src/compiler/nir/nir_lower_point_size_mov.c

   1 /*
   2  * Copyright © 2019 Collabora Ltd
   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_builder.h"
  26
  27 /** nir_lower_point_size_mov.c
  28  *
  29  * This pass lowers glPointSize into gl_PointSize, by adding a uniform
  30  * and a move from that uniform to VARYING_SLOT_PSIZ. This is useful for
  31  * OpenGL ES level hardware that lack constant point-size hardware state.
  32  */
  33
  34 static bool
  35 lower_impl(nir_function_impl *impl,
  36            const gl_state_index16 *pointsize_state_tokens,
  37            nir_variable *out)
  38 {
  39    nir_shader *shader = impl->function->shader;
  40    nir_builder b;
  41    nir_variable *in;
  42
  43    nir_builder_init(&b, impl);
  44    b.cursor = nir_before_cf_list(&impl->body);
  45
  46    in = nir_variable_create(shader, nir_var_uniform,
  47                             glsl_float_type(), "gl_PointSizeClampedMESA");
  48    in->num_state_slots = 1;
  49    in->state_slots = ralloc_array(in, nir_state_slot, 1);
  50    memcpy(in->state_slots[0].tokens,
  51          pointsize_state_tokens,
  52          sizeof(in->state_slots[0].tokens));
  53
  54    if (!out) {
  55       out = nir_variable_create(shader, nir_var_shader_out,
  56                                 glsl_float_type(), "gl_PointSize");
  57       out->data.location = VARYING_SLOT_PSIZ;
  58    }
  59
  60    nir_copy_var(&b, out, in);
  61
  62    nir_metadata_preserve(impl, nir_metadata_block_index |
  63                                nir_metadata_dominance);
  64    return true;
  65 }
  66
  67 void
  68 nir_lower_point_size_mov(nir_shader *shader,
  69                          const gl_state_index16 *pointsize_state_tokens)
  70 {
  71    assert(shader->info.stage != MESA_SHADER_FRAGMENT &&
  72           shader->info.stage != MESA_SHADER_COMPUTE);
  73
  74    nir_variable *out = NULL;
  75    nir_foreach_shader_out_variable(var, shader) {
  76       if (var->data.location == VARYING_SLOT_PSIZ) {
  77          out = var;
  78          break;
  79       }
  80    }
  81
  82    lower_impl(nir_shader_get_entrypoint(shader), pointsize_state_tokens,
  83               out);
  84 }