1/*
2 * Copyright © 2016 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_builder.h"
25#include "program/prog_instruction.h"
26
27static nir_variable *
28make_uniform(nir_shader *nir, const gl_state_index16 *tokens)
29{
30   /* Note: name must be prefixed with "gl_" to trigger slot based
31    * special handling in uniform setup.
32    */
33   nir_variable *var =
34      nir_variable_create(nir, nir_var_uniform, glsl_int_type(),
35                          "gl_PatchVerticesIn");
36   var->num_state_slots = 1;
37   var->state_slots = ralloc_array(var, nir_state_slot, var->num_state_slots);
38   memcpy(var->state_slots[0].tokens, tokens, sizeof(*tokens) * STATE_LENGTH);
39   var->state_slots[0].swizzle = SWIZZLE_XXXX;
40
41   return var;
42}
43
44/**
45 * This pass lowers the load_patch_vertices_in intrinsic.
46 *
47 * - If we statically know the value, we lower it to a constant.
48 *   (If a TES is linked against a TCS, the TCS tells us the TES input count.)
49 *
50 * - If not, and we're given Mesa state slots, we lower it to a uniform.
51 *
52 * - Otherwise, we leave it as a system value.
53 *
54 * This pass must be run after nir_lower_system_values().
55 */
56bool
57nir_lower_patch_vertices(nir_shader *nir,
58                         unsigned static_count,
59                         const gl_state_index16 *uniform_state_tokens)
60{
61   bool progress = false;
62   nir_variable *var = NULL;
63
64   /* If there's no static count and we don't want uniforms, there's no
65    * lowering to do...just bail early.
66    */
67   if (static_count == 0 && !uniform_state_tokens)
68      return false;
69
70   nir_foreach_function(function, nir) {
71      if (function->impl) {
72         nir_foreach_block(block, function->impl) {
73            nir_builder b;
74            nir_builder_init(&b, function->impl);
75            nir_foreach_instr_safe(instr, block) {
76               if (instr->type == nir_instr_type_intrinsic) {
77                  nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
78                  if (intr->intrinsic != nir_intrinsic_load_patch_vertices_in)
79                     continue;
80
81                  b.cursor = nir_before_instr(&intr->instr);
82
83                  nir_ssa_def *val = NULL;
84                  if (static_count) {
85                     val = nir_imm_int(&b, static_count);
86                  } else {
87                     if (!var)
88                        var = make_uniform(nir, uniform_state_tokens);
89
90                     val = nir_load_var(&b, var);
91                  }
92
93                  progress = true;
94                  nir_ssa_def_rewrite_uses(&intr->dest.ssa,
95                                           val);
96                  nir_instr_remove(instr);
97               }
98            }
99         }
100
101         if (progress) {
102            nir_metadata_preserve(function->impl, nir_metadata_block_index |
103                                                  nir_metadata_dominance);
104         }
105      }
106   }
107
108   return progress;
109}
110