src/compiler/nir/nir_lower_clip_halfz.c

   1 /*
   2  * Copyright 2018-2019 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  * on the rights to use, copy, modify, merge, publish, distribute, sub
   8  * license, and/or sell copies of the Software, and to permit persons to whom
   9  * the 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 NON-INFRINGEMENT. IN NO EVENT SHALL
  18  * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
  19  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  20  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  21  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #include "nir_builder.h"
  25
  26 static void
  27 lower_pos_write(nir_builder *b, struct nir_instr *instr)
  28 {
  29    if (instr->type != nir_instr_type_intrinsic)
  30       return;
  31
  32    nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
  33    if (intr->intrinsic != nir_intrinsic_store_deref)
  34       return;
  35
  36    nir_variable *var = nir_intrinsic_get_var(intr, 0);
  37    if (var->data.mode != nir_var_shader_out ||
  38        var->data.location != VARYING_SLOT_POS)
  39       return;
  40
  41    b->cursor = nir_before_instr(&intr->instr);
  42
  43    nir_ssa_def *pos = nir_ssa_for_src(b, intr->src[1], 4);
  44    nir_ssa_def *def = nir_vec4(b,
  45                                nir_channel(b, pos, 0),
  46                                nir_channel(b, pos, 1),
  47                                nir_fmul_imm(b,
  48                                             nir_fadd(b,
  49                                                      nir_channel(b, pos, 2),
  50                                                      nir_channel(b, pos, 3)),
  51                                             0.5),
  52                                nir_channel(b, pos, 3));
  53    nir_instr_rewrite_src(&intr->instr, intr->src + 1, nir_src_for_ssa(def));
  54 }
  55
  56 void
  57 nir_lower_clip_halfz(nir_shader *shader)
  58 {
  59    if (shader->info.stage != MESA_SHADER_VERTEX &&
  60        shader->info.stage != MESA_SHADER_GEOMETRY &&
  61        shader->info.stage != MESA_SHADER_TESS_EVAL)
  62       return;
  63
  64    nir_foreach_function(function, shader) {
  65       if (function->impl) {
  66          nir_builder b;
  67          nir_builder_init(&b, function->impl);
  68
  69          nir_foreach_block(block, function->impl) {
  70             nir_foreach_instr_safe(instr, block) {
  71                lower_pos_write(&b, instr);
  72             }
  73          }
  74
  75          nir_metadata_preserve(function->impl, nir_metadata_block_index |
  76                                                nir_metadata_dominance);
  77       }
  78    }
  79 }