lp_bld_logic.c revision 8c34a41278b8bfd36e4bd8ab2e417430382b3365 
1/**************************************************************************
2 *
3 * Copyright 2009 VMware, Inc.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28/**
29 * @file
30 * Helper functions for logical operations.
31 *
32 * @author Jose Fonseca <jfonseca@vmware.com>
33 */
34
35
36#include "util/u_cpu_detect.h"
37#include "util/u_memory.h"
38#include "util/u_debug.h"
39
40#include "lp_bld_type.h"
41#include "lp_bld_const.h"
42#include "lp_bld_init.h"
43#include "lp_bld_intr.h"
44#include "lp_bld_debug.h"
45#include "lp_bld_logic.h"
46
47
48/*
49 * XXX
50 *
51 * Selection with vector conditional like
52 *
53 *    select <4 x i1> %C, %A, %B
54 *
55 * is valid IR (e.g. llvm/test/Assembler/vector-select.ll), but it is not
56 * supported on any backend.
57 *
58 * Expanding the boolean vector to full SIMD register width, as in
59 *
60 *    sext <4 x i1> %C to <4 x i32>
61 *
62 * is valid and supported (e.g., llvm/test/CodeGen/X86/vec_compare.ll), but
63 * it causes assertion failures in LLVM 2.6. It appears to work correctly on
64 * LLVM 2.7.
65 */
66
67
68/**
69 * Build code to compare two values 'a' and 'b' of 'type' using the given func.
70 * \param func  one of PIPE_FUNC_x
71 * The result values will be 0 for false or ~0 for true.
72 */
73LLVMValueRef
74lp_build_compare(struct gallivm_state *gallivm,
75                 const struct lp_type type,
76                 unsigned func,
77                 LLVMValueRef a,
78                 LLVMValueRef b)
79{
80   LLVMBuilderRef builder = gallivm->builder;
81   LLVMTypeRef int_vec_type = lp_build_int_vec_type(gallivm, type);
82   LLVMValueRef zeros = LLVMConstNull(int_vec_type);
83   LLVMValueRef ones = LLVMConstAllOnes(int_vec_type);
84   LLVMValueRef cond;
85   LLVMValueRef res;
86
87   assert(func >= PIPE_FUNC_NEVER);
88   assert(func <= PIPE_FUNC_ALWAYS);
89   assert(lp_check_value(type, a));
90   assert(lp_check_value(type, b));
91
92   if(func == PIPE_FUNC_NEVER)
93      return zeros;
94   if(func == PIPE_FUNC_ALWAYS)
95      return ones;
96
97#if defined(PIPE_ARCH_X86) || defined(PIPE_ARCH_X86_64)
98   /*
99    * There are no unsigned integer comparison instructions in SSE.
100    */
101
102   if (!type.floating && !type.sign &&
103       type.width * type.length == 128 &&
104       util_cpu_caps.has_sse2 &&
105       (func == PIPE_FUNC_LESS ||
106        func == PIPE_FUNC_LEQUAL ||
107        func == PIPE_FUNC_GREATER ||
108        func == PIPE_FUNC_GEQUAL) &&
109       (gallivm_debug & GALLIVM_DEBUG_PERF)) {
110         debug_printf("%s: inefficient <%u x i%u> unsigned comparison\n",
111                      __FUNCTION__, type.length, type.width);
112   }
113#endif
114
115#if HAVE_LLVM < 0x0207
116#if defined(PIPE_ARCH_X86) || defined(PIPE_ARCH_X86_64)
117   if(type.width * type.length == 128) {
118      if(type.floating && util_cpu_caps.has_sse) {
119         /* float[4] comparison */
120         LLVMTypeRef vec_type = lp_build_vec_type(gallivm, type);
121         LLVMValueRef args[3];
122         unsigned cc;
123         boolean swap;
124
125         swap = FALSE;
126         switch(func) {
127         case PIPE_FUNC_EQUAL:
128            cc = 0;
129            break;
130         case PIPE_FUNC_NOTEQUAL:
131            cc = 4;
132            break;
133         case PIPE_FUNC_LESS:
134            cc = 1;
135            break;
136         case PIPE_FUNC_LEQUAL:
137            cc = 2;
138            break;
139         case PIPE_FUNC_GREATER:
140            cc = 1;
141            swap = TRUE;
142            break;
143         case PIPE_FUNC_GEQUAL:
144            cc = 2;
145            swap = TRUE;
146            break;
147         default:
148            assert(0);
149            return lp_build_undef(gallivm, type);
150         }
151
152         if(swap) {
153            args[0] = b;
154            args[1] = a;
155         }
156         else {
157            args[0] = a;
158            args[1] = b;
159         }
160
161         args[2] = LLVMConstInt(LLVMInt8TypeInContext(gallivm->context), cc, 0);
162         res = lp_build_intrinsic(builder,
163                                  "llvm.x86.sse.cmp.ps",
164                                  vec_type,
165                                  args, 3);
166         res = LLVMBuildBitCast(builder, res, int_vec_type, "");
167         return res;
168      }
169      else if(util_cpu_caps.has_sse2) {
170         /* int[4] comparison */
171         static const struct {
172            unsigned swap:1;
173            unsigned eq:1;
174            unsigned gt:1;
175            unsigned not:1;
176         } table[] = {
177            {0, 0, 0, 1}, /* PIPE_FUNC_NEVER */
178            {1, 0, 1, 0}, /* PIPE_FUNC_LESS */
179            {0, 1, 0, 0}, /* PIPE_FUNC_EQUAL */
180            {0, 0, 1, 1}, /* PIPE_FUNC_LEQUAL */
181            {0, 0, 1, 0}, /* PIPE_FUNC_GREATER */
182            {0, 1, 0, 1}, /* PIPE_FUNC_NOTEQUAL */
183            {1, 0, 1, 1}, /* PIPE_FUNC_GEQUAL */
184            {0, 0, 0, 0}  /* PIPE_FUNC_ALWAYS */
185         };
186         const char *pcmpeq;
187         const char *pcmpgt;
188         LLVMValueRef args[2];
189         LLVMValueRef res;
190         LLVMTypeRef vec_type = lp_build_vec_type(gallivm, type);
191
192         switch (type.width) {
193         case 8:
194            pcmpeq = "llvm.x86.sse2.pcmpeq.b";
195            pcmpgt = "llvm.x86.sse2.pcmpgt.b";
196            break;
197         case 16:
198            pcmpeq = "llvm.x86.sse2.pcmpeq.w";
199            pcmpgt = "llvm.x86.sse2.pcmpgt.w";
200            break;
201         case 32:
202            pcmpeq = "llvm.x86.sse2.pcmpeq.d";
203            pcmpgt = "llvm.x86.sse2.pcmpgt.d";
204            break;
205         default:
206            assert(0);
207            return lp_build_undef(gallivm, type);
208         }
209
210         /* There are no unsigned comparison instructions. So flip the sign bit
211          * so that the results match.
212          */
213         if (table[func].gt && !type.sign) {
214            LLVMValueRef msb = lp_build_const_int_vec(gallivm, type, (unsigned long long)1 << (type.width - 1));
215            a = LLVMBuildXor(builder, a, msb, "");
216            b = LLVMBuildXor(builder, b, msb, "");
217         }
218
219         if(table[func].swap) {
220            args[0] = b;
221            args[1] = a;
222         }
223         else {
224            args[0] = a;
225            args[1] = b;
226         }
227
228         if(table[func].eq)
229            res = lp_build_intrinsic(builder, pcmpeq, vec_type, args, 2);
230         else if (table[func].gt)
231            res = lp_build_intrinsic(builder, pcmpgt, vec_type, args, 2);
232         else
233            res = LLVMConstNull(vec_type);
234
235         if(table[func].not)
236            res = LLVMBuildNot(builder, res, "");
237
238         return res;
239      }
240   } /* if (type.width * type.length == 128) */
241#endif
242#endif /* HAVE_LLVM < 0x0207 */
243
244   /* XXX: It is not clear if we should use the ordered or unordered operators */
245
246   if(type.floating) {
247      LLVMRealPredicate op;
248      switch(func) {
249      case PIPE_FUNC_NEVER:
250         op = LLVMRealPredicateFalse;
251         break;
252      case PIPE_FUNC_ALWAYS:
253         op = LLVMRealPredicateTrue;
254         break;
255      case PIPE_FUNC_EQUAL:
256         op = LLVMRealUEQ;
257         break;
258      case PIPE_FUNC_NOTEQUAL:
259         op = LLVMRealUNE;
260         break;
261      case PIPE_FUNC_LESS:
262         op = LLVMRealULT;
263         break;
264      case PIPE_FUNC_LEQUAL:
265         op = LLVMRealULE;
266         break;
267      case PIPE_FUNC_GREATER:
268         op = LLVMRealUGT;
269         break;
270      case PIPE_FUNC_GEQUAL:
271         op = LLVMRealUGE;
272         break;
273      default:
274         assert(0);
275         return lp_build_undef(gallivm, type);
276      }
277
278#if HAVE_LLVM >= 0x0207
279      cond = LLVMBuildFCmp(builder, op, a, b, "");
280      res = LLVMBuildSExt(builder, cond, int_vec_type, "");
281#else
282      if (type.length == 1) {
283         cond = LLVMBuildFCmp(builder, op, a, b, "");
284         res = LLVMBuildSExt(builder, cond, int_vec_type, "");
285      }
286      else {
287         unsigned i;
288
289         res = LLVMGetUndef(int_vec_type);
290
291         debug_printf("%s: warning: using slow element-wise float"
292                      " vector comparison\n", __FUNCTION__);
293         for (i = 0; i < type.length; ++i) {
294            LLVMValueRef index = lp_build_const_int32(gallivm, i);
295            cond = LLVMBuildFCmp(builder, op,
296                                 LLVMBuildExtractElement(builder, a, index, ""),
297                                 LLVMBuildExtractElement(builder, b, index, ""),
298                                 "");
299            cond = LLVMBuildSelect(builder, cond,
300                                   LLVMConstExtractElement(ones, index),
301                                   LLVMConstExtractElement(zeros, index),
302                                   "");
303            res = LLVMBuildInsertElement(builder, res, cond, index, "");
304         }
305      }
306#endif
307   }
308   else {
309      LLVMIntPredicate op;
310      switch(func) {
311      case PIPE_FUNC_EQUAL:
312         op = LLVMIntEQ;
313         break;
314      case PIPE_FUNC_NOTEQUAL:
315         op = LLVMIntNE;
316         break;
317      case PIPE_FUNC_LESS:
318         op = type.sign ? LLVMIntSLT : LLVMIntULT;
319         break;
320      case PIPE_FUNC_LEQUAL:
321         op = type.sign ? LLVMIntSLE : LLVMIntULE;
322         break;
323      case PIPE_FUNC_GREATER:
324         op = type.sign ? LLVMIntSGT : LLVMIntUGT;
325         break;
326      case PIPE_FUNC_GEQUAL:
327         op = type.sign ? LLVMIntSGE : LLVMIntUGE;
328         break;
329      default:
330         assert(0);
331         return lp_build_undef(gallivm, type);
332      }
333
334#if HAVE_LLVM >= 0x0207
335      cond = LLVMBuildICmp(builder, op, a, b, "");
336      res = LLVMBuildSExt(builder, cond, int_vec_type, "");
337#else
338      if (type.length == 1) {
339         cond = LLVMBuildICmp(builder, op, a, b, "");
340         res = LLVMBuildSExt(builder, cond, int_vec_type, "");
341      }
342      else {
343         unsigned i;
344
345         res = LLVMGetUndef(int_vec_type);
346
347         if (gallivm_debug & GALLIVM_DEBUG_PERF) {
348            debug_printf("%s: using slow element-wise int"
349                         " vector comparison\n", __FUNCTION__);
350         }
351
352         for(i = 0; i < type.length; ++i) {
353            LLVMValueRef index = lp_build_const_int32(gallivm, i);
354            cond = LLVMBuildICmp(builder, op,
355                                 LLVMBuildExtractElement(builder, a, index, ""),
356                                 LLVMBuildExtractElement(builder, b, index, ""),
357                                 "");
358            cond = LLVMBuildSelect(builder, cond,
359                                   LLVMConstExtractElement(ones, index),
360                                   LLVMConstExtractElement(zeros, index),
361                                   "");
362            res = LLVMBuildInsertElement(builder, res, cond, index, "");
363         }
364      }
365#endif
366   }
367
368   return res;
369}
370
371
372
373/**
374 * Build code to compare two values 'a' and 'b' using the given func.
375 * \param func  one of PIPE_FUNC_x
376 * The result values will be 0 for false or ~0 for true.
377 */
378LLVMValueRef
379lp_build_cmp(struct lp_build_context *bld,
380             unsigned func,
381             LLVMValueRef a,
382             LLVMValueRef b)
383{
384   return lp_build_compare(bld->gallivm, bld->type, func, a, b);
385}
386
387
388/**
389 * Return (mask & a) | (~mask & b);
390 */
391LLVMValueRef
392lp_build_select_bitwise(struct lp_build_context *bld,
393                        LLVMValueRef mask,
394                        LLVMValueRef a,
395                        LLVMValueRef b)
396{
397   LLVMBuilderRef builder = bld->gallivm->builder;
398   struct lp_type type = bld->type;
399   LLVMValueRef res;
400
401   assert(lp_check_value(type, a));
402   assert(lp_check_value(type, b));
403
404   if (a == b) {
405      return a;
406   }
407
408   if(type.floating) {
409      LLVMTypeRef int_vec_type = lp_build_int_vec_type(bld->gallivm, type);
410      a = LLVMBuildBitCast(builder, a, int_vec_type, "");
411      b = LLVMBuildBitCast(builder, b, int_vec_type, "");
412   }
413
414   a = LLVMBuildAnd(builder, a, mask, "");
415
416   /* This often gets translated to PANDN, but sometimes the NOT is
417    * pre-computed and stored in another constant. The best strategy depends
418    * on available registers, so it is not a big deal -- hopefully LLVM does
419    * the right decision attending the rest of the program.
420    */
421   b = LLVMBuildAnd(builder, b, LLVMBuildNot(builder, mask, ""), "");
422
423   res = LLVMBuildOr(builder, a, b, "");
424
425   if(type.floating) {
426      LLVMTypeRef vec_type = lp_build_vec_type(bld->gallivm, type);
427      res = LLVMBuildBitCast(builder, res, vec_type, "");
428   }
429
430   return res;
431}
432
433
434/**
435 * Return mask ? a : b;
436 *
437 * mask is a bitwise mask, composed of 0 or ~0 for each element. Any other value
438 * will yield unpredictable results.
439 */
440LLVMValueRef
441lp_build_select(struct lp_build_context *bld,
442                LLVMValueRef mask,
443                LLVMValueRef a,
444                LLVMValueRef b)
445{
446   LLVMBuilderRef builder = bld->gallivm->builder;
447   LLVMContextRef lc = bld->gallivm->context;
448   struct lp_type type = bld->type;
449   LLVMValueRef res;
450
451   assert(lp_check_value(type, a));
452   assert(lp_check_value(type, b));
453
454   if(a == b)
455      return a;
456
457   if (type.length == 1) {
458      mask = LLVMBuildTrunc(builder, mask, LLVMInt1TypeInContext(lc), "");
459      res = LLVMBuildSelect(builder, mask, a, b, "");
460   }
461   else if (0) {
462      /* Generate a vector select.
463       *
464       * XXX: Using vector selects would avoid emitting intrinsics, but they aren't
465       * properly supported yet.
466       *
467       * LLVM 3.0 includes experimental support provided the -promote-elements
468       * options is passed to LLVM's command line (e.g., via
469       * llvm::cl::ParseCommandLineOptions), but resulting code quality is much
470       * worse, probably because some optimization passes don't know how to
471       * handle vector selects.
472       *
473       * See also:
474       * - http://lists.cs.uiuc.edu/pipermail/llvmdev/2011-October/043659.html
475       */
476
477      /* Convert the mask to a vector of booleans.
478       * XXX: There are two ways to do this. Decide what's best.
479       */
480      if (1) {
481         LLVMTypeRef bool_vec_type = LLVMVectorType(LLVMInt1TypeInContext(lc), type.length);
482         mask = LLVMBuildTrunc(builder, mask, bool_vec_type, "");
483      } else {
484         mask = LLVMBuildICmp(builder, LLVMIntNE, mask, LLVMConstNull(bld->int_vec_type), "");
485      }
486      res = LLVMBuildSelect(builder, mask, a, b, "");
487   }
488   else if (util_cpu_caps.has_sse4_1 &&
489            type.width * type.length == 128 &&
490            !LLVMIsConstant(a) &&
491            !LLVMIsConstant(b) &&
492            !LLVMIsConstant(mask)) {
493      const char *intrinsic;
494      LLVMTypeRef arg_type;
495      LLVMValueRef args[3];
496
497      if (type.floating &&
498          type.width == 64) {
499         intrinsic = "llvm.x86.sse41.blendvpd";
500         arg_type = LLVMVectorType(LLVMDoubleTypeInContext(lc), 2);
501      } else if (type.floating &&
502                 type.width == 32) {
503         intrinsic = "llvm.x86.sse41.blendvps";
504         arg_type = LLVMVectorType(LLVMFloatTypeInContext(lc), 4);
505      } else {
506         intrinsic = "llvm.x86.sse41.pblendvb";
507         arg_type = LLVMVectorType(LLVMInt8TypeInContext(lc), 16);
508      }
509
510      if (arg_type != bld->int_vec_type) {
511         mask = LLVMBuildBitCast(builder, mask, arg_type, "");
512      }
513
514      if (arg_type != bld->vec_type) {
515         a = LLVMBuildBitCast(builder, a, arg_type, "");
516         b = LLVMBuildBitCast(builder, b, arg_type, "");
517      }
518
519      args[0] = b;
520      args[1] = a;
521      args[2] = mask;
522
523      res = lp_build_intrinsic(builder, intrinsic,
524                               arg_type, args, Elements(args));
525
526      if (arg_type != bld->vec_type) {
527         res = LLVMBuildBitCast(builder, res, bld->vec_type, "");
528      }
529   }
530   else {
531      res = lp_build_select_bitwise(bld, mask, a, b);
532   }
533
534   return res;
535}
536
537
538/**
539 * Return mask ? a : b;
540 *
541 * mask is a TGSI_WRITEMASK_xxx.
542 */
543LLVMValueRef
544lp_build_select_aos(struct lp_build_context *bld,
545                    unsigned mask,
546                    LLVMValueRef a,
547                    LLVMValueRef b)
548{
549   LLVMBuilderRef builder = bld->gallivm->builder;
550   const struct lp_type type = bld->type;
551   const unsigned n = type.length;
552   unsigned i, j;
553
554   assert((mask & ~0xf) == 0);
555   assert(lp_check_value(type, a));
556   assert(lp_check_value(type, b));
557
558   if(a == b)
559      return a;
560   if((mask & 0xf) == 0xf)
561      return a;
562   if((mask & 0xf) == 0x0)
563      return b;
564   if(a == bld->undef || b == bld->undef)
565      return bld->undef;
566
567   /*
568    * There are two major ways of accomplishing this:
569    * - with a shuffle
570    * - with a select
571    *
572    * The flip between these is empirical and might need to be adjusted.
573    */
574   if (n <= 4) {
575      /*
576       * Shuffle.
577       */
578      LLVMTypeRef elem_type = LLVMInt32TypeInContext(bld->gallivm->context);
579      LLVMValueRef shuffles[LP_MAX_VECTOR_LENGTH];
580
581      for(j = 0; j < n; j += 4)
582         for(i = 0; i < 4; ++i)
583            shuffles[j + i] = LLVMConstInt(elem_type,
584                                           (mask & (1 << i) ? 0 : n) + j + i,
585                                           0);
586
587      return LLVMBuildShuffleVector(builder, a, b, LLVMConstVector(shuffles, n), "");
588   }
589   else {
590      LLVMValueRef mask_vec = lp_build_const_mask_aos(bld->gallivm, type, mask);
591      return lp_build_select(bld, mask_vec, a, b);
592   }
593}
594