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 "common/gen_debug.h"
  27
  28 namespace brw {
  29
  30 void
  31 vec4_vs_visitor::emit_prolog()
  32 {
  33 }
  34
  35
  36 dst_reg *
  37 vec4_vs_visitor::make_reg_for_system_value(int location)
  38 {
  39    /* VertexID is stored by the VF as the last vertex element, but
  40     * we don't represent it with a flag in inputs_read, so we call
  41     * it VERT_ATTRIB_MAX, which setup_attributes() picks up on.
  42     */
  43    dst_reg *reg = new(mem_ctx) dst_reg(ATTR, VERT_ATTRIB_MAX);
  44
  45    switch (location) {
  46    case SYSTEM_VALUE_BASE_VERTEX:
  47       reg->writemask = WRITEMASK_X;
  48       vs_prog_data->uses_basevertex = true;
  49       break;
  50    case SYSTEM_VALUE_BASE_INSTANCE:
  51       reg->writemask = WRITEMASK_Y;
  52       vs_prog_data->uses_baseinstance = true;
  53       break;
  54    case SYSTEM_VALUE_VERTEX_ID:
  55    case SYSTEM_VALUE_VERTEX_ID_ZERO_BASE:
  56       reg->writemask = WRITEMASK_Z;
  57       vs_prog_data->uses_vertexid = true;
  58       break;
  59    case SYSTEM_VALUE_INSTANCE_ID:
  60       reg->writemask = WRITEMASK_W;
  61       vs_prog_data->uses_instanceid = true;
  62       break;
  63    case SYSTEM_VALUE_DRAW_ID:
  64       reg = new(mem_ctx) dst_reg(ATTR, VERT_ATTRIB_MAX + 1);
  65       reg->writemask = WRITEMASK_X;
  66       vs_prog_data->uses_drawid = true;
  67       break;
  68    default:
  69       unreachable("not reached");
  70    }
  71
  72    return reg;
  73 }
  74
  75
  76 void
  77 vec4_vs_visitor::emit_urb_write_header(int mrf)
  78 {
  79    /* No need to do anything for VS; an implied write to this MRF will be
  80     * performed by VS_OPCODE_URB_WRITE.
  81     */
  82    (void) mrf;
  83 }
  84
  85
  86 vec4_instruction *
  87 vec4_vs_visitor::emit_urb_write_opcode(bool complete)
  88 {
  89    /* For VS, the URB writes end the thread. */
  90    if (complete) {
  91       if (INTEL_DEBUG & DEBUG_SHADER_TIME)
  92          emit_shader_time_end();
  93    }
  94
  95    vec4_instruction *inst = emit(VS_OPCODE_URB_WRITE);
  96    inst->urb_write_flags = complete ?
  97       BRW_URB_WRITE_EOT_COMPLETE : BRW_URB_WRITE_NO_FLAGS;
  98
  99    return inst;
 100 }
 101
 102
 103 void
 104 vec4_vs_visitor::emit_urb_slot(dst_reg reg, int varying)
 105 {
 106    reg.type = BRW_REGISTER_TYPE_F;
 107    output_reg[varying][0].type = reg.type;
 108
 109    switch (varying) {
 110    case VARYING_SLOT_COL0:
 111    case VARYING_SLOT_COL1:
 112    case VARYING_SLOT_BFC0:
 113    case VARYING_SLOT_BFC1: {
 114       /* These built-in varyings are only supported in compatibility mode,
 115        * and we only support GS in core profile.  So, this must be a vertex
 116        * shader.
 117        */
 118       vec4_instruction *inst = emit_generic_urb_slot(reg, varying, 0);
 119       if (inst && key->clamp_vertex_color)
 120          inst->saturate = true;
 121       break;
 122    }
 123    default:
 124       return vec4_visitor::emit_urb_slot(reg, varying);
 125    }
 126 }
 127
 128
 129 void
 130 vec4_vs_visitor::emit_clip_distances(dst_reg reg, int offset)
 131 {
 132    /* From the GLSL 1.30 spec, section 7.1 (Vertex Shader Special Variables):
 133     *
 134     *     "If a linked set of shaders forming the vertex stage contains no
 135     *     static write to gl_ClipVertex or gl_ClipDistance, but the
 136     *     application has requested clipping against user clip planes through
 137     *     the API, then the coordinate written to gl_Position is used for
 138     *     comparison against the user clip planes."
 139     *
 140     * This function is only called if the shader didn't write to
 141     * gl_ClipDistance.  Accordingly, we use gl_ClipVertex to perform clipping
 142     * if the user wrote to it; otherwise we use gl_Position.
 143     */
 144    gl_varying_slot clip_vertex = VARYING_SLOT_CLIP_VERTEX;
 145    if (!(prog_data->vue_map.slots_valid & VARYING_BIT_CLIP_VERTEX)) {
 146       clip_vertex = VARYING_SLOT_POS;
 147    }
 148
 149    for (int i = 0; i + offset < key->nr_userclip_plane_consts && i < 4;
 150         ++i) {
 151       reg.writemask = 1 << i;
 152       emit(DP4(reg,
 153                src_reg(output_reg[clip_vertex][0]),
 154                src_reg(this->userplane[i + offset])));
 155    }
 156 }
 157
 158
 159 void
 160 vec4_vs_visitor::setup_uniform_clipplane_values()
 161 {
 162    for (int i = 0; i < key->nr_userclip_plane_consts; ++i) {
 163       this->userplane[i] = dst_reg(UNIFORM, this->uniforms);
 164       this->userplane[i].type = BRW_REGISTER_TYPE_F;
 165       for (int j = 0; j < 4; ++j) {
 166          stage_prog_data->param[this->uniforms * 4 + j] =
 167             (gl_constant_value *) &clip_planes[i][j];
 168       }
 169       ++this->uniforms;
 170    }
 171 }
 172
 173
 174 void
 175 vec4_vs_visitor::emit_thread_end()
 176 {
 177    setup_uniform_clipplane_values();
 178
 179    /* Lower legacy ff and ClipVertex clipping to clip distances */
 180    if (key->nr_userclip_plane_consts > 0) {
 181       current_annotation = "user clip distances";
 182
 183       output_reg[VARYING_SLOT_CLIP_DIST0][0] =
 184          dst_reg(this, glsl_type::vec4_type);
 185       output_reg[VARYING_SLOT_CLIP_DIST1][0] =
 186          dst_reg(this, glsl_type::vec4_type);
 187       output_num_components[VARYING_SLOT_CLIP_DIST0][0] = 4;
 188       output_num_components[VARYING_SLOT_CLIP_DIST1][0] = 4;
 189
 190       emit_clip_distances(output_reg[VARYING_SLOT_CLIP_DIST0][0], 0);
 191       emit_clip_distances(output_reg[VARYING_SLOT_CLIP_DIST1][0], 4);
 192    }
 193
 194    /* For VS, we always end the thread by emitting a single vertex.
 195     * emit_urb_write_opcode() will take care of setting the eot flag on the
 196     * SEND instruction.
 197     */
 198    emit_vertex();
 199 }
 200
 201
 202 vec4_vs_visitor::vec4_vs_visitor(const struct brw_compiler *compiler,
 203                                  void *log_data,
 204                                  const struct brw_vs_prog_key *key,
 205                                  struct brw_vs_prog_data *vs_prog_data,
 206                                  const nir_shader *shader,
 207                                  gl_clip_plane *clip_planes,
 208                                  void *mem_ctx,
 209                                  int shader_time_index,
 210                                  bool use_legacy_snorm_formula)
 211    : vec4_visitor(compiler, log_data, &key->tex, &vs_prog_data->base, shader,
 212                   mem_ctx, false /* no_spills */, shader_time_index),
 213      key(key),
 214      vs_prog_data(vs_prog_data),
 215      clip_planes(clip_planes),
 216      use_legacy_snorm_formula(use_legacy_snorm_formula)
 217 {
 218 }
 219
 220
 221 } /* namespace brw */