nir: See through an fneg to apply existing optimizations
[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
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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', ('u2f32', a)), ('u2f32', 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 # ignore this opt when the result is used by a bcsel or if so we can make
162 # use of conditional modifiers on supported hardware.
163 (('flt(is_not_used_by_conditional)', ('fadd(is_used_once)', a, ('fneg', b)), 0.0), ('flt', a, b)),
164
165 (('fge', ('fneg', ('fabs', a)), 0.0), ('feq', a, 0.0)),
166 (('bcsel', ('flt', b, a), b, a), ('fmin', a, b)),
167 (('bcsel', ('flt', a, b), b, a), ('fmax', a, b)),
168 (('bcsel', ('inot', a), b, c), ('bcsel', a, c, b)),
169 (('bcsel', a, ('bcsel', a, b, c), d), ('bcsel', a, b, d)),
170 (('bcsel', a, True, 'b@bool'), ('ior', a, b)),
171 (('fmin', a, a), a),
172 (('fmax', a, a), a),
173 (('imin', a, a), a),
174 (('imax', a, a), a),
175 (('umin', a, a), a),
176 (('umax', a, a), a),
177 (('fmin', a, ('fneg', a)), ('fneg', ('fabs', a))),
178 (('imin', a, ('ineg', a)), ('ineg', ('iabs', a))),
179 (('fmin', a, ('fneg', ('fabs', a))), ('fneg', ('fabs', a))),
180 (('imin', a, ('ineg', ('iabs', a))), ('ineg', ('iabs', a))),
181 (('fmin', a, ('fabs', a)), a),
182 (('imin', a, ('iabs', a)), a),
183 (('fmax', a, ('fneg', ('fabs', a))), a),
184 (('imax', a, ('ineg', ('iabs', a))), a),
185 (('fmax', a, ('fabs', a)), ('fabs', a)),
186 (('imax', a, ('iabs', a)), ('iabs', a)),
187 (('fmax', a, ('fneg', a)), ('fabs', a)),
188 (('imax', a, ('ineg', a)), ('iabs', a)),
189 (('~fmin', ('fmax', a, 0.0), 1.0), ('fsat', a), '!options->lower_fsat'),
190 (('~fmax', ('fmin', a, 1.0), 0.0), ('fsat', a), '!options->lower_fsat'),
191 (('fsat', a), ('fmin', ('fmax', a, 0.0), 1.0), 'options->lower_fsat'),
192 (('fsat', ('fsat', a)), ('fsat', a)),
193 (('fmin', ('fmax', ('fmin', ('fmax', a, b), c), b), c), ('fmin', ('fmax', a, b), c)),
194 (('imin', ('imax', ('imin', ('imax', a, b), c), b), c), ('imin', ('imax', a, b), c)),
195 (('umin', ('umax', ('umin', ('umax', a, b), c), b), c), ('umin', ('umax', a, b), c)),
196 (('fmax', ('fsat', a), '#b@32(is_zero_to_one)'), ('fsat', ('fmax', a, b))),
197 (('fmin', ('fsat', a), '#b@32(is_zero_to_one)'), ('fsat', ('fmin', a, b))),
198 (('extract_u8', ('imin', ('imax', a, 0), 0xff), 0), ('imin', ('imax', a, 0), 0xff)),
199 (('~ior', ('flt', a, b), ('flt', a, c)), ('flt', a, ('fmax', b, c))),
200 (('~ior', ('flt', a, c), ('flt', b, c)), ('flt', ('fmin', a, b), c)),
201 (('~ior', ('fge', a, b), ('fge', a, c)), ('fge', a, ('fmin', b, c))),
202 (('~ior', ('fge', a, c), ('fge', b, c)), ('fge', ('fmax', a, b), c)),
203 (('fabs', ('slt', a, b)), ('slt', a, b)),
204 (('fabs', ('sge', a, b)), ('sge', a, b)),
205 (('fabs', ('seq', a, b)), ('seq', a, b)),
206 (('fabs', ('sne', a, b)), ('sne', a, b)),
207 (('slt', a, b), ('b2f', ('flt', a, b)), 'options->lower_scmp'),
208 (('sge', a, b), ('b2f', ('fge', a, b)), 'options->lower_scmp'),
209 (('seq', a, b), ('b2f', ('feq', a, b)), 'options->lower_scmp'),
210 (('sne', a, b), ('b2f', ('fne', a, b)), 'options->lower_scmp'),
211 (('fne', ('fneg', a), a), ('fne', a, 0.0)),
212 (('feq', ('fneg', a), a), ('feq', a, 0.0)),
213 # Emulating booleans
214 (('imul', ('b2i', a), ('b2i', b)), ('b2i', ('iand', a, b))),
215 (('fmul', ('b2f', a), ('b2f', b)), ('b2f', ('iand', a, b))),
216 (('fsat', ('fadd', ('b2f', a), ('b2f', b))), ('b2f', ('ior', a, b))),
217 (('iand', 'a@bool', 1.0), ('b2f', a)),
218 # True/False are ~0 and 0 in NIR. b2i of True is 1, and -1 is ~0 (True).
219 (('ineg', ('b2i@32', a)), a),
220 (('flt', ('fneg', ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
221 (('flt', ('fsub', 0.0, ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
222 # Comparison with the same args. Note that these are not done for
223 # the float versions because NaN always returns false on float
224 # inequalities.
225 (('ilt', a, a), False),
226 (('ige', a, a), True),
227 (('ieq', a, a), True),
228 (('ine', a, a), False),
229 (('ult', a, a), False),
230 (('uge', a, a), True),
231 # Logical and bit operations
232 (('fand', a, 0.0), 0.0),
233 (('iand', a, a), a),
234 (('iand', a, ~0), a),
235 (('iand', a, 0), 0),
236 (('ior', a, a), a),
237 (('ior', a, 0), a),
238 (('ior', a, True), True),
239 (('fxor', a, a), 0.0),
240 (('ixor', a, a), 0),
241 (('ixor', a, 0), a),
242 (('inot', ('inot', a)), a),
243 # DeMorgan's Laws
244 (('iand', ('inot', a), ('inot', b)), ('inot', ('ior', a, b))),
245 (('ior', ('inot', a), ('inot', b)), ('inot', ('iand', a, b))),
246 # Shift optimizations
247 (('ishl', 0, a), 0),
248 (('ishl', a, 0), a),
249 (('ishr', 0, a), 0),
250 (('ishr', a, 0), a),
251 (('ushr', 0, a), 0),
252 (('ushr', a, 0), a),
253 (('iand', 0xff, ('ushr@32', a, 24)), ('ushr', a, 24)),
254 (('iand', 0xffff, ('ushr@32', a, 16)), ('ushr', a, 16)),
255 # Exponential/logarithmic identities
256 (('~fexp2', ('flog2', a)), a), # 2^lg2(a) = a
257 (('~flog2', ('fexp2', a)), a), # lg2(2^a) = a
258 (('fpow', a, b), ('fexp2', ('fmul', ('flog2', a), b)), 'options->lower_fpow'), # a^b = 2^(lg2(a)*b)
259 (('~fexp2', ('fmul', ('flog2', a), b)), ('fpow', a, b), '!options->lower_fpow'), # 2^(lg2(a)*b) = a^b
260 (('~fexp2', ('fadd', ('fmul', ('flog2', a), b), ('fmul', ('flog2', c), d))),
261 ('~fmul', ('fpow', a, b), ('fpow', c, d)), '!options->lower_fpow'), # 2^(lg2(a) * b + lg2(c) + d) = a^b * c^d
262 (('~fpow', a, 1.0), a),
263 (('~fpow', a, 2.0), ('fmul', a, a)),
264 (('~fpow', a, 4.0), ('fmul', ('fmul', a, a), ('fmul', a, a))),
265 (('~fpow', 2.0, a), ('fexp2', a)),
266 (('~fpow', ('fpow', a, 2.2), 0.454545), a),
267 (('~fpow', ('fabs', ('fpow', a, 2.2)), 0.454545), ('fabs', a)),
268 (('~fsqrt', ('fexp2', a)), ('fexp2', ('fmul', 0.5, a))),
269 (('~frcp', ('fexp2', a)), ('fexp2', ('fneg', a))),
270 (('~frsq', ('fexp2', a)), ('fexp2', ('fmul', -0.5, a))),
271 (('~flog2', ('fsqrt', a)), ('fmul', 0.5, ('flog2', a))),
272 (('~flog2', ('frcp', a)), ('fneg', ('flog2', a))),
273 (('~flog2', ('frsq', a)), ('fmul', -0.5, ('flog2', a))),
274 (('~flog2', ('fpow', a, b)), ('fmul', b, ('flog2', a))),
275 (('~fmul', ('fexp2', a), ('fexp2', b)), ('fexp2', ('fadd', a, b))),
276 # Division and reciprocal
277 (('~fdiv', 1.0, a), ('frcp', a)),
278 (('fdiv', a, b), ('fmul', a, ('frcp', b)), 'options->lower_fdiv'),
279 (('~frcp', ('frcp', a)), a),
280 (('~frcp', ('fsqrt', a)), ('frsq', a)),
281 (('fsqrt', a), ('frcp', ('frsq', a)), 'options->lower_fsqrt'),
282 (('~frcp', ('frsq', a)), ('fsqrt', a), '!options->lower_fsqrt'),
283 # Boolean simplifications
284 (('ieq', 'a@bool', True), a),
285 (('ine(is_not_used_by_if)', 'a@bool', True), ('inot', a)),
286 (('ine', 'a@bool', False), a),
287 (('ieq(is_not_used_by_if)', 'a@bool', False), ('inot', 'a')),
288 (('bcsel', a, True, False), a),
289 (('bcsel', a, False, True), ('inot', a)),
290 (('bcsel@32', a, 1.0, 0.0), ('b2f', a)),
291 (('bcsel@32', a, 0.0, 1.0), ('b2f', ('inot', a))),
292 (('bcsel@32', a, -1.0, -0.0), ('fneg', ('b2f', a))),
293 (('bcsel@32', a, -0.0, -1.0), ('fneg', ('b2f', ('inot', a)))),
294 (('bcsel', True, b, c), b),
295 (('bcsel', False, b, c), c),
296 # The result of this should be hit by constant propagation and, in the
297 # next round of opt_algebraic, get picked up by one of the above two.
298 (('bcsel', '#a', b, c), ('bcsel', ('ine', 'a', 0), b, c)),
299
300 (('bcsel', a, b, b), b),
301 (('fcsel', a, b, b), b),
302
303 # Conversions
304 (('i2b', ('b2i', a)), a),
305 (('f2i32', ('ftrunc', a)), ('f2i32', a)),
306 (('f2u32', ('ftrunc', a)), ('f2u32', a)),
307 (('i2b', ('ineg', a)), ('i2b', a)),
308 (('i2b', ('iabs', a)), ('i2b', a)),
309 (('fabs', ('b2f', a)), ('b2f', a)),
310 (('iabs', ('b2i', a)), ('b2i', a)),
311
312 # Packing and then unpacking does nothing
313 (('unpack_64_2x32_split_x', ('pack_64_2x32_split', a, b)), a),
314 (('unpack_64_2x32_split_y', ('pack_64_2x32_split', a, b)), b),
315 (('pack_64_2x32_split', ('unpack_64_2x32_split_x', a),
316 ('unpack_64_2x32_split_y', a)), a),
317
318 # Byte extraction
319 (('ushr', a, 24), ('extract_u8', a, 3), '!options->lower_extract_byte'),
320 (('iand', 0xff, ('ushr', a, 16)), ('extract_u8', a, 2), '!options->lower_extract_byte'),
321 (('iand', 0xff, ('ushr', a, 8)), ('extract_u8', a, 1), '!options->lower_extract_byte'),
322 (('iand', 0xff, a), ('extract_u8', a, 0), '!options->lower_extract_byte'),
323
324 # Word extraction
325 (('ushr', a, 16), ('extract_u16', a, 1), '!options->lower_extract_word'),
326 (('iand', 0xffff, a), ('extract_u16', a, 0), '!options->lower_extract_word'),
327
328 # Subtracts
329 (('~fsub', a, ('fsub', 0.0, b)), ('fadd', a, b)),
330 (('isub', a, ('isub', 0, b)), ('iadd', a, b)),
331 (('ussub_4x8', a, 0), a),
332 (('ussub_4x8', a, ~0), 0),
333 (('fsub', a, b), ('fadd', a, ('fneg', b)), 'options->lower_sub'),
334 (('isub', a, b), ('iadd', a, ('ineg', b)), 'options->lower_sub'),
335 (('fneg', a), ('fsub', 0.0, a), 'options->lower_negate'),
336 (('ineg', a), ('isub', 0, a), 'options->lower_negate'),
337 (('~fadd', a, ('fsub', 0.0, b)), ('fsub', a, b)),
338 (('iadd', a, ('isub', 0, b)), ('isub', a, b)),
339 (('fabs', ('fsub', 0.0, a)), ('fabs', a)),
340 (('iabs', ('isub', 0, a)), ('iabs', a)),
341
342 # Propagate negation up multiplication chains
343 (('fmul', ('fneg', a), b), ('fneg', ('fmul', a, b))),
344 (('imul', ('ineg', a), b), ('ineg', ('imul', a, b))),
345
346 # Propagate constants up multiplication chains
347 (('~fmul(is_used_once)', ('fmul(is_used_once)', 'a(is_not_const)', 'b(is_not_const)'), '#c'), ('fmul', ('fmul', a, c), b)),
348 (('imul(is_used_once)', ('imul(is_used_once)', 'a(is_not_const)', 'b(is_not_const)'), '#c'), ('imul', ('imul', a, c), b)),
349 (('~fadd(is_used_once)', ('fadd(is_used_once)', 'a(is_not_const)', 'b(is_not_const)'), '#c'), ('fadd', ('fadd', a, c), b)),
350 (('iadd(is_used_once)', ('iadd(is_used_once)', 'a(is_not_const)', 'b(is_not_const)'), '#c'), ('iadd', ('iadd', a, c), b)),
351
352 # Reassociate constants in add/mul chains so they can be folded together.
353 # For now, we mostly only handle cases where the constants are separated by
354 # a single non-constant. We could do better eventually.
355 (('~fmul', '#a', ('fmul', b, '#c')), ('fmul', ('fmul', a, c), b)),
356 (('imul', '#a', ('imul', b, '#c')), ('imul', ('imul', a, c), b)),
357 (('~fadd', '#a', ('fadd', b, '#c')), ('fadd', ('fadd', a, c), b)),
358 (('~fadd', '#a', ('fneg', ('fadd', b, '#c'))), ('fadd', ('fadd', a, ('fneg', c)), ('fneg', b))),
359 (('iadd', '#a', ('iadd', b, '#c')), ('iadd', ('iadd', a, c), b)),
360
361 # By definition...
362 (('bcsel', ('ige', ('find_lsb', a), 0), ('find_lsb', a), -1), ('find_lsb', a)),
363 (('bcsel', ('ige', ('ifind_msb', a), 0), ('ifind_msb', a), -1), ('ifind_msb', a)),
364 (('bcsel', ('ige', ('ufind_msb', a), 0), ('ufind_msb', a), -1), ('ufind_msb', a)),
365
366 (('bcsel', ('ine', a, 0), ('find_lsb', a), -1), ('find_lsb', a)),
367 (('bcsel', ('ine', a, 0), ('ifind_msb', a), -1), ('ifind_msb', a)),
368 (('bcsel', ('ine', a, 0), ('ufind_msb', a), -1), ('ufind_msb', a)),
369
370 (('bcsel', ('ine', a, -1), ('ifind_msb', a), -1), ('ifind_msb', a)),
371
372 # Misc. lowering
373 (('fmod@32', a, b), ('fsub', a, ('fmul', b, ('ffloor', ('fdiv', a, b)))), 'options->lower_fmod32'),
374 (('fmod@64', a, b), ('fsub', a, ('fmul', b, ('ffloor', ('fdiv', a, b)))), 'options->lower_fmod64'),
375 (('frem', a, b), ('fsub', a, ('fmul', b, ('ftrunc', ('fdiv', a, b)))), 'options->lower_fmod32'),
376 (('uadd_carry@32', a, b), ('b2i', ('ult', ('iadd', a, b), a)), 'options->lower_uadd_carry'),
377 (('usub_borrow@32', a, b), ('b2i', ('ult', a, b)), 'options->lower_usub_borrow'),
378
379 (('bitfield_insert', 'base', 'insert', 'offset', 'bits'),
380 ('bcsel', ('ilt', 31, 'bits'), 'insert',
381 ('bfi', ('bfm', 'bits', 'offset'), 'insert', 'base')),
382 'options->lower_bitfield_insert'),
383
384 (('ibitfield_extract', 'value', 'offset', 'bits'),
385 ('bcsel', ('ilt', 31, 'bits'), 'value',
386 ('ibfe', 'value', 'offset', 'bits')),
387 'options->lower_bitfield_extract'),
388
389 (('ubitfield_extract', 'value', 'offset', 'bits'),
390 ('bcsel', ('ult', 31, 'bits'), 'value',
391 ('ubfe', 'value', 'offset', 'bits')),
392 'options->lower_bitfield_extract'),
393
394 (('extract_i8', a, 'b@32'),
395 ('ishr', ('ishl', a, ('imul', ('isub', 3, b), 8)), 24),
396 'options->lower_extract_byte'),
397
398 (('extract_u8', a, 'b@32'),
399 ('iand', ('ushr', a, ('imul', b, 8)), 0xff),
400 'options->lower_extract_byte'),
401
402 (('extract_i16', a, 'b@32'),
403 ('ishr', ('ishl', a, ('imul', ('isub', 1, b), 16)), 16),
404 'options->lower_extract_word'),
405
406 (('extract_u16', a, 'b@32'),
407 ('iand', ('ushr', a, ('imul', b, 16)), 0xffff),
408 'options->lower_extract_word'),
409
410 (('pack_unorm_2x16', 'v'),
411 ('pack_uvec2_to_uint',
412 ('f2u32', ('fround_even', ('fmul', ('fsat', 'v'), 65535.0)))),
413 'options->lower_pack_unorm_2x16'),
414
415 (('pack_unorm_4x8', 'v'),
416 ('pack_uvec4_to_uint',
417 ('f2u32', ('fround_even', ('fmul', ('fsat', 'v'), 255.0)))),
418 'options->lower_pack_unorm_4x8'),
419
420 (('pack_snorm_2x16', 'v'),
421 ('pack_uvec2_to_uint',
422 ('f2i32', ('fround_even', ('fmul', ('fmin', 1.0, ('fmax', -1.0, 'v')), 32767.0)))),
423 'options->lower_pack_snorm_2x16'),
424
425 (('pack_snorm_4x8', 'v'),
426 ('pack_uvec4_to_uint',
427 ('f2i32', ('fround_even', ('fmul', ('fmin', 1.0, ('fmax', -1.0, 'v')), 127.0)))),
428 'options->lower_pack_snorm_4x8'),
429
430 (('unpack_unorm_2x16', 'v'),
431 ('fdiv', ('u2f32', ('vec2', ('extract_u16', 'v', 0),
432 ('extract_u16', 'v', 1))),
433 65535.0),
434 'options->lower_unpack_unorm_2x16'),
435
436 (('unpack_unorm_4x8', 'v'),
437 ('fdiv', ('u2f32', ('vec4', ('extract_u8', 'v', 0),
438 ('extract_u8', 'v', 1),
439 ('extract_u8', 'v', 2),
440 ('extract_u8', 'v', 3))),
441 255.0),
442 'options->lower_unpack_unorm_4x8'),
443
444 (('unpack_snorm_2x16', 'v'),
445 ('fmin', 1.0, ('fmax', -1.0, ('fdiv', ('i2f32', ('vec2', ('extract_i16', 'v', 0),
446 ('extract_i16', 'v', 1))),
447 32767.0))),
448 'options->lower_unpack_snorm_2x16'),
449
450 (('unpack_snorm_4x8', 'v'),
451 ('fmin', 1.0, ('fmax', -1.0, ('fdiv', ('i2f32', ('vec4', ('extract_i8', 'v', 0),
452 ('extract_i8', 'v', 1),
453 ('extract_i8', 'v', 2),
454 ('extract_i8', 'v', 3))),
455 127.0))),
456 'options->lower_unpack_snorm_4x8'),
457 ]
458
459 def fexp2i(exp, bits):
460 # We assume that exp is already in the right range.
461 if bits == 32:
462 return ('ishl', ('iadd', exp, 127), 23)
463 elif bits == 64:
464 return ('pack_64_2x32_split', 0, ('ishl', ('iadd', exp, 1023), 20))
465 else:
466 assert False
467
468 def ldexp(f, exp, bits):
469 # First, we clamp exp to a reasonable range. The maximum possible range
470 # for a normal exponent is [-126, 127] and, throwing in denormals, you get
471 # a maximum range of [-149, 127]. This means that we can potentially have
472 # a swing of +-276. If you start with FLT_MAX, you actually have to do
473 # ldexp(FLT_MAX, -278) to get it to flush all the way to zero. The GLSL
474 # spec, on the other hand, only requires that we handle an exponent value
475 # in the range [-126, 128]. This implementation is *mostly* correct; it
476 # handles a range on exp of [-252, 254] which allows you to create any
477 # value (including denorms if the hardware supports it) and to adjust the
478 # exponent of any normal value to anything you want.
479 if bits == 32:
480 exp = ('imin', ('imax', exp, -252), 254)
481 elif bits == 64:
482 exp = ('imin', ('imax', exp, -2044), 2046)
483 else:
484 assert False
485
486 # Now we compute two powers of 2, one for exp/2 and one for exp-exp/2.
487 # (We use ishr which isn't the same for -1, but the -1 case still works
488 # since we use exp-exp/2 as the second exponent.) While the spec
489 # technically defines ldexp as f * 2.0^exp, simply multiplying once doesn't
490 # work with denormals and doesn't allow for the full swing in exponents
491 # that you can get with normalized values. Instead, we create two powers
492 # of two and multiply by them each in turn. That way the effective range
493 # of our exponent is doubled.
494 pow2_1 = fexp2i(('ishr', exp, 1), bits)
495 pow2_2 = fexp2i(('isub', exp, ('ishr', exp, 1)), bits)
496 return ('fmul', ('fmul', f, pow2_1), pow2_2)
497
498 optimizations += [
499 (('ldexp@32', 'x', 'exp'), ldexp('x', 'exp', 32)),
500 (('ldexp@64', 'x', 'exp'), ldexp('x', 'exp', 64)),
501 ]
502
503 # Unreal Engine 4 demo applications open-codes bitfieldReverse()
504 def bitfield_reverse(u):
505 step1 = ('ior', ('ishl', u, 16), ('ushr', u, 16))
506 step2 = ('ior', ('ishl', ('iand', step1, 0x00ff00ff), 8), ('ushr', ('iand', step1, 0xff00ff00), 8))
507 step3 = ('ior', ('ishl', ('iand', step2, 0x0f0f0f0f), 4), ('ushr', ('iand', step2, 0xf0f0f0f0), 4))
508 step4 = ('ior', ('ishl', ('iand', step3, 0x33333333), 2), ('ushr', ('iand', step3, 0xcccccccc), 2))
509 step5 = ('ior', ('ishl', ('iand', step4, 0x55555555), 1), ('ushr', ('iand', step4, 0xaaaaaaaa), 1))
510
511 return step5
512
513 optimizations += [(bitfield_reverse('x@32'), ('bitfield_reverse', 'x'))]
514
515 # For any float comparison operation, "cmp", if you have "a == a && a cmp b"
516 # then the "a == a" is redundant because it's equivalent to "a is not NaN"
517 # and, if a is a NaN then the second comparison will fail anyway.
518 for op in ['flt', 'fge', 'feq']:
519 optimizations += [
520 (('iand', ('feq', a, a), (op, a, b)), (op, a, b)),
521 (('iand', ('feq', a, a), (op, b, a)), (op, b, a)),
522 ]
523
524 # Add optimizations to handle the case where the result of a ternary is
525 # compared to a constant. This way we can take things like
526 #
527 # (a ? 0 : 1) > 0
528 #
529 # and turn it into
530 #
531 # a ? (0 > 0) : (1 > 0)
532 #
533 # which constant folding will eat for lunch. The resulting ternary will
534 # further get cleaned up by the boolean reductions above and we will be
535 # left with just the original variable "a".
536 for op in ['flt', 'fge', 'feq', 'fne',
537 'ilt', 'ige', 'ieq', 'ine', 'ult', 'uge']:
538 optimizations += [
539 ((op, ('bcsel', 'a', '#b', '#c'), '#d'),
540 ('bcsel', 'a', (op, 'b', 'd'), (op, 'c', 'd'))),
541 ((op, '#d', ('bcsel', a, '#b', '#c')),
542 ('bcsel', 'a', (op, 'd', 'b'), (op, 'd', 'c'))),
543 ]
544
545 # This section contains "late" optimizations that should be run before
546 # creating ffmas and calling regular optimizations for the final time.
547 # Optimizations should go here if they help code generation and conflict
548 # with the regular optimizations.
549 before_ffma_optimizations = [
550 # Propagate constants down multiplication chains
551 (('~fmul(is_used_once)', ('fmul(is_used_once)', 'a(is_not_const)', '#b'), 'c(is_not_const)'), ('fmul', ('fmul', a, c), b)),
552 (('imul(is_used_once)', ('imul(is_used_once)', 'a(is_not_const)', '#b'), 'c(is_not_const)'), ('imul', ('imul', a, c), b)),
553 (('~fadd(is_used_once)', ('fadd(is_used_once)', 'a(is_not_const)', '#b'), 'c(is_not_const)'), ('fadd', ('fadd', a, c), b)),
554 (('iadd(is_used_once)', ('iadd(is_used_once)', 'a(is_not_const)', '#b'), 'c(is_not_const)'), ('iadd', ('iadd', a, c), b)),
555
556 (('~fadd', ('fmul', a, b), ('fmul', a, c)), ('fmul', a, ('fadd', b, c))),
557 (('iadd', ('imul', a, b), ('imul', a, c)), ('imul', a, ('iadd', b, c))),
558 (('~fadd', ('fneg', a), a), 0.0),
559 (('iadd', ('ineg', a), a), 0),
560 (('iadd', ('ineg', a), ('iadd', a, b)), b),
561 (('iadd', a, ('iadd', ('ineg', a), b)), b),
562 (('~fadd', ('fneg', a), ('fadd', a, b)), b),
563 (('~fadd', a, ('fadd', ('fneg', a), b)), b),
564 ]
565
566 # This section contains "late" optimizations that should be run after the
567 # regular optimizations have finished. Optimizations should go here if
568 # they help code generation but do not necessarily produce code that is
569 # more easily optimizable.
570 late_optimizations = [
571 # Most of these optimizations aren't quite safe when you get infinity or
572 # Nan involved but the first one should be fine.
573 (('flt', ('fadd', a, b), 0.0), ('flt', a, ('fneg', b))),
574 (('flt', ('fneg', ('fadd', a, b)), 0.0), ('flt', ('fneg', a), b)),
575 (('~fge', ('fadd', a, b), 0.0), ('fge', a, ('fneg', b))),
576 (('~fge', ('fneg', ('fadd', a, b)), 0.0), ('fge', ('fneg', a), b)),
577 (('~feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
578 (('~fne', ('fadd', a, b), 0.0), ('fne', a, ('fneg', b))),
579
580 (('fdot2', a, b), ('fdot_replicated2', a, b), 'options->fdot_replicates'),
581 (('fdot3', a, b), ('fdot_replicated3', a, b), 'options->fdot_replicates'),
582 (('fdot4', a, b), ('fdot_replicated4', a, b), 'options->fdot_replicates'),
583 (('fdph', a, b), ('fdph_replicated', a, b), 'options->fdot_replicates'),
584
585 (('b2f(is_used_more_than_once)', ('inot', a)), ('bcsel', a, 0.0, 1.0)),
586 (('fneg(is_used_more_than_once)', ('b2f', ('inot', a))), ('bcsel', a, -0.0, -1.0)),
587
588 # we do these late so that we don't get in the way of creating ffmas
589 (('fmin', ('fadd(is_used_once)', '#c', a), ('fadd(is_used_once)', '#c', b)), ('fadd', c, ('fmin', a, b))),
590 (('fmax', ('fadd(is_used_once)', '#c', a), ('fadd(is_used_once)', '#c', b)), ('fadd', c, ('fmax', a, b))),
591 ]
592
593 print nir_algebraic.AlgebraicPass("nir_opt_algebraic", optimizations).render()
594 print nir_algebraic.AlgebraicPass("nir_opt_algebraic_before_ffma",
595 before_ffma_optimizations).render()
596 print nir_algebraic.AlgebraicPass("nir_opt_algebraic_late",
597 late_optimizations).render()