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27
28
29/**
30 * @file
31 * Blend LLVM IR generation -- SoA layout.
32 *
33 * Blending in SoA is much faster than AoS, especially when separate rgb/alpha
34 * factors/functions are used, since no channel masking/shuffling is necessary
35 * and we can achieve the full throughput of the SIMD operations. Furthermore
36 * the fragment shader output is also in SoA, so it fits nicely with the rest
37 * of the fragment pipeline.
38 *
39 * The drawback is that to be displayed the color buffer needs to be in AoS
40 * layout, so we need to tile/untile the color buffer before/after rendering.
41 * A color buffer like
42 *
43 *  R11 G11 B11 A11 R12 G12 B12 A12  R13 G13 B13 A13 R14 G14 B14 A14  ...
44 *  R21 G21 B21 A21 R22 G22 B22 A22  R23 G23 B23 A23 R24 G24 B24 A24  ...
45 *
46 *  R31 G31 B31 A31 R32 G32 B32 A32  R33 G33 B33 A33 R34 G34 B34 A34  ...
47 *  R41 G41 B41 A41 R42 G42 B42 A42  R43 G43 B43 A43 R44 G44 B44 A44  ...
48 *
49 *  ... ... ... ... ... ... ... ...  ... ... ... ... ... ... ... ...  ...
50 *
51 * will actually be stored in memory as
52 *
53 *  R11 R12 R21 R22 R13 R14 R23 R24 ... G11 G12 G21 G22 G13 G14 G23 G24 ... B11 B12 B21 B22 B13 B14 B23 B24 ... A11 A12 A21 A22 A13 A14 A23 A24 ...
54 *  R31 R32 R41 R42 R33 R34 R43 R44 ... G31 G32 G41 G42 G33 G34 G43 G44 ... B31 B32 B41 B42 B33 B34 B43 B44 ... A31 A32 A41 A42 A33 A34 A43 A44 ...
55 *  ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
56 *
57 * NOTE: Run lp_blend_test after any change to this file.
58 *
59 * You can also run lp_blend_test to obtain AoS vs SoA benchmarks. Invoking it
60 * as:
61 *
62 *  lp_blend_test -o blend.tsv
63 *
64 * will generate a tab-seperated-file with the test results and performance
65 * measurements.
66 *
67 * @author Jose Fonseca <jfonseca@vmware.com>
68 */
69
70
71#include "pipe/p_state.h"
72#include "util/u_debug.h"
73
74#include "gallivm/lp_bld_type.h"
75#include "gallivm/lp_bld_arit.h"
76#include "gallivm/lp_bld_init.h"
77#include "lp_bld_blend.h"
78
79
80/**
81 * We may use the same values several times, so we keep them here to avoid
82 * recomputing them. Also reusing the values allows us to do simplifications
83 * that LLVM optimization passes wouldn't normally be able to do.
84 */
85struct lp_build_blend_soa_context
86{
87   struct lp_build_context base;
88
89   LLVMValueRef src[4];
90   LLVMValueRef dst[4];
91   LLVMValueRef con[4];
92
93   LLVMValueRef inv_src[4];
94   LLVMValueRef inv_dst[4];
95   LLVMValueRef inv_con[4];
96
97   LLVMValueRef src_alpha_saturate;
98
99   /**
100    * We store all factors in a table in order to eliminate redundant
101    * multiplications later.
102    * Indexes are: factor[src,dst][color,term][r,g,b,a]
103    */
104   LLVMValueRef factor[2][2][4];
105
106   /**
107    * Table with all terms.
108    * Indexes are: term[src,dst][r,g,b,a]
109    */
110   LLVMValueRef term[2][4];
111};
112
113
114/**
115 * Build a single SOA blend factor for a color channel.
116 * \param i  the color channel in [0,3]
117 */
118static LLVMValueRef
119lp_build_blend_soa_factor(struct lp_build_blend_soa_context *bld,
120                          unsigned factor, unsigned i)
121{
122   /*
123    * Compute src/first term RGB
124    */
125   switch (factor) {
126   case PIPE_BLENDFACTOR_ONE:
127      return bld->base.one;
128   case PIPE_BLENDFACTOR_SRC_COLOR:
129      return bld->src[i];
130   case PIPE_BLENDFACTOR_SRC_ALPHA:
131      return bld->src[3];
132   case PIPE_BLENDFACTOR_DST_COLOR:
133      return bld->dst[i];
134   case PIPE_BLENDFACTOR_DST_ALPHA:
135      return bld->dst[3];
136   case PIPE_BLENDFACTOR_SRC_ALPHA_SATURATE:
137      if(i == 3)
138         return bld->base.one;
139      else {
140         if(!bld->inv_dst[3])
141            bld->inv_dst[3] = lp_build_comp(&bld->base, bld->dst[3]);
142         if(!bld->src_alpha_saturate)
143            bld->src_alpha_saturate = lp_build_min(&bld->base, bld->src[3], bld->inv_dst[3]);
144         return bld->src_alpha_saturate;
145      }
146   case PIPE_BLENDFACTOR_CONST_COLOR:
147      return bld->con[i];
148   case PIPE_BLENDFACTOR_CONST_ALPHA:
149      return bld->con[3];
150   case PIPE_BLENDFACTOR_SRC1_COLOR:
151      /* TODO */
152      assert(0);
153      return bld->base.zero;
154   case PIPE_BLENDFACTOR_SRC1_ALPHA:
155      /* TODO */
156      assert(0);
157      return bld->base.zero;
158   case PIPE_BLENDFACTOR_ZERO:
159      return bld->base.zero;
160   case PIPE_BLENDFACTOR_INV_SRC_COLOR:
161      if(!bld->inv_src[i])
162         bld->inv_src[i] = lp_build_comp(&bld->base, bld->src[i]);
163      return bld->inv_src[i];
164   case PIPE_BLENDFACTOR_INV_SRC_ALPHA:
165      if(!bld->inv_src[3])
166         bld->inv_src[3] = lp_build_comp(&bld->base, bld->src[3]);
167      return bld->inv_src[3];
168   case PIPE_BLENDFACTOR_INV_DST_COLOR:
169      if(!bld->inv_dst[i])
170         bld->inv_dst[i] = lp_build_comp(&bld->base, bld->dst[i]);
171      return bld->inv_dst[i];
172   case PIPE_BLENDFACTOR_INV_DST_ALPHA:
173      if(!bld->inv_dst[3])
174         bld->inv_dst[3] = lp_build_comp(&bld->base, bld->dst[3]);
175      return bld->inv_dst[3];
176   case PIPE_BLENDFACTOR_INV_CONST_COLOR:
177      if(!bld->inv_con[i])
178         bld->inv_con[i] = lp_build_comp(&bld->base, bld->con[i]);
179      return bld->inv_con[i];
180   case PIPE_BLENDFACTOR_INV_CONST_ALPHA:
181      if(!bld->inv_con[3])
182         bld->inv_con[3] = lp_build_comp(&bld->base, bld->con[3]);
183      return bld->inv_con[3];
184   case PIPE_BLENDFACTOR_INV_SRC1_COLOR:
185      /* TODO */
186      assert(0);
187      return bld->base.zero;
188   case PIPE_BLENDFACTOR_INV_SRC1_ALPHA:
189      /* TODO */
190      assert(0);
191      return bld->base.zero;
192   default:
193      assert(0);
194      return bld->base.zero;
195   }
196}
197
198
199/**
200 * Generate blend code in SOA mode.
201 * \param rt  render target index (to index the blend / colormask state)
202 * \param src  src/fragment color
203 * \param dst  dst/framebuffer color
204 * \param con  constant blend color
205 * \param res  the result/output
206 */
207void
208lp_build_blend_soa(struct gallivm_state *gallivm,
209                   const struct pipe_blend_state *blend,
210                   struct lp_type type,
211                   unsigned rt,
212                   LLVMValueRef src[4],
213                   LLVMValueRef dst[4],
214                   LLVMValueRef con[4],
215                   LLVMValueRef res[4])
216{
217   LLVMBuilderRef builder = gallivm->builder;
218   struct lp_build_blend_soa_context bld;
219   unsigned i, j, k;
220
221   assert(rt < PIPE_MAX_COLOR_BUFS);
222
223   /* Setup build context */
224   memset(&bld, 0, sizeof bld);
225   lp_build_context_init(&bld.base, gallivm, type);
226   for (i = 0; i < 4; ++i) {
227      bld.src[i] = src[i];
228      bld.dst[i] = dst[i];
229      bld.con[i] = con[i];
230   }
231
232   for (i = 0; i < 4; ++i) {
233      /* only compute blending for the color channels enabled for writing */
234      if (blend->rt[rt].colormask & (1 << i)) {
235         if (blend->logicop_enable) {
236            if(!type.floating) {
237               res[i] = lp_build_logicop(builder, blend->logicop_func, src[i], dst[i]);
238            }
239            else
240               res[i] = dst[i];
241         }
242         else if (blend->rt[rt].blend_enable) {
243            unsigned src_factor = i < 3 ? blend->rt[rt].rgb_src_factor : blend->rt[rt].alpha_src_factor;
244            unsigned dst_factor = i < 3 ? blend->rt[rt].rgb_dst_factor : blend->rt[rt].alpha_dst_factor;
245            unsigned func = i < 3 ? blend->rt[rt].rgb_func : blend->rt[rt].alpha_func;
246            boolean func_commutative = lp_build_blend_func_commutative(func);
247
248            /*
249             * Compute src/dst factors.
250             */
251
252            bld.factor[0][0][i] = src[i];
253            bld.factor[0][1][i] = lp_build_blend_soa_factor(&bld, src_factor, i);
254            bld.factor[1][0][i] = dst[i];
255            bld.factor[1][1][i] = lp_build_blend_soa_factor(&bld, dst_factor, i);
256
257            /*
258             * Check if lp_build_blend can perform any optimisations
259             */
260            res[i] = lp_build_blend(&bld.base,
261                                    func,
262                                    src_factor,
263                                    dst_factor,
264                                    bld.factor[0][0][i],
265                                    bld.factor[1][0][i],
266                                    bld.factor[0][1][i],
267                                    bld.factor[1][1][i],
268                                    true,
269                                    true);
270
271            if (res[i]) {
272               continue;
273            }
274
275            /*
276             * Compute src/dst terms
277             */
278
279            for(k = 0; k < 2; ++k) {
280               /* See if this multiplication has been previously computed */
281               for(j = 0; j < i; ++j) {
282                  if((bld.factor[k][0][j] == bld.factor[k][0][i] &&
283                      bld.factor[k][1][j] == bld.factor[k][1][i]) ||
284                     (bld.factor[k][0][j] == bld.factor[k][1][i] &&
285                      bld.factor[k][1][j] == bld.factor[k][0][i]))
286                     break;
287               }
288
289               if(j < i && bld.term[k][j])
290                  bld.term[k][i] = bld.term[k][j];
291               else
292                  bld.term[k][i] = lp_build_mul(&bld.base, bld.factor[k][0][i], bld.factor[k][1][i]);
293
294               if (src_factor == PIPE_BLENDFACTOR_ZERO &&
295                   (dst_factor == PIPE_BLENDFACTOR_DST_ALPHA ||
296                    dst_factor == PIPE_BLENDFACTOR_INV_DST_ALPHA)) {
297                  /* XXX special case these combos to work around an apparent
298                   * bug in LLVM.
299                   * This hack disables the check for multiplication by zero
300                   * in lp_bld_mul().  When we optimize away the
301                   * multiplication, something goes wrong during code
302                   * generation and we segfault at runtime.
303                   */
304                  LLVMValueRef zeroSave = bld.base.zero;
305                  bld.base.zero = NULL;
306                  bld.term[k][i] = lp_build_mul(&bld.base, bld.factor[k][0][i],
307                                                bld.factor[k][1][i]);
308                  bld.base.zero = zeroSave;
309               }
310            }
311
312            /*
313             * Combine terms
314             */
315
316            /* See if this function has been previously applied */
317            for(j = 0; j < i; ++j) {
318               unsigned prev_func = j < 3 ? blend->rt[rt].rgb_func : blend->rt[rt].alpha_func;
319               unsigned func_reverse = lp_build_blend_func_reverse(func, prev_func);
320
321               if((!func_reverse &&
322                   bld.term[0][j] == bld.term[0][i] &&
323                   bld.term[1][j] == bld.term[1][i]) ||
324                  ((func_commutative || func_reverse) &&
325                   bld.term[0][j] == bld.term[1][i] &&
326                   bld.term[1][j] == bld.term[0][i]))
327                  break;
328            }
329
330            if(j < i)
331               res[i] = res[j];
332            else
333               res[i] = lp_build_blend_func(&bld.base, func, bld.term[0][i], bld.term[1][i]);
334         }
335         else {
336            res[i] = src[i];
337         }
338      }
339      else {
340         res[i] = dst[i];
341      }
342   }
343}
344