('isub', 3, b), 8)), 24),
318 'options->lower_extract_byte'),
319
320 (('extract_u8', a, b),
321 ('iand', ('ushr', a, ('imul', b, 8)), 0xff),
322 'options->lower_extract_byte'),
323
324 (('extract_i16', a, b),
325 ('ishr', ('ishl', a, ('imul', ('isub', 1, b), 16)), 16),
326 'options->lower_extract_word'),
327
328 (('extract_u16', a, b),
329 ('iand', ('ushr', a, ('imul', b, 16)), 0xffff),
330 'options->lower_extract_word'),
331
332 (('pack_unorm_2x16', 'v'),
333 ('pack_uvec2_to_uint',
334 ('f2u', ('fround_even', ('fmul', ('fsat', 'v'), 65535.0)))),
335 'options->lower_pack_unorm_2x16'),
336
337 (('pack_unorm_4x8', 'v'),
338 ('pack_uvec4_to_uint',
339 ('f2u', ('fround_even', ('fmul', ('fsat', 'v'), 255.0)))),
340 'options->lower_pack_unorm_4x8'),
341
342 (('pack_snorm_2x16', 'v'),
343 ('pack_uvec2_to_uint',
344 ('f2i', ('fround_even', ('fmul', ('fmin', 1.0, ('fmax', -1.0, 'v')), 32767.0)))),
345 'options->lower_pack_snorm_2x16'),
346
347 (('pack_snorm_4x8', 'v'),
348 ('pack_uvec4_to_uint',
349 ('f2i', ('fround_even', ('fmul', ('fmin', 1.0, ('fmax', -1.0, 'v')), 127.0)))),
350 'options->lower_pack_snorm_4x8'),
351
352 (('unpack_unorm_2x16', 'v'),
353 ('fdiv', ('u2f', ('vec2', ('extract_u16', 'v', 0),
354 ('extract_u16', 'v', 1))),
355 65535.0),
356 'options->lower_unpack_unorm_2x16'),
357
358 (('unpack_unorm_4x8', 'v'),
359 ('fdiv', ('u2f', ('vec4', ('extract_u8', 'v', 0),
360 ('extract_u8', 'v', 1),
361 ('extract_u8', 'v', 2),
362 ('extract_u8', 'v', 3))),
363 255.0),
364 'options->lower_unpack_unorm_4x8'),
365
366 (('unpack_snorm_2x16', 'v'),
367 ('fmin', 1.0, ('fmax', -1.0, ('fdiv', ('i2f', ('vec2', ('extract_i16', 'v', 0),
368 ('extract_i16', 'v', 1))),
369 32767.0))),
370 'options->lower_unpack_snorm_2x16'),
371
372 (('unpack_snorm_4x8', 'v'),
373 ('fmin', 1.0, ('fmax', -1.0, ('fdiv', ('i2f', ('vec4', ('extract_i8', 'v', 0),
374 ('extract_i8', 'v', 1),
375 ('extract_i8', 'v', 2),
376 ('extract_i8', 'v', 3))),
377 127.0))),
378 'options->lower_unpack_snorm_4x8'),
379 ]
380
381 def fexp2i(exp):
382 # We assume that exp is already in the range [-126, 127].
383 return ('ishl', ('iadd', exp, 127), 23)
384
385 def ldexp32(f, exp):
386 # First, we clamp exp to a reasonable range. The maximum possible range
387 # for a normal exponent is [-126, 127] and, throwing in denormals, you get
388 # a maximum range of [-149, 127]. This means that we can potentially have
389 # a swing of +-276. If you start with FLT_MAX, you actually have to do
390 # ldexp(FLT_MAX, -278) to get it to flush all the way to zero. The GLSL
391 # spec, on the other hand, only requires that we handle an exponent value
392 # in the range [-126, 128]. This implementation is *mostly* correct; it
393 # handles a range on exp of [-252, 254] which allows you to create any
394 # value (including denorms if the hardware supports it) and to adjust the
395 # exponent of any normal value to anything you want.
396 exp = ('imin', ('imax', exp, -252), 254)
397
398 # Now we compute two powers of 2, one for exp/2 and one for exp-exp/2.
399 # (We use ishr which isn't the same for -1, but the -1 case still works
400 # since we use exp-exp/2 as the second exponent.) While the spec
401 # technically defines ldexp as f * 2.0^exp, simply multiplying once doesn't
402 # work with denormals and doesn't allow for the full swing in exponents
403 # that you can get with normalized values. Instead, we create two powers
404 # of two and multiply by them each in turn. That way the effective range
405 # of our exponent is doubled.
406 pow2_1 = fexp2i(('ishr', exp, 1))
407 pow2_2 = fexp2i(('isub', exp, ('ishr', exp, 1)))
408 return ('fmul', ('fmul', f, pow2_1), pow2_2)
409
410 optimizations += [(('ldexp', 'x', 'exp'), ldexp32('x', 'exp'))]
411
412 # Unreal Engine 4 demo applications open-codes bitfieldReverse()
413 def bitfield_reverse(u):
414 step1 = ('ior', ('ishl', u, 16), ('ushr', u, 16))
415 step2 = ('ior', ('ishl', ('iand', step1, 0x00ff00ff), 8), ('ushr', ('iand', step1, 0xff00ff00), 8))
416 step3 = ('ior', ('ishl', ('iand', step2, 0x0f0f0f0f), 4), ('ushr', ('iand', step2, 0xf0f0f0f0), 4))
417 step4 = ('ior', ('ishl', ('iand', step3, 0x33333333), 2), ('ushr', ('iand', step3, 0xcccccccc), 2))
418 step5 = ('ior', ('ishl', ('iand', step4, 0x55555555), 1), ('ushr', ('iand', step4, 0xaaaaaaaa), 1))
419
420 return step5
421
422 optimizations += [(bitfield_reverse('x@32'), ('bitfield_reverse', 'x'))]
423
424
425 # Add optimizations to handle the case where the result of a ternary is
426 # compared to a constant. This way we can take things like
427 #
428 # (a ? 0 : 1) > 0
429 #
430 # and turn it into
431 #
432 # a ? (0 > 0) : (1 > 0)
433 #
434 # which constant folding will eat for lunch. The resulting ternary will
435 # further get cleaned up by the boolean reductions above and we will be
436 # left with just the original variable "a".
437 for op in ['flt', 'fge', 'feq', 'fne',
438 'ilt', 'ige', 'ieq', 'ine', 'ult', 'uge']:
439 optimizations += [
440 ((op, ('bcsel', 'a', '#b', '#c'), '#d'),
441 ('bcsel', 'a', (op, 'b', 'd'), (op, 'c', 'd'))),
442 ((op, '#d', ('bcsel', a, '#b', '#c')),
443 ('bcsel', 'a', (op, 'd', 'b'), (op, 'd', 'c'))),
444 ]
445
446 # This section contains "late" optimizations that should be run after the
447 # regular optimizations have finished. Optimizations should go here if
448 # they help code generation but do not necessarily produce code that is
449 # more easily optimizable.
450 late_optimizations = [
451 # Most of these optimizations aren't quite safe when you get infinity or
452 # Nan involved but the first one should be fine.
453 (('flt', ('fadd', a, b), 0.0), ('flt', a, ('fneg', b))),
454 (('~fge', ('fadd', a, b), 0.0), ('fge', a, ('fneg', b))),
455 (('~feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
456 (('~fne', ('fadd', a, b), 0.0), ('fne', a, ('fneg', b))),
457
458 (('fdot2', a, b), ('fdot_replicated2', a, b), 'options->fdot_replicates'),
459 (('fdot3', a, b), ('fdot_replicated3', a, b), 'options->fdot_replicates'),
460 (('fdot4', a, b), ('fdot_replicated4', a, b), 'options->fdot_replicates'),
461 (('fdph', a, b), ('fdph_replicated', a, b), 'options->fdot_replicates'),
462 ]
463
464 print nir_algebraic.AlgebraicPass("nir_opt_algebraic", optimizations).render()
465 print nir_algebraic.AlgebraicPass("nir_opt_algebraic_late",
466 late_optimizations).render()