nir/algebraic: Optimize common array indexing sequence
[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][(cond)]" where "#" inicates
49 # that 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, and (cond) specifies an additional condition function
52 # (see nir_search_helpers.h).
53 #
54 # For constants, you have to be careful to make sure that it is the right
55 # type because python is unaware of the source and destination types of the
56 # opcodes.
57 #
58 # All expression types can have a bit-size specified. For opcodes, this
59 # looks like "op@32", for variables it is "a@32" or "a@uint32" to specify a
60 # type and size, and for literals, you can write "2.0@32". In the search half
61 # of the expression this indicates that it should only match that particular
62 # bit-size. In the replace half of the expression this indicates that the
63 # constructed value should have that bit-size.
64
65 optimizations = [
66
67 (('imul', a, '#b@32(is_pos_power_of_two)'), ('ishl', a, ('find_lsb', b))),
68 (('imul', a, '#b@32(is_neg_power_of_two)'), ('ineg', ('ishl', a, ('find_lsb', ('iabs', b))))),
69 (('udiv', a, '#b@32(is_pos_power_of_two)'), ('ushr', a, ('find_lsb', b))),
70 (('idiv', a, '#b@32(is_pos_power_of_two)'), ('imul', ('isign', a), ('ushr', ('iabs', a), ('find_lsb', b))), 'options->lower_idiv'),
71 (('idiv', a, '#b@32(is_neg_power_of_two)'), ('ineg', ('imul', ('isign', a), ('ushr', ('iabs', a), ('find_lsb', ('iabs', b))))), 'options->lower_idiv'),
72 (('umod', a, '#b(is_pos_power_of_two)'), ('iand', a, ('isub', b, 1))),
73
74 (('fneg', ('fneg', a)), a),
75 (('ineg', ('ineg', a)), a),
76 (('fabs', ('fabs', a)), ('fabs', a)),
77 (('fabs', ('fneg', a)), ('fabs', a)),
78 (('fabs', ('u2f', a)), ('u2f', a)),
79 (('iabs', ('iabs', a)), ('iabs', a)),
80 (('iabs', ('ineg', a)), ('iabs', a)),
81 (('~fadd', a, 0.0), a),
82 (('iadd', a, 0), a),
83 (('usadd_4x8', a, 0), a),
84 (('usadd_4x8', a, ~0), ~0),
85 (('~fadd', ('fmul', a, b), ('fmul', a, c)), ('fmul', a, ('fadd', b, c))),
86 (('iadd', ('imul', a, b), ('imul', a, c)), ('imul', a, ('iadd', b, c))),
87 (('~fadd', ('fneg', a), a), 0.0),
88 (('iadd', ('ineg', a), a), 0),
89 (('iadd', ('ineg', a), ('iadd', a, b)), b),
90 (('iadd', a, ('iadd', ('ineg', a), b)), b),
91 (('~fadd', ('fneg', a), ('fadd', a, b)), b),
92 (('~fadd', a, ('fadd', ('fneg', a), b)), b),
93 (('~fmul', a, 0.0), 0.0),
94 (('imul', a, 0), 0),
95 (('umul_unorm_4x8', a, 0), 0),
96 (('umul_unorm_4x8', a, ~0), a),
97 (('fmul', a, 1.0), a),
98 (('imul', a, 1), a),
99 (('fmul', a, -1.0), ('fneg', a)),
100 (('imul', a, -1), ('ineg', a)),
101 (('~ffma', 0.0, a, b), b),
102 (('~ffma', a, 0.0, b), b),
103 (('~ffma', a, b, 0.0), ('fmul', a, b)),
104 (('ffma', a, 1.0, b), ('fadd', a, b)),
105 (('ffma', 1.0, a, b), ('fadd', a, b)),
106 (('~flrp', a, b, 0.0), a),
107 (('~flrp', a, b, 1.0), b),
108 (('~flrp', a, a, b), a),
109 (('~flrp', 0.0, a, b), ('fmul', a, b)),
110 (('~flrp', a, b, ('b2f', c)), ('bcsel', c, b, a), 'options->lower_flrp32'),
111 (('flrp@32', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp32'),
112 (('flrp@64', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp64'),
113 (('ffract', a), ('fsub', a, ('ffloor', a)), 'options->lower_ffract'),
114 (('~fadd', ('fmul', a, ('fadd', 1.0, ('fneg', ('b2f', c)))), ('fmul', b, ('b2f', c))), ('bcsel', c, b, a), 'options->lower_flrp32'),
115 (('~fadd@32', ('fmul', a, ('fadd', 1.0, ('fneg', c ))), ('fmul', b, c )), ('flrp', a, b, c), '!options->lower_flrp32'),
116 (('~fadd@64', ('fmul', a, ('fadd', 1.0, ('fneg', c ))), ('fmul', b, c )), ('flrp', a, b, c), '!options->lower_flrp64'),
117 (('~fadd', a, ('fmul', ('b2f', c), ('fadd', b, ('fneg', a)))), ('bcsel', c, b, a), 'options->lower_flrp32'),
118 (('~fadd@32', a, ('fmul', c , ('fadd', b, ('fneg', a)))), ('flrp', a, b, c), '!options->lower_flrp32'),
119 (('~fadd@64', a, ('fmul', c , ('fadd', b, ('fneg', a)))), ('flrp', a, b, c), '!options->lower_flrp64'),
120 (('ffma', a, b, c), ('fadd', ('fmul', a, b), c), 'options->lower_ffma'),
121 (('~fadd', ('fmul', a, b), c), ('ffma', a, b, c), 'options->fuse_ffma'),
122
123 # (a * #b + #c) << #d
124 # ((a * #b) << #d) + (#c << #d)
125 # (a * (#b << #d)) + (#c << #d)
126 (('ishl', ('iadd', ('imul', a, '#b'), '#c'), '#d'),
127 ('iadd', ('imul', a, ('ishl', b, d)), ('ishl', c, d))),
128
129 # (a * #b) << #c
130 # a * (#b << #c)
131 (('ishl', ('imul', a, '#b'), '#c'), ('imul', a, ('ishl', b, c))),
132
133 # Comparison simplifications
134 (('~inot', ('flt', a, b)), ('fge', a, b)),
135 (('~inot', ('fge', a, b)), ('flt', a, b)),
136 (('~inot', ('feq', a, b)), ('fne', a, b)),
137 (('~inot', ('fne', a, b)), ('feq', a, b)),
138 (('inot', ('ilt', a, b)), ('ige', a, b)),
139 (('inot', ('ige', a, b)), ('ilt', a, b)),
140 (('inot', ('ieq', a, b)), ('ine', a, b)),
141 (('inot', ('ine', a, b)), ('ieq', a, b)),
142
143 # 0.0 >= b2f(a)
144 # b2f(a) <= 0.0
145 # b2f(a) == 0.0 because b2f(a) can only be 0 or 1
146 # inot(a)
147 (('fge', 0.0, ('b2f', a)), ('inot', a)),
148
149 # 0.0 < fabs(a)
150 # fabs(a) > 0.0
151 # fabs(a) != 0.0 because fabs(a) must be >= 0
152 # a != 0.0
153 (('flt', 0.0, ('fabs', a)), ('fne', a, 0.0)),
154
155 (('fge', ('fneg', ('fabs', a)), 0.0), ('feq', a, 0.0)),
156 (('bcsel', ('flt', b, a), b, a), ('fmin', a, b)),
157 (('bcsel', ('flt', a, b), b, a), ('fmax', a, b)),
158 (('bcsel', ('inot', 'a@bool'), b, c), ('bcsel', a, c, b)),
159 (('bcsel', a, ('bcsel', a, b, c), d), ('bcsel', a, b, d)),
160 (('bcsel', a, True, 'b@bool'), ('ior', a, b)),
161 (('fmin', a, a), a),
162 (('fmax', a, a), a),
163 (('imin', a, a), a),
164 (('imax', a, a), a),
165 (('umin', a, a), a),
166 (('umax', a, a), a),
167 (('~fmin', ('fmax', a, 0.0), 1.0), ('fsat', a), '!options->lower_fsat'),
168 (('~fmax', ('fmin', a, 1.0), 0.0), ('fsat', a), '!options->lower_fsat'),
169 (('fsat', a), ('fmin', ('fmax', a, 0.0), 1.0), 'options->lower_fsat'),
170 (('fsat', ('fsat', a)), ('fsat', a)),
171 (('fmin', ('fmax', ('fmin', ('fmax', a, b), c), b), c), ('fmin', ('fmax', a, b), c)),
172 (('imin', ('imax', ('imin', ('imax', a, b), c), b), c), ('imin', ('imax', a, b), c)),
173 (('umin', ('umax', ('umin', ('umax', a, b), c), b), c), ('umin', ('umax', a, b), c)),
174 (('extract_u8', ('imin', ('imax', a, 0), 0xff), 0), ('imin', ('imax', a, 0), 0xff)),
175 (('~ior', ('flt', a, b), ('flt', a, c)), ('flt', a, ('fmax', b, c))),
176 (('~ior', ('flt', a, c), ('flt', b, c)), ('flt', ('fmin', a, b), c)),
177 (('~ior', ('fge', a, b), ('fge', a, c)), ('fge', a, ('fmin', b, c))),
178 (('~ior', ('fge', a, c), ('fge', b, c)), ('fge', ('fmax', a, b), c)),
179 (('fabs', ('slt', a, b)), ('slt', a, b)),
180 (('fabs', ('sge', a, b)), ('sge', a, b)),
181 (('fabs', ('seq', a, b)), ('seq', a, b)),
182 (('fabs', ('sne', a, b)), ('sne', a, b)),
183 (('slt', a, b), ('b2f', ('flt', a, b)), 'options->lower_scmp'),
184 (('sge', a, b), ('b2f', ('fge', a, b)), 'options->lower_scmp'),
185 (('seq', a, b), ('b2f', ('feq', a, b)), 'options->lower_scmp'),
186 (('sne', a, b), ('b2f', ('fne', a, b)), 'options->lower_scmp'),
187 (('fne', ('fneg', a), a), ('fne', a, 0.0)),
188 (('feq', ('fneg', a), a), ('feq', a, 0.0)),
189 # Emulating booleans
190 (('imul', ('b2i', a), ('b2i', b)), ('b2i', ('iand', a, b))),
191 (('fmul', ('b2f', a), ('b2f', b)), ('b2f', ('iand', a, b))),
192 (('fsat', ('fadd', ('b2f', a), ('b2f', b))), ('b2f', ('ior', a, b))),
193 (('iand', 'a@bool', 1.0), ('b2f', a)),
194 (('flt', ('fneg', ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
195 (('flt', ('fsub', 0.0, ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
196 # Comparison with the same args. Note that these are not done for
197 # the float versions because NaN always returns false on float
198 # inequalities.
199 (('ilt', a, a), False),
200 (('ige', a, a), True),
201 (('ieq', a, a), True),
202 (('ine', a, a), False),
203 (('ult', a, a), False),
204 (('uge', a, a), True),
205 # Logical and bit operations
206 (('fand', a, 0.0), 0.0),
207 (('iand', a, a), a),
208 (('iand', a, ~0), a),
209 (('iand', a, 0), 0),
210 (('ior', a, a), a),
211 (('ior', a, 0), a),
212 (('ior', a, True), True),
213 (('fxor', a, a), 0.0),
214 (('ixor', a, a), 0),
215 (('ixor', a, 0), a),
216 (('inot', ('inot', a)), a),
217 # DeMorgan's Laws
218 (('iand', ('inot', a), ('inot', b)), ('inot', ('ior', a, b))),
219 (('ior', ('inot', a), ('inot', b)), ('inot', ('iand', a, b))),
220 # Shift optimizations
221 (('ishl', 0, a), 0),
222 (('ishl', a, 0), a),
223 (('ishr', 0, a), 0),
224 (('ishr', a, 0), a),
225 (('ushr', 0, a), 0),
226 (('ushr', a, 0), a),
227 (('iand', 0xff, ('ushr', a, 24)), ('ushr', a, 24)),
228 (('iand', 0xffff, ('ushr', a, 16)), ('ushr', a, 16)),
229 # Exponential/logarithmic identities
230 (('~fexp2', ('flog2', a)), a), # 2^lg2(a) = a
231 (('~flog2', ('fexp2', a)), a), # lg2(2^a) = a
232 (('fpow', a, b), ('fexp2', ('fmul', ('flog2', a), b)), 'options->lower_fpow'), # a^b = 2^(lg2(a)*b)
233 (('~fexp2', ('fmul', ('flog2', a), b)), ('fpow', a, b), '!options->lower_fpow'), # 2^(lg2(a)*b) = a^b
234 (('~fexp2', ('fadd', ('fmul', ('flog2', a), b), ('fmul', ('flog2', c), d))),
235 ('~fmul', ('fpow', a, b), ('fpow', c, d)), '!options->lower_fpow'), # 2^(lg2(a) * b + lg2(c) + d) = a^b * c^d
236 (('~fpow', a, 1.0), a),
237 (('~fpow', a, 2.0), ('fmul', a, a)),
238 (('~fpow', a, 4.0), ('fmul', ('fmul', a, a), ('fmul', a, a))),
239 (('~fpow', 2.0, a), ('fexp2', a)),
240 (('~fpow', ('fpow', a, 2.2), 0.454545), a),
241 (('~fpow', ('fabs', ('fpow', a, 2.2)), 0.454545), ('fabs', a)),
242 (('~fsqrt', ('fexp2', a)), ('fexp2', ('fmul', 0.5, a))),
243 (('~frcp', ('fexp2', a)), ('fexp2', ('fneg', a))),
244 (('~frsq', ('fexp2', a)), ('fexp2', ('fmul', -0.5, a))),
245 (('~flog2', ('fsqrt', a)), ('fmul', 0.5, ('flog2', a))),
246 (('~flog2', ('frcp', a)), ('fneg', ('flog2', a))),
247 (('~flog2', ('frsq', a)), ('fmul', -0.5, ('flog2', a))),
248 (('~flog2', ('fpow', a, b)), ('fmul', b, ('flog2', a))),
249 (('~fmul', ('fexp2', a), ('fexp2', b)), ('fexp2', ('fadd', a, b))),
250 # Division and reciprocal
251 (('~fdiv', 1.0, a), ('frcp', a)),
252 (('fdiv', a, b), ('fmul', a, ('frcp', b)), 'options->lower_fdiv'),
253 (('~frcp', ('frcp', a)), a),
254 (('~frcp', ('fsqrt', a)), ('frsq', a)),
255 (('fsqrt', a), ('frcp', ('frsq', a)), 'options->lower_fsqrt'),
256 (('~frcp', ('frsq', a)), ('fsqrt', a), '!options->lower_fsqrt'),
257 # Boolean simplifications
258 (('ieq', 'a@bool', True), a),
259 (('ine', 'a@bool', True), ('inot', a)),
260 (('ine', 'a@bool', False), a),
261 (('ieq', 'a@bool', False), ('inot', 'a')),
262 (('bcsel', a, True, False), ('ine', a, 0)),
263 (('bcsel', a, False, True), ('ieq', a, 0)),
264 (('bcsel', True, b, c), b),
265 (('bcsel', False, b, c), c),
266 # The result of this should be hit by constant propagation and, in the
267 # next round of opt_algebraic, get picked up by one of the above two.
268 (('bcsel', '#a', b, c), ('bcsel', ('ine', 'a', 0), b, c)),
269
270 (('bcsel', a, b, b), b),
271 (('fcsel', a, b, b), b),
272
273 # Conversions
274 (('i2b', ('b2i', a)), a),
275 (('f2i', ('ftrunc', a)), ('f2i', a)),
276 (('f2u', ('ftrunc', a)), ('f2u', a)),
277 (('i2b', ('ineg', a)), ('i2b', a)),
278 (('i2b', ('iabs', a)), ('i2b', a)),
279 (('fabs', ('b2f', a)), ('b2f', a)),
280 (('iabs', ('b2i', a)), ('b2i', a)),
281
282 # Byte extraction
283 (('ushr', a, 24), ('extract_u8', a, 3), '!options->lower_extract_byte'),
284 (('iand', 0xff, ('ushr', a, 16)), ('extract_u8', a, 2), '!options->lower_extract_byte'),
285 (('iand', 0xff, ('ushr', a, 8)), ('extract_u8', a, 1), '!options->lower_extract_byte'),
286 (('iand', 0xff, a), ('extract_u8', a, 0), '!options->lower_extract_byte'),
287
288 # Word extraction
289 (('ushr', a, 16), ('extract_u16', a, 1), '!options->lower_extract_word'),
290 (('iand', 0xffff, a), ('extract_u16', a, 0), '!options->lower_extract_word'),
291
292 # Subtracts
293 (('~fsub', a, ('fsub', 0.0, b)), ('fadd', a, b)),
294 (('isub', a, ('isub', 0, b)), ('iadd', a, b)),
295 (('ussub_4x8', a, 0), a),
296 (('ussub_4x8', a, ~0), 0),
297 (('fsub', a, b), ('fadd', a, ('fneg', b)), 'options->lower_sub'),
298 (('isub', a, b), ('iadd', a, ('ineg', b)), 'options->lower_sub'),
299 (('fneg', a), ('fsub', 0.0, a), 'options->lower_negate'),
300 (('ineg', a), ('isub', 0, a), 'options->lower_negate'),
301 (('~fadd', a, ('fsub', 0.0, b)), ('fsub', a, b)),
302 (('iadd', a, ('isub', 0, b)), ('isub', a, b)),
303 (('fabs', ('fsub', 0.0, a)), ('fabs', a)),
304 (('iabs', ('isub', 0, a)), ('iabs', a)),
305
306 # Propagate negation up multiplication chains
307 (('fmul', ('fneg', a), b), ('fneg', ('fmul', a, b))),
308 (('imul', ('ineg', a), b), ('ineg', ('imul', a, b))),
309
310 # Reassociate constants in add/mul chains so they can be folded together.
311 # For now, we only handle cases where the constants are separated by
312 # a single non-constant. We could do better eventually.
313 (('~fmul', '#a', ('fmul', b, '#c')), ('fmul', ('fmul', a, c), b)),
314 (('imul', '#a', ('imul', b, '#c')), ('imul', ('imul', a, c), b)),
315 (('~fadd', '#a', ('fadd', b, '#c')), ('fadd', ('fadd', a, c), b)),
316 (('iadd', '#a', ('iadd', b, '#c')), ('iadd', ('iadd', a, c), b)),
317
318 # Misc. lowering
319 (('fmod@32', a, b), ('fsub', a, ('fmul', b, ('ffloor', ('fdiv', a, b)))), 'options->lower_fmod32'),
320 (('fmod@64', a, b), ('fsub', a, ('fmul', b, ('ffloor', ('fdiv', a, b)))), 'options->lower_fmod64'),
321 (('frem', a, b), ('fsub', a, ('fmul', b, ('ftrunc', ('fdiv', a, b)))), 'options->lower_fmod32'),
322 (('uadd_carry@32', a, b), ('b2i', ('ult', ('iadd', a, b), a)), 'options->lower_uadd_carry'),
323 (('usub_borrow@32', a, b), ('b2i', ('ult', a, b)), 'options->lower_usub_borrow'),
324
325 (('bitfield_insert', 'base', 'insert', 'offset', 'bits'),
326 ('bcsel', ('ilt', 31, 'bits'), 'insert',
327 ('bfi', ('bfm', 'bits', 'offset'), 'insert', 'base')),
328 'options->lower_bitfield_insert'),
329
330 (('ibitfield_extract', 'value', 'offset', 'bits'),
331 ('bcsel', ('ilt', 31, 'bits'), 'value',
332 ('ibfe', 'value', 'offset', 'bits')),
333 'options->lower_bitfield_extract'),
334
335 (('ubitfield_extract', 'value', 'offset', 'bits'),
336 ('bcsel', ('ult', 31, 'bits'), 'value',
337 ('ubfe', 'value', 'offset', 'bits')),
338 'options->lower_bitfield_extract'),
339
340 (('extract_i8', a, b),
341 ('ishr', ('ishl', a, ('imul', ('isub', 3, b), 8)), 24),
342 'options->lower_extract_byte'),
343
344 (('extract_u8', a, b),
345 ('iand', ('ushr', a, ('imul', b, 8)), 0xff),
346 'options->lower_extract_byte'),
347
348 (('extract_i16', a, b),
349 ('ishr', ('ishl', a, ('imul', ('isub', 1, b), 16)), 16),
350 'options->lower_extract_word'),
351
352 (('extract_u16', a, b),
353 ('iand', ('ushr', a, ('imul', b, 16)), 0xffff),
354 'options->lower_extract_word'),
355
356 (('pack_unorm_2x16', 'v'),
357 ('pack_uvec2_to_uint',
358 ('f2u', ('fround_even', ('fmul', ('fsat', 'v'), 65535.0)))),
359 'options->lower_pack_unorm_2x16'),
360
361 (('pack_unorm_4x8', 'v'),
362 ('pack_uvec4_to_uint',
363 ('f2u', ('fround_even', ('fmul', ('fsat', 'v'), 255.0)))),
364 'options->lower_pack_unorm_4x8'),
365
366 (('pack_snorm_2x16', 'v'),
367 ('pack_uvec2_to_uint',
368 ('f2i', ('fround_even', ('fmul', ('fmin', 1.0, ('fmax', -1.0, 'v')), 32767.0)))),
369 'options->lower_pack_snorm_2x16'),
370
371 (('pack_snorm_4x8', 'v'),
372 ('pack_uvec4_to_uint',
373 ('f2i', ('fround_even', ('fmul', ('fmin', 1.0, ('fmax', -1.0, 'v')), 127.0)))),
374 'options->lower_pack_snorm_4x8'),
375
376 (('unpack_unorm_2x16', 'v'),
377 ('fdiv', ('u2f', ('vec2', ('extract_u16', 'v', 0),
378 ('extract_u16', 'v', 1))),
379 65535.0),
380 'options->lower_unpack_unorm_2x16'),
381
382 (('unpack_unorm_4x8', 'v'),
383 ('fdiv', ('u2f', ('vec4', ('extract_u8', 'v', 0),
384 ('extract_u8', 'v', 1),
385 ('extract_u8', 'v', 2),
386 ('extract_u8', 'v', 3))),
387 255.0),
388 'options->lower_unpack_unorm_4x8'),
389
390 (('unpack_snorm_2x16', 'v'),
391 ('fmin', 1.0, ('fmax', -1.0, ('fdiv', ('i2f', ('vec2', ('extract_i16', 'v', 0),
392 ('extract_i16', 'v', 1))),
393 32767.0))),
394 'options->lower_unpack_snorm_2x16'),
395
396 (('unpack_snorm_4x8', 'v'),
397 ('fmin', 1.0, ('fmax', -1.0, ('fdiv', ('i2f', ('vec4', ('extract_i8', 'v', 0),
398 ('extract_i8', 'v', 1),
399 ('extract_i8', 'v', 2),
400 ('extract_i8', 'v', 3))),
401 127.0))),
402 'options->lower_unpack_snorm_4x8'),
403 ]
404
405 def fexp2i(exp, bits):
406 # We assume that exp is already in the right range.
407 if bits == 32:
408 return ('ishl', ('iadd', exp, 127), 23)
409 elif bits == 64:
410 return ('pack_double_2x32_split', 0, ('ishl', ('iadd', exp, 1023), 20))
411 else:
412 assert False
413
414 def ldexp(f, exp, bits):
415 # First, we clamp exp to a reasonable range. The maximum possible range
416 # for a normal exponent is [-126, 127] and, throwing in denormals, you get
417 # a maximum range of [-149, 127]. This means that we can potentially have
418 # a swing of +-276. If you start with FLT_MAX, you actually have to do
419 # ldexp(FLT_MAX, -278) to get it to flush all the way to zero. The GLSL
420 # spec, on the other hand, only requires that we handle an exponent value
421 # in the range [-126, 128]. This implementation is *mostly* correct; it
422 # handles a range on exp of [-252, 254] which allows you to create any
423 # value (including denorms if the hardware supports it) and to adjust the
424 # exponent of any normal value to anything you want.
425 if bits == 32:
426 exp = ('imin', ('imax', exp, -252), 254)
427 elif bits == 64:
428 exp = ('imin', ('imax', exp, -2044), 2046)
429 else:
430 assert False
431
432 # Now we compute two powers of 2, one for exp/2 and one for exp-exp/2.
433 # (We use ishr which isn't the same for -1, but the -1 case still works
434 # since we use exp-exp/2 as the second exponent.) While the spec
435 # technically defines ldexp as f * 2.0^exp, simply multiplying once doesn't
436 # work with denormals and doesn't allow for the full swing in exponents
437 # that you can get with normalized values. Instead, we create two powers
438 # of two and multiply by them each in turn. That way the effective range
439 # of our exponent is doubled.
440 pow2_1 = fexp2i(('ishr', exp, 1), bits)
441 pow2_2 = fexp2i(('isub', exp, ('ishr', exp, 1)), bits)
442 return ('fmul', ('fmul', f, pow2_1), pow2_2)
443
444 optimizations += [
445 (('ldexp@32', 'x', 'exp'), ldexp('x', 'exp', 32)),
446 (('ldexp@64', 'x', 'exp'), ldexp('x', 'exp', 64)),
447 ]
448
449 # Unreal Engine 4 demo applications open-codes bitfieldReverse()
450 def bitfield_reverse(u):
451 step1 = ('ior', ('ishl', u, 16), ('ushr', u, 16))
452 step2 = ('ior', ('ishl', ('iand', step1, 0x00ff00ff), 8), ('ushr', ('iand', step1, 0xff00ff00), 8))
453 step3 = ('ior', ('ishl', ('iand', step2, 0x0f0f0f0f), 4), ('ushr', ('iand', step2, 0xf0f0f0f0), 4))
454 step4 = ('ior', ('ishl', ('iand', step3, 0x33333333), 2), ('ushr', ('iand', step3, 0xcccccccc), 2))
455 step5 = ('ior', ('ishl', ('iand', step4, 0x55555555), 1), ('ushr', ('iand', step4, 0xaaaaaaaa), 1))
456
457 return step5
458
459 optimizations += [(bitfield_reverse('x@32'), ('bitfield_reverse', 'x'))]
460
461
462 # Add optimizations to handle the case where the result of a ternary is
463 # compared to a constant. This way we can take things like
464 #
465 # (a ? 0 : 1) > 0
466 #
467 # and turn it into
468 #
469 # a ? (0 > 0) : (1 > 0)
470 #
471 # which constant folding will eat for lunch. The resulting ternary will
472 # further get cleaned up by the boolean reductions above and we will be
473 # left with just the original variable "a".
474 for op in ['flt', 'fge', 'feq', 'fne',
475 'ilt', 'ige', 'ieq', 'ine', 'ult', 'uge']:
476 optimizations += [
477 ((op, ('bcsel', 'a', '#b', '#c'), '#d'),
478 ('bcsel', 'a', (op, 'b', 'd'), (op, 'c', 'd'))),
479 ((op, '#d', ('bcsel', a, '#b', '#c')),
480 ('bcsel', 'a', (op, 'd', 'b'), (op, 'd', 'c'))),
481 ]
482
483 # This section contains "late" optimizations that should be run after the
484 # regular optimizations have finished. Optimizations should go here if
485 # they help code generation but do not necessarily produce code that is
486 # more easily optimizable.
487 late_optimizations = [
488 # Most of these optimizations aren't quite safe when you get infinity or
489 # Nan involved but the first one should be fine.
490 (('flt', ('fadd', a, b), 0.0), ('flt', a, ('fneg', b))),
491 (('~fge', ('fadd', a, b), 0.0), ('fge', a, ('fneg', b))),
492 (('~feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
493 (('~fne', ('fadd', a, b), 0.0), ('fne', a, ('fneg', b))),
494
495 (('fdot2', a, b), ('fdot_replicated2', a, b), 'options->fdot_replicates'),
496 (('fdot3', a, b), ('fdot_replicated3', a, b), 'options->fdot_replicates'),
497 (('fdot4', a, b), ('fdot_replicated4', a, b), 'options->fdot_replicates'),
498 (('fdph', a, b), ('fdph_replicated', a, b), 'options->fdot_replicates'),
499 ]
500
501 print nir_algebraic.AlgebraicPass("nir_opt_algebraic", optimizations).render()
502 print nir_algebraic.AlgebraicPass("nir_opt_algebraic_late",
503 late_optimizations).render()