f60c338b6246ad6f9cbf001ea2e8f23515c3626b
[mesa.git] / src / compiler / nir / nir_opt_algebraic.py
1 #
2 # Copyright (C) 2014 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 # Authors:
24 # Jason Ekstrand (jason@jlekstrand.net)
25
26 import nir_algebraic
27
28 # Convenience variables
29 a = 'a'
30 b = 'b'
31 c = 'c'
32 d = 'd'
33
34 # Written in the form (<search>, <replace>) where <search> is an expression
35 # and <replace> is either an expression or a value. An expression is
36 # defined as a tuple of the form ([~]<op>, <src0>, <src1>, <src2>, <src3>)
37 # where each source is either an expression or a value. A value can be
38 # either a numeric constant or a string representing a variable name.
39 #
40 # If the opcode in a search expression is prefixed by a '~' character, this
41 # indicates that the operation is inexact. Such operations will only get
42 # applied to SSA values that do not have the exact bit set. This should be
43 # used by by any optimizations that are not bit-for-bit exact. It should not,
44 # however, be used for backend-requested lowering operations as those need to
45 # happen regardless of precision.
46 #
47 # Variable names are specified as "[#]name[@type][(cond)]" where "#" inicates
48 # that the given variable will only match constants and the type indicates that
49 # the given variable will only match values from ALU instructions with the
50 # given output type, and (cond) specifies an additional condition function
51 # (see nir_search_helpers.h).
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
66 (('imul', a, '#b@32(is_pos_power_of_two)'), ('ishl', a, ('find_lsb', b))),
67 (('imul', a, '#b@32(is_neg_power_of_two)'), ('ineg', ('ishl', a, ('find_lsb', ('iabs', b))))),
68 (('udiv', a, 1), a),
69 (('idiv', a, 1), a),
70 (('umod', a, 1), 0),
71 (('imod', a, 1), 0),
72 (('udiv', a, '#b@32(is_pos_power_of_two)'), ('ushr', a, ('find_lsb', b))),
73 (('idiv', a, '#b@32(is_pos_power_of_two)'), ('imul', ('isign', a), ('ushr', ('iabs', a), ('find_lsb', b))), 'options->lower_idiv'),
74 (('idiv', a, '#b@32(is_neg_power_of_two)'), ('ineg', ('imul', ('isign', a), ('ushr', ('iabs', a), ('find_lsb', ('iabs', b))))), 'options->lower_idiv'),
75 (('umod', a, '#b(is_pos_power_of_two)'), ('iand', a, ('isub', b, 1))),
76
77 (('fneg', ('fneg', a)), a),
78 (('ineg', ('ineg', a)), a),
79 (('fabs', ('fabs', a)), ('fabs', a)),
80 (('fabs', ('fneg', a)), ('fabs', a)),
81 (('fabs', ('u2f', a)), ('u2f', a)),
82 (('iabs', ('iabs', a)), ('iabs', a)),
83 (('iabs', ('ineg', a)), ('iabs', a)),
84 (('~fadd', a, 0.0), a),
85 (('iadd', a, 0), a),
86 (('usadd_4x8', a, 0), a),
87 (('usadd_4x8', a, ~0), ~0),
88 (('~fadd', ('fmul', a, b), ('fmul', a, c)), ('fmul', a, ('fadd', b, c))),
89 (('iadd', ('imul', a, b), ('imul', a, c)), ('imul', a, ('iadd', b, c))),
90 (('~fadd', ('fneg', a), a), 0.0),
91 (('iadd', ('ineg', a), a), 0),
92 (('iadd', ('ineg', a), ('iadd', a, b)), b),
93 (('iadd', a, ('iadd', ('ineg', a), b)), b),
94 (('~fadd', ('fneg', a), ('fadd', a, b)), b),
95 (('~fadd', a, ('fadd', ('fneg', a), b)), b),
96 (('~fmul', a, 0.0), 0.0),
97 (('imul', a, 0), 0),
98 (('umul_unorm_4x8', a, 0), 0),
99 (('umul_unorm_4x8', a, ~0), a),
100 (('fmul', a, 1.0), a),
101 (('imul', a, 1), a),
102 (('fmul', a, -1.0), ('fneg', a)),
103 (('imul', a, -1), ('ineg', a)),
104 (('~ffma', 0.0, a, b), b),
105 (('~ffma', a, 0.0, b), b),
106 (('~ffma', a, b, 0.0), ('fmul', a, b)),
107 (('ffma', a, 1.0, b), ('fadd', a, b)),
108 (('ffma', 1.0, a, b), ('fadd', a, b)),
109 (('~flrp', a, b, 0.0), a),
110 (('~flrp', a, b, 1.0), b),
111 (('~flrp', a, a, b), a),
112 (('~flrp', 0.0, a, b), ('fmul', a, b)),
113 (('~flrp', a, b, ('b2f', c)), ('bcsel', c, b, a), 'options->lower_flrp32'),
114 (('~flrp', a, 0.0, c), ('fadd', ('fmul', ('fneg', a), c), a)),
115 (('flrp@32', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp32'),
116 (('flrp@64', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp64'),
117 (('ffract', a), ('fsub', a, ('ffloor', a)), 'options->lower_ffract'),
118 (('~fadd', ('fmul', a, ('fadd', 1.0, ('fneg', ('b2f', c)))), ('fmul', b, ('b2f', c))), ('bcsel', c, b, a), 'options->lower_flrp32'),
119 (('~fadd@32', ('fmul', a, ('fadd', 1.0, ('fneg', c ))), ('fmul', b, c )), ('flrp', a, b, c), '!options->lower_flrp32'),
120 (('~fadd@64', ('fmul', a, ('fadd', 1.0, ('fneg', c ))), ('fmul', b, c )), ('flrp', a, b, c), '!options->lower_flrp64'),
121 (('~fadd', a, ('fmul', ('b2f', c), ('fadd', b, ('fneg', a)))), ('bcsel', c, b, a), 'options->lower_flrp32'),
122 (('~fadd@32', a, ('fmul', c , ('fadd', b, ('fneg', a)))), ('flrp', a, b, c), '!options->lower_flrp32'),
123 (('~fadd@64', a, ('fmul', c , ('fadd', b, ('fneg', a)))), ('flrp', a, b, c), '!options->lower_flrp64'),
124 (('ffma', a, b, c), ('fadd', ('fmul', a, b), c), 'options->lower_ffma'),
125 (('~fadd', ('fmul', a, b), c), ('ffma', a, b, c), 'options->fuse_ffma'),
126
127 # (a * #b + #c) << #d
128 # ((a * #b) << #d) + (#c << #d)
129 # (a * (#b << #d)) + (#c << #d)
130 (('ishl', ('iadd', ('imul', a, '#b'), '#c'), '#d'),
131 ('iadd', ('imul', a, ('ishl', b, d)), ('ishl', c, d))),
132
133 # (a * #b) << #c
134 # a * (#b << #c)
135 (('ishl', ('imul', a, '#b'), '#c'), ('imul', a, ('ishl', b, c))),
136
137 # Comparison simplifications
138 (('~inot', ('flt', a, b)), ('fge', a, b)),
139 (('~inot', ('fge', a, b)), ('flt', a, b)),
140 (('~inot', ('feq', a, b)), ('fne', a, b)),
141 (('~inot', ('fne', a, b)), ('feq', a, b)),
142 (('inot', ('ilt', a, b)), ('ige', a, b)),
143 (('inot', ('ige', a, b)), ('ilt', a, b)),
144 (('inot', ('ieq', a, b)), ('ine', a, b)),
145 (('inot', ('ine', a, b)), ('ieq', a, b)),
146
147 # 0.0 >= b2f(a)
148 # b2f(a) <= 0.0
149 # b2f(a) == 0.0 because b2f(a) can only be 0 or 1
150 # inot(a)
151 (('fge', 0.0, ('b2f', a)), ('inot', a)),
152
153 (('fge', ('fneg', ('b2f', a)), 0.0), ('inot', a)),
154
155 # 0.0 < fabs(a)
156 # fabs(a) > 0.0
157 # fabs(a) != 0.0 because fabs(a) must be >= 0
158 # a != 0.0
159 (('flt', 0.0, ('fabs', a)), ('fne', a, 0.0)),
160
161 (('fge', ('fneg', ('fabs', a)), 0.0), ('feq', a, 0.0)),
162 (('bcsel', ('flt', b, a), b, a), ('fmin', a, b)),
163 (('bcsel', ('flt', a, b), b, a), ('fmax', a, b)),
164 (('bcsel', ('inot', a), b, c), ('bcsel', a, c, b)),
165 (('bcsel', a, ('bcsel', a, b, c), d), ('bcsel', a, b, d)),
166 (('bcsel', a, True, 'b@bool'), ('ior', a, b)),
167 (('fmin', a, a), a),
168 (('fmax', a, a), a),
169 (('imin', a, a), a),
170 (('imax', a, a), a),
171 (('umin', a, a), a),
172 (('umax', a, a), a),
173 (('fmin', a, ('fneg', a)), ('fneg', ('fabs', a))),
174 (('imin', a, ('ineg', a)), ('ineg', ('iabs', a))),
175 (('fmin', a, ('fneg', ('fabs', a))), ('fneg', ('fabs', a))),
176 (('imin', a, ('ineg', ('iabs', a))), ('ineg', ('iabs', a))),
177 (('fmin', a, ('fabs', a)), a),
178 (('imin', a, ('iabs', a)), a),
179 (('fmax', a, ('fneg', ('fabs', a))), a),
180 (('imax', a, ('ineg', ('iabs', a))), a),
181 (('fmax', a, ('fabs', a)), ('fabs', a)),
182 (('imax', a, ('iabs', a)), ('iabs', a)),
183 (('fmax', a, ('fneg', a)), ('fabs', a)),
184 (('imax', a, ('ineg', a)), ('iabs', a)),
185 (('~fmin', ('fmax', a, 0.0), 1.0), ('fsat', a), '!options->lower_fsat'),
186 (('~fmax', ('fmin', a, 1.0), 0.0), ('fsat', a), '!options->lower_fsat'),
187 (('fsat', a), ('fmin', ('fmax', a, 0.0), 1.0), 'options->lower_fsat'),
188 (('fsat', ('fsat', a)), ('fsat', a)),
189 (('fmin', ('fmax', ('fmin', ('fmax', a, b), c), b), c), ('fmin', ('fmax', a, b), c)),
190 (('imin', ('imax', ('imin', ('imax', a, b), c), b), c), ('imin', ('imax', a, b), c)),
191 (('umin', ('umax', ('umin', ('umax', a, b), c), b), c), ('umin', ('umax', a, b), c)),
192 (('fmax', ('fsat', a), '#b@32(is_zero_to_one)'), ('fsat', ('fmax', a, b))),
193 (('fmin', ('fsat', a), '#b@32(is_zero_to_one)'), ('fsat', ('fmin', a, b))),
194 (('extract_u8', ('imin', ('imax', a, 0), 0xff), 0), ('imin', ('imax', a, 0), 0xff)),
195 (('~ior', ('flt', a, b), ('flt', a, c)), ('flt', a, ('fmax', b, c))),
196 (('~ior', ('flt', a, c), ('flt', b, c)), ('flt', ('fmin', a, b), c)),
197 (('~ior', ('fge', a, b), ('fge', a, c)), ('fge', a, ('fmin', b, c))),
198 (('~ior', ('fge', a, c), ('fge', b, c)), ('fge', ('fmax', a, b), c)),
199 (('fabs', ('slt', a, b)), ('slt', a, b)),
200 (('fabs', ('sge', a, b)), ('sge', a, b)),
201 (('fabs', ('seq', a, b)), ('seq', a, b)),
202 (('fabs', ('sne', a, b)), ('sne', a, b)),
203 (('slt', a, b), ('b2f', ('flt', a, b)), 'options->lower_scmp'),
204 (('sge', a, b), ('b2f', ('fge', a, b)), 'options->lower_scmp'),
205 (('seq', a, b), ('b2f', ('feq', a, b)), 'options->lower_scmp'),
206 (('sne', a, b), ('b2f', ('fne', a, b)), 'options->lower_scmp'),
207 (('fne', ('fneg', a), a), ('fne', a, 0.0)),
208 (('feq', ('fneg', a), a), ('feq', a, 0.0)),
209 # Emulating booleans
210 (('imul', ('b2i', a), ('b2i', b)), ('b2i', ('iand', a, b))),
211 (('fmul', ('b2f', a), ('b2f', b)), ('b2f', ('iand', a, b))),
212 (('fsat', ('fadd', ('b2f', a), ('b2f', b))), ('b2f', ('ior', a, b))),
213 (('iand', 'a@bool', 1.0), ('b2f', a)),
214 # True/False are ~0 and 0 in NIR. b2i of True is 1, and -1 is ~0 (True).
215 (('ineg', ('b2i', a)), a),
216 (('flt', ('fneg', ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
217 (('flt', ('fsub', 0.0, ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
218 # Comparison with the same args. Note that these are not done for
219 # the float versions because NaN always returns false on float
220 # inequalities.
221 (('ilt', a, a), False),
222 (('ige', a, a), True),
223 (('ieq', a, a), True),
224 (('ine', a, a), False),
225 (('ult', a, a), False),
226 (('uge', a, a), True),
227 # Logical and bit operations
228 (('fand', a, 0.0), 0.0),
229 (('iand', a, a), a),
230 (('iand', a, ~0), a),
231 (('iand', a, 0), 0),
232 (('ior', a, a), a),
233 (('ior', a, 0), a),
234 (('ior', a, True), True),
235 (('fxor', a, a), 0.0),
236 (('ixor', a, a), 0),
237 (('ixor', a, 0), a),
238 (('inot', ('inot', a)), a),
239 # DeMorgan's Laws
240 (('iand', ('inot', a), ('inot', b)), ('inot', ('ior', a, b))),
241 (('ior', ('inot', a), ('inot', b)), ('inot', ('iand', a, b))),
242 # Shift optimizations
243 (('ishl', 0, a), 0),
244 (('ishl', a, 0), a),
245 (('ishr', 0, a), 0),
246 (('ishr', a, 0), a),
247 (('ushr', 0, a), 0),
248 (('ushr', a, 0), a),
249 (('iand', 0xff, ('ushr', a, 24)), ('ushr', a, 24)),
250 (('iand', 0xffff, ('ushr', a, 16)), ('ushr', a, 16)),
251 # Exponential/logarithmic identities
252 (('~fexp2', ('flog2', a)), a), # 2^lg2(a) = a
253 (('~flog2', ('fexp2', a)), a), # lg2(2^a) = a
254 (('fpow', a, b), ('fexp2', ('fmul', ('flog2', a), b)), 'options->lower_fpow'), # a^b = 2^(lg2(a)*b)
255 (('~fexp2', ('fmul', ('flog2', a), b)), ('fpow', a, b), '!options->lower_fpow'), # 2^(lg2(a)*b) = a^b
256 (('~fexp2', ('fadd', ('fmul', ('flog2', a), b), ('fmul', ('flog2', c), d))),
257 ('~fmul', ('fpow', a, b), ('fpow', c, d)), '!options->lower_fpow'), # 2^(lg2(a) * b + lg2(c) + d) = a^b * c^d
258 (('~fpow', a, 1.0), a),
259 (('~fpow', a, 2.0), ('fmul', a, a)),
260 (('~fpow', a, 4.0), ('fmul', ('fmul', a, a), ('fmul', a, a))),
261 (('~fpow', 2.0, a), ('fexp2', a)),
262 (('~fpow', ('fpow', a, 2.2), 0.454545), a),
263 (('~fpow', ('fabs', ('fpow', a, 2.2)), 0.454545), ('fabs', a)),
264 (('~fsqrt', ('fexp2', a)), ('fexp2', ('fmul', 0.5, a))),
265 (('~frcp', ('fexp2', a)), ('fexp2', ('fneg', a))),
266 (('~frsq', ('fexp2', a)), ('fexp2', ('fmul', -0.5, a))),
267 (('~flog2', ('fsqrt', a)), ('fmul', 0.5, ('flog2', a))),
268 (('~flog2', ('frcp', a)), ('fneg', ('flog2', a))),
269 (('~flog2', ('frsq', a)), ('fmul', -0.5, ('flog2', a))),
270 (('~flog2', ('fpow', a, b)), ('fmul', b, ('flog2', a))),
271 (('~fmul', ('fexp2', a), ('fexp2', b)), ('fexp2', ('fadd', a, b))),
272 # Division and reciprocal
273 (('~fdiv', 1.0, a), ('frcp', a)),
274 (('fdiv', a, b), ('fmul', a, ('frcp', b)), 'options->lower_fdiv'),
275 (('~frcp', ('frcp', a)), a),
276 (('~frcp', ('fsqrt', a)), ('frsq', a)),
277 (('fsqrt', a), ('frcp', ('frsq', a)), 'options->lower_fsqrt'),
278 (('~frcp', ('frsq', a)), ('fsqrt', a), '!options->lower_fsqrt'),
279 # Boolean simplifications
280 (('ieq', 'a@bool', True), a),
281 (('ine(is_not_used_by_if)', 'a@bool', True), ('inot', a)),
282 (('ine', 'a@bool', False), a),
283 (('ieq(is_not_used_by_if)', 'a@bool', False), ('inot', 'a')),
284 (('bcsel', a, True, False), a),
285 (('bcsel', a, False, True), ('inot', a)),
286 (('bcsel@32', a, 1.0, 0.0), ('b2f', a)),
287 (('bcsel@32', a, 0.0, 1.0), ('b2f', ('inot', a))),
288 (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', a))),
289 (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('inot', a)))),
290 (('bcsel', True, b, c), b),
291 (('bcsel', False, b, c), c),
292 # The result of this should be hit by constant propagation and, in the
293 # next round of opt_algebraic, get picked up by one of the above two.
294 (('bcsel', '#a', b, c), ('bcsel', ('ine', 'a', 0), b, c)),
295
296 (('bcsel', a, b, b), b),
297 (('fcsel', a, b, b), b),
298
299 # Conversions
300 (('i2b', ('b2i', a)), a),
301 (('f2i', ('ftrunc', a)), ('f2i', a)),
302 (('f2u', ('ftrunc', a)), ('f2u', a)),
303 (('i2b', ('ineg', a)), ('i2b', a)),
304 (('i2b', ('iabs', a)), ('i2b', a)),
305 (('fabs', ('b2f', a)), ('b2f', a)),
306 (('iabs', ('b2i', a)), ('b2i', a)),
307
308 # Packing and then unpacking does nothing
309 (('unpack_64_2x32_split_x', ('pack_64_2x32_split', a, b)), a),
310 (('unpack_64_2x32_split_y', ('pack_64_2x32_split', a, b)), b),
311 (('pack_64_2x32_split', ('unpack_64_2x32_split_x', a),
312 ('unpack_64_2x32_split_y', a)), a),
313
314 # Byte extraction
315 (('ushr', a, 24), ('extract_u8', a, 3), '!options->lower_extract_byte'),
316 (('iand', 0xff, ('ushr', a, 16)), ('extract_u8', a, 2), '!options->lower_extract_byte'),
317 (('iand', 0xff, ('ushr', a, 8)), ('extract_u8', a, 1), '!options->lower_extract_byte'),
318 (('iand', 0xff, a), ('extract_u8', a, 0), '!options->lower_extract_byte'),
319
320 # Word extraction
321 (('ushr', a, 16), ('extract_u16', a, 1), '!options->lower_extract_word'),
322 (('iand', 0xffff, a), ('extract_u16', a, 0), '!options->lower_extract_word'),
323
324 # Subtracts
325 (('~fsub', a, ('fsub', 0.0, b)), ('fadd', a, b)),
326 (('isub', a, ('isub', 0, b)), ('iadd', a, b)),
327 (('ussub_4x8', a, 0), a),
328 (('ussub_4x8', a, ~0), 0),
329 (('fsub', a, b), ('fadd', a, ('fneg', b)), 'options->lower_sub'),
330 (('isub', a, b), ('iadd', a, ('ineg', b)), 'options->lower_sub'),
331 (('fneg', a), ('fsub', 0.0, a), 'options->lower_negate'),
332 (('ineg', a), ('isub', 0, a), 'options->lower_negate'),
333 (('~fadd', a, ('fsub', 0.0, b)), ('fsub', a, b)),
334 (('iadd', a, ('isub', 0, b)), ('isub', a, b)),
335 (('fabs', ('fsub', 0.0, a)), ('fabs', a)),
336 (('iabs', ('isub', 0, a)), ('iabs', a)),
337
338 # Propagate negation up multiplication chains
339 (('fmul', ('fneg', a), b), ('fneg', ('fmul', a, b))),
340 (('imul', ('ineg', a), b), ('ineg', ('imul', a, b))),
341
342 # Reassociate constants in add/mul chains so they can be folded together.
343 # For now, we only handle cases where the constants are separated by
344 # a single non-constant. We could do better eventually.
345 (('~fmul', '#a', ('fmul', b, '#c')), ('fmul', ('fmul', a, c), b)),
346 (('imul', '#a', ('imul', b, '#c')), ('imul', ('imul', a, c), b)),
347 (('~fadd', '#a', ('fadd', b, '#c')), ('fadd', ('fadd', a, c), b)),
348 (('iadd', '#a', ('iadd', b, '#c')), ('iadd', ('iadd', a, c), b)),
349
350 # Misc. lowering
351 (('fmod@32', a, b), ('fsub', a, ('fmul', b, ('ffloor', ('fdiv', a, b)))), 'options->lower_fmod32'),
352 (('fmod@64', a, b), ('fsub', a, ('fmul', b, ('ffloor', ('fdiv', a, b)))), 'options->lower_fmod64'),
353 (('frem', a, b), ('fsub', a, ('fmul', b, ('ftrunc', ('fdiv', a, b)))), 'options->lower_fmod32'),
354 (('uadd_carry@32', a, b), ('b2i', ('ult', ('iadd', a, b), a)), 'options->lower_uadd_carry'),
355 (('usub_borrow@32', a, b), ('b2i', ('ult', a, b)), 'options->lower_usub_borrow'),
356
357 (('bitfield_insert', 'base', 'insert', 'offset', 'bits'),
358 ('bcsel', ('ilt', 31, 'bits'), 'insert',
359 ('bfi', ('bfm', 'bits', 'offset'), 'insert', 'base')),
360 'options->lower_bitfield_insert'),
361
362 (('ibitfield_extract', 'value', 'offset', 'bits'),
363 ('bcsel', ('ilt', 31, 'bits'), 'value',
364 ('ibfe', 'value', 'offset', 'bits')),
365 'options->lower_bitfield_extract'),
366
367 (('ubitfield_extract', 'value', 'offset', 'bits'),
368 ('bcsel', ('ult', 31, 'bits'), 'value',
369 ('ubfe', 'value', 'offset', 'bits')),
370 'options->lower_bitfield_extract'),
371
372 (('extract_i8', a, 'b@32'),
373 ('ishr', ('ishl', a, ('imul', ('isub', 3, b), 8)), 24),
374 'options->lower_extract_byte'),
375
376 (('extract_u8', a, 'b@32'),
377 ('iand', ('ushr', a, ('imul', b, 8)), 0xff),
378 'options->lower_extract_byte'),
379
380 (('extract_i16', a, 'b@32'),
381 ('ishr', ('ishl', a, ('imul', ('isub', 1, b), 16)), 16),
382 'options->lower_extract_word'),
383
384 (('extract_u16', a, 'b@32'),
385 ('iand', ('ushr', a, ('imul', b, 16)), 0xffff),
386 'options->lower_extract_word'),
387
388 (('pack_unorm_2x16', 'v'),
389 ('pack_uvec2_to_uint',
390 ('f2u', ('fround_even', ('fmul', ('fsat', 'v'), 65535.0)))),
391 'options->lower_pack_unorm_2x16'),
392
393 (('pack_unorm_4x8', 'v'),
394 ('pack_uvec4_to_uint',
395 ('f2u', ('fround_even', ('fmul', ('fsat', 'v'), 255.0)))),
396 'options->lower_pack_unorm_4x8'),
397
398 (('pack_snorm_2x16', 'v'),
399 ('pack_uvec2_to_uint',
400 ('f2i', ('fround_even', ('fmul', ('fmin', 1.0, ('fmax', -1.0, 'v')), 32767.0)))),
401 'options->lower_pack_snorm_2x16'),
402
403 (('pack_snorm_4x8', 'v'),
404 ('pack_uvec4_to_uint',
405 ('f2i', ('fround_even', ('fmul', ('fmin', 1.0, ('fmax', -1.0, 'v')), 127.0)))),
406 'options->lower_pack_snorm_4x8'),
407
408 (('unpack_unorm_2x16', 'v'),
409 ('fdiv', ('u2f', ('vec2', ('extract_u16', 'v', 0),
410 ('extract_u16', 'v', 1))),
411 65535.0),
412 'options->lower_unpack_unorm_2x16'),
413
414 (('unpack_unorm_4x8', 'v'),
415 ('fdiv', ('u2f', ('vec4', ('extract_u8', 'v', 0),
416 ('extract_u8', 'v', 1),
417 ('extract_u8', 'v', 2),
418 ('extract_u8', 'v', 3))),
419 255.0),
420 'options->lower_unpack_unorm_4x8'),
421
422 (('unpack_snorm_2x16', 'v'),
423 ('fmin', 1.0, ('fmax', -1.0, ('fdiv', ('i2f', ('vec2', ('extract_i16', 'v', 0),
424 ('extract_i16', 'v', 1))),
425 32767.0))),
426 'options->lower_unpack_snorm_2x16'),
427
428 (('unpack_snorm_4x8', 'v'),
429 ('fmin', 1.0, ('fmax', -1.0, ('fdiv', ('i2f', ('vec4', ('extract_i8', 'v', 0),
430 ('extract_i8', 'v', 1),
431 ('extract_i8', 'v', 2),
432 ('extract_i8', 'v', 3))),
433 127.0))),
434 'options->lower_unpack_snorm_4x8'),
435 ]
436
437 def fexp2i(exp, bits):
438 # We assume that exp is already in the right range.
439 if bits == 32:
440 return ('ishl', ('iadd', exp, 127), 23)
441 elif bits == 64:
442 return ('pack_64_2x32_split', 0, ('ishl', ('iadd', exp, 1023), 20))
443 else:
444 assert False
445
446 def ldexp(f, exp, bits):
447 # First, we clamp exp to a reasonable range. The maximum possible range
448 # for a normal exponent is [-126, 127] and, throwing in denormals, you get
449 # a maximum range of [-149, 127]. This means that we can potentially have
450 # a swing of +-276. If you start with FLT_MAX, you actually have to do
451 # ldexp(FLT_MAX, -278) to get it to flush all the way to zero. The GLSL
452 # spec, on the other hand, only requires that we handle an exponent value
453 # in the range [-126, 128]. This implementation is *mostly* correct; it
454 # handles a range on exp of [-252, 254] which allows you to create any
455 # value (including denorms if the hardware supports it) and to adjust the
456 # exponent of any normal value to anything you want.
457 if bits == 32:
458 exp = ('imin', ('imax', exp, -252), 254)
459 elif bits == 64:
460 exp = ('imin', ('imax', exp, -2044), 2046)
461 else:
462 assert False
463
464 # Now we compute two powers of 2, one for exp/2 and one for exp-exp/2.
465 # (We use ishr which isn't the same for -1, but the -1 case still works
466 # since we use exp-exp/2 as the second exponent.) While the spec
467 # technically defines ldexp as f * 2.0^exp, simply multiplying once doesn't
468 # work with denormals and doesn't allow for the full swing in exponents
469 # that you can get with normalized values. Instead, we create two powers
470 # of two and multiply by them each in turn. That way the effective range
471 # of our exponent is doubled.
472 pow2_1 = fexp2i(('ishr', exp, 1), bits)
473 pow2_2 = fexp2i(('isub', exp, ('ishr', exp, 1)), bits)
474 return ('fmul', ('fmul', f, pow2_1), pow2_2)
475
476 optimizations += [
477 (('ldexp@32', 'x', 'exp'), ldexp('x', 'exp', 32)),
478 (('ldexp@64', 'x', 'exp'), ldexp('x', 'exp', 64)),
479 ]
480
481 # Unreal Engine 4 demo applications open-codes bitfieldReverse()
482 def bitfield_reverse(u):
483 step1 = ('ior', ('ishl', u, 16), ('ushr', u, 16))
484 step2 = ('ior', ('ishl', ('iand', step1, 0x00ff00ff), 8), ('ushr', ('iand', step1, 0xff00ff00), 8))
485 step3 = ('ior', ('ishl', ('iand', step2, 0x0f0f0f0f), 4), ('ushr', ('iand', step2, 0xf0f0f0f0), 4))
486 step4 = ('ior', ('ishl', ('iand', step3, 0x33333333), 2), ('ushr', ('iand', step3, 0xcccccccc), 2))
487 step5 = ('ior', ('ishl', ('iand', step4, 0x55555555), 1), ('ushr', ('iand', step4, 0xaaaaaaaa), 1))
488
489 return step5
490
491 optimizations += [(bitfield_reverse('x@32'), ('bitfield_reverse', 'x'))]
492
493 # For any float comparison operation, "cmp", if you have "a == a && a cmp b"
494 # then the "a == a" is redundant because it's equivalent to "a is not NaN"
495 # and, if a is a NaN then the second comparison will fail anyway.
496 for op in ['flt', 'fge', 'feq']:
497 optimizations += [
498 (('iand', ('feq', a, a), (op, a, b)), (op, a, b)),
499 (('iand', ('feq', a, a), (op, b, a)), (op, b, a)),
500 ]
501
502 # Add optimizations to handle the case where the result of a ternary is
503 # compared to a constant. This way we can take things like
504 #
505 # (a ? 0 : 1) > 0
506 #
507 # and turn it into
508 #
509 # a ? (0 > 0) : (1 > 0)
510 #
511 # which constant folding will eat for lunch. The resulting ternary will
512 # further get cleaned up by the boolean reductions above and we will be
513 # left with just the original variable "a".
514 for op in ['flt', 'fge', 'feq', 'fne',
515 'ilt', 'ige', 'ieq', 'ine', 'ult', 'uge']:
516 optimizations += [
517 ((op, ('bcsel', 'a', '#b', '#c'), '#d'),
518 ('bcsel', 'a', (op, 'b', 'd'), (op, 'c', 'd'))),
519 ((op, '#d', ('bcsel', a, '#b', '#c')),
520 ('bcsel', 'a', (op, 'd', 'b'), (op, 'd', 'c'))),
521 ]
522
523 # This section contains "late" optimizations that should be run after the
524 # regular optimizations have finished. Optimizations should go here if
525 # they help code generation but do not necessarily produce code that is
526 # more easily optimizable.
527 late_optimizations = [
528 # Most of these optimizations aren't quite safe when you get infinity or
529 # Nan involved but the first one should be fine.
530 (('flt', ('fadd', a, b), 0.0), ('flt', a, ('fneg', b))),
531 (('~fge', ('fadd', a, b), 0.0), ('fge', a, ('fneg', b))),
532 (('~feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
533 (('~fne', ('fadd', a, b), 0.0), ('fne', a, ('fneg', b))),
534
535 (('fdot2', a, b), ('fdot_replicated2', a, b), 'options->fdot_replicates'),
536 (('fdot3', a, b), ('fdot_replicated3', a, b), 'options->fdot_replicates'),
537 (('fdot4', a, b), ('fdot_replicated4', a, b), 'options->fdot_replicates'),
538 (('fdph', a, b), ('fdph_replicated', a, b), 'options->fdot_replicates'),
539
540 (('b2f(is_used_more_than_once)', ('inot', a)), ('bcsel', a, 0.0, 1.0)),
541 (('fneg(is_used_more_than_once)', ('b2f', ('inot', a))), ('bcsel', a, -0.0, -1.0)),
542
543 # we do these late so that we don't get in the way of creating ffmas
544 (('fmin', ('fadd(is_used_once)', '#c', a), ('fadd(is_used_once)', '#c', b)), ('fadd', c, ('fmin', a, b))),
545 (('fmax', ('fadd(is_used_once)', '#c', a), ('fadd(is_used_once)', '#c', b)), ('fadd', c, ('fmax', a, b))),
546 ]
547
548 print nir_algebraic.AlgebraicPass("nir_opt_algebraic", optimizations).render()
549 print nir_algebraic.AlgebraicPass("nir_opt_algebraic_late",
550 late_optimizations).render()