src/mesa/state_tracker/st_nir_lower_builtin.c

   1 /*
   2  * Copyright © 2016 Red Hat
   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 FROM,
  20  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  21  * SOFTWARE.
  22  */
  23
  24 /* Lowering pass that lowers accesses to built-in uniform variables.
  25  * Built-in uniforms are not necessarily packed the same way that
  26  * normal uniform structs are, for example:
  27  *
  28  *    struct gl_FogParameters {
  29  *       vec4 color;
  30  *       float density;
  31  *       float start;
  32  *       float end;
  33  *       float scale;
  34  *    };
  35  *
  36  * is packed into vec4[2], whereas the same struct would be packed
  37  * (by gallium), as vec4[5] if it where not built-in.  Because of
  38  * this, we need to replace (for example) access like:
  39  *
  40  *    vec1 ssa_1 = intrinsic load_var () (gl_Fog.start) ()
  41  *
  42  * with:
  43  *
  44  *    vec4 ssa_2 = intrinsic load_var () (fog.params) ()
  45  *    vec1 ssa_1 = ssa_2.y
  46  *
  47  * with appropriate substitutions in the uniform variables list:
  48  *
  49  *    decl_var uniform INTERP_MODE_NONE gl_FogParameters gl_Fog (0, 0)
  50  *
  51  * would become:
  52  *
  53  *    decl_var uniform INTERP_MODE_NONE vec4 state.fog.color (0, 0)
  54  *    decl_var uniform INTERP_MODE_NONE vec4 state.fog.params (0, 1)
  55  *
  56  * See in particular 'struct gl_builtin_uniform_element'.
  57  */
  58
  59 #include "compiler/nir/nir.h"
  60 #include "compiler/nir/nir_builder.h"
  61 #include "compiler/nir/nir_deref.h"
  62 #include "st_nir.h"
  63 #include "compiler/glsl/ir.h"
  64 #include "uniforms.h"
  65 #include "program/prog_instruction.h"
  66
  67 typedef struct {
  68    nir_shader *shader;
  69    nir_builder builder;
  70    void *mem_ctx;
  71 } lower_builtin_state;
  72
  73 static const struct gl_builtin_uniform_element *
  74 get_element(const struct gl_builtin_uniform_desc *desc, nir_deref_path *path)
  75 {
  76    int idx = 1;
  77
  78    assert(path->path[0]->deref_type == nir_deref_type_var);
  79
  80    if ((desc->num_elements == 1) && (desc->elements[0].field == NULL))
  81       return NULL;
  82
  83    /* we handle arrays in get_variable(): */
  84    if (path->path[idx]->deref_type == nir_deref_type_array)
  85       idx++;
  86
  87    /* don't need to deal w/ non-struct or array of non-struct: */
  88    if (!path->path[idx])
  89       return NULL;
  90
  91    if (path->path[idx]->deref_type != nir_deref_type_struct)
  92       return NULL;
  93
  94    assert(path->path[idx]->strct.index < desc->num_elements);
  95
  96    return &desc->elements[path->path[idx]->strct.index ];
  97 }
  98
  99 static nir_variable *
 100 get_variable(lower_builtin_state *state, nir_deref_path *path,
 101              const struct gl_builtin_uniform_element *element)
 102 {
 103    nir_shader *shader = state->shader;
 104    gl_state_index16 tokens[STATE_LENGTH];
 105    int idx = 1;
 106
 107    memcpy(tokens, element->tokens, sizeof(tokens));
 108
 109    if (path->path[idx]->deref_type == nir_deref_type_array) {
 110       /* we need to fixup the array index slot: */
 111       switch (tokens[0]) {
 112       case STATE_MODELVIEW_MATRIX:
 113       case STATE_PROJECTION_MATRIX:
 114       case STATE_MVP_MATRIX:
 115       case STATE_TEXTURE_MATRIX:
 116       case STATE_PROGRAM_MATRIX:
 117       case STATE_LIGHT:
 118       case STATE_LIGHTPROD:
 119       case STATE_TEXGEN:
 120       case STATE_TEXENV_COLOR:
 121       case STATE_CLIPPLANE:
 122          tokens[1] = nir_src_as_uint(path->path[idx]->arr.index);
 123          break;
 124       }
 125    }
 126
 127    char *name = _mesa_program_state_string(tokens);
 128
 129    nir_foreach_uniform_variable(var, shader) {
 130       if (strcmp(var->name, name) == 0) {
 131          free(name);
 132          return var;
 133       }
 134    }
 135
 136    /* variable doesn't exist yet, so create it: */
 137    nir_variable *var =
 138       nir_variable_create(shader, nir_var_uniform, glsl_vec4_type(), name);
 139
 140    var->num_state_slots = 1;
 141    var->state_slots = rzalloc_array(var, nir_state_slot, 1);
 142    memcpy(var->state_slots[0].tokens, tokens,
 143           sizeof(var->state_slots[0].tokens));
 144
 145    free(name);
 146
 147    return var;
 148 }
 149
 150 static bool
 151 lower_builtin_block(lower_builtin_state *state, nir_block *block)
 152 {
 153    nir_builder *b = &state->builder;
 154    bool progress = false;
 155
 156    nir_foreach_instr_safe(instr, block) {
 157       if (instr->type != nir_instr_type_intrinsic)
 158          continue;
 159
 160       nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
 161
 162       if (intrin->intrinsic != nir_intrinsic_load_deref)
 163          continue;
 164
 165       nir_variable *var =
 166          nir_deref_instr_get_variable(nir_src_as_deref(intrin->src[0]));
 167       if (var->data.mode != nir_var_uniform)
 168          continue;
 169
 170       /* built-in's will always start with "gl_" */
 171       if (strncmp(var->name, "gl_", 3) != 0)
 172          continue;
 173
 174       const struct gl_builtin_uniform_desc *desc =
 175          _mesa_glsl_get_builtin_uniform_desc(var->name);
 176
 177       /* if no descriptor, it isn't something we need to handle specially: */
 178       if (!desc)
 179          continue;
 180
 181       nir_deref_path path;
 182       nir_deref_path_init(&path, nir_src_as_deref(intrin->src[0]), NULL);
 183
 184       const struct gl_builtin_uniform_element *element = get_element(desc, &path);
 185
 186       /* matrix elements (array_deref) do not need special handling: */
 187       if (!element) {
 188          nir_deref_path_finish(&path);
 189          continue;
 190       }
 191
 192       /* remove existing var from uniform list: */
 193       exec_node_remove(&var->node);
 194       /* the _self_link() ensures we can remove multiple times, rather than
 195        * trying to keep track of what we have already removed:
 196        */
 197       exec_node_self_link(&var->node);
 198
 199       nir_variable *new_var = get_variable(state, &path, element);
 200       nir_deref_path_finish(&path);
 201
 202       b->cursor = nir_before_instr(instr);
 203
 204       nir_ssa_def *def = nir_load_var(b, new_var);
 205
 206       /* swizzle the result: */
 207       unsigned swiz[NIR_MAX_VEC_COMPONENTS] = {0};
 208       for (unsigned i = 0; i < 4; i++) {
 209          swiz[i] = GET_SWZ(element->swizzle, i);
 210          assert(swiz[i] <= SWIZZLE_W);
 211       }
 212       def = nir_swizzle(b, def, swiz, intrin->num_components);
 213
 214       /* and rewrite uses of original instruction: */
 215       assert(intrin->dest.is_ssa);
 216       nir_ssa_def_rewrite_uses(&intrin->dest.ssa, nir_src_for_ssa(def));
 217
 218       /* at this point intrin should be unused.  We need to remove it
 219        * (rather than waiting for DCE pass) to avoid dangling reference
 220        * to remove'd var.  And we have to remove the original uniform
 221        * var since we don't want it to get uniform space allocated.
 222        */
 223       nir_instr_remove(&intrin->instr);
 224
 225       progress = true;
 226    }
 227
 228    return progress;
 229 }
 230
 231 static void
 232 lower_builtin_impl(lower_builtin_state *state, nir_function_impl *impl)
 233 {
 234    nir_builder_init(&state->builder, impl);
 235    state->mem_ctx = ralloc_parent(impl);
 236
 237    bool progress = false;
 238    nir_foreach_block(block, impl) {
 239       progress |= lower_builtin_block(state, block);
 240    }
 241
 242    if (progress)
 243       nir_remove_dead_derefs_impl(impl);
 244
 245    nir_metadata_preserve(impl, nir_metadata_block_index |
 246                                nir_metadata_dominance);
 247 }
 248
 249 void
 250 st_nir_lower_builtin(nir_shader *shader)
 251 {
 252    lower_builtin_state state;
 253    state.shader = shader;
 254    nir_foreach_function(function, shader) {
 255       if (function->impl)
 256          lower_builtin_impl(&state, function->impl);
 257    }
 258 }