src/compiler/glsl/ir_set_program_inouts.cpp

   1 /*
   2  * Copyright © 2010 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  * \file ir_set_program_inouts.cpp
  26  *
  27  * Sets the inputs_read and outputs_written of Mesa programs.
  28  *
  29  * Mesa programs (gl_program, not gl_shader_program) have a set of
  30  * flags indicating which varyings are read and written.  Computing
  31  * which are actually read from some sort of backend code can be
  32  * tricky when variable array indexing involved.  So this pass
  33  * provides support for setting inputs_read and outputs_written right
  34  * from the GLSL IR.
  35  */
  36
  37 #include "main/core.h" /* for struct gl_program */
  38 #include "ir.h"
  39 #include "ir_visitor.h"
  40 #include "compiler/glsl_types.h"
  41
  42 namespace {
  43
  44 class ir_set_program_inouts_visitor : public ir_hierarchical_visitor {
  45 public:
  46    ir_set_program_inouts_visitor(struct gl_program *prog,
  47                                  gl_shader_stage shader_stage)
  48    {
  49       this->prog = prog;
  50       this->shader_stage = shader_stage;
  51    }
  52    ~ir_set_program_inouts_visitor()
  53    {
  54    }
  55
  56    virtual ir_visitor_status visit_enter(ir_dereference_array *);
  57    virtual ir_visitor_status visit_enter(ir_function_signature *);
  58    virtual ir_visitor_status visit_enter(ir_discard *);
  59    virtual ir_visitor_status visit_enter(ir_texture *);
  60    virtual ir_visitor_status visit(ir_dereference_variable *);
  61
  62 private:
  63    void mark_whole_variable(ir_variable *var);
  64    bool try_mark_partial_variable(ir_variable *var, ir_rvalue *index);
  65
  66    struct gl_program *prog;
  67    gl_shader_stage shader_stage;
  68 };
  69
  70 } /* anonymous namespace */
  71
  72 static inline bool
  73 is_shader_inout(ir_variable *var)
  74 {
  75    return var->data.mode == ir_var_shader_in ||
  76           var->data.mode == ir_var_shader_out ||
  77           var->data.mode == ir_var_system_value;
  78 }
  79
  80 static void
  81 mark(struct gl_program *prog, ir_variable *var, int offset, int len,
  82      gl_shader_stage stage)
  83 {
  84    /* As of GLSL 1.20, varyings can only be floats, floating-point
  85     * vectors or matrices, or arrays of them.  For Mesa programs using
  86     * inputs_read/outputs_written, everything but matrices uses one
  87     * slot, while matrices use a slot per column.  Presumably
  88     * something doing a more clever packing would use something other
  89     * than inputs_read/outputs_written.
  90     */
  91
  92    for (int i = 0; i < len; i++) {
  93       assert(var->data.location != -1);
  94
  95       int idx = var->data.location + offset + i;
  96       bool is_patch_generic = var->data.patch &&
  97                               idx != VARYING_SLOT_TESS_LEVEL_INNER &&
  98                               idx != VARYING_SLOT_TESS_LEVEL_OUTER &&
  99                               idx != VARYING_SLOT_BOUNDING_BOX0 &&
 100                               idx != VARYING_SLOT_BOUNDING_BOX1;
 101       GLbitfield64 bitfield;
 102
 103       if (is_patch_generic) {
 104          assert(idx >= VARYING_SLOT_PATCH0 && idx < VARYING_SLOT_TESS_MAX);
 105          bitfield = BITFIELD64_BIT(idx - VARYING_SLOT_PATCH0);
 106       }
 107       else {
 108          assert(idx < VARYING_SLOT_MAX);
 109          bitfield = BITFIELD64_BIT(idx);
 110       }
 111
 112       if (var->data.mode == ir_var_shader_in) {
 113          if (is_patch_generic)
 114             prog->info.patch_inputs_read |= bitfield;
 115          else
 116             prog->info.inputs_read |= bitfield;
 117
 118          /* double inputs read is only for vertex inputs */
 119          if (stage == MESA_SHADER_VERTEX &&
 120              var->type->without_array()->is_dual_slot())
 121             prog->info.double_inputs_read |= bitfield;
 122
 123          if (stage == MESA_SHADER_FRAGMENT) {
 124             prog->info.fs.uses_sample_qualifier |= var->data.sample;
 125          }
 126       } else if (var->data.mode == ir_var_system_value) {
 127          prog->SystemValuesRead |= bitfield;
 128       } else {
 129          assert(var->data.mode == ir_var_shader_out);
 130          if (is_patch_generic) {
 131             prog->info.patch_outputs_written |= bitfield;
 132          } else if (!var->data.read_only) {
 133             prog->info.outputs_written |= bitfield;
 134             if (var->data.index > 0)
 135                prog->SecondaryOutputsWritten |= bitfield;
 136          }
 137
 138          if (var->data.fb_fetch_output)
 139             prog->info.outputs_read |= bitfield;
 140       }
 141    }
 142 }
 143
 144 /**
 145  * Mark an entire variable as used.  Caller must ensure that the variable
 146  * represents a shader input or output.
 147  */
 148 void
 149 ir_set_program_inouts_visitor::mark_whole_variable(ir_variable *var)
 150 {
 151    const glsl_type *type = var->type;
 152    bool is_vertex_input = false;
 153    if (this->shader_stage == MESA_SHADER_GEOMETRY &&
 154        var->data.mode == ir_var_shader_in && type->is_array()) {
 155       type = type->fields.array;
 156    }
 157
 158    if (this->shader_stage == MESA_SHADER_TESS_CTRL &&
 159        var->data.mode == ir_var_shader_in) {
 160       assert(type->is_array());
 161       type = type->fields.array;
 162    }
 163
 164    if (this->shader_stage == MESA_SHADER_TESS_CTRL &&
 165        var->data.mode == ir_var_shader_out && !var->data.patch) {
 166       assert(type->is_array());
 167       type = type->fields.array;
 168    }
 169
 170    if (this->shader_stage == MESA_SHADER_TESS_EVAL &&
 171        var->data.mode == ir_var_shader_in && !var->data.patch) {
 172       assert(type->is_array());
 173       type = type->fields.array;
 174    }
 175
 176    if (this->shader_stage == MESA_SHADER_VERTEX &&
 177        var->data.mode == ir_var_shader_in)
 178       is_vertex_input = true;
 179
 180    mark(this->prog, var, 0, type->count_attribute_slots(is_vertex_input),
 181         this->shader_stage);
 182 }
 183
 184 /* Default handler: Mark all the locations in the variable as used. */
 185 ir_visitor_status
 186 ir_set_program_inouts_visitor::visit(ir_dereference_variable *ir)
 187 {
 188    if (!is_shader_inout(ir->var))
 189       return visit_continue;
 190
 191    mark_whole_variable(ir->var);
 192
 193    return visit_continue;
 194 }
 195
 196 /**
 197  * Try to mark a portion of the given variable as used.  Caller must ensure
 198  * that the variable represents a shader input or output which can be indexed
 199  * into in array fashion (an array or matrix).  For the purpose of geometry
 200  * shader inputs (which are always arrays*), this means that the array element
 201  * must be something that can be indexed into in array fashion.
 202  *
 203  * *Except gl_PrimitiveIDIn, as noted below.
 204  *
 205  * For tessellation control shaders all inputs and non-patch outputs are
 206  * arrays. For tessellation evaluation shaders non-patch inputs are arrays.
 207  *
 208  * If the index can't be interpreted as a constant, or some other problem
 209  * occurs, then nothing will be marked and false will be returned.
 210  */
 211 bool
 212 ir_set_program_inouts_visitor::try_mark_partial_variable(ir_variable *var,
 213                                                          ir_rvalue *index)
 214 {
 215    const glsl_type *type = var->type;
 216
 217    if (this->shader_stage == MESA_SHADER_GEOMETRY &&
 218        var->data.mode == ir_var_shader_in) {
 219       /* The only geometry shader input that is not an array is
 220        * gl_PrimitiveIDIn, and in that case, this code will never be reached,
 221        * because gl_PrimitiveIDIn can't be indexed into in array fashion.
 222        */
 223       assert(type->is_array());
 224       type = type->fields.array;
 225    }
 226
 227    if (this->shader_stage == MESA_SHADER_TESS_CTRL &&
 228        var->data.mode == ir_var_shader_in) {
 229       assert(type->is_array());
 230       type = type->fields.array;
 231    }
 232
 233    if (this->shader_stage == MESA_SHADER_TESS_CTRL &&
 234        var->data.mode == ir_var_shader_out && !var->data.patch) {
 235       assert(type->is_array());
 236       type = type->fields.array;
 237    }
 238
 239    if (this->shader_stage == MESA_SHADER_TESS_EVAL &&
 240        var->data.mode == ir_var_shader_in && !var->data.patch) {
 241       assert(type->is_array());
 242       type = type->fields.array;
 243    }
 244
 245    /* TODO: implement proper arrays of arrays support
 246     * for now let the caller mark whole variable as used.
 247     */
 248    if (type->is_array() && type->fields.array->is_array())
 249       return false;
 250
 251    /* The code below only handles:
 252     *
 253     * - Indexing into matrices
 254     * - Indexing into arrays of (matrices, vectors, or scalars)
 255     *
 256     * All other possibilities are either prohibited by GLSL (vertex inputs and
 257     * fragment outputs can't be structs) or should have been eliminated by
 258     * lowering passes (do_vec_index_to_swizzle() gets rid of indexing into
 259     * vectors, and lower_packed_varyings() gets rid of structs that occur in
 260     * varyings).
 261     *
 262     * However, we don't use varying packing in all cases - tessellation
 263     * shaders bypass it.  This means we'll see varying structs and arrays
 264     * of structs here.  For now, we just give up so the caller marks the
 265     * entire variable as used.
 266     */
 267    if (!(type->is_matrix() ||
 268         (type->is_array() &&
 269          (type->fields.array->is_numeric() ||
 270           type->fields.array->is_boolean())))) {
 271
 272       /* If we don't know how to handle this case, give up and let the
 273        * caller mark the whole variable as used.
 274        */
 275       return false;
 276    }
 277
 278    ir_constant *index_as_constant = index->as_constant();
 279    if (!index_as_constant)
 280       return false;
 281
 282    unsigned elem_width;
 283    unsigned num_elems;
 284    if (type->is_array()) {
 285       num_elems = type->length;
 286       if (type->fields.array->is_matrix())
 287          elem_width = type->fields.array->matrix_columns;
 288       else
 289          elem_width = 1;
 290    } else {
 291       num_elems = type->matrix_columns;
 292       elem_width = 1;
 293    }
 294
 295    if (index_as_constant->value.u[0] >= num_elems) {
 296       /* Constant index outside the bounds of the matrix/array.  This could
 297        * arise as a result of constant folding of a legal GLSL program.
 298        *
 299        * Even though the spec says that indexing outside the bounds of a
 300        * matrix/array results in undefined behaviour, we don't want to pass
 301        * out-of-range values to mark() (since this could result in slots that
 302        * don't exist being marked as used), so just let the caller mark the
 303        * whole variable as used.
 304        */
 305       return false;
 306    }
 307
 308    /* double element width for double types that takes two slots */
 309    if (this->shader_stage != MESA_SHADER_VERTEX ||
 310        var->data.mode != ir_var_shader_in) {
 311       if (type->without_array()->is_dual_slot())
 312          elem_width *= 2;
 313    }
 314
 315    mark(this->prog, var, index_as_constant->value.u[0] * elem_width,
 316         elem_width, this->shader_stage);
 317    return true;
 318 }
 319
 320 static bool
 321 is_multiple_vertices(gl_shader_stage stage, ir_variable *var)
 322 {
 323    if (var->data.patch)
 324       return false;
 325
 326    if (var->data.mode == ir_var_shader_in)
 327       return stage == MESA_SHADER_GEOMETRY ||
 328              stage == MESA_SHADER_TESS_CTRL ||
 329              stage == MESA_SHADER_TESS_EVAL;
 330    if (var->data.mode == ir_var_shader_out)
 331       return stage == MESA_SHADER_TESS_CTRL;
 332
 333    return false;
 334 }
 335
 336 ir_visitor_status
 337 ir_set_program_inouts_visitor::visit_enter(ir_dereference_array *ir)
 338 {
 339    /* Note: for geometry shader inputs, lower_named_interface_blocks may
 340     * create 2D arrays, so we need to be able to handle those.  2D arrays
 341     * shouldn't be able to crop up for any other reason.
 342     */
 343    if (ir_dereference_array * const inner_array =
 344        ir->array->as_dereference_array()) {
 345       /*          ir => foo[i][j]
 346        * inner_array => foo[i]
 347        */
 348       if (ir_dereference_variable * const deref_var =
 349           inner_array->array->as_dereference_variable()) {
 350          if (is_multiple_vertices(this->shader_stage, deref_var->var)) {
 351             /* foo is a geometry or tessellation shader input, so i is
 352              * the vertex, and j the part of the input we're accessing.
 353              */
 354             if (try_mark_partial_variable(deref_var->var, ir->array_index))
 355             {
 356                /* We've now taken care of foo and j, but i might contain a
 357                 * subexpression that accesses shader inputs.  So manually
 358                 * visit i and then continue with the parent.
 359                 */
 360                inner_array->array_index->accept(this);
 361                return visit_continue_with_parent;
 362             }
 363          }
 364       }
 365    } else if (ir_dereference_variable * const deref_var =
 366               ir->array->as_dereference_variable()) {
 367       /* ir => foo[i], where foo is a variable. */
 368       if (is_multiple_vertices(this->shader_stage, deref_var->var)) {
 369          /* foo is a geometry or tessellation shader input, so i is
 370           * the vertex, and we're accessing the entire input.
 371           */
 372          mark_whole_variable(deref_var->var);
 373          /* We've now taken care of foo, but i might contain a subexpression
 374           * that accesses shader inputs.  So manually visit i and then
 375           * continue with the parent.
 376           */
 377          ir->array_index->accept(this);
 378          return visit_continue_with_parent;
 379       } else if (is_shader_inout(deref_var->var)) {
 380          /* foo is a shader input/output, but not a geometry shader input,
 381           * so i is the part of the input we're accessing.
 382           */
 383          if (try_mark_partial_variable(deref_var->var, ir->array_index))
 384             return visit_continue_with_parent;
 385       }
 386    }
 387
 388    /* The expression is something we don't recognize.  Just visit its
 389     * subexpressions.
 390     */
 391    return visit_continue;
 392 }
 393
 394 ir_visitor_status
 395 ir_set_program_inouts_visitor::visit_enter(ir_function_signature *ir)
 396 {
 397    /* We don't want to descend into the function parameters and
 398     * consider them as shader inputs or outputs.
 399     */
 400    visit_list_elements(this, &ir->body);
 401    return visit_continue_with_parent;
 402 }
 403
 404 ir_visitor_status
 405 ir_set_program_inouts_visitor::visit_enter(ir_discard *)
 406 {
 407    /* discards are only allowed in fragment shaders. */
 408    assert(this->shader_stage == MESA_SHADER_FRAGMENT);
 409
 410    prog->info.fs.uses_discard = true;
 411
 412    return visit_continue;
 413 }
 414
 415 ir_visitor_status
 416 ir_set_program_inouts_visitor::visit_enter(ir_texture *ir)
 417 {
 418    if (ir->op == ir_tg4)
 419       prog->UsesGather = true;
 420    return visit_continue;
 421 }
 422
 423 void
 424 do_set_program_inouts(exec_list *instructions, struct gl_program *prog,
 425                       gl_shader_stage shader_stage)
 426 {
 427    ir_set_program_inouts_visitor v(prog, shader_stage);
 428
 429    prog->info.inputs_read = 0;
 430    prog->info.outputs_written = 0;
 431    prog->SecondaryOutputsWritten = 0;
 432    prog->info.outputs_read = 0;
 433    prog->info.patch_inputs_read = 0;
 434    prog->info.patch_outputs_written = 0;
 435    prog->SystemValuesRead = 0;
 436    if (shader_stage == MESA_SHADER_FRAGMENT) {
 437       prog->info.fs.uses_sample_qualifier = false;
 438       prog->info.fs.uses_discard = false;
 439    }
 440    visit_list_elements(&v, instructions);
 441 }