1 /*
2 * Copyright © 2018 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 #include "nir.h"
25 #include "nir_xfb_info.h"
26 #include "gl_nir_linker.h"
27 #include "linker_util.h"
28 #include "main/context.h"
29 #include "util/u_math.h"
30
31 /**
32 * This file does the linking of GLSL transform feedback using NIR.
33 */
34
35 void
gl_nir_link_assign_xfb_resources(struct gl_context * ctx,struct gl_shader_program * prog)36 gl_nir_link_assign_xfb_resources(struct gl_context *ctx,
37 struct gl_shader_program *prog)
38 {
39 /*
40 * From ARB_gl_spirv spec:
41 *
42 * "- If the *Xfb* Execution Mode is set, any output variable that is at
43 * least partially captured:
44 * * must be decorated with an *XfbBuffer*, declaring the capturing buffer
45 * * must have at least one captured output variable in the capturing
46 * buffer decorated with an *XfbStride* (and all such *XfbStride* values
47 * for the capturing buffer must be equal)
48 * - If the *Xfb* Execution Mode is set, any captured output:
49 * * must be a non-structure decorated with *Offset* or a member of a
50 * structure whose type member is decorated with *Offset*"
51 *
52 * Note the "must be", meaning that explicit buffer, offset and stride are
53 * mandatory. So as this is intended to work with SPIR-V shaders we don't
54 * need to calculate the offset or the stride.
55 */
56
57 struct gl_program *xfb_prog = prog->last_vert_prog;
58
59 if (xfb_prog == NULL)
60 return;
61
62 /* free existing varyings, if any */
63 for (unsigned i = 0; i < prog->TransformFeedback.NumVarying; i++)
64 free(prog->TransformFeedback.VaryingNames[i]);
65 free(prog->TransformFeedback.VaryingNames);
66
67 nir_xfb_info *xfb_info = NULL;
68 nir_xfb_varyings_info *varyings_info = NULL;
69
70 /* Find last stage before fragment shader */
71 for (int stage = MESA_SHADER_FRAGMENT - 1; stage >= 0; stage--) {
72 struct gl_linked_shader *sh = prog->_LinkedShaders[stage];
73
74 if (sh && stage != MESA_SHADER_TESS_CTRL) {
75 xfb_info = nir_gather_xfb_info_with_varyings(sh->Program->nir, NULL, &varyings_info);
76 break;
77 }
78 }
79
80 struct gl_transform_feedback_info *linked_xfb =
81 rzalloc(xfb_prog, struct gl_transform_feedback_info);
82 xfb_prog->sh.LinkedTransformFeedback = linked_xfb;
83
84 if (!xfb_info) {
85 prog->TransformFeedback.NumVarying = 0;
86 linked_xfb->NumOutputs = 0;
87 linked_xfb->NumVarying = 0;
88 linked_xfb->ActiveBuffers = 0;
89 return;
90 }
91
92 for (unsigned buf = 0; buf < MAX_FEEDBACK_BUFFERS; buf++)
93 prog->TransformFeedback.BufferStride[buf] = xfb_info->buffers[buf].stride;
94
95 prog->TransformFeedback.NumVarying = varyings_info->varying_count;
96 prog->TransformFeedback.VaryingNames =
97 malloc(sizeof(GLchar *) * varyings_info->varying_count);
98
99 linked_xfb->Outputs =
100 rzalloc_array(xfb_prog,
101 struct gl_transform_feedback_output,
102 xfb_info->output_count);
103 linked_xfb->NumOutputs = xfb_info->output_count;
104
105 linked_xfb->Varyings =
106 rzalloc_array(xfb_prog,
107 struct gl_transform_feedback_varying_info,
108 varyings_info->varying_count);
109 linked_xfb->NumVarying = varyings_info->varying_count;
110
111 int buffer_index = 0; /* Corresponds to GL_TRANSFORM_FEEDBACK_BUFFER_INDEX */
112 int xfb_buffer =
113 (varyings_info->varying_count > 0) ?
114 xfb_info->outputs[0].buffer : 0;
115
116 for (unsigned i = 0; i < varyings_info->varying_count; i++) {
117 nir_xfb_varying_info *xfb_varying = &varyings_info->varyings[i];
118
119 /* From ARB_gl_spirv spec:
120 *
121 * "19. How should the program interface query operations behave for
122 * program objects created from SPIR-V shaders?
123 *
124 * DISCUSSION: we previously said we didn't need reflection to work
125 * for SPIR-V shaders (at least for the first version), however we
126 * are left with specifying how it should "not work". The primary
127 * issue is that SPIR-V binaries are not required to have names
128 * associated with variables. They can be associated in debug
129 * information, but there is no requirement for that to be present,
130 * and it should not be relied upon."
131 *
132 * Options:"
133 *
134 * <skip>
135 *
136 * "RESOLVED. Pick (c), but also allow debug names to be returned
137 * if an implementation wants to."
138 *
139 * So names are considered optional debug info, so the linker needs to
140 * work without them, and returning them is optional. For simplicity at
141 * this point we are ignoring names
142 */
143 prog->TransformFeedback.VaryingNames[i] = NULL;
144
145 if (xfb_buffer != xfb_varying->buffer) {
146 buffer_index++;
147 xfb_buffer = xfb_varying->buffer;
148 }
149
150 struct gl_transform_feedback_varying_info *varying =
151 linked_xfb->Varyings + i;
152
153 /* ARB_gl_spirv: see above. */
154 varying->Name = NULL;
155 varying->Type = glsl_get_gl_type(xfb_varying->type);
156 varying->BufferIndex = buffer_index;
157 varying->Size = glsl_type_is_array(xfb_varying->type) ?
158 glsl_get_length(xfb_varying->type) : 1;
159 varying->Offset = xfb_varying->offset;
160 }
161
162 for (unsigned i = 0; i < xfb_info->output_count; i++) {
163 nir_xfb_output_info *xfb_output = &xfb_info->outputs[i];
164
165 struct gl_transform_feedback_output *output =
166 linked_xfb->Outputs + i;
167
168 output->OutputRegister = xfb_output->location;
169 output->OutputBuffer = xfb_output->buffer;
170 output->NumComponents = util_bitcount(xfb_output->component_mask);
171 output->StreamId = xfb_info->buffer_to_stream[xfb_output->buffer];
172 output->DstOffset = xfb_output->offset / 4;
173 output->ComponentOffset = xfb_output->component_offset;
174 }
175
176 /* Make sure MaxTransformFeedbackBuffers is <= 32 so the bitmask for
177 * tracking the number of buffers doesn't overflow.
178 */
179 unsigned buffers = 0;
180 assert(ctx->Const.MaxTransformFeedbackBuffers <= sizeof(buffers) * 8);
181
182 for (unsigned buf = 0; buf < MAX_FEEDBACK_BUFFERS; buf++) {
183 if (xfb_info->buffers[buf].stride > 0) {
184 linked_xfb->Buffers[buf].Stride = xfb_info->buffers[buf].stride / 4;
185 linked_xfb->Buffers[buf].NumVaryings = xfb_info->buffers[buf].varying_count;
186 buffers |= 1 << buf;
187 }
188 }
189
190 linked_xfb->ActiveBuffers = buffers;
191
192 ralloc_free(xfb_info);
193 }
194