1/*
2 * Copyright © 2011 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21 * IN THE SOFTWARE.
22 */
23
24/**
25 * @file brw_vue_map.c
26 *
27 * This file computes the "VUE map" for a (non-fragment) shader stage, which
28 * describes the layout of its output varyings.  The VUE map is used to match
29 * outputs from one stage with the inputs of the next.
30 *
31 * Largely, varyings can be placed however we like - producers/consumers simply
32 * have to agree on the layout.  However, there is also a "VUE Header" that
33 * prescribes a fixed-layout for items that interact with fixed function
34 * hardware, such as the clipper and rasterizer.
35 *
36 * Authors:
37 *   Paul Berry <stereotype441@gmail.com>
38 *   Chris Forbes <chrisf@ijw.co.nz>
39 *   Eric Anholt <eric@anholt.net>
40 */
41
42
43#include "brw_compiler.h"
44#include "dev/gen_debug.h"
45
46static inline void
47assign_vue_slot(struct brw_vue_map *vue_map, int varying, int slot)
48{
49   /* Make sure this varying hasn't been assigned a slot already */
50   assert (vue_map->varying_to_slot[varying] == -1);
51
52   vue_map->varying_to_slot[varying] = slot;
53   vue_map->slot_to_varying[slot] = varying;
54}
55
56/**
57 * Compute the VUE map for a shader stage.
58 */
59void
60brw_compute_vue_map(const struct gen_device_info *devinfo,
61                    struct brw_vue_map *vue_map,
62                    uint64_t slots_valid,
63                    bool separate)
64{
65   /* Keep using the packed/contiguous layout on old hardware - we only need
66    * the SSO layout when using geometry/tessellation shaders or 32 FS input
67    * varyings, which only exist on Gen >= 6.  It's also a bit more efficient.
68    */
69   if (devinfo->gen < 6)
70      separate = false;
71
72   if (separate) {
73      /* In SSO mode, we don't know whether the adjacent stage will
74       * read/write gl_ClipDistance, which has a fixed slot location.
75       * We have to assume the worst and reserve a slot for it, or else
76       * the rest of our varyings will be off by a slot.
77       *
78       * Note that we don't have to worry about COL/BFC, as those built-in
79       * variables only exist in legacy GL, which only supports VS and FS.
80       */
81      slots_valid |= BITFIELD64_BIT(VARYING_SLOT_CLIP_DIST0);
82      slots_valid |= BITFIELD64_BIT(VARYING_SLOT_CLIP_DIST1);
83   }
84
85   vue_map->slots_valid = slots_valid;
86   vue_map->separate = separate;
87
88   /* gl_Layer and gl_ViewportIndex don't get their own varying slots -- they
89    * are stored in the first VUE slot (VARYING_SLOT_PSIZ).
90    */
91   slots_valid &= ~(VARYING_BIT_LAYER | VARYING_BIT_VIEWPORT);
92
93   /* Make sure that the values we store in vue_map->varying_to_slot and
94    * vue_map->slot_to_varying won't overflow the signed chars that are used
95    * to store them.  Note that since vue_map->slot_to_varying sometimes holds
96    * values equal to BRW_VARYING_SLOT_COUNT, we need to ensure that
97    * BRW_VARYING_SLOT_COUNT is <= 127, not 128.
98    */
99   STATIC_ASSERT(BRW_VARYING_SLOT_COUNT <= 127);
100
101   for (int i = 0; i < BRW_VARYING_SLOT_COUNT; ++i) {
102      vue_map->varying_to_slot[i] = -1;
103      vue_map->slot_to_varying[i] = BRW_VARYING_SLOT_PAD;
104   }
105
106   int slot = 0;
107
108   /* VUE header: format depends on chip generation and whether clipping is
109    * enabled.
110    *
111    * See the Sandybridge PRM, Volume 2 Part 1, section 1.5.1 (page 30),
112    * "Vertex URB Entry (VUE) Formats" which describes the VUE header layout.
113    */
114   if (devinfo->gen < 6) {
115      /* There are 8 dwords in VUE header pre-Ironlake:
116       * dword 0-3 is indices, point width, clip flags.
117       * dword 4-7 is ndc position
118       * dword 8-11 is the first vertex data.
119       *
120       * On Ironlake the VUE header is nominally 20 dwords, but the hardware
121       * will accept the same header layout as Gen4 [and should be a bit faster]
122       */
123      assign_vue_slot(vue_map, VARYING_SLOT_PSIZ, slot++);
124      assign_vue_slot(vue_map, BRW_VARYING_SLOT_NDC, slot++);
125      assign_vue_slot(vue_map, VARYING_SLOT_POS, slot++);
126   } else {
127      /* There are 8 or 16 DWs (D0-D15) in VUE header on Sandybridge:
128       * dword 0-3 of the header is indices, point width, clip flags.
129       * dword 4-7 is the 4D space position
130       * dword 8-15 of the vertex header is the user clip distance if
131       * enabled.
132       * dword 8-11 or 16-19 is the first vertex element data we fill.
133       */
134      assign_vue_slot(vue_map, VARYING_SLOT_PSIZ, slot++);
135      assign_vue_slot(vue_map, VARYING_SLOT_POS, slot++);
136      if (slots_valid & BITFIELD64_BIT(VARYING_SLOT_CLIP_DIST0))
137         assign_vue_slot(vue_map, VARYING_SLOT_CLIP_DIST0, slot++);
138      if (slots_valid & BITFIELD64_BIT(VARYING_SLOT_CLIP_DIST1))
139         assign_vue_slot(vue_map, VARYING_SLOT_CLIP_DIST1, slot++);
140
141      /* front and back colors need to be consecutive so that we can use
142       * ATTRIBUTE_SWIZZLE_INPUTATTR_FACING to swizzle them when doing
143       * two-sided color.
144       */
145      if (slots_valid & BITFIELD64_BIT(VARYING_SLOT_COL0))
146         assign_vue_slot(vue_map, VARYING_SLOT_COL0, slot++);
147      if (slots_valid & BITFIELD64_BIT(VARYING_SLOT_BFC0))
148         assign_vue_slot(vue_map, VARYING_SLOT_BFC0, slot++);
149      if (slots_valid & BITFIELD64_BIT(VARYING_SLOT_COL1))
150         assign_vue_slot(vue_map, VARYING_SLOT_COL1, slot++);
151      if (slots_valid & BITFIELD64_BIT(VARYING_SLOT_BFC1))
152         assign_vue_slot(vue_map, VARYING_SLOT_BFC1, slot++);
153   }
154
155   /* The hardware doesn't care about the rest of the vertex outputs, so we
156    * can assign them however we like.  For normal programs, we simply assign
157    * them contiguously.
158    *
159    * For separate shader pipelines, we first assign built-in varyings
160    * contiguous slots.  This works because ARB_separate_shader_objects
161    * requires that all shaders have matching built-in varying interface
162    * blocks.  Next, we assign generic varyings based on their location
163    * (either explicit or linker assigned).  This guarantees a fixed layout.
164    *
165    * We generally don't need to assign a slot for VARYING_SLOT_CLIP_VERTEX,
166    * since it's encoded as the clip distances by emit_clip_distances().
167    * However, it may be output by transform feedback, and we'd rather not
168    * recompute state when TF changes, so we just always include it.
169    */
170   uint64_t builtins = slots_valid & BITFIELD64_MASK(VARYING_SLOT_VAR0);
171   while (builtins != 0) {
172      const int varying = ffsll(builtins) - 1;
173      if (vue_map->varying_to_slot[varying] == -1) {
174         assign_vue_slot(vue_map, varying, slot++);
175      }
176      builtins &= ~BITFIELD64_BIT(varying);
177   }
178
179   const int first_generic_slot = slot;
180   uint64_t generics = slots_valid & ~BITFIELD64_MASK(VARYING_SLOT_VAR0);
181   while (generics != 0) {
182      const int varying = ffsll(generics) - 1;
183      if (separate) {
184         slot = first_generic_slot + varying - VARYING_SLOT_VAR0;
185      }
186      assign_vue_slot(vue_map, varying, slot++);
187      generics &= ~BITFIELD64_BIT(varying);
188   }
189
190   vue_map->num_slots = slot;
191   vue_map->num_per_vertex_slots = 0;
192   vue_map->num_per_patch_slots = 0;
193}
194
195/**
196 * Compute the VUE map for tessellation control shader outputs and
197 * tessellation evaluation shader inputs.
198 */
199void
200brw_compute_tess_vue_map(struct brw_vue_map *vue_map,
201                         uint64_t vertex_slots,
202                         uint32_t patch_slots)
203{
204   /* I don't think anything actually uses this... */
205   vue_map->slots_valid = vertex_slots;
206
207   /* separate isn't really meaningful, but make sure it's initialized */
208   vue_map->separate = false;
209
210   vertex_slots &= ~(VARYING_BIT_TESS_LEVEL_OUTER |
211                     VARYING_BIT_TESS_LEVEL_INNER);
212
213   /* Make sure that the values we store in vue_map->varying_to_slot and
214    * vue_map->slot_to_varying won't overflow the signed chars that are used
215    * to store them.  Note that since vue_map->slot_to_varying sometimes holds
216    * values equal to VARYING_SLOT_TESS_MAX , we need to ensure that
217    * VARYING_SLOT_TESS_MAX is <= 127, not 128.
218    */
219   STATIC_ASSERT(VARYING_SLOT_TESS_MAX <= 127);
220
221   for (int i = 0; i < VARYING_SLOT_TESS_MAX ; ++i) {
222      vue_map->varying_to_slot[i] = -1;
223      vue_map->slot_to_varying[i] = BRW_VARYING_SLOT_PAD;
224   }
225
226   int slot = 0;
227
228   /* The first 8 DWords are reserved for the "Patch Header".
229    *
230    * VARYING_SLOT_TESS_LEVEL_OUTER / INNER live here, but the exact layout
231    * depends on the domain type.  They might not be in slots 0 and 1 as
232    * described here, but pretending they're separate allows us to uniquely
233    * identify them by distinct slot locations.
234    */
235   assign_vue_slot(vue_map, VARYING_SLOT_TESS_LEVEL_INNER, slot++);
236   assign_vue_slot(vue_map, VARYING_SLOT_TESS_LEVEL_OUTER, slot++);
237
238   /* first assign per-patch varyings */
239   while (patch_slots != 0) {
240      const int varying = ffsll(patch_slots) - 1;
241      if (vue_map->varying_to_slot[varying + VARYING_SLOT_PATCH0] == -1) {
242         assign_vue_slot(vue_map, varying + VARYING_SLOT_PATCH0, slot++);
243      }
244      patch_slots &= ~BITFIELD64_BIT(varying);
245   }
246
247   /* apparently, including the patch header... */
248   vue_map->num_per_patch_slots = slot;
249
250   /* then assign per-vertex varyings for each vertex in our patch */
251   while (vertex_slots != 0) {
252      const int varying = ffsll(vertex_slots) - 1;
253      if (vue_map->varying_to_slot[varying] == -1) {
254         assign_vue_slot(vue_map, varying, slot++);
255      }
256      vertex_slots &= ~BITFIELD64_BIT(varying);
257   }
258
259   vue_map->num_per_vertex_slots = slot - vue_map->num_per_patch_slots;
260   vue_map->num_slots = slot;
261}
262
263static const char *
264varying_name(brw_varying_slot slot)
265{
266   assume(slot < BRW_VARYING_SLOT_COUNT);
267
268   if (slot < VARYING_SLOT_MAX)
269      return gl_varying_slot_name((gl_varying_slot) slot);
270
271   static const char *brw_names[] = {
272      [BRW_VARYING_SLOT_NDC - VARYING_SLOT_MAX] = "BRW_VARYING_SLOT_NDC",
273      [BRW_VARYING_SLOT_PAD - VARYING_SLOT_MAX] = "BRW_VARYING_SLOT_PAD",
274      [BRW_VARYING_SLOT_PNTC - VARYING_SLOT_MAX] = "BRW_VARYING_SLOT_PNTC",
275   };
276
277   return brw_names[slot - VARYING_SLOT_MAX];
278}
279
280void
281brw_print_vue_map(FILE *fp, const struct brw_vue_map *vue_map)
282{
283   if (vue_map->num_per_vertex_slots > 0 || vue_map->num_per_patch_slots > 0) {
284      fprintf(fp, "PUE map (%d slots, %d/patch, %d/vertex, %s)\n",
285              vue_map->num_slots,
286              vue_map->num_per_patch_slots,
287              vue_map->num_per_vertex_slots,
288              vue_map->separate ? "SSO" : "non-SSO");
289      for (int i = 0; i < vue_map->num_slots; i++) {
290         if (vue_map->slot_to_varying[i] >= VARYING_SLOT_PATCH0) {
291            fprintf(fp, "  [%d] VARYING_SLOT_PATCH%d\n", i,
292                    vue_map->slot_to_varying[i] - VARYING_SLOT_PATCH0);
293         } else {
294            fprintf(fp, "  [%d] %s\n", i,
295                    varying_name(vue_map->slot_to_varying[i]));
296         }
297      }
298   } else {
299      fprintf(fp, "VUE map (%d slots, %s)\n",
300              vue_map->num_slots, vue_map->separate ? "SSO" : "non-SSO");
301      for (int i = 0; i < vue_map->num_slots; i++) {
302         fprintf(fp, "  [%d] %s\n", i,
303                 varying_name(vue_map->slot_to_varying[i]));
304      }
305   }
306   fprintf(fp, "\n");
307}
308