1/**************************************************************************
2 *
3 * Copyright 2010 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 SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
17 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
18 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
19 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
20 * USE OR OTHER DEALINGS IN THE SOFTWARE.
21 *
22 * The above copyright notice and this permission notice (including the
23 * next paragraph) shall be included in all copies or substantial portions
24 * of the Software.
25 *
26 **************************************************************************/
27
28
29#include "util/u_debug.h"
30#include "util/u_cpu_detect.h"
31#include "util/u_math.h"
32#include "lp_bld_debug.h"
33#include "lp_bld_const.h"
34#include "lp_bld_format.h"
35#include "lp_bld_gather.h"
36#include "lp_bld_swizzle.h"
37#include "lp_bld_type.h"
38#include "lp_bld_init.h"
39#include "lp_bld_intr.h"
40#include "lp_bld_pack.h"
41
42
43/**
44 * Get the pointer to one element from scatter positions in memory.
45 *
46 * @sa lp_build_gather()
47 */
48LLVMValueRef
49lp_build_gather_elem_ptr(struct gallivm_state *gallivm,
50                         unsigned length,
51                         LLVMValueRef base_ptr,
52                         LLVMValueRef offsets,
53                         unsigned i)
54{
55   LLVMValueRef offset;
56   LLVMValueRef ptr;
57
58   assert(LLVMTypeOf(base_ptr) == LLVMPointerType(LLVMInt8TypeInContext(gallivm->context), 0));
59
60   if (length == 1) {
61      assert(i == 0);
62      offset = offsets;
63   } else {
64      LLVMValueRef index = lp_build_const_int32(gallivm, i);
65      offset = LLVMBuildExtractElement(gallivm->builder, offsets, index, "");
66   }
67
68   ptr = LLVMBuildGEP(gallivm->builder, base_ptr, &offset, 1, "");
69
70   return ptr;
71}
72
73
74/**
75 * Gather one element from scatter positions in memory.
76 *
77 * @sa lp_build_gather()
78 */
79LLVMValueRef
80lp_build_gather_elem(struct gallivm_state *gallivm,
81                     unsigned length,
82                     unsigned src_width,
83                     unsigned dst_width,
84                     boolean aligned,
85                     LLVMValueRef base_ptr,
86                     LLVMValueRef offsets,
87                     unsigned i,
88                     boolean vector_justify)
89{
90   LLVMTypeRef src_type = LLVMIntTypeInContext(gallivm->context, src_width);
91   LLVMTypeRef src_ptr_type = LLVMPointerType(src_type, 0);
92   LLVMTypeRef dst_elem_type = LLVMIntTypeInContext(gallivm->context, dst_width);
93   LLVMValueRef ptr;
94   LLVMValueRef res;
95
96   assert(LLVMTypeOf(base_ptr) == LLVMPointerType(LLVMInt8TypeInContext(gallivm->context), 0));
97
98   ptr = lp_build_gather_elem_ptr(gallivm, length, base_ptr, offsets, i);
99   ptr = LLVMBuildBitCast(gallivm->builder, ptr, src_ptr_type, "");
100   res = LLVMBuildLoad(gallivm->builder, ptr, "");
101
102   /* XXX
103    * On some archs we probably really want to avoid having to deal
104    * with alignments lower than 4 bytes (if fetch size is a power of
105    * two >= 32). On x86 it doesn't matter, however.
106    * We should be able to guarantee full alignment for any kind of texture
107    * fetch (except ARB_texture_buffer_range, oops), but not vertex fetch
108    * (there's PIPE_CAP_VERTEX_BUFFER_OFFSET_4BYTE_ALIGNED_ONLY and friends
109    * but I don't think that's quite what we wanted).
110    * For ARB_texture_buffer_range, PIPE_CAP_TEXTURE_BUFFER_OFFSET_ALIGNMENT
111    * looks like a good fit, but it seems this cap bit (and OpenGL) aren't
112    * enforcing what we want (which is what d3d10 does, the offset needs to
113    * be aligned to element size, but GL has bytes regardless of element
114    * size which would only leave us with minimum alignment restriction of 16
115    * which doesn't make much sense if the type isn't 4x32bit). Due to
116    * translation of offsets to first_elem in sampler_views it actually seems
117    * gallium could not do anything else except 16 no matter what...
118    */
119   if (!aligned) {
120      LLVMSetAlignment(res, 1);
121   } else if (!util_is_power_of_two_or_zero(src_width)) {
122      /*
123       * Full alignment is impossible, assume the caller really meant
124       * the individual elements were aligned (e.g. 3x32bit format).
125       * And yes the generated code may otherwise crash, llvm will
126       * really assume 128bit alignment with a 96bit fetch (I suppose
127       * that makes sense as it can just assume the upper 32bit to be
128       * whatever).
129       * Maybe the caller should be able to explicitly set this, but
130       * this should cover all the 3-channel formats.
131       */
132      if (((src_width / 24) * 24 == src_width) &&
133           util_is_power_of_two_or_zero(src_width / 24)) {
134          LLVMSetAlignment(res, src_width / 24);
135      } else {
136         LLVMSetAlignment(res, 1);
137      }
138   }
139
140   assert(src_width <= dst_width);
141   if (src_width < dst_width) {
142      res = LLVMBuildZExt(gallivm->builder, res, dst_elem_type, "");
143      if (vector_justify) {
144#ifdef PIPE_ARCH_BIG_ENDIAN
145         res = LLVMBuildShl(gallivm->builder, res,
146                            LLVMConstInt(dst_elem_type, dst_width - src_width, 0), "");
147#endif
148      }
149   }
150
151   return res;
152}
153
154
155/**
156 * Gather one element from scatter positions in memory.
157 * Nearly the same as above, however the individual elements
158 * may be vectors themselves, and fetches may be float type.
159 * Can also do pad vector instead of ZExt.
160 *
161 * @sa lp_build_gather()
162 */
163static LLVMValueRef
164lp_build_gather_elem_vec(struct gallivm_state *gallivm,
165                         unsigned length,
166                         unsigned src_width,
167                         LLVMTypeRef src_type,
168                         struct lp_type dst_type,
169                         boolean aligned,
170                         LLVMValueRef base_ptr,
171                         LLVMValueRef offsets,
172                         unsigned i,
173                         boolean vector_justify)
174{
175   LLVMValueRef ptr, res;
176   LLVMTypeRef src_ptr_type = LLVMPointerType(src_type, 0);
177   assert(LLVMTypeOf(base_ptr) == LLVMPointerType(LLVMInt8TypeInContext(gallivm->context), 0));
178
179   ptr = lp_build_gather_elem_ptr(gallivm, length, base_ptr, offsets, i);
180   ptr = LLVMBuildBitCast(gallivm->builder, ptr, src_ptr_type, "");
181   res = LLVMBuildLoad(gallivm->builder, ptr, "");
182
183   /* XXX
184    * On some archs we probably really want to avoid having to deal
185    * with alignments lower than 4 bytes (if fetch size is a power of
186    * two >= 32). On x86 it doesn't matter, however.
187    * We should be able to guarantee full alignment for any kind of texture
188    * fetch (except ARB_texture_buffer_range, oops), but not vertex fetch
189    * (there's PIPE_CAP_VERTEX_BUFFER_OFFSET_4BYTE_ALIGNED_ONLY and friends
190    * but I don't think that's quite what we wanted).
191    * For ARB_texture_buffer_range, PIPE_CAP_TEXTURE_BUFFER_OFFSET_ALIGNMENT
192    * looks like a good fit, but it seems this cap bit (and OpenGL) aren't
193    * enforcing what we want (which is what d3d10 does, the offset needs to
194    * be aligned to element size, but GL has bytes regardless of element
195    * size which would only leave us with minimum alignment restriction of 16
196    * which doesn't make much sense if the type isn't 4x32bit). Due to
197    * translation of offsets to first_elem in sampler_views it actually seems
198    * gallium could not do anything else except 16 no matter what...
199    */
200   if (!aligned) {
201      LLVMSetAlignment(res, 1);
202   } else if (!util_is_power_of_two_or_zero(src_width)) {
203      /*
204       * Full alignment is impossible, assume the caller really meant
205       * the individual elements were aligned (e.g. 3x32bit format).
206       * And yes the generated code may otherwise crash, llvm will
207       * really assume 128bit alignment with a 96bit fetch (I suppose
208       * that makes sense as it can just assume the upper 32bit to be
209       * whatever).
210       * Maybe the caller should be able to explicitly set this, but
211       * this should cover all the 3-channel formats.
212       */
213      if (((src_width / 24) * 24 == src_width) &&
214           util_is_power_of_two_or_zero(src_width / 24)) {
215          LLVMSetAlignment(res, src_width / 24);
216      } else {
217         LLVMSetAlignment(res, 1);
218      }
219   }
220
221   assert(src_width <= dst_type.width * dst_type.length);
222   if (src_width < dst_type.width * dst_type.length) {
223      if (dst_type.length > 1) {
224         res = lp_build_pad_vector(gallivm, res, dst_type.length);
225         /*
226          * vector_justify hopefully a non-issue since we only deal
227          * with src_width >= 32 here?
228          */
229      } else {
230         LLVMTypeRef dst_elem_type = lp_build_vec_type(gallivm, dst_type);
231
232         /*
233          * Only valid if src_ptr_type is int type...
234          */
235         res = LLVMBuildZExt(gallivm->builder, res, dst_elem_type, "");
236
237#ifdef PIPE_ARCH_BIG_ENDIAN
238         if (vector_justify) {
239         res = LLVMBuildShl(gallivm->builder, res,
240                            LLVMConstInt(dst_elem_type,
241                                         dst_type.width - src_width, 0), "");
242         }
243         if (src_width == 48) {
244            /* Load 3x16 bit vector.
245             * The sequence of loads on big-endian hardware proceeds as follows.
246             * 16-bit fields are denoted by X, Y, Z, and 0.  In memory, the sequence
247             * of three fields appears in the order X, Y, Z.
248             *
249             * Load 32-bit word: 0.0.X.Y
250             * Load 16-bit halfword: 0.0.0.Z
251             * Rotate left: 0.X.Y.0
252             * Bitwise OR: 0.X.Y.Z
253             *
254             * The order in which we need the fields in the result is 0.Z.Y.X,
255             * the same as on little-endian; permute 16-bit fields accordingly
256             * within 64-bit register:
257             */
258            LLVMValueRef shuffles[4] = {
259               lp_build_const_int32(gallivm, 2),
260               lp_build_const_int32(gallivm, 1),
261               lp_build_const_int32(gallivm, 0),
262               lp_build_const_int32(gallivm, 3),
263            };
264            res = LLVMBuildBitCast(gallivm->builder, res,
265                                   lp_build_vec_type(gallivm, lp_type_uint_vec(16, 4*16)), "");
266            res = LLVMBuildShuffleVector(gallivm->builder, res, res, LLVMConstVector(shuffles, 4), "");
267            res = LLVMBuildBitCast(gallivm->builder, res, dst_elem_type, "");
268         }
269#endif
270      }
271   }
272   return res;
273}
274
275
276
277
278static LLVMValueRef
279lp_build_gather_avx2(struct gallivm_state *gallivm,
280                     unsigned length,
281                     unsigned src_width,
282                     struct lp_type dst_type,
283                     LLVMValueRef base_ptr,
284                     LLVMValueRef offsets)
285{
286   LLVMBuilderRef builder = gallivm->builder;
287   LLVMTypeRef src_type, src_vec_type;
288   LLVMValueRef res;
289   struct lp_type res_type = dst_type;
290   res_type.length *= length;
291
292   if (dst_type.floating) {
293      src_type = src_width == 64 ? LLVMDoubleTypeInContext(gallivm->context) :
294                                   LLVMFloatTypeInContext(gallivm->context);
295   } else {
296      src_type = LLVMIntTypeInContext(gallivm->context, src_width);
297   }
298   src_vec_type = LLVMVectorType(src_type, length);
299
300   /* XXX should allow hw scaling (can handle i8, i16, i32, i64 for x86) */
301   assert(LLVMTypeOf(base_ptr) == LLVMPointerType(LLVMInt8TypeInContext(gallivm->context), 0));
302
303   if (0) {
304      /*
305       * XXX: This will cause LLVM pre 3.7 to hang; it works on LLVM 3.8 but
306       * will not use the AVX2 gather instrinsics (even with llvm 4.0), at
307       * least with Haswell. See
308       * http://lists.llvm.org/pipermail/llvm-dev/2016-January/094448.html
309       * And the generated code doing the emulation is quite a bit worse
310       * than what we get by doing it ourselves too.
311       */
312      LLVMTypeRef i32_type = LLVMIntTypeInContext(gallivm->context, 32);
313      LLVMTypeRef i32_vec_type = LLVMVectorType(i32_type, length);
314      LLVMTypeRef i1_type = LLVMIntTypeInContext(gallivm->context, 1);
315      LLVMTypeRef i1_vec_type = LLVMVectorType(i1_type, length);
316      LLVMTypeRef src_ptr_type = LLVMPointerType(src_type, 0);
317      LLVMValueRef src_ptr;
318
319      base_ptr = LLVMBuildBitCast(builder, base_ptr, src_ptr_type, "");
320
321      /* Rescale offsets from bytes to elements */
322      LLVMValueRef scale = LLVMConstInt(i32_type, src_width/8, 0);
323      scale = lp_build_broadcast(gallivm, i32_vec_type, scale);
324      assert(LLVMTypeOf(offsets) == i32_vec_type);
325      offsets = LLVMBuildSDiv(builder, offsets, scale, "");
326
327      src_ptr = LLVMBuildGEP(builder, base_ptr, &offsets, 1, "vector-gep");
328
329      char intrinsic[64];
330      util_snprintf(intrinsic, sizeof intrinsic, "llvm.masked.gather.v%u%s%u",
331                    length, dst_type.floating ? "f" : "i", src_width);
332      LLVMValueRef alignment = LLVMConstInt(i32_type, src_width/8, 0);
333      LLVMValueRef mask = LLVMConstAllOnes(i1_vec_type);
334      LLVMValueRef passthru = LLVMGetUndef(src_vec_type);
335
336      LLVMValueRef args[] = { src_ptr, alignment, mask, passthru };
337
338      res = lp_build_intrinsic(builder, intrinsic, src_vec_type, args, 4, 0);
339   } else {
340      LLVMTypeRef i8_type = LLVMIntTypeInContext(gallivm->context, 8);
341      const char *intrinsic = NULL;
342      unsigned l_idx = 0;
343
344      assert(src_width == 32 || src_width == 64);
345      if (src_width == 32) {
346         assert(length == 4 || length == 8);
347      } else {
348         assert(length == 2 || length == 4);
349      }
350
351      static const char *intrinsics[2][2][2] = {
352
353         {{"llvm.x86.avx2.gather.d.d",
354           "llvm.x86.avx2.gather.d.d.256"},
355          {"llvm.x86.avx2.gather.d.q",
356           "llvm.x86.avx2.gather.d.q.256"}},
357
358         {{"llvm.x86.avx2.gather.d.ps",
359           "llvm.x86.avx2.gather.d.ps.256"},
360          {"llvm.x86.avx2.gather.d.pd",
361           "llvm.x86.avx2.gather.d.pd.256"}},
362      };
363
364      if ((src_width == 32 && length == 8) ||
365          (src_width == 64 && length == 4)) {
366         l_idx = 1;
367      }
368      intrinsic = intrinsics[dst_type.floating][src_width == 64][l_idx];
369
370      LLVMValueRef passthru = LLVMGetUndef(src_vec_type);
371      LLVMValueRef mask = LLVMConstAllOnes(src_vec_type);
372      mask = LLVMConstBitCast(mask, src_vec_type);
373      LLVMValueRef scale = LLVMConstInt(i8_type, 1, 0);
374
375      LLVMValueRef args[] = { passthru, base_ptr, offsets, mask, scale };
376
377      res = lp_build_intrinsic(builder, intrinsic, src_vec_type, args, 5, 0);
378   }
379   res = LLVMBuildBitCast(builder, res, lp_build_vec_type(gallivm, res_type), "");
380
381   return res;
382}
383
384
385/**
386 * Gather elements from scatter positions in memory into a single vector.
387 * Use for fetching texels from a texture.
388 * For SSE, typical values are length=4, src_width=32, dst_width=32.
389 *
390 * When src_width < dst_width, the return value can be justified in
391 * one of two ways:
392 * "integer justification" is used when the caller treats the destination
393 * as a packed integer bitmask, as described by the channels' "shift" and
394 * "width" fields;
395 * "vector justification" is used when the caller casts the destination
396 * to a vector and needs channel X to be in vector element 0.
397 *
398 * @param length length of the offsets
399 * @param src_width src element width in bits
400 * @param dst_type result element type (src will be expanded to fit,
401 *        but truncation is not allowed)
402 *        (this may be a vector, must be pot sized)
403 * @param aligned whether the data is guaranteed to be aligned (to src_width)
404 * @param base_ptr base pointer, needs to be a i8 pointer type.
405 * @param offsets vector with offsets
406 * @param vector_justify select vector rather than integer justification
407 */
408LLVMValueRef
409lp_build_gather(struct gallivm_state *gallivm,
410                unsigned length,
411                unsigned src_width,
412                struct lp_type dst_type,
413                boolean aligned,
414                LLVMValueRef base_ptr,
415                LLVMValueRef offsets,
416                boolean vector_justify)
417{
418   LLVMValueRef res;
419   boolean need_expansion = src_width < dst_type.width * dst_type.length;
420   boolean vec_fetch;
421   struct lp_type fetch_type, fetch_dst_type;
422   LLVMTypeRef src_type;
423
424   assert(src_width <= dst_type.width * dst_type.length);
425
426   /*
427    * This is quite a mess...
428    * Figure out if the fetch should be done as:
429    * a) scalar or vector
430    * b) float or int
431    *
432    * As an example, for a 96bit fetch expanded into 4x32bit, it is better
433    * to use (3x32bit) vector type (then pad the vector). Otherwise, the
434    * zext will cause extra instructions.
435    * However, the same isn't true for 3x16bit (the codegen for that is
436    * completely worthless on x86 simd, and for 3x8bit is is way worse
437    * still, don't try that... (To get really good code out of llvm for
438    * these cases, the only way is to decompose the fetches manually
439    * into 1x32bit/1x16bit, or 1x16/1x8bit respectively, although the latter
440    * case requires sse41, otherwise simple scalar zext is way better.
441    * But probably not important enough, so don't bother.)
442    * Also, we try to honor the floating bit of destination (but isn't
443    * possible if caller asks for instance for 2x32bit dst_type with
444    * 48bit fetch - the idea would be to use 3x16bit fetch, pad and
445    * cast to 2x32f type, so the fetch is always int and on top of that
446    * we avoid the vec pad and use scalar zext due the above mentioned
447    * issue).
448    * Note this is optimized for x86 sse2 and up backend. Could be tweaked
449    * for other archs if necessary...
450    */
451   if (((src_width % 32) == 0) && ((src_width % dst_type.width) == 0) &&
452       (dst_type.length > 1)) {
453      /* use vector fetch (if dst_type is vector) */
454      vec_fetch = TRUE;
455      if (dst_type.floating) {
456         fetch_type = lp_type_float_vec(dst_type.width, src_width);
457      } else {
458         fetch_type = lp_type_int_vec(dst_type.width, src_width);
459      }
460      /* intentionally not using lp_build_vec_type here */
461      src_type = LLVMVectorType(lp_build_elem_type(gallivm, fetch_type),
462                                fetch_type.length);
463      fetch_dst_type = fetch_type;
464      fetch_dst_type.length = dst_type.length;
465    } else {
466      /* use scalar fetch */
467      vec_fetch = FALSE;
468      if (dst_type.floating && ((src_width == 32) || (src_width == 64))) {
469         fetch_type = lp_type_float(src_width);
470      } else {
471         fetch_type = lp_type_int(src_width);
472      }
473      src_type = lp_build_vec_type(gallivm, fetch_type);
474      fetch_dst_type = fetch_type;
475      fetch_dst_type.width = dst_type.width * dst_type.length;
476   }
477
478   if (length == 1) {
479      /* Scalar */
480      res = lp_build_gather_elem_vec(gallivm, length,
481                                     src_width, src_type, fetch_dst_type,
482                                     aligned, base_ptr, offsets, 0,
483                                     vector_justify);
484      return LLVMBuildBitCast(gallivm->builder, res,
485                              lp_build_vec_type(gallivm, dst_type), "");
486      /*
487       * Excluding expansion from these paths because if you need it for
488       * 32bit/64bit fetches you're doing it wrong (this is gather, not
489       * conversion) and it would be awkward for floats.
490       */
491   } else if (util_cpu_caps.has_avx2 && !need_expansion &&
492              src_width == 32 && (length == 4 || length == 8)) {
493      return lp_build_gather_avx2(gallivm, length, src_width, dst_type,
494                                  base_ptr, offsets);
495   /*
496    * This looks bad on paper wrt throughtput/latency on Haswell.
497    * Even on Broadwell it doesn't look stellar.
498    * Albeit no measurements were done (but tested to work).
499    * Should definitely enable on Skylake.
500    * (In general, should be more of a win if the fetch is 256bit wide -
501    * this is true for the 32bit case above too.)
502    */
503   } else if (0 && util_cpu_caps.has_avx2 && !need_expansion &&
504              src_width == 64 && (length == 2 || length == 4)) {
505      return lp_build_gather_avx2(gallivm, length, src_width, dst_type,
506                                  base_ptr, offsets);
507   } else {
508      /* Vector */
509
510      LLVMValueRef elems[LP_MAX_VECTOR_WIDTH / 8];
511      unsigned i;
512      boolean vec_zext = FALSE;
513      struct lp_type res_type, gather_res_type;
514      LLVMTypeRef res_t, gather_res_t;
515
516      res_type = fetch_dst_type;
517      res_type.length *= length;
518      gather_res_type = res_type;
519
520      if (src_width == 16 && dst_type.width == 32 && dst_type.length == 1) {
521         /*
522          * Note that llvm is never able to optimize zext/insert combos
523          * directly (i.e. zero the simd reg, then place the elements into
524          * the appropriate place directly). (I think this has to do with
525          * scalar/vector transition.) And scalar 16->32bit zext simd loads
526          * aren't possible (instead loading to scalar reg first).
527          * No idea about other archs...
528          * We could do this manually, but instead we just use a vector
529          * zext, which is simple enough (and, in fact, llvm might optimize
530          * this away).
531          * (We're not trying that with other bit widths as that might not be
532          * easier, in particular with 8 bit values at least with only sse2.)
533          */
534         assert(vec_fetch == FALSE);
535         gather_res_type.width /= 2;
536         fetch_dst_type = fetch_type;
537         src_type = lp_build_vec_type(gallivm, fetch_type);
538         vec_zext = TRUE;
539      }
540      res_t = lp_build_vec_type(gallivm, res_type);
541      gather_res_t = lp_build_vec_type(gallivm, gather_res_type);
542      res = LLVMGetUndef(gather_res_t);
543      for (i = 0; i < length; ++i) {
544         LLVMValueRef index = lp_build_const_int32(gallivm, i);
545         elems[i] = lp_build_gather_elem_vec(gallivm, length,
546                                             src_width, src_type, fetch_dst_type,
547                                             aligned, base_ptr, offsets, i,
548                                             vector_justify);
549         if (!vec_fetch) {
550            res = LLVMBuildInsertElement(gallivm->builder, res, elems[i], index, "");
551         }
552      }
553      if (vec_zext) {
554         res = LLVMBuildZExt(gallivm->builder, res, res_t, "");
555         if (vector_justify) {
556#ifdef PIPE_ARCH_BIG_ENDIAN
557            unsigned sv = dst_type.width - src_width;
558            res = LLVMBuildShl(gallivm->builder, res,
559                               lp_build_const_int_vec(gallivm, res_type, sv), "");
560#endif
561         }
562      }
563      if (vec_fetch) {
564         /*
565          * Do bitcast now otherwise llvm might get some funny ideas wrt
566          * float/int types...
567          */
568         for (i = 0; i < length; i++) {
569            elems[i] = LLVMBuildBitCast(gallivm->builder, elems[i],
570                                        lp_build_vec_type(gallivm, dst_type), "");
571         }
572         res = lp_build_concat(gallivm, elems, dst_type, length);
573      } else {
574         struct lp_type really_final_type = dst_type;
575         assert(res_type.length * res_type.width ==
576                dst_type.length * dst_type.width * length);
577         really_final_type.length *= length;
578         res = LLVMBuildBitCast(gallivm->builder, res,
579                                lp_build_vec_type(gallivm, really_final_type), "");
580      }
581   }
582
583   return res;
584}
585
586LLVMValueRef
587lp_build_gather_values(struct gallivm_state * gallivm,
588                       LLVMValueRef * values,
589                       unsigned value_count)
590{
591   LLVMTypeRef vec_type = LLVMVectorType(LLVMTypeOf(values[0]), value_count);
592   LLVMBuilderRef builder = gallivm->builder;
593   LLVMValueRef vec = LLVMGetUndef(vec_type);
594   unsigned i;
595
596   for (i = 0; i < value_count; i++) {
597      LLVMValueRef index = lp_build_const_int32(gallivm, i);
598      vec = LLVMBuildInsertElement(builder, vec, values[i], index, "");
599   }
600   return vec;
601}
602