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1 /*
2  * Copyright © 2022 Konstantin Seurer
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 #ifndef VK_BVH_BUILD_HELPERS_H
25 #define VK_BVH_BUILD_HELPERS_H
26 
27 #include "vk_bvh.h"
28 
29 #define VK_FORMAT_UNDEFINED                  0
30 #define VK_FORMAT_R4G4_UNORM_PACK8           1
31 #define VK_FORMAT_R4G4B4A4_UNORM_PACK16      2
32 #define VK_FORMAT_B4G4R4A4_UNORM_PACK16      3
33 #define VK_FORMAT_R5G6B5_UNORM_PACK16        4
34 #define VK_FORMAT_B5G6R5_UNORM_PACK16        5
35 #define VK_FORMAT_R5G5B5A1_UNORM_PACK16      6
36 #define VK_FORMAT_B5G5R5A1_UNORM_PACK16      7
37 #define VK_FORMAT_A1R5G5B5_UNORM_PACK16      8
38 #define VK_FORMAT_R8_UNORM                   9
39 #define VK_FORMAT_R8_SNORM                   10
40 #define VK_FORMAT_R8_USCALED                 11
41 #define VK_FORMAT_R8_SSCALED                 12
42 #define VK_FORMAT_R8_UINT                    13
43 #define VK_FORMAT_R8_SINT                    14
44 #define VK_FORMAT_R8_SRGB                    15
45 #define VK_FORMAT_R8G8_UNORM                 16
46 #define VK_FORMAT_R8G8_SNORM                 17
47 #define VK_FORMAT_R8G8_USCALED               18
48 #define VK_FORMAT_R8G8_SSCALED               19
49 #define VK_FORMAT_R8G8_UINT                  20
50 #define VK_FORMAT_R8G8_SINT                  21
51 #define VK_FORMAT_R8G8_SRGB                  22
52 #define VK_FORMAT_R8G8B8_UNORM               23
53 #define VK_FORMAT_R8G8B8_SNORM               24
54 #define VK_FORMAT_R8G8B8_USCALED             25
55 #define VK_FORMAT_R8G8B8_SSCALED             26
56 #define VK_FORMAT_R8G8B8_UINT                27
57 #define VK_FORMAT_R8G8B8_SINT                28
58 #define VK_FORMAT_R8G8B8_SRGB                29
59 #define VK_FORMAT_B8G8R8_UNORM               30
60 #define VK_FORMAT_B8G8R8_SNORM               31
61 #define VK_FORMAT_B8G8R8_USCALED             32
62 #define VK_FORMAT_B8G8R8_SSCALED             33
63 #define VK_FORMAT_B8G8R8_UINT                34
64 #define VK_FORMAT_B8G8R8_SINT                35
65 #define VK_FORMAT_B8G8R8_SRGB                36
66 #define VK_FORMAT_R8G8B8A8_UNORM             37
67 #define VK_FORMAT_R8G8B8A8_SNORM             38
68 #define VK_FORMAT_R8G8B8A8_USCALED           39
69 #define VK_FORMAT_R8G8B8A8_SSCALED           40
70 #define VK_FORMAT_R8G8B8A8_UINT              41
71 #define VK_FORMAT_R8G8B8A8_SINT              42
72 #define VK_FORMAT_R8G8B8A8_SRGB              43
73 #define VK_FORMAT_B8G8R8A8_UNORM             44
74 #define VK_FORMAT_B8G8R8A8_SNORM             45
75 #define VK_FORMAT_B8G8R8A8_USCALED           46
76 #define VK_FORMAT_B8G8R8A8_SSCALED           47
77 #define VK_FORMAT_B8G8R8A8_UINT              48
78 #define VK_FORMAT_B8G8R8A8_SINT              49
79 #define VK_FORMAT_B8G8R8A8_SRGB              50
80 #define VK_FORMAT_A8B8G8R8_UNORM_PACK32      51
81 #define VK_FORMAT_A8B8G8R8_SNORM_PACK32      52
82 #define VK_FORMAT_A8B8G8R8_USCALED_PACK32    53
83 #define VK_FORMAT_A8B8G8R8_SSCALED_PACK32    54
84 #define VK_FORMAT_A8B8G8R8_UINT_PACK32       55
85 #define VK_FORMAT_A8B8G8R8_SINT_PACK32       56
86 #define VK_FORMAT_A8B8G8R8_SRGB_PACK32       57
87 #define VK_FORMAT_A2R10G10B10_UNORM_PACK32   58
88 #define VK_FORMAT_A2R10G10B10_SNORM_PACK32   59
89 #define VK_FORMAT_A2R10G10B10_USCALED_PACK32 60
90 #define VK_FORMAT_A2R10G10B10_SSCALED_PACK32 61
91 #define VK_FORMAT_A2R10G10B10_UINT_PACK32    62
92 #define VK_FORMAT_A2R10G10B10_SINT_PACK32    63
93 #define VK_FORMAT_A2B10G10R10_UNORM_PACK32   64
94 #define VK_FORMAT_A2B10G10R10_SNORM_PACK32   65
95 #define VK_FORMAT_A2B10G10R10_USCALED_PACK32 66
96 #define VK_FORMAT_A2B10G10R10_SSCALED_PACK32 67
97 #define VK_FORMAT_A2B10G10R10_UINT_PACK32    68
98 #define VK_FORMAT_A2B10G10R10_SINT_PACK32    69
99 #define VK_FORMAT_R16_UNORM                  70
100 #define VK_FORMAT_R16_SNORM                  71
101 #define VK_FORMAT_R16_USCALED                72
102 #define VK_FORMAT_R16_SSCALED                73
103 #define VK_FORMAT_R16_UINT                   74
104 #define VK_FORMAT_R16_SINT                   75
105 #define VK_FORMAT_R16_SFLOAT                 76
106 #define VK_FORMAT_R16G16_UNORM               77
107 #define VK_FORMAT_R16G16_SNORM               78
108 #define VK_FORMAT_R16G16_USCALED             79
109 #define VK_FORMAT_R16G16_SSCALED             80
110 #define VK_FORMAT_R16G16_UINT                81
111 #define VK_FORMAT_R16G16_SINT                82
112 #define VK_FORMAT_R16G16_SFLOAT              83
113 #define VK_FORMAT_R16G16B16_UNORM            84
114 #define VK_FORMAT_R16G16B16_SNORM            85
115 #define VK_FORMAT_R16G16B16_USCALED          86
116 #define VK_FORMAT_R16G16B16_SSCALED          87
117 #define VK_FORMAT_R16G16B16_UINT             88
118 #define VK_FORMAT_R16G16B16_SINT             89
119 #define VK_FORMAT_R16G16B16_SFLOAT           90
120 #define VK_FORMAT_R16G16B16A16_UNORM         91
121 #define VK_FORMAT_R16G16B16A16_SNORM         92
122 #define VK_FORMAT_R16G16B16A16_USCALED       93
123 #define VK_FORMAT_R16G16B16A16_SSCALED       94
124 #define VK_FORMAT_R16G16B16A16_UINT          95
125 #define VK_FORMAT_R16G16B16A16_SINT          96
126 #define VK_FORMAT_R16G16B16A16_SFLOAT        97
127 #define VK_FORMAT_R32_UINT                   98
128 #define VK_FORMAT_R32_SINT                   99
129 #define VK_FORMAT_R32_SFLOAT                 100
130 #define VK_FORMAT_R32G32_UINT                101
131 #define VK_FORMAT_R32G32_SINT                102
132 #define VK_FORMAT_R32G32_SFLOAT              103
133 #define VK_FORMAT_R32G32B32_UINT             104
134 #define VK_FORMAT_R32G32B32_SINT             105
135 #define VK_FORMAT_R32G32B32_SFLOAT           106
136 #define VK_FORMAT_R32G32B32A32_UINT          107
137 #define VK_FORMAT_R32G32B32A32_SINT          108
138 #define VK_FORMAT_R32G32B32A32_SFLOAT        109
139 #define VK_FORMAT_R64_UINT                   110
140 #define VK_FORMAT_R64_SINT                   111
141 #define VK_FORMAT_R64_SFLOAT                 112
142 #define VK_FORMAT_R64G64_UINT                113
143 #define VK_FORMAT_R64G64_SINT                114
144 #define VK_FORMAT_R64G64_SFLOAT              115
145 #define VK_FORMAT_R64G64B64_UINT             116
146 #define VK_FORMAT_R64G64B64_SINT             117
147 #define VK_FORMAT_R64G64B64_SFLOAT           118
148 #define VK_FORMAT_R64G64B64A64_UINT          119
149 #define VK_FORMAT_R64G64B64A64_SINT          120
150 #define VK_FORMAT_R64G64B64A64_SFLOAT        121
151 
152 #define VK_INDEX_TYPE_UINT16    0
153 #define VK_INDEX_TYPE_UINT32    1
154 #define VK_INDEX_TYPE_NONE_KHR  1000165000
155 #define VK_INDEX_TYPE_UINT8_EXT 1000265000
156 
157 #define VK_GEOMETRY_TYPE_TRIANGLES_KHR 0
158 #define VK_GEOMETRY_TYPE_AABBS_KHR     1
159 #define VK_GEOMETRY_TYPE_INSTANCES_KHR 2
160 
161 #define VK_GEOMETRY_INSTANCE_TRIANGLE_FACING_CULL_DISABLE_BIT_KHR 1
162 #define VK_GEOMETRY_INSTANCE_TRIANGLE_FLIP_FACING_BIT_KHR         2
163 #define VK_GEOMETRY_INSTANCE_FORCE_OPAQUE_BIT_KHR                 4
164 #define VK_GEOMETRY_INSTANCE_FORCE_NO_OPAQUE_BIT_KHR              8
165 
166 #define TYPE(type, align)                                                                                              \
167    layout(buffer_reference, buffer_reference_align = align, scalar) buffer type##_ref                                  \
168    {                                                                                                                   \
169       type value;                                                                                                      \
170    };
171 
172 #define REF(type)  type##_ref
173 #define VOID_REF   uint64_t
174 #define NULL       0
175 #define DEREF(var) var.value
176 
177 #define SIZEOF(type) uint32_t(uint64_t(REF(type)(uint64_t(0)) + 1))
178 
179 #define OFFSET(ptr, offset) (uint64_t(ptr) + offset)
180 
181 #define INFINITY (1.0 / 0.0)
182 #define NAN      (0.0 / 0.0)
183 
184 #define INDEX(type, ptr, index) REF(type)(OFFSET(ptr, (index)*SIZEOF(type)))
185 
186 TYPE(int8_t, 1);
187 TYPE(uint8_t, 1);
188 TYPE(int16_t, 2);
189 TYPE(uint16_t, 2);
190 TYPE(int32_t, 4);
191 TYPE(uint32_t, 4);
192 TYPE(int64_t, 8);
193 TYPE(uint64_t, 8);
194 
195 TYPE(float, 4);
196 
197 TYPE(vec2, 4);
198 TYPE(vec3, 4);
199 TYPE(vec4, 4);
200 
201 TYPE(uvec4, 16);
202 
203 TYPE(VOID_REF, 8);
204 
205 /* copied from u_math.h */
206 uint32_t
align(uint32_t value,uint32_t alignment)207 align(uint32_t value, uint32_t alignment)
208 {
209    return (value + alignment - 1) & ~(alignment - 1);
210 }
211 
212 int32_t
to_emulated_float(float f)213 to_emulated_float(float f)
214 {
215    int32_t bits = floatBitsToInt(f);
216    return f < 0 ? -2147483648 - bits : bits;
217 }
218 
219 float
from_emulated_float(int32_t bits)220 from_emulated_float(int32_t bits)
221 {
222    return intBitsToFloat(bits < 0 ? -2147483648 - bits : bits);
223 }
224 
225 TYPE(vk_aabb, 4);
226 
227 struct key_id_pair {
228    uint32_t id;
229    uint32_t key;
230 };
231 TYPE(key_id_pair, 4);
232 
233 TYPE(vk_accel_struct_serialization_header, 8);
234 
235 TYPE(vk_ir_header, 4);
236 TYPE(vk_ir_node, 4);
237 TYPE(vk_ir_box_node, 4);
238 TYPE(vk_ir_triangle_node, 4);
239 TYPE(vk_ir_aabb_node, 4);
240 TYPE(vk_ir_instance_node, 8);
241 
242 TYPE(vk_global_sync_data, 4);
243 
244 uint32_t
ir_id_to_offset(uint32_t id)245 ir_id_to_offset(uint32_t id)
246 {
247    return id & (~3u);
248 }
249 
250 uint32_t
ir_id_to_type(uint32_t id)251 ir_id_to_type(uint32_t id)
252 {
253    return id & 3u;
254 }
255 
256 uint32_t
pack_ir_node_id(uint32_t offset,uint32_t type)257 pack_ir_node_id(uint32_t offset, uint32_t type)
258 {
259    return offset | type;
260 }
261 
262 float
aabb_surface_area(vk_aabb aabb)263 aabb_surface_area(vk_aabb aabb)
264 {
265    vec3 diagonal = aabb.max - aabb.min;
266    return 2 * diagonal.x * diagonal.y + 2 * diagonal.y * diagonal.z + 2 * diagonal.x * diagonal.z;
267 }
268 
269 /* Just a wrapper for 3 uints. */
270 struct triangle_indices {
271    uint32_t index[3];
272 };
273 
274 triangle_indices
load_indices(VOID_REF indices,uint32_t index_format,uint32_t global_id)275 load_indices(VOID_REF indices, uint32_t index_format, uint32_t global_id)
276 {
277    triangle_indices result;
278 
279    uint32_t index_base = global_id * 3;
280 
281    switch (index_format) {
282    case VK_INDEX_TYPE_UINT16: {
283       result.index[0] = DEREF(INDEX(uint16_t, indices, index_base + 0));
284       result.index[1] = DEREF(INDEX(uint16_t, indices, index_base + 1));
285       result.index[2] = DEREF(INDEX(uint16_t, indices, index_base + 2));
286       break;
287    }
288    case VK_INDEX_TYPE_UINT32: {
289       result.index[0] = DEREF(INDEX(uint32_t, indices, index_base + 0));
290       result.index[1] = DEREF(INDEX(uint32_t, indices, index_base + 1));
291       result.index[2] = DEREF(INDEX(uint32_t, indices, index_base + 2));
292       break;
293    }
294    case VK_INDEX_TYPE_NONE_KHR: {
295       result.index[0] = index_base + 0;
296       result.index[1] = index_base + 1;
297       result.index[2] = index_base + 2;
298       break;
299    }
300    case VK_INDEX_TYPE_UINT8_EXT: {
301       result.index[0] = DEREF(INDEX(uint8_t, indices, index_base + 0));
302       result.index[1] = DEREF(INDEX(uint8_t, indices, index_base + 1));
303       result.index[2] = DEREF(INDEX(uint8_t, indices, index_base + 2));
304       break;
305    }
306    }
307 
308    return result;
309 }
310 
311 /* Just a wrapper for 3 vec4s. */
312 struct triangle_vertices {
313    vec4 vertex[3];
314 };
315 
316 TYPE(float16_t, 2);
317 
318 triangle_vertices
load_vertices(VOID_REF vertices,triangle_indices indices,uint32_t vertex_format,uint32_t stride)319 load_vertices(VOID_REF vertices, triangle_indices indices, uint32_t vertex_format, uint32_t stride)
320 {
321    triangle_vertices result;
322 
323    for (uint32_t i = 0; i < 3; i++) {
324       VOID_REF vertex_ptr = OFFSET(vertices, indices.index[i] * stride);
325       vec4 vertex = vec4(0.0, 0.0, 0.0, 1.0);
326 
327       switch (vertex_format) {
328       case VK_FORMAT_R32G32_SFLOAT:
329          vertex.x = DEREF(INDEX(float, vertex_ptr, 0));
330          vertex.y = DEREF(INDEX(float, vertex_ptr, 1));
331          break;
332       case VK_FORMAT_R32G32B32_SFLOAT:
333       case VK_FORMAT_R32G32B32A32_SFLOAT:
334          vertex.x = DEREF(INDEX(float, vertex_ptr, 0));
335          vertex.y = DEREF(INDEX(float, vertex_ptr, 1));
336          vertex.z = DEREF(INDEX(float, vertex_ptr, 2));
337          break;
338       case VK_FORMAT_R16G16_SFLOAT:
339          vertex.x = DEREF(INDEX(float16_t, vertex_ptr, 0));
340          vertex.y = DEREF(INDEX(float16_t, vertex_ptr, 1));
341          break;
342       case VK_FORMAT_R16G16B16_SFLOAT:
343       case VK_FORMAT_R16G16B16A16_SFLOAT:
344          vertex.x = DEREF(INDEX(float16_t, vertex_ptr, 0));
345          vertex.y = DEREF(INDEX(float16_t, vertex_ptr, 1));
346          vertex.z = DEREF(INDEX(float16_t, vertex_ptr, 2));
347          break;
348       case VK_FORMAT_R16G16_SNORM:
349          vertex.x = max(-1.0, DEREF(INDEX(int16_t, vertex_ptr, 0)) / float(0x7FFF));
350          vertex.y = max(-1.0, DEREF(INDEX(int16_t, vertex_ptr, 1)) / float(0x7FFF));
351          break;
352       case VK_FORMAT_R16G16B16A16_SNORM:
353          vertex.x = max(-1.0, DEREF(INDEX(int16_t, vertex_ptr, 0)) / float(0x7FFF));
354          vertex.y = max(-1.0, DEREF(INDEX(int16_t, vertex_ptr, 1)) / float(0x7FFF));
355          vertex.z = max(-1.0, DEREF(INDEX(int16_t, vertex_ptr, 2)) / float(0x7FFF));
356          break;
357       case VK_FORMAT_R8G8_SNORM:
358          vertex.x = max(-1.0, DEREF(INDEX(int8_t, vertex_ptr, 0)) / float(0x7F));
359          vertex.y = max(-1.0, DEREF(INDEX(int8_t, vertex_ptr, 1)) / float(0x7F));
360          break;
361       case VK_FORMAT_R8G8B8A8_SNORM:
362          vertex.x = max(-1.0, DEREF(INDEX(int8_t, vertex_ptr, 0)) / float(0x7F));
363          vertex.y = max(-1.0, DEREF(INDEX(int8_t, vertex_ptr, 1)) / float(0x7F));
364          vertex.z = max(-1.0, DEREF(INDEX(int8_t, vertex_ptr, 2)) / float(0x7F));
365          break;
366       case VK_FORMAT_R16G16_UNORM:
367          vertex.x = DEREF(INDEX(uint16_t, vertex_ptr, 0)) / float(0xFFFF);
368          vertex.y = DEREF(INDEX(uint16_t, vertex_ptr, 1)) / float(0xFFFF);
369          break;
370       case VK_FORMAT_R16G16B16A16_UNORM:
371          vertex.x = DEREF(INDEX(uint16_t, vertex_ptr, 0)) / float(0xFFFF);
372          vertex.y = DEREF(INDEX(uint16_t, vertex_ptr, 1)) / float(0xFFFF);
373          vertex.z = DEREF(INDEX(uint16_t, vertex_ptr, 2)) / float(0xFFFF);
374          break;
375       case VK_FORMAT_R8G8_UNORM:
376          vertex.x = DEREF(INDEX(uint8_t, vertex_ptr, 0)) / float(0xFF);
377          vertex.y = DEREF(INDEX(uint8_t, vertex_ptr, 1)) / float(0xFF);
378          break;
379       case VK_FORMAT_R8G8B8A8_UNORM:
380          vertex.x = DEREF(INDEX(uint8_t, vertex_ptr, 0)) / float(0xFF);
381          vertex.y = DEREF(INDEX(uint8_t, vertex_ptr, 1)) / float(0xFF);
382          vertex.z = DEREF(INDEX(uint8_t, vertex_ptr, 2)) / float(0xFF);
383          break;
384       case VK_FORMAT_A2B10G10R10_UNORM_PACK32: {
385          uint32_t data = DEREF(REF(uint32_t)(vertex_ptr));
386          vertex.x = float(data & 0x3FF) / 0x3FF;
387          vertex.y = float((data >> 10) & 0x3FF) / 0x3FF;
388          vertex.z = float((data >> 20) & 0x3FF) / 0x3FF;
389          break;
390       }
391       }
392 
393       result.vertex[i] = vertex;
394    }
395 
396    return result;
397 }
398 
399 /** Compute ceiling of integer quotient of A divided by B.
400     From macros.h */
401 #define DIV_ROUND_UP(A, B) (((A) + (B)-1) / (B))
402 
403 #ifdef USE_GLOBAL_SYNC
404 
405 /* There might be more invocations available than tasks to do.
406  * In that case, the fetched task index is greater than the
407  * counter offset for the next phase. To avoid out-of-bounds
408  * accessing, phases will be skipped until the task index is
409  * is in-bounds again. */
410 uint32_t num_tasks_to_skip = 0;
411 uint32_t phase_index = 0;
412 bool should_skip = false;
413 shared uint32_t global_task_index;
414 
415 shared uint32_t shared_phase_index;
416 
417 uint32_t
task_count(REF (vk_ir_header)header)418 task_count(REF(vk_ir_header) header)
419 {
420    uint32_t phase_index = DEREF(header).sync_data.phase_index;
421    return DEREF(header).sync_data.task_counts[phase_index & 1];
422 }
423 
424 /* Sets the task count for the next phase. */
425 void
set_next_task_count(REF (vk_ir_header)header,uint32_t new_count)426 set_next_task_count(REF(vk_ir_header) header, uint32_t new_count)
427 {
428    uint32_t phase_index = DEREF(header).sync_data.phase_index;
429    DEREF(header).sync_data.task_counts[(phase_index + 1) & 1] = new_count;
430 }
431 
432 /*
433  * This function has two main objectives:
434  * Firstly, it partitions pending work among free invocations.
435  * Secondly, it guarantees global synchronization between different phases.
436  *
437  * After every call to fetch_task, a new task index is returned.
438  * fetch_task will also set num_tasks_to_skip. Use should_execute_phase
439  * to determine if the current phase should be executed or skipped.
440  *
441  * Since tasks are assigned per-workgroup, there is a possibility of the task index being
442  * greater than the total task count.
443  */
444 uint32_t
fetch_task(REF (vk_ir_header)header,bool did_work)445 fetch_task(REF(vk_ir_header) header, bool did_work)
446 {
447    /* Perform a memory + control barrier for all buffer writes for the entire workgroup.
448     * This guarantees that once the workgroup leaves the PHASE loop, all invocations have finished
449     * and their results are written to memory. */
450    controlBarrier(gl_ScopeWorkgroup, gl_ScopeDevice, gl_StorageSemanticsBuffer,
451                   gl_SemanticsAcquireRelease | gl_SemanticsMakeAvailable | gl_SemanticsMakeVisible);
452    if (gl_LocalInvocationIndex == 0) {
453       if (did_work)
454          atomicAdd(DEREF(header).sync_data.task_done_counter, 1);
455       global_task_index = atomicAdd(DEREF(header).sync_data.task_started_counter, 1);
456 
457       do {
458          /* Perform a memory barrier to refresh the current phase's end counter, in case
459           * another workgroup changed it. */
460          memoryBarrier(gl_ScopeDevice, gl_StorageSemanticsBuffer,
461                        gl_SemanticsAcquireRelease | gl_SemanticsMakeAvailable | gl_SemanticsMakeVisible);
462 
463          /* The first invocation of the first workgroup in a new phase is responsible to initiate the
464           * switch to a new phase. It is only possible to switch to a new phase if all tasks of the
465           * previous phase have been completed. Switching to a new phase and incrementing the phase
466           * end counter in turn notifies all invocations for that phase that it is safe to execute.
467           */
468          if (global_task_index == DEREF(header).sync_data.current_phase_end_counter &&
469              DEREF(header).sync_data.task_done_counter == DEREF(header).sync_data.current_phase_end_counter) {
470             if (DEREF(header).sync_data.next_phase_exit_flag != 0) {
471                DEREF(header).sync_data.phase_index = TASK_INDEX_INVALID;
472                memoryBarrier(gl_ScopeDevice, gl_StorageSemanticsBuffer,
473                              gl_SemanticsAcquireRelease | gl_SemanticsMakeAvailable | gl_SemanticsMakeVisible);
474             } else {
475                atomicAdd(DEREF(header).sync_data.phase_index, 1);
476                DEREF(header).sync_data.current_phase_start_counter = DEREF(header).sync_data.current_phase_end_counter;
477                /* Ensure the changes to the phase index and start/end counter are visible for other
478                 * workgroup waiting in the loop. */
479                memoryBarrier(gl_ScopeDevice, gl_StorageSemanticsBuffer,
480                              gl_SemanticsAcquireRelease | gl_SemanticsMakeAvailable | gl_SemanticsMakeVisible);
481                atomicAdd(DEREF(header).sync_data.current_phase_end_counter,
482                          DIV_ROUND_UP(task_count(header), gl_WorkGroupSize.x));
483             }
484             break;
485          }
486 
487          /* If other invocations have finished all nodes, break out; there is no work to do */
488          if (DEREF(header).sync_data.phase_index == TASK_INDEX_INVALID) {
489             break;
490          }
491       } while (global_task_index >= DEREF(header).sync_data.current_phase_end_counter);
492 
493       shared_phase_index = DEREF(header).sync_data.phase_index;
494    }
495 
496    barrier();
497    if (DEREF(header).sync_data.phase_index == TASK_INDEX_INVALID)
498       return TASK_INDEX_INVALID;
499 
500    num_tasks_to_skip = shared_phase_index - phase_index;
501 
502    uint32_t local_task_index = global_task_index - DEREF(header).sync_data.current_phase_start_counter;
503    return local_task_index * gl_WorkGroupSize.x + gl_LocalInvocationID.x;
504 }
505 
506 bool
should_execute_phase()507 should_execute_phase()
508 {
509    if (num_tasks_to_skip > 0) {
510       /* Skip to next phase. */
511       ++phase_index;
512       --num_tasks_to_skip;
513       return false;
514    }
515    return true;
516 }
517 
518 #define PHASE(header)                                                                                                  \
519    for (; task_index != TASK_INDEX_INVALID && should_execute_phase(); task_index = fetch_task(header, true))
520 #endif
521 
522 #endif
523