nir/opcodes: Make ldexp take an explicitly 32-bit int
[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@32', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp32'),
102 (('flrp@64', a, b, c), ('fadd', ('fmul', c, ('fsub', b, a)), a), 'options->lower_flrp64'),
103 (('ffract', a), ('fsub', a, ('ffloor', a)), 'options->lower_ffract'),
104 (('~fadd', ('fmul', a, ('fadd', 1.0, ('fneg', ('b2f', c)))), ('fmul', b, ('b2f', c))), ('bcsel', c, b, a), 'options->lower_flrp32'),
105 (('~fadd@32', ('fmul', a, ('fadd', 1.0, ('fneg', c ))), ('fmul', b, c )), ('flrp', a, b, c), '!options->lower_flrp32'),
106 (('~fadd@64', ('fmul', a, ('fadd', 1.0, ('fneg', c ))), ('fmul', b, c )), ('flrp', a, b, c), '!options->lower_flrp64'),
107 (('~fadd', a, ('fmul', ('b2f', c), ('fadd', b, ('fneg', a)))), ('bcsel', c, b, a), 'options->lower_flrp32'),
108 (('~fadd@32', a, ('fmul', c , ('fadd', b, ('fneg', a)))), ('flrp', a, b, c), '!options->lower_flrp32'),
109 (('~fadd@64', a, ('fmul', c , ('fadd', b, ('fneg', a)))), ('flrp', a, b, c), '!options->lower_flrp64'),
110 (('ffma', a, b, c), ('fadd', ('fmul', a, b), c), 'options->lower_ffma'),
111 (('~fadd', ('fmul', a, b), c), ('ffma', a, b, c), '!options->lower_ffma'),
112 # Comparison simplifications
113 (('~inot', ('flt', a, b)), ('fge', a, b)),
114 (('~inot', ('fge', a, b)), ('flt', a, b)),
115 (('~inot', ('feq', a, b)), ('fne', a, b)),
116 (('~inot', ('fne', a, b)), ('feq', a, b)),
117 (('inot', ('ilt', a, b)), ('ige', a, b)),
118 (('inot', ('ige', a, b)), ('ilt', a, b)),
119 (('inot', ('ieq', a, b)), ('ine', a, b)),
120 (('inot', ('ine', a, b)), ('ieq', a, b)),
121
122 # 0.0 >= b2f(a)
123 # b2f(a) <= 0.0
124 # b2f(a) == 0.0 because b2f(a) can only be 0 or 1
125 # inot(a)
126 (('fge', 0.0, ('b2f', a)), ('inot', a)),
127
128 # 0.0 < fabs(a)
129 # fabs(a) > 0.0
130 # fabs(a) != 0.0 because fabs(a) must be >= 0
131 # a != 0.0
132 (('flt', 0.0, ('fabs', a)), ('fne', a, 0.0)),
133
134 (('fge', ('fneg', ('fabs', a)), 0.0), ('feq', a, 0.0)),
135 (('bcsel', ('flt', b, a), b, a), ('fmin', a, b)),
136 (('bcsel', ('flt', a, b), b, a), ('fmax', a, b)),
137 (('bcsel', ('inot', 'a@bool'), b, c), ('bcsel', a, c, b)),
138 (('bcsel', a, ('bcsel', a, b, c), d), ('bcsel', a, b, d)),
139 (('bcsel', a, True, 'b@bool'), ('ior', a, b)),
140 (('fmin', a, a), a),
141 (('fmax', a, a), a),
142 (('imin', a, a), a),
143 (('imax', a, a), a),
144 (('umin', a, a), a),
145 (('umax', a, a), a),
146 (('~fmin', ('fmax', a, 0.0), 1.0), ('fsat', a), '!options->lower_fsat'),
147 (('~fmax', ('fmin', a, 1.0), 0.0), ('fsat', a), '!options->lower_fsat'),
148 (('fsat', a), ('fmin', ('fmax', a, 0.0), 1.0), 'options->lower_fsat'),
149 (('fsat', ('fsat', a)), ('fsat', a)),
150 (('fmin', ('fmax', ('fmin', ('fmax', a, b), c), b), c), ('fmin', ('fmax', a, b), c)),
151 (('imin', ('imax', ('imin', ('imax', a, b), c), b), c), ('imin', ('imax', a, b), c)),
152 (('umin', ('umax', ('umin', ('umax', a, b), c), b), c), ('umin', ('umax', a, b), c)),
153 (('extract_u8', ('imin', ('imax', a, 0), 0xff), 0), ('imin', ('imax', a, 0), 0xff)),
154 (('~ior', ('flt', a, b), ('flt', a, c)), ('flt', a, ('fmax', b, c))),
155 (('~ior', ('flt', a, c), ('flt', b, c)), ('flt', ('fmin', a, b), c)),
156 (('~ior', ('fge', a, b), ('fge', a, c)), ('fge', a, ('fmin', b, c))),
157 (('~ior', ('fge', a, c), ('fge', b, c)), ('fge', ('fmax', a, b), c)),
158 (('fabs', ('slt', a, b)), ('slt', a, b)),
159 (('fabs', ('sge', a, b)), ('sge', a, b)),
160 (('fabs', ('seq', a, b)), ('seq', a, b)),
161 (('fabs', ('sne', a, b)), ('sne', a, b)),
162 (('slt', a, b), ('b2f', ('flt', a, b)), 'options->lower_scmp'),
163 (('sge', a, b), ('b2f', ('fge', a, b)), 'options->lower_scmp'),
164 (('seq', a, b), ('b2f', ('feq', a, b)), 'options->lower_scmp'),
165 (('sne', a, b), ('b2f', ('fne', a, b)), 'options->lower_scmp'),
166 (('fne', ('fneg', a), a), ('fne', a, 0.0)),
167 (('feq', ('fneg', a), a), ('feq', a, 0.0)),
168 # Emulating booleans
169 (('imul', ('b2i', a), ('b2i', b)), ('b2i', ('iand', a, b))),
170 (('fmul', ('b2f', a), ('b2f', b)), ('b2f', ('iand', a, b))),
171 (('fsat', ('fadd', ('b2f', a), ('b2f', b))), ('b2f', ('ior', a, b))),
172 (('iand', 'a@bool', 1.0), ('b2f', a)),
173 (('flt', ('fneg', ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
174 (('flt', ('fsub', 0.0, ('b2f', a)), 0), a), # Generated by TGSI KILL_IF.
175 # Comparison with the same args. Note that these are not done for
176 # the float versions because NaN always returns false on float
177 # inequalities.
178 (('ilt', a, a), False),
179 (('ige', a, a), True),
180 (('ieq', a, a), True),
181 (('ine', a, a), False),
182 (('ult', a, a), False),
183 (('uge', a, a), True),
184 # Logical and bit operations
185 (('fand', a, 0.0), 0.0),
186 (('iand', a, a), a),
187 (('iand', a, ~0), a),
188 (('iand', a, 0), 0),
189 (('ior', a, a), a),
190 (('ior', a, 0), a),
191 (('fxor', a, a), 0.0),
192 (('ixor', a, a), 0),
193 (('ixor', a, 0), a),
194 (('inot', ('inot', a)), a),
195 # DeMorgan's Laws
196 (('iand', ('inot', a), ('inot', b)), ('inot', ('ior', a, b))),
197 (('ior', ('inot', a), ('inot', b)), ('inot', ('iand', a, b))),
198 # Shift optimizations
199 (('ishl', 0, a), 0),
200 (('ishl', a, 0), a),
201 (('ishr', 0, a), 0),
202 (('ishr', a, 0), a),
203 (('ushr', 0, a), 0),
204 (('ushr', a, 0), a),
205 (('iand', 0xff, ('ushr', a, 24)), ('ushr', a, 24)),
206 (('iand', 0xffff, ('ushr', a, 16)), ('ushr', a, 16)),
207 # Exponential/logarithmic identities
208 (('~fexp2', ('flog2', a)), a), # 2^lg2(a) = a
209 (('~flog2', ('fexp2', a)), a), # lg2(2^a) = a
210 (('fpow', a, b), ('fexp2', ('fmul', ('flog2', a), b)), 'options->lower_fpow'), # a^b = 2^(lg2(a)*b)
211 (('~fexp2', ('fmul', ('flog2', a), b)), ('fpow', a, b), '!options->lower_fpow'), # 2^(lg2(a)*b) = a^b
212 (('~fexp2', ('fadd', ('fmul', ('flog2', a), b), ('fmul', ('flog2', c), d))),
213 ('~fmul', ('fpow', a, b), ('fpow', c, d)), '!options->lower_fpow'), # 2^(lg2(a) * b + lg2(c) + d) = a^b * c^d
214 (('~fpow', a, 1.0), a),
215 (('~fpow', a, 2.0), ('fmul', a, a)),
216 (('~fpow', a, 4.0), ('fmul', ('fmul', a, a), ('fmul', a, a))),
217 (('~fpow', 2.0, a), ('fexp2', a)),
218 (('~fpow', ('fpow', a, 2.2), 0.454545), a),
219 (('~fpow', ('fabs', ('fpow', a, 2.2)), 0.454545), ('fabs', a)),
220 (('~fsqrt', ('fexp2', a)), ('fexp2', ('fmul', 0.5, a))),
221 (('~frcp', ('fexp2', a)), ('fexp2', ('fneg', a))),
222 (('~frsq', ('fexp2', a)), ('fexp2', ('fmul', -0.5, a))),
223 (('~flog2', ('fsqrt', a)), ('fmul', 0.5, ('flog2', a))),
224 (('~flog2', ('frcp', a)), ('fneg', ('flog2', a))),
225 (('~flog2', ('frsq', a)), ('fmul', -0.5, ('flog2', a))),
226 (('~flog2', ('fpow', a, b)), ('fmul', b, ('flog2', a))),
227 (('~fadd', ('flog2', a), ('flog2', b)), ('flog2', ('fmul', a, b))),
228 (('~fadd', ('flog2', a), ('fneg', ('flog2', b))), ('flog2', ('fdiv', a, b))),
229 (('~fmul', ('fexp2', a), ('fexp2', b)), ('fexp2', ('fadd', a, b))),
230 # Division and reciprocal
231 (('~fdiv', 1.0, a), ('frcp', a)),
232 (('fdiv', a, b), ('fmul', a, ('frcp', b)), 'options->lower_fdiv'),
233 (('~frcp', ('frcp', a)), a),
234 (('~frcp', ('fsqrt', a)), ('frsq', a)),
235 (('fsqrt', a), ('frcp', ('frsq', a)), 'options->lower_fsqrt'),
236 (('~frcp', ('frsq', a)), ('fsqrt', a), '!options->lower_fsqrt'),
237 # Boolean simplifications
238 (('ieq', 'a@bool', True), a),
239 (('ine', 'a@bool', True), ('inot', a)),
240 (('ine', 'a@bool', False), a),
241 (('ieq', 'a@bool', False), ('inot', 'a')),
242 (('bcsel', a, True, False), ('ine', a, 0)),
243 (('bcsel', a, False, True), ('ieq', a, 0)),
244 (('bcsel', True, b, c), b),
245 (('bcsel', False, b, c), c),
246 # The result of this should be hit by constant propagation and, in the
247 # next round of opt_algebraic, get picked up by one of the above two.
248 (('bcsel', '#a', b, c), ('bcsel', ('ine', 'a', 0), b, c)),
249
250 (('bcsel', a, b, b), b),
251 (('fcsel', a, b, b), b),
252
253 # Conversions
254 (('i2b', ('b2i', a)), a),
255 (('f2i', ('ftrunc', a)), ('f2i', a)),
256 (('f2u', ('ftrunc', a)), ('f2u', a)),
257 (('i2b', ('ineg', a)), ('i2b', a)),
258 (('i2b', ('iabs', a)), ('i2b', a)),
259 (('fabs', ('b2f', a)), ('b2f', a)),
260 (('iabs', ('b2i', a)), ('b2i', a)),
261
262 # Byte extraction
263 (('ushr', a, 24), ('extract_u8', a, 3), '!options->lower_extract_byte'),
264 (('iand', 0xff, ('ushr', a, 16)), ('extract_u8', a, 2), '!options->lower_extract_byte'),
265 (('iand', 0xff, ('ushr', a, 8)), ('extract_u8', a, 1), '!options->lower_extract_byte'),
266 (('iand', 0xff, a), ('extract_u8', a, 0), '!options->lower_extract_byte'),
267
268 # Word extraction
269 (('ushr', a, 16), ('extract_u16', a, 1), '!options->lower_extract_word'),
270 (('iand', 0xffff, a), ('extract_u16', a, 0), '!options->lower_extract_word'),
271
272 # Subtracts
273 (('~fsub', a, ('fsub', 0.0, b)), ('fadd', a, b)),
274 (('isub', a, ('isub', 0, b)), ('iadd', a, b)),
275 (('ussub_4x8', a, 0), a),
276 (('ussub_4x8', a, ~0), 0),
277 (('fsub', a, b), ('fadd', a, ('fneg', b)), 'options->lower_sub'),
278 (('isub', a, b), ('iadd', a, ('ineg', b)), 'options->lower_sub'),
279 (('fneg', a), ('fsub', 0.0, a), 'options->lower_negate'),
280 (('ineg', a), ('isub', 0, a), 'options->lower_negate'),
281 (('~fadd', a, ('fsub', 0.0, b)), ('fsub', a, b)),
282 (('iadd', a, ('isub', 0, b)), ('isub', a, b)),
283 (('fabs', ('fsub', 0.0, a)), ('fabs', a)),
284 (('iabs', ('isub', 0, a)), ('iabs', a)),
285
286 # Propagate negation up multiplication chains
287 (('fmul', ('fneg', a), b), ('fneg', ('fmul', a, b))),
288 (('imul', ('ineg', a), b), ('ineg', ('imul', a, b))),
289
290 # Reassociate constants in add/mul chains so they can be folded together.
291 # For now, we only handle cases where the constants are separated by
292 # a single non-constant. We could do better eventually.
293 (('~fmul', '#a', ('fmul', b, '#c')), ('fmul', ('fmul', a, c), b)),
294 (('imul', '#a', ('imul', b, '#c')), ('imul', ('imul', a, c), b)),
295 (('~fadd', '#a', ('fadd', b, '#c')), ('fadd', ('fadd', a, c), b)),
296 (('iadd', '#a', ('iadd', b, '#c')), ('iadd', ('iadd', a, c), b)),
297
298 # Misc. lowering
299 (('fmod', a, b), ('fsub', a, ('fmul', b, ('ffloor', ('fdiv', a, b)))), 'options->lower_fmod'),
300 (('frem', a, b), ('fsub', a, ('fmul', b, ('ftrunc', ('fdiv', a, b)))), 'options->lower_fmod'),
301 (('uadd_carry@32', a, b), ('b2i', ('ult', ('iadd', a, b), a)), 'options->lower_uadd_carry'),
302 (('usub_borrow@32', a, b), ('b2i', ('ult', a, b)), 'options->lower_usub_borrow'),
303
304 (('bitfield_insert', 'base', 'insert', 'offset', 'bits'),
305 ('bcsel', ('ilt', 31, 'bits'), 'insert',
306 ('bfi', ('bfm', 'bits', 'offset'), 'insert', 'base')),
307 'options->lower_bitfield_insert'),
308
309 (('ibitfield_extract', 'value', 'offset', 'bits'),
310 ('bcsel', ('ilt', 31, 'bits'), 'value',
311 ('ibfe', 'value', 'offset', 'bits')),
312 'options->lower_bitfield_extract'),
313
314 (('ubitfield_extract', 'value', 'offset', 'bits'),
315 ('bcsel', ('ult', 31, 'bits'), 'value',
316 ('ubfe', 'value', 'offset', 'bits')),
317 'options->lower_bitfield_extract'),
318
319 (('extract_i8', a, b),
320 ('ishr', ('ishl', a, ('imul', ('isub', 3, b), 8)), 24),
321 'options->lower_extract_byte'),
322
323 (('extract_u8', a, b),
324 ('iand', ('ushr', a, ('imul', b, 8)), 0xff),
325 'options->lower_extract_byte'),
326
327 (('extract_i16', a, b),
328 ('ishr', ('ishl', a, ('imul', ('isub', 1, b), 16)), 16),
329 'options->lower_extract_word'),
330
331 (('extract_u16', a, b),
332 ('iand', ('ushr', a, ('imul', b, 16)), 0xffff),
333 'options->lower_extract_word'),
334
335 (('pack_unorm_2x16', 'v'),
336 ('pack_uvec2_to_uint',
337 ('f2u', ('fround_even', ('fmul', ('fsat', 'v'), 65535.0)))),
338 'options->lower_pack_unorm_2x16'),
339
340 (('pack_unorm_4x8', 'v'),
341 ('pack_uvec4_to_uint',
342 ('f2u', ('fround_even', ('fmul', ('fsat', 'v'), 255.0)))),
343 'options->lower_pack_unorm_4x8'),
344
345 (('pack_snorm_2x16', 'v'),
346 ('pack_uvec2_to_uint',
347 ('f2i', ('fround_even', ('fmul', ('fmin', 1.0, ('fmax', -1.0, 'v')), 32767.0)))),
348 'options->lower_pack_snorm_2x16'),
349
350 (('pack_snorm_4x8', 'v'),
351 ('pack_uvec4_to_uint',
352 ('f2i', ('fround_even', ('fmul', ('fmin', 1.0, ('fmax', -1.0, 'v')), 127.0)))),
353 'options->lower_pack_snorm_4x8'),
354
355 (('unpack_unorm_2x16', 'v'),
356 ('fdiv', ('u2f', ('vec2', ('extract_u16', 'v', 0),
357 ('extract_u16', 'v', 1))),
358 65535.0),
359 'options->lower_unpack_unorm_2x16'),
360
361 (('unpack_unorm_4x8', 'v'),
362 ('fdiv', ('u2f', ('vec4', ('extract_u8', 'v', 0),
363 ('extract_u8', 'v', 1),
364 ('extract_u8', 'v', 2),
365 ('extract_u8', 'v', 3))),
366 255.0),
367 'options->lower_unpack_unorm_4x8'),
368
369 (('unpack_snorm_2x16', 'v'),
370 ('fmin', 1.0, ('fmax', -1.0, ('fdiv', ('i2f', ('vec2', ('extract_i16', 'v', 0),
371 ('extract_i16', 'v', 1))),
372 32767.0))),
373 'options->lower_unpack_snorm_2x16'),
374
375 (('unpack_snorm_4x8', 'v'),
376 ('fmin', 1.0, ('fmax', -1.0, ('fdiv', ('i2f', ('vec4', ('extract_i8', 'v', 0),
377 ('extract_i8', 'v', 1),
378 ('extract_i8', 'v', 2),
379 ('extract_i8', 'v', 3))),
380 127.0))),
381 'options->lower_unpack_snorm_4x8'),
382 ]
383
384 def fexp2i(exp):
385 # We assume that exp is already in the range [-126, 127].
386 return ('ishl', ('iadd', exp, 127), 23)
387
388 def ldexp32(f, exp):
389 # First, we clamp exp to a reasonable range. The maximum possible range
390 # for a normal exponent is [-126, 127] and, throwing in denormals, you get
391 # a maximum range of [-149, 127]. This means that we can potentially have
392 # a swing of +-276. If you start with FLT_MAX, you actually have to do
393 # ldexp(FLT_MAX, -278) to get it to flush all the way to zero. The GLSL
394 # spec, on the other hand, only requires that we handle an exponent value
395 # in the range [-126, 128]. This implementation is *mostly* correct; it
396 # handles a range on exp of [-252, 254] which allows you to create any
397 # value (including denorms if the hardware supports it) and to adjust the
398 # exponent of any normal value to anything you want.
399 exp = ('imin', ('imax', exp, -252), 254)
400
401 # Now we compute two powers of 2, one for exp/2 and one for exp-exp/2.
402 # (We use ishr which isn't the same for -1, but the -1 case still works
403 # since we use exp-exp/2 as the second exponent.) While the spec
404 # technically defines ldexp as f * 2.0^exp, simply multiplying once doesn't
405 # work with denormals and doesn't allow for the full swing in exponents
406 # that you can get with normalized values. Instead, we create two powers
407 # of two and multiply by them each in turn. That way the effective range
408 # of our exponent is doubled.
409 pow2_1 = fexp2i(('ishr', exp, 1))
410 pow2_2 = fexp2i(('isub', exp, ('ishr', exp, 1)))
411 return ('fmul', ('fmul', f, pow2_1), pow2_2)
412
413 optimizations += [(('ldexp@32', 'x', 'exp'), ldexp32('x', 'exp'))]
414
415 # Unreal Engine 4 demo applications open-codes bitfieldReverse()
416 def bitfield_reverse(u):
417 step1 = ('ior', ('ishl', u, 16), ('ushr', u, 16))
418 step2 = ('ior', ('ishl', ('iand', step1, 0x00ff00ff), 8), ('ushr', ('iand', step1, 0xff00ff00), 8))
419 step3 = ('ior', ('ishl', ('iand', step2, 0x0f0f0f0f), 4), ('ushr', ('iand', step2, 0xf0f0f0f0), 4))
420 step4 = ('ior', ('ishl', ('iand', step3, 0x33333333), 2), ('ushr', ('iand', step3, 0xcccccccc), 2))
421 step5 = ('ior', ('ishl', ('iand', step4, 0x55555555), 1), ('ushr', ('iand', step4, 0xaaaaaaaa), 1))
422
423 return step5
424
425 optimizations += [(bitfield_reverse('x@32'), ('bitfield_reverse', 'x'))]
426
427
428 # Add optimizations to handle the case where the result of a ternary is
429 # compared to a constant. This way we can take things like
430 #
431 # (a ? 0 : 1) > 0
432 #
433 # and turn it into
434 #
435 # a ? (0 > 0) : (1 > 0)
436 #
437 # which constant folding will eat for lunch. The resulting ternary will
438 # further get cleaned up by the boolean reductions above and we will be
439 # left with just the original variable "a".
440 for op in ['flt', 'fge', 'feq', 'fne',
441 'ilt', 'ige', 'ieq', 'ine', 'ult', 'uge']:
442 optimizations += [
443 ((op, ('bcsel', 'a', '#b', '#c'), '#d'),
444 ('bcsel', 'a', (op, 'b', 'd'), (op, 'c', 'd'))),
445 ((op, '#d', ('bcsel', a, '#b', '#c')),
446 ('bcsel', 'a', (op, 'd', 'b'), (op, 'd', 'c'))),
447 ]
448
449 # This section contains "late" optimizations that should be run after the
450 # regular optimizations have finished. Optimizations should go here if
451 # they help code generation but do not necessarily produce code that is
452 # more easily optimizable.
453 late_optimizations = [
454 # Most of these optimizations aren't quite safe when you get infinity or
455 # Nan involved but the first one should be fine.
456 (('flt', ('fadd', a, b), 0.0), ('flt', a, ('fneg', b))),
457 (('~fge', ('fadd', a, b), 0.0), ('fge', a, ('fneg', b))),
458 (('~feq', ('fadd', a, b), 0.0), ('feq', a, ('fneg', b))),
459 (('~fne', ('fadd', a, b), 0.0), ('fne', a, ('fneg', b))),
460
461 (('fdot2', a, b), ('fdot_replicated2', a, b), 'options->fdot_replicates'),
462 (('fdot3', a, b), ('fdot_replicated3', a, b), 'options->fdot_replicates'),
463 (('fdot4', a, b), ('fdot_replicated4', a, b), 'options->fdot_replicates'),
464 (('fdph', a, b), ('fdph_replicated', a, b), 'options->fdot_replicates'),
465 ]
466
467 print nir_algebraic.AlgebraicPass("nir_opt_algebraic", optimizations).render()
468 print nir_algebraic.AlgebraicPass("nir_opt_algebraic_late",
469 late_optimizations).render()