summaryrefslogtreecommitdiff
path: root/src/gallium/auxiliary/gallivm/lp_bld_conv.c
blob: 20aa2577830bf538d7214f34b8ec62080af79f9c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
/**************************************************************************
 *
 * Copyright 2009 VMware, Inc.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sub license, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 **************************************************************************/


/**
 * @file
 * Helper functions for type conversions.
 *
 * We want to use the fastest type for a given computation whenever feasible.
 * The other side of this is that we need to be able convert between several
 * types accurately and efficiently.
 *
 * Conversion between types of different bit width is quite complex since a 
 *
 * To remember there are a few invariants in type conversions:
 *
 * - register width must remain constant:
 *
 *     src_type.width * src_type.length == dst_type.width * dst_type.length
 *
 * - total number of elements must remain constant:
 *
 *     src_type.length * num_srcs == dst_type.length * num_dsts
 *
 * It is not always possible to do the conversion both accurately and
 * efficiently, usually due to lack of adequate machine instructions. In these
 * cases it is important not to cut shortcuts here and sacrifice accuracy, as
 * there this functions can be used anywhere. In the future we might have a
 * precision parameter which can gauge the accuracy vs efficiency compromise,
 * but for now if the data conversion between two stages happens to be the
 * bottleneck, then most likely should just avoid converting at all and run
 * both stages with the same type.
 *
 * Make sure to run lp_test_conv unit test after any change to this file.
 *
 * @author Jose Fonseca <jfonseca@vmware.com>
 */


#include "util/u_debug.h"
#include "util/u_math.h"
#include "util/u_cpu_detect.h"

#include "lp_bld_type.h"
#include "lp_bld_const.h"
#include "lp_bld_arit.h"
#include "lp_bld_pack.h"
#include "lp_bld_conv.h"


/**
 * Special case for converting clamped IEEE-754 floats to unsigned norms.
 *
 * The mathematical voodoo below may seem excessive but it is actually
 * paramount we do it this way for several reasons. First, there is no single
 * precision FP to unsigned integer conversion Intel SSE instruction. Second,
 * secondly, even if there was, since the FP's mantissa takes only a fraction
 * of register bits the typically scale and cast approach would require double
 * precision for accurate results, and therefore half the throughput
 *
 * Although the result values can be scaled to an arbitrary bit width specified
 * by dst_width, the actual result type will have the same width.
 *
 * Ex: src = { float, float, float, float }
 * return { i32, i32, i32, i32 } where each value is in [0, 2^dst_width-1].
 */
LLVMValueRef
lp_build_clamped_float_to_unsigned_norm(LLVMBuilderRef builder,
                                        struct lp_type src_type,
                                        unsigned dst_width,
                                        LLVMValueRef src)
{
   LLVMTypeRef int_vec_type = lp_build_int_vec_type(src_type);
   LLVMValueRef res;
   unsigned mantissa;
   unsigned n;
   unsigned long long ubound;
   unsigned long long mask;
   double scale;
   double bias;

   assert(src_type.floating);

   mantissa = lp_mantissa(src_type);

   /* We cannot carry more bits than the mantissa */
   n = MIN2(mantissa, dst_width);

   /* This magic coefficients will make the desired result to appear in the
    * lowest significant bits of the mantissa.
    */
   ubound = ((unsigned long long)1 << n);
   mask = ubound - 1;
   scale = (double)mask/ubound;
   bias = (double)((unsigned long long)1 << (mantissa - n));

   res = LLVMBuildFMul(builder, src, lp_build_const_vec(src_type, scale), "");
   res = LLVMBuildFAdd(builder, res, lp_build_const_vec(src_type, bias), "");
   res = LLVMBuildBitCast(builder, res, int_vec_type, "");

   if(dst_width > n) {
      int shift = dst_width - n;
      res = LLVMBuildShl(builder, res, lp_build_const_int_vec(src_type, shift), "");

      /* TODO: Fill in the empty lower bits for additional precision? */
      /* YES: this fixes progs/trivial/tri-z-eq.c.
       * Otherwise vertex Z=1.0 values get converted to something like
       * 0xfffffb00 and the test for equality with 0xffffffff fails.
       */
#if 0
      {
         LLVMValueRef msb;
         msb = LLVMBuildLShr(builder, res, lp_build_const_int_vec(src_type, dst_width - 1), "");
         msb = LLVMBuildShl(builder, msb, lp_build_const_int_vec(src_type, shift), "");
         msb = LLVMBuildSub(builder, msb, lp_build_const_int_vec(src_type, 1), "");
         res = LLVMBuildOr(builder, res, msb, "");
      }
#elif 0
      while(shift > 0) {
         res = LLVMBuildOr(builder, res, LLVMBuildLShr(builder, res, lp_build_const_int_vec(src_type, n), ""), "");
         shift -= n;
         n *= 2;
      }
#endif
   }
   else
      res = LLVMBuildAnd(builder, res, lp_build_const_int_vec(src_type, mask), "");

   return res;
}


/**
 * Inverse of lp_build_clamped_float_to_unsigned_norm above.
 * Ex: src = { i32, i32, i32, i32 } with values in range [0, 2^src_width-1]
 * return {float, float, float, float} with values in range [0, 1].
 */
LLVMValueRef
lp_build_unsigned_norm_to_float(LLVMBuilderRef builder,
                                unsigned src_width,
                                struct lp_type dst_type,
                                LLVMValueRef src)
{
   LLVMTypeRef vec_type = lp_build_vec_type(dst_type);
   LLVMTypeRef int_vec_type = lp_build_int_vec_type(dst_type);
   LLVMValueRef bias_;
   LLVMValueRef res;
   unsigned mantissa;
   unsigned n;
   unsigned long long ubound;
   unsigned long long mask;
   double scale;
   double bias;

   assert(dst_type.floating);

   /* Special-case int8->float, though most cases could be handled
    * this way:
    */
   if (src_width == 8) {
      scale = 1.0/255.0;
      res = LLVMBuildSIToFP(builder, src, vec_type, "");
      res = LLVMBuildFMul(builder, res, lp_build_const_vec(dst_type, scale), "");
      return res;
   }

   mantissa = lp_mantissa(dst_type);

   n = MIN2(mantissa, src_width);

   ubound = ((unsigned long long)1 << n);
   mask = ubound - 1;
   scale = (double)ubound/mask;
   bias = (double)((unsigned long long)1 << (mantissa - n));

   res = src;

   if(src_width > mantissa) {
      int shift = src_width - mantissa;
      res = LLVMBuildLShr(builder, res, lp_build_const_int_vec(dst_type, shift), "");
   }

   bias_ = lp_build_const_vec(dst_type, bias);

   res = LLVMBuildOr(builder,
                     res,
                     LLVMBuildBitCast(builder, bias_, int_vec_type, ""), "");

   res = LLVMBuildBitCast(builder, res, vec_type, "");

   res = LLVMBuildFSub(builder, res, bias_, "");
   res = LLVMBuildFMul(builder, res, lp_build_const_vec(dst_type, scale), "");

   return res;
}


/**
 * Generic type conversion.
 *
 * TODO: Take a precision argument, or even better, add a new precision member
 * to the lp_type union.
 */
void
lp_build_conv(LLVMBuilderRef builder,
              struct lp_type src_type,
              struct lp_type dst_type,
              const LLVMValueRef *src, unsigned num_srcs,
              LLVMValueRef *dst, unsigned num_dsts)
{
   struct lp_type tmp_type;
   LLVMValueRef tmp[LP_MAX_VECTOR_LENGTH];
   unsigned num_tmps;
   unsigned i;

   /* We must not loose or gain channels. Only precision */
   assert(src_type.length * num_srcs == dst_type.length * num_dsts);

   assert(src_type.length <= LP_MAX_VECTOR_LENGTH);
   assert(dst_type.length <= LP_MAX_VECTOR_LENGTH);
   assert(num_srcs <= LP_MAX_VECTOR_LENGTH);
   assert(num_dsts <= LP_MAX_VECTOR_LENGTH);

   tmp_type = src_type;
   for(i = 0; i < num_srcs; ++i) {
      assert(lp_check_value(src_type, src[i]));
      tmp[i] = src[i];
   }
   num_tmps = num_srcs;


   /* Special case 4x4f --> 1x16ub 
    */
   if (src_type.floating == 1 &&
       src_type.fixed    == 0 &&
       src_type.sign     == 1 &&
       src_type.norm     == 0 &&
       src_type.width    == 32 &&
       src_type.length   == 4 &&

       dst_type.floating == 0 &&
       dst_type.fixed    == 0 &&
       dst_type.sign     == 0 &&
       dst_type.norm     == 1 &&
       dst_type.width    == 8 &&
       dst_type.length   == 16)
   {
      int i;

      for (i = 0; i < num_dsts; i++, src += 4) {
         struct lp_type int16_type = dst_type;
         struct lp_type int32_type = dst_type;
         LLVMValueRef lo, hi;
         LLVMValueRef src_int0;
         LLVMValueRef src_int1;
         LLVMValueRef src_int2;
         LLVMValueRef src_int3;
         LLVMTypeRef int16_vec_type;
         LLVMTypeRef int32_vec_type;
         LLVMTypeRef src_vec_type;
         LLVMTypeRef dst_vec_type;
         LLVMValueRef const_255f;
         LLVMValueRef a, b, c, d;

         int16_type.width *= 2;
         int16_type.length /= 2;
         int16_type.sign = 1;

         int32_type.width *= 4;
         int32_type.length /= 4;
         int32_type.sign = 1;

         src_vec_type   = lp_build_vec_type(src_type);
         dst_vec_type   = lp_build_vec_type(dst_type);
         int16_vec_type = lp_build_vec_type(int16_type);
         int32_vec_type = lp_build_vec_type(int32_type);

         const_255f = lp_build_const_vec(src_type, 255.0f);

         a = LLVMBuildFMul(builder, src[0], const_255f, "");
         b = LLVMBuildFMul(builder, src[1], const_255f, "");
         c = LLVMBuildFMul(builder, src[2], const_255f, "");
         d = LLVMBuildFMul(builder, src[3], const_255f, "");

         /* lp_build_round generates excessively general code without
          * sse2, so do rounding manually.
          */
         if (!util_cpu_caps.has_sse2) {
            LLVMValueRef const_half = lp_build_const_vec(src_type, 0.5f);

            a = LLVMBuildFAdd(builder, a, const_half, "");
            b = LLVMBuildFAdd(builder, b, const_half, "");
            c = LLVMBuildFAdd(builder, c, const_half, "");
            d = LLVMBuildFAdd(builder, d, const_half, "");

            src_int0 = LLVMBuildFPToSI(builder, a, int32_vec_type, "");
            src_int1 = LLVMBuildFPToSI(builder, b, int32_vec_type, "");
            src_int2 = LLVMBuildFPToSI(builder, c, int32_vec_type, "");
            src_int3 = LLVMBuildFPToSI(builder, d, int32_vec_type, "");
         }
         else {
            struct lp_build_context bld;

            bld.builder = builder;
            bld.type = src_type;
            bld.vec_type = src_vec_type;
            bld.int_elem_type = lp_build_elem_type(int32_type);
            bld.int_vec_type = int32_vec_type;
            bld.undef = lp_build_undef(src_type);
            bld.zero = lp_build_zero(src_type);
            bld.one = lp_build_one(src_type);

            src_int0 = lp_build_iround(&bld, a);
            src_int1 = lp_build_iround(&bld, b);
            src_int2 = lp_build_iround(&bld, c);
            src_int3 = lp_build_iround(&bld, d);
         }

         lo = lp_build_pack2(builder, int32_type, int16_type, src_int0, src_int1);
         hi = lp_build_pack2(builder, int32_type, int16_type, src_int2, src_int3);
         dst[i] = lp_build_pack2(builder, int16_type, dst_type, lo, hi);
      }
      return; 
   }

   /*
    * Clamp if necessary
    */

   if(memcmp(&src_type, &dst_type, sizeof src_type) != 0) {
      struct lp_build_context bld;
      double src_min = lp_const_min(src_type);
      double dst_min = lp_const_min(dst_type);
      double src_max = lp_const_max(src_type);
      double dst_max = lp_const_max(dst_type);
      LLVMValueRef thres;

      lp_build_context_init(&bld, builder, tmp_type);

      if(src_min < dst_min) {
         if(dst_min == 0.0)
            thres = bld.zero;
         else
            thres = lp_build_const_vec(src_type, dst_min);
         for(i = 0; i < num_tmps; ++i)
            tmp[i] = lp_build_max(&bld, tmp[i], thres);
      }

      if(src_max > dst_max) {
         if(dst_max == 1.0)
            thres = bld.one;
         else
            thres = lp_build_const_vec(src_type, dst_max);
         for(i = 0; i < num_tmps; ++i)
            tmp[i] = lp_build_min(&bld, tmp[i], thres);
      }
   }

   /*
    * Scale to the narrowest range
    */

   if(dst_type.floating) {
      /* Nothing to do */
   }
   else if(tmp_type.floating) {
      if(!dst_type.fixed && !dst_type.sign && dst_type.norm) {
         for(i = 0; i < num_tmps; ++i) {
            tmp[i] = lp_build_clamped_float_to_unsigned_norm(builder,
                                                             tmp_type,
                                                             dst_type.width,
                                                             tmp[i]);
         }
         tmp_type.floating = FALSE;
      }
      else {
         double dst_scale = lp_const_scale(dst_type);
         LLVMTypeRef tmp_vec_type;

         if (dst_scale != 1.0) {
            LLVMValueRef scale = lp_build_const_vec(tmp_type, dst_scale);
            for(i = 0; i < num_tmps; ++i)
               tmp[i] = LLVMBuildFMul(builder, tmp[i], scale, "");
         }

         /* Use an equally sized integer for intermediate computations */
         tmp_type.floating = FALSE;
         tmp_vec_type = lp_build_vec_type(tmp_type);
         for(i = 0; i < num_tmps; ++i) {
#if 0
            if(dst_type.sign)
               tmp[i] = LLVMBuildFPToSI(builder, tmp[i], tmp_vec_type, "");
            else
               tmp[i] = LLVMBuildFPToUI(builder, tmp[i], tmp_vec_type, "");
#else
           /* FIXME: there is no SSE counterpart for LLVMBuildFPToUI */
            tmp[i] = LLVMBuildFPToSI(builder, tmp[i], tmp_vec_type, "");
#endif
         }
      }
   }
   else {
      unsigned src_shift = lp_const_shift(src_type);
      unsigned dst_shift = lp_const_shift(dst_type);

      /* FIXME: compensate different offsets too */
      if(src_shift > dst_shift) {
         LLVMValueRef shift = lp_build_const_int_vec(tmp_type, src_shift - dst_shift);
         for(i = 0; i < num_tmps; ++i)
            if(src_type.sign)
               tmp[i] = LLVMBuildAShr(builder, tmp[i], shift, "");
            else
               tmp[i] = LLVMBuildLShr(builder, tmp[i], shift, "");
      }
   }

   /*
    * Truncate or expand bit width
    *
    * No data conversion should happen here, although the sign bits are
    * crucial to avoid bad clamping.
    */

   {
      struct lp_type new_type;

      new_type = tmp_type;
      new_type.sign   = dst_type.sign;
      new_type.width  = dst_type.width;
      new_type.length = dst_type.length;

      lp_build_resize(builder, tmp_type, new_type, tmp, num_srcs, tmp, num_dsts);

      tmp_type = new_type;
      num_tmps = num_dsts;
   }

   /*
    * Scale to the widest range
    */

   if(src_type.floating) {
      /* Nothing to do */
   }
   else if(!src_type.floating && dst_type.floating) {
      if(!src_type.fixed && !src_type.sign && src_type.norm) {
         for(i = 0; i < num_tmps; ++i) {
            tmp[i] = lp_build_unsigned_norm_to_float(builder,
                                                     src_type.width,
                                                     dst_type,
                                                     tmp[i]);
         }
         tmp_type.floating = TRUE;
      }
      else {
         double src_scale = lp_const_scale(src_type);
         LLVMTypeRef tmp_vec_type;

         /* Use an equally sized integer for intermediate computations */
         tmp_type.floating = TRUE;
         tmp_type.sign = TRUE;
         tmp_vec_type = lp_build_vec_type(tmp_type);
         for(i = 0; i < num_tmps; ++i) {
#if 0
            if(dst_type.sign)
               tmp[i] = LLVMBuildSIToFP(builder, tmp[i], tmp_vec_type, "");
            else
               tmp[i] = LLVMBuildUIToFP(builder, tmp[i], tmp_vec_type, "");
#else
            /* FIXME: there is no SSE counterpart for LLVMBuildUIToFP */
            tmp[i] = LLVMBuildSIToFP(builder, tmp[i], tmp_vec_type, "");
#endif
          }

          if (src_scale != 1.0) {
             LLVMValueRef scale = lp_build_const_vec(tmp_type, 1.0/src_scale);
             for(i = 0; i < num_tmps; ++i)
                tmp[i] = LLVMBuildFMul(builder, tmp[i], scale, "");
          }
      }
    }
    else {
       unsigned src_shift = lp_const_shift(src_type);
       unsigned dst_shift = lp_const_shift(dst_type);

       /* FIXME: compensate different offsets too */
       if(src_shift < dst_shift) {
          LLVMValueRef shift = lp_build_const_int_vec(tmp_type, dst_shift - src_shift);
          for(i = 0; i < num_tmps; ++i)
             tmp[i] = LLVMBuildShl(builder, tmp[i], shift, "");
       }
    }

   for(i = 0; i < num_dsts; ++i) {
      dst[i] = tmp[i];
      assert(lp_check_value(dst_type, dst[i]));
   }
}


/**
 * Bit mask conversion.
 *
 * This will convert the integer masks that match the given types.
 *
 * The mask values should 0 or -1, i.e., all bits either set to zero or one.
 * Any other value will likely cause in unpredictable results.
 *
 * This is basically a very trimmed down version of lp_build_conv.
 */
void
lp_build_conv_mask(LLVMBuilderRef builder,
                   struct lp_type src_type,
                   struct lp_type dst_type,
                   const LLVMValueRef *src, unsigned num_srcs,
                   LLVMValueRef *dst, unsigned num_dsts)
{
   /* Register width must remain constant */
   assert(src_type.width * src_type.length == dst_type.width * dst_type.length);

   /* We must not loose or gain channels. Only precision */
   assert(src_type.length * num_srcs == dst_type.length * num_dsts);

   /*
    * Drop
    *
    * We assume all values are 0 or -1
    */

   src_type.floating = FALSE;
   src_type.fixed = FALSE;
   src_type.sign = TRUE;
   src_type.norm = FALSE;

   dst_type.floating = FALSE;
   dst_type.fixed = FALSE;
   dst_type.sign = TRUE;
   dst_type.norm = FALSE;

   /*
    * Truncate or expand bit width
    */

   if(src_type.width > dst_type.width) {
      assert(num_dsts == 1);
      dst[0] = lp_build_pack(builder, src_type, dst_type, TRUE, src, num_srcs);
   }
   else if(src_type.width < dst_type.width) {
      assert(num_srcs == 1);
      lp_build_unpack(builder, src_type, dst_type, src[0], dst, num_dsts);
   }
   else {
      assert(num_srcs == num_dsts);
      memcpy(dst, src, num_dsts * sizeof *dst);
   }
}