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 * Note: This linking pass is currently tailored for ARB_gl_spirv needs and
35 * particularities.
36 */
37
38void
39gl_nir_link_assign_xfb_resources(struct gl_context *ctx,
40                                 struct gl_shader_program *prog)
41{
42   /*
43    * From ARB_gl_spirv spec:
44    *
45    *    "- If the *Xfb* Execution Mode is set, any output variable that is at
46    *       least partially captured:
47    *       * must be decorated with an *XfbBuffer*, declaring the capturing buffer
48    *       * must have at least one captured output variable in the capturing
49    *         buffer decorated with an *XfbStride* (and all such *XfbStride* values
50    *         for the capturing buffer must be equal)
51    *     - If the *Xfb* Execution Mode is set, any captured output:
52    *       * must be a non-structure decorated with *Offset* or a member of a
53    *         structure whose type member is decorated with *Offset*"
54    *
55    * Note the "must be", meaning that explicit buffer, offset and stride are
56    * mandatory. So as this is intended to work with SPIR-V shaders we don't
57    * need to calculate the offset or the stride.
58    */
59
60   struct gl_program *xfb_prog = prog->last_vert_prog;
61
62   if (xfb_prog == NULL)
63      return;
64
65   /* free existing varyings, if any */
66   for (unsigned i = 0; i < prog->TransformFeedback.NumVarying; i++)
67      free(prog->TransformFeedback.VaryingNames[i]);
68   free(prog->TransformFeedback.VaryingNames);
69
70   nir_xfb_info *xfb_info = NULL;
71   nir_xfb_varyings_info *varyings_info = NULL;
72
73   /* Find last stage before fragment shader */
74   for (int stage = MESA_SHADER_FRAGMENT - 1; stage >= 0; stage--) {
75      struct gl_linked_shader *sh = prog->_LinkedShaders[stage];
76
77      if (sh && stage != MESA_SHADER_TESS_CTRL) {
78         xfb_info = nir_gather_xfb_info_with_varyings(sh->Program->nir, NULL, &varyings_info);
79         break;
80      }
81   }
82
83   struct gl_transform_feedback_info *linked_xfb =
84      rzalloc(xfb_prog, struct gl_transform_feedback_info);
85   xfb_prog->sh.LinkedTransformFeedback = linked_xfb;
86
87   if (!xfb_info) {
88      prog->TransformFeedback.NumVarying = 0;
89      linked_xfb->NumOutputs = 0;
90      linked_xfb->NumVarying = 0;
91      linked_xfb->ActiveBuffers = 0;
92      return;
93   }
94
95   for (unsigned buf = 0; buf < MAX_FEEDBACK_BUFFERS; buf++)
96      prog->TransformFeedback.BufferStride[buf] = xfb_info->buffers[buf].stride;
97
98   prog->TransformFeedback.NumVarying = varyings_info->varying_count;
99   prog->TransformFeedback.VaryingNames =
100      malloc(sizeof(GLchar *) * varyings_info->varying_count);
101
102   linked_xfb->Outputs =
103      rzalloc_array(xfb_prog,
104                    struct gl_transform_feedback_output,
105                    xfb_info->output_count);
106   linked_xfb->NumOutputs = xfb_info->output_count;
107
108   linked_xfb->Varyings =
109      rzalloc_array(xfb_prog,
110                    struct gl_transform_feedback_varying_info,
111                    varyings_info->varying_count);
112   linked_xfb->NumVarying = varyings_info->varying_count;
113
114   int buffer_index = 0; /* Corresponds to GL_TRANSFORM_FEEDBACK_BUFFER_INDEX */
115   int xfb_buffer =
116      (varyings_info->varying_count > 0) ?
117      xfb_info->outputs[0].buffer : 0;
118
119   for (unsigned i = 0; i < varyings_info->varying_count; i++) {
120      nir_xfb_varying_info *xfb_varying = &varyings_info->varyings[i];
121
122      /* From ARB_gl_spirv spec:
123       *
124       *    "19. How should the program interface query operations behave for
125       *         program objects created from SPIR-V shaders?
126       *
127       *     DISCUSSION: we previously said we didn't need reflection to work
128       *     for SPIR-V shaders (at least for the first version), however we
129       *     are left with specifying how it should "not work". The primary
130       *     issue is that SPIR-V binaries are not required to have names
131       *     associated with variables. They can be associated in debug
132       *     information, but there is no requirement for that to be present,
133       *     and it should not be relied upon."
134       *
135       *     Options:"
136       *
137       *     <skip>
138       *
139       *     "RESOLVED.  Pick (c), but also allow debug names to be returned
140       *      if an implementation wants to."
141       *
142       * So names are considered optional debug info, so the linker needs to
143       * work without them, and returning them is optional. For simplicity at
144       * this point we are ignoring names
145       */
146      prog->TransformFeedback.VaryingNames[i] = NULL;
147
148      if (xfb_buffer != xfb_varying->buffer) {
149         buffer_index++;
150         xfb_buffer = xfb_varying->buffer;
151      }
152
153      struct gl_transform_feedback_varying_info *varying =
154         linked_xfb->Varyings + i;
155
156      /* ARB_gl_spirv: see above. */
157      varying->Name = NULL;
158      varying->Type = glsl_get_gl_type(xfb_varying->type);
159      varying->BufferIndex = buffer_index;
160      varying->Size = glsl_type_is_array(xfb_varying->type) ?
161         glsl_get_length(xfb_varying->type) : 1;
162      varying->Offset = xfb_varying->offset;
163   }
164
165   for (unsigned i = 0; i < xfb_info->output_count; i++) {
166      nir_xfb_output_info *xfb_output = &xfb_info->outputs[i];
167
168      struct gl_transform_feedback_output *output =
169         linked_xfb->Outputs + i;
170
171      output->OutputRegister = xfb_output->location;
172      output->OutputBuffer = xfb_output->buffer;
173      output->NumComponents = util_bitcount(xfb_output->component_mask);
174      output->StreamId = xfb_info->buffer_to_stream[xfb_output->buffer];
175      output->DstOffset = xfb_output->offset / 4;
176      output->ComponentOffset = xfb_output->component_offset;
177   }
178
179   /* Make sure MaxTransformFeedbackBuffers is <= 32 so the bitmask for
180    * tracking the number of buffers doesn't overflow.
181    */
182   unsigned buffers = 0;
183   assert(ctx->Const.MaxTransformFeedbackBuffers <= sizeof(buffers) * 8);
184
185   for (unsigned buf = 0; buf < MAX_FEEDBACK_BUFFERS; buf++) {
186      if (xfb_info->buffers[buf].stride > 0) {
187         linked_xfb->Buffers[buf].Stride = xfb_info->buffers[buf].stride / 4;
188         linked_xfb->Buffers[buf].NumVaryings = xfb_info->buffers[buf].varying_count;
189         buffers |= 1 << buf;
190      }
191   }
192
193   linked_xfb->ActiveBuffers = buffers;
194
195   ralloc_free(xfb_info);
196}
197