src/compiler/nir/nir_lower_patch_vertices.c

   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
  27 static nir_variable *
  28 make_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  */
  56 bool
  57 nir_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                                            nir_src_for_ssa(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 }