aboutsummaryrefslogtreecommitdiffstats
path: root/src/compiler/nir/nir_lower_wpos_ytransform.c
blob: 444e211b6801d06074bf313470a073a392cc4d46 (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
/*
 * Copyright © 2015 Red Hat
 *
 * 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, sublicense,
 * 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 NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS 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.
 */

#include "nir.h"
#include "nir_builder.h"
#include "program/prog_instruction.h"

/* Lower gl_FragCoord (and fddy) to account for driver's requested coordinate-
 * origin and pixel-center vs. shader.  If transformation is required, a
 * gl_FbWposYTransform uniform is inserted (with the specified state-slots)
 * and additional instructions are inserted to transform gl_FragCoord (and
 * fddy src arg).
 *
 * This is based on the logic in emit_wpos()/emit_wpos_adjustment() in TGSI
 * compiler.
 *
 * Run before nir_lower_io.
 */

typedef struct {
   const nir_lower_wpos_ytransform_options *options;
   nir_shader   *shader;
   nir_builder   b;
   nir_variable *transform;
} lower_wpos_ytransform_state;

static nir_ssa_def *
get_transform(lower_wpos_ytransform_state *state)
{
   if (state->transform == NULL) {
      /* NOTE: name must be prefixed w/ "gl_" to trigger slot based
       * special handling in uniform setup:
       */
      nir_variable *var = nir_variable_create(state->shader,
                                              nir_var_uniform,
                                              glsl_vec4_type(),
                                              "gl_FbWposYTransform");

      var->num_state_slots = 1;
      var->state_slots = ralloc_array(var, nir_state_slot, 1);
      var->state_slots[0].swizzle = SWIZZLE_XYZW;
      memcpy(var->state_slots[0].tokens, state->options->state_tokens,
             sizeof(var->state_slots[0].tokens));
      var->data.how_declared = nir_var_hidden;
      state->transform = var;
   }
   return nir_load_var(&state->b, state->transform);
}

/* NIR equiv of TGSI CMP instruction: */
static nir_ssa_def *
nir_cmp(nir_builder *b, nir_ssa_def *src0, nir_ssa_def *src1, nir_ssa_def *src2)
{
   return nir_bcsel(b, nir_flt(b, src0, nir_imm_float(b, 0.0)), src1, src2);
}

/* see emit_wpos_adjustment() in st_mesa_to_tgsi.c */
static void
emit_wpos_adjustment(lower_wpos_ytransform_state *state,
                     nir_intrinsic_instr *intr, nir_variable *fragcoord,
                     bool invert, float adjX, float adjY[2])
{
   nir_builder *b = &state->b;
   nir_ssa_def *wpostrans, *wpos_temp, *wpos_temp_y, *wpos_input;

   assert(intr->dest.is_ssa);

   b->cursor = nir_before_instr(&intr->instr);

   wpostrans = get_transform(state);
   wpos_input = nir_load_var(b, fragcoord);

   /* First, apply the coordinate shift: */
   if (adjX || adjY[0] || adjY[1]) {
      if (adjY[0] != adjY[1]) {
         /* Adjust the y coordinate by adjY[1] or adjY[0] respectively
          * depending on whether inversion is actually going to be applied
          * or not, which is determined by testing against the inversion
          * state variable used below, which will be either +1 or -1.
          */
         nir_ssa_def *adj_temp;

         adj_temp = nir_cmp(b,
                            nir_channel(b, wpostrans, invert ? 2 : 0),
                            nir_imm_vec4(b, adjX, adjY[0], 0.0f, 0.0f),
                            nir_imm_vec4(b, adjX, adjY[1], 0.0f, 0.0f));

         wpos_temp = nir_fadd(b, wpos_input, adj_temp);
      } else {
         wpos_temp = nir_fadd(b,
                              wpos_input,
                              nir_imm_vec4(b, adjX, adjY[0], 0.0f, 0.0f));
      }
      wpos_input = wpos_temp;
   } else {
      /* MOV wpos_temp, input[wpos]
       */
      wpos_temp = wpos_input;
   }

   /* Now the conditional y flip: STATE_FB_WPOS_Y_TRANSFORM.xy/zw will be
    * inversion/identity, or the other way around if we're drawing to an FBO.
    */
   if (invert) {
      /* wpos_temp.y = wpos_input * wpostrans.xxxx + wpostrans.yyyy */
      wpos_temp_y = nir_fadd(b, nir_fmul(b, nir_channel(b, wpos_temp, 1),
                                            nir_channel(b, wpostrans, 0)),
                                nir_channel(b, wpostrans, 1));
   } else {
      /* wpos_temp.y = wpos_input * wpostrans.zzzz + wpostrans.wwww */
      wpos_temp_y = nir_fadd(b, nir_fmul(b, nir_channel(b, wpos_temp, 1),
                                            nir_channel(b, wpostrans, 2)),
                                nir_channel(b, wpostrans, 3));
   }

   wpos_temp = nir_vec4(b,
                        nir_channel(b, wpos_temp, 0),
                        wpos_temp_y,
                        nir_channel(b, wpos_temp, 2),
                        nir_channel(b, wpos_temp, 3));

   nir_ssa_def_rewrite_uses(&intr->dest.ssa, nir_src_for_ssa(wpos_temp));
}

static void
lower_fragcoord(lower_wpos_ytransform_state *state,
                nir_intrinsic_instr *intr, nir_variable *fragcoord)
{
   const nir_lower_wpos_ytransform_options *options = state->options;
   float adjX = 0.0f;
   float adjY[2] = { 0.0f, 0.0f };
   bool invert = false;

   /* Based on logic in emit_wpos():
    *
    * Query the pixel center conventions supported by the pipe driver and set
    * adjX, adjY to help out if it cannot handle the requested one internally.
    *
    * The bias of the y-coordinate depends on whether y-inversion takes place
    * (adjY[1]) or not (adjY[0]), which is in turn dependent on whether we are
    * drawing to an FBO (causes additional inversion), and whether the pipe
    * driver origin and the requested origin differ (the latter condition is
    * stored in the 'invert' variable).
    *
    * For height = 100 (i = integer, h = half-integer, l = lower, u = upper):
    *
    * center shift only:
    * i -> h: +0.5
    * h -> i: -0.5
    *
    * inversion only:
    * l,i -> u,i: ( 0.0 + 1.0) * -1 + 100 = 99
    * l,h -> u,h: ( 0.5 + 0.0) * -1 + 100 = 99.5
    * u,i -> l,i: (99.0 + 1.0) * -1 + 100 = 0
    * u,h -> l,h: (99.5 + 0.0) * -1 + 100 = 0.5
    *
    * inversion and center shift:
    * l,i -> u,h: ( 0.0 + 0.5) * -1 + 100 = 99.5
    * l,h -> u,i: ( 0.5 + 0.5) * -1 + 100 = 99
    * u,i -> l,h: (99.0 + 0.5) * -1 + 100 = 0.5
    * u,h -> l,i: (99.5 + 0.5) * -1 + 100 = 0
    */

   if (fragcoord->data.origin_upper_left) {
      /* Fragment shader wants origin in upper-left */
      if (options->fs_coord_origin_upper_left) {
         /* the driver supports upper-left origin */
      } else if (options->fs_coord_origin_lower_left) {
         /* the driver supports lower-left origin, need to invert Y */
         invert = true;
      } else {
         unreachable("invalid options");
      }
   } else {
      /* Fragment shader wants origin in lower-left */
      if (options->fs_coord_origin_lower_left) {
         /* the driver supports lower-left origin */
      } else if (options->fs_coord_origin_upper_left) {
         /* the driver supports upper-left origin, need to invert Y */
         invert = true;
      } else {
         unreachable("invalid options");
      }
   }

   if (fragcoord->data.pixel_center_integer) {
      /* Fragment shader wants pixel center integer */
      if (options->fs_coord_pixel_center_integer) {
         /* the driver supports pixel center integer */
         adjY[1] = 1.0f;
      } else if (options->fs_coord_pixel_center_half_integer) {
         /* the driver supports pixel center half integer, need to bias X,Y */
         adjX = -0.5f;
         adjY[0] = -0.5f;
         adjY[1] = 0.5f;
      } else {
         unreachable("invalid options");
      }
   } else {
      /* Fragment shader wants pixel center half integer */
      if (options->fs_coord_pixel_center_half_integer) {
         /* the driver supports pixel center half integer */
      } else if (options->fs_coord_pixel_center_integer) {
         /* the driver supports pixel center integer, need to bias X,Y */
         adjX = adjY[0] = adjY[1] = 0.5f;
      } else {
         unreachable("invalid options");
      }
   }

   emit_wpos_adjustment(state, intr, fragcoord, invert, adjX, adjY);
}

static void
lower_load_pointcoord(lower_wpos_ytransform_state *state,
                      nir_intrinsic_instr *intr)
{
   nir_builder *b = &state->b;
   b->cursor = nir_after_instr(&intr->instr);

   nir_ssa_def *pntc = &intr->dest.ssa;
   nir_ssa_def *transform = get_transform(state);
   nir_ssa_def *y = nir_channel(b, pntc, 1);
   /* The offset is 1 if we're flipping, 0 otherwise. */
   nir_ssa_def *offset = nir_fmax(b, nir_channel(b, transform, 2),
                                  nir_imm_float(b, 0.0));
   /* Flip the sign of y if we're flipping. */
   nir_ssa_def *scaled = nir_fmul(b, y, nir_channel(b, transform, 0));

   /* Reassemble the vector. */
   nir_ssa_def *flipped_pntc = nir_vec2(b,
                                        nir_channel(b, pntc, 0),
                                        nir_fadd(b, offset, scaled));

   nir_ssa_def_rewrite_uses_after(&intr->dest.ssa, nir_src_for_ssa(flipped_pntc),
                                  flipped_pntc->parent_instr);
}

/* turns 'fddy(p)' into 'fddy(fmul(p, transform.x))' */
static void
lower_fddy(lower_wpos_ytransform_state *state, nir_alu_instr *fddy)
{
   nir_builder *b = &state->b;
   nir_ssa_def *p, *pt, *trans;

   b->cursor = nir_before_instr(&fddy->instr);

   p = nir_ssa_for_alu_src(b, fddy, 0);
   trans = get_transform(state);
   pt = nir_fmul(b, p, nir_channel(b, trans, 0));

   nir_instr_rewrite_src(&fddy->instr,
                         &fddy->src[0].src,
                         nir_src_for_ssa(pt));

   for (unsigned i = 0; i < 4; i++)
      fddy->src[0].swizzle[i] = MIN2(i, pt->num_components - 1);
}

/* Multiply interp_deref_at_offset's offset by transform.x to flip it. */
static void
lower_interp_deref_at_offset(lower_wpos_ytransform_state *state,
                           nir_intrinsic_instr *interp)
{
   nir_builder *b = &state->b;
   nir_ssa_def *offset;
   nir_ssa_def *flip_y;

   b->cursor = nir_before_instr(&interp->instr);

   offset = nir_ssa_for_src(b, interp->src[1], 2);
   flip_y = nir_fmul(b, nir_channel(b, offset, 1),
                        nir_channel(b, get_transform(state), 0));
   nir_instr_rewrite_src(&interp->instr, &interp->src[1],
                         nir_src_for_ssa(nir_vec2(b, nir_channel(b, offset, 0),
                                                     flip_y)));
}

static void
lower_load_sample_pos(lower_wpos_ytransform_state *state,
                      nir_intrinsic_instr *intr)
{
   nir_builder *b = &state->b;
   b->cursor = nir_after_instr(&intr->instr);

   nir_ssa_def *pos = &intr->dest.ssa;
   nir_ssa_def *scale = nir_channel(b, get_transform(state), 0);
   nir_ssa_def *neg_scale = nir_channel(b, get_transform(state), 2);
   /* Either y or 1-y for scale equal to 1 or -1 respectively. */
   nir_ssa_def *flipped_y =
               nir_fadd(b, nir_fmax(b, neg_scale, nir_imm_float(b, 0.0)),
                        nir_fmul(b, nir_channel(b, pos, 1), scale));
   nir_ssa_def *flipped_pos = nir_vec2(b, nir_channel(b, pos, 0), flipped_y);

   nir_ssa_def_rewrite_uses_after(&intr->dest.ssa, nir_src_for_ssa(flipped_pos),
                                  flipped_pos->parent_instr);
}

static void
lower_wpos_ytransform_block(lower_wpos_ytransform_state *state, nir_block *block)
{
   nir_foreach_instr_safe(instr, block) {
      if (instr->type == nir_instr_type_intrinsic) {
         nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
         if (intr->intrinsic == nir_intrinsic_load_deref) {
            nir_deref_instr *deref = nir_src_as_deref(intr->src[0]);
            nir_variable *var = nir_deref_instr_get_variable(deref);

            if ((var->data.mode == nir_var_shader_in &&
                 var->data.location == VARYING_SLOT_POS) ||
                (var->data.mode == nir_var_system_value &&
                 var->data.location == SYSTEM_VALUE_FRAG_COORD)) {
               /* gl_FragCoord should not have array/struct derefs: */
               lower_fragcoord(state, intr, var);
            } else if (var->data.mode == nir_var_system_value &&
                       var->data.location == SYSTEM_VALUE_SAMPLE_POS) {
               lower_load_sample_pos(state, intr);
            } else if (var->data.mode == nir_var_shader_in &&
                       var->data.location == VARYING_SLOT_PNTC &&
                       state->shader->options->lower_wpos_pntc) {
               lower_load_pointcoord(state, intr);
            }
         } else if (intr->intrinsic == nir_intrinsic_load_frag_coord) {
            lower_fragcoord(state, intr, NULL);
         } else if (intr->intrinsic == nir_intrinsic_load_sample_pos) {
            lower_load_sample_pos(state, intr);
         } else if (intr->intrinsic == nir_intrinsic_interp_deref_at_offset) {
            lower_interp_deref_at_offset(state, intr);
         }
      } else if (instr->type == nir_instr_type_alu) {
         nir_alu_instr *alu = nir_instr_as_alu(instr);
         if (alu->op == nir_op_fddy ||
             alu->op == nir_op_fddy_fine ||
             alu->op == nir_op_fddy_coarse)
            lower_fddy(state, alu);
      }
   }
}

static void
lower_wpos_ytransform_impl(lower_wpos_ytransform_state *state, nir_function_impl *impl)
{
   nir_builder_init(&state->b, impl);

   nir_foreach_block(block, impl) {
      lower_wpos_ytransform_block(state, block);
   }
   nir_metadata_preserve(impl, nir_metadata_block_index |
                               nir_metadata_dominance);
}

bool
nir_lower_wpos_ytransform(nir_shader *shader,
                          const nir_lower_wpos_ytransform_options *options)
{
   lower_wpos_ytransform_state state = {
      .options = options,
      .shader = shader,
   };

   assert(shader->info.stage == MESA_SHADER_FRAGMENT);

   nir_foreach_function(function, shader) {
      if (function->impl)
         lower_wpos_ytransform_impl(&state, function->impl);
   }

   return state.transform != NULL;
}