src/intel/compiler/brw_vec4_vs_visitor.cpp

   1 /*
   2  * Copyright © 2013 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
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24
  25 #include "brw_vec4_vs.h"
  26 #include "dev/gen_debug.h"
  27
  28 namespace brw {
  29
  30 void
  31 vec4_vs_visitor::emit_prolog()
  32 {
  33 }
  34
  35
  36 void
  37 vec4_vs_visitor::emit_urb_write_header(int mrf)
  38 {
  39    /* No need to do anything for VS; an implied write to this MRF will be
  40     * performed by VS_OPCODE_URB_WRITE.
  41     */
  42    (void) mrf;
  43 }
  44
  45
  46 vec4_instruction *
  47 vec4_vs_visitor::emit_urb_write_opcode(bool complete)
  48 {
  49    /* For VS, the URB writes end the thread. */
  50    if (complete) {
  51       if (INTEL_DEBUG & DEBUG_SHADER_TIME)
  52          emit_shader_time_end();
  53    }
  54
  55    vec4_instruction *inst = emit(VS_OPCODE_URB_WRITE);
  56    inst->urb_write_flags = complete ?
  57       BRW_URB_WRITE_EOT_COMPLETE : BRW_URB_WRITE_NO_FLAGS;
  58
  59    return inst;
  60 }
  61
  62
  63 void
  64 vec4_vs_visitor::emit_urb_slot(dst_reg reg, int varying)
  65 {
  66    reg.type = BRW_REGISTER_TYPE_F;
  67    output_reg[varying][0].type = reg.type;
  68
  69    switch (varying) {
  70    case VARYING_SLOT_COL0:
  71    case VARYING_SLOT_COL1:
  72    case VARYING_SLOT_BFC0:
  73    case VARYING_SLOT_BFC1: {
  74       /* These built-in varyings are only supported in compatibility mode,
  75        * and we only support GS in core profile.  So, this must be a vertex
  76        * shader.
  77        */
  78       vec4_instruction *inst = emit_generic_urb_slot(reg, varying, 0);
  79       if (inst && key->clamp_vertex_color)
  80          inst->saturate = true;
  81       break;
  82    }
  83    default:
  84       return vec4_visitor::emit_urb_slot(reg, varying);
  85    }
  86 }
  87
  88
  89 void
  90 vec4_vs_visitor::emit_clip_distances(dst_reg reg, int offset)
  91 {
  92    /* From the GLSL 1.30 spec, section 7.1 (Vertex Shader Special Variables):
  93     *
  94     *     "If a linked set of shaders forming the vertex stage contains no
  95     *     static write to gl_ClipVertex or gl_ClipDistance, but the
  96     *     application has requested clipping against user clip planes through
  97     *     the API, then the coordinate written to gl_Position is used for
  98     *     comparison against the user clip planes."
  99     *
 100     * This function is only called if the shader didn't write to
 101     * gl_ClipDistance.  Accordingly, we use gl_ClipVertex to perform clipping
 102     * if the user wrote to it; otherwise we use gl_Position.
 103     */
 104    gl_varying_slot clip_vertex = VARYING_SLOT_CLIP_VERTEX;
 105    if (!(prog_data->vue_map.slots_valid & VARYING_BIT_CLIP_VERTEX)) {
 106       clip_vertex = VARYING_SLOT_POS;
 107    }
 108
 109    for (int i = 0; i + offset < key->nr_userclip_plane_consts && i < 4;
 110         ++i) {
 111       reg.writemask = 1 << i;
 112       emit(DP4(reg,
 113                src_reg(output_reg[clip_vertex][0]),
 114                src_reg(this->userplane[i + offset])));
 115    }
 116 }
 117
 118
 119 void
 120 vec4_vs_visitor::setup_uniform_clipplane_values()
 121 {
 122    if (key->nr_userclip_plane_consts == 0)
 123       return;
 124
 125    assert(stage_prog_data->nr_params == (unsigned)this->uniforms * 4);
 126    brw_stage_prog_data_add_params(stage_prog_data,
 127                                   key->nr_userclip_plane_consts * 4);
 128
 129    for (int i = 0; i < key->nr_userclip_plane_consts; ++i) {
 130       this->userplane[i] = dst_reg(UNIFORM, this->uniforms);
 131       this->userplane[i].type = BRW_REGISTER_TYPE_F;
 132       for (int j = 0; j < 4; ++j) {
 133          stage_prog_data->param[this->uniforms * 4 + j] =
 134             BRW_PARAM_BUILTIN_CLIP_PLANE(i, j);
 135       }
 136       ++this->uniforms;
 137    }
 138 }
 139
 140
 141 void
 142 vec4_vs_visitor::emit_thread_end()
 143 {
 144    setup_uniform_clipplane_values();
 145
 146    /* Lower legacy ff and ClipVertex clipping to clip distances */
 147    if (key->nr_userclip_plane_consts > 0) {
 148       current_annotation = "user clip distances";
 149
 150       output_reg[VARYING_SLOT_CLIP_DIST0][0] =
 151          dst_reg(this, glsl_type::vec4_type);
 152       output_reg[VARYING_SLOT_CLIP_DIST1][0] =
 153          dst_reg(this, glsl_type::vec4_type);
 154       output_num_components[VARYING_SLOT_CLIP_DIST0][0] = 4;
 155       output_num_components[VARYING_SLOT_CLIP_DIST1][0] = 4;
 156
 157       emit_clip_distances(output_reg[VARYING_SLOT_CLIP_DIST0][0], 0);
 158       emit_clip_distances(output_reg[VARYING_SLOT_CLIP_DIST1][0], 4);
 159    }
 160
 161    /* For VS, we always end the thread by emitting a single vertex.
 162     * emit_urb_write_opcode() will take care of setting the eot flag on the
 163     * SEND instruction.
 164     */
 165    emit_vertex();
 166 }
 167
 168
 169 vec4_vs_visitor::vec4_vs_visitor(const struct brw_compiler *compiler,
 170                                  void *log_data,
 171                                  const struct brw_vs_prog_key *key,
 172                                  struct brw_vs_prog_data *vs_prog_data,
 173                                  const nir_shader *shader,
 174                                  void *mem_ctx,
 175                                  int shader_time_index)
 176    : vec4_visitor(compiler, log_data, &key->tex, &vs_prog_data->base, shader,
 177                   mem_ctx, false /* no_spills */, shader_time_index),
 178      key(key),
 179      vs_prog_data(vs_prog_data)
 180 {
 181 }
 182
 183
 184 } /* namespace brw */