src/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 InputsRead and OutputsWritten of Mesa programs.
  28  *
  29  * Additionally, for fragment shaders, sets the InterpQualifier array, the
  30  * IsCentroid and IsSample bitfields, and the UsesDFdy flag.
  31  *
  32  * Mesa programs (gl_program, not gl_shader_program) have a set of
  33  * flags indicating which varyings are read and written.  Computing
  34  * which are actually read from some sort of backend code can be
  35  * tricky when variable array indexing involved.  So this pass
  36  * provides support for setting InputsRead and OutputsWritten right
  37  * from the GLSL IR.
  38  */
  39
  40 #include "main/core.h" /* for struct gl_program */
  41 #include "ir.h"
  42 #include "ir_visitor.h"
  43 #include "glsl_types.h"
  44
  45 namespace {
  46
  47 class ir_set_program_inouts_visitor : public ir_hierarchical_visitor {
  48 public:
  49    ir_set_program_inouts_visitor(struct gl_program *prog,
  50                                  gl_shader_stage shader_stage)
  51    {
  52       this->prog = prog;
  53       this->shader_stage = shader_stage;
  54    }
  55    ~ir_set_program_inouts_visitor()
  56    {
  57    }
  58
  59    virtual ir_visitor_status visit_enter(ir_dereference_array *);
  60    virtual ir_visitor_status visit_enter(ir_function_signature *);
  61    virtual ir_visitor_status visit_enter(ir_expression *);
  62    virtual ir_visitor_status visit_enter(ir_discard *);
  63    virtual ir_visitor_status visit_enter(ir_texture *);
  64    virtual ir_visitor_status visit(ir_dereference_variable *);
  65
  66 private:
  67    void mark_whole_variable(ir_variable *var);
  68    bool try_mark_partial_variable(ir_variable *var, ir_rvalue *index);
  69
  70    struct gl_program *prog;
  71    gl_shader_stage shader_stage;
  72 };
  73
  74 } /* anonymous namespace */
  75
  76 static inline bool
  77 is_shader_inout(ir_variable *var)
  78 {
  79    return var->data.mode == ir_var_shader_in ||
  80           var->data.mode == ir_var_shader_out ||
  81           var->data.mode == ir_var_system_value;
  82 }
  83
  84 static inline bool
  85 is_dual_slot(ir_variable *var)
  86 {
  87    const glsl_type *type = var->type->without_array();
  88    return type == glsl_type::dvec4_type || type == glsl_type::dvec3_type;
  89 }
  90
  91 static void
  92 mark(struct gl_program *prog, ir_variable *var, int offset, int len,
  93      bool is_fragment_shader)
  94 {
  95    /* As of GLSL 1.20, varyings can only be floats, floating-point
  96     * vectors or matrices, or arrays of them.  For Mesa programs using
  97     * InputsRead/OutputsWritten, everything but matrices uses one
  98     * slot, while matrices use a slot per column.  Presumably
  99     * something doing a more clever packing would use something other
 100     * than InputsRead/OutputsWritten.
 101     */
 102
 103    for (int i = 0; i < len; i++) {
 104       bool dual_slot = is_dual_slot(var);
 105       int idx = var->data.location + var->data.index + offset + i;
 106       bool is_patch_generic = var->data.patch &&
 107                               idx != VARYING_SLOT_TESS_LEVEL_INNER &&
 108                               idx != VARYING_SLOT_TESS_LEVEL_OUTER;
 109       GLbitfield64 bitfield;
 110
 111       if (is_patch_generic) {
 112          assert(idx >= VARYING_SLOT_PATCH0 && idx < VARYING_SLOT_TESS_MAX);
 113          bitfield = BITFIELD64_BIT(idx - VARYING_SLOT_PATCH0);
 114       }
 115       else {
 116          assert(idx < VARYING_SLOT_MAX);
 117          bitfield = BITFIELD64_BIT(idx);
 118       }
 119
 120       if (var->data.mode == ir_var_shader_in) {
 121          if (is_patch_generic)
 122             prog->PatchInputsRead |= bitfield;
 123          else
 124             prog->InputsRead |= bitfield;
 125
 126          if (dual_slot)
 127             prog->DoubleInputsRead |= bitfield;
 128          if (is_fragment_shader) {
 129             gl_fragment_program *fprog = (gl_fragment_program *) prog;
 130             fprog->InterpQualifier[idx] =
 131                (glsl_interp_qualifier) var->data.interpolation;
 132             if (var->data.centroid)
 133                fprog->IsCentroid |= bitfield;
 134             if (var->data.sample)
 135                fprog->IsSample |= bitfield;
 136          }
 137       } else if (var->data.mode == ir_var_system_value) {
 138          prog->SystemValuesRead |= bitfield;
 139       } else {
 140          assert(var->data.mode == ir_var_shader_out);
 141          if (is_patch_generic)
 142             prog->PatchOutputsWritten |= bitfield;
 143          else
 144             prog->OutputsWritten |= bitfield;
 145       }
 146    }
 147 }
 148
 149 /**
 150  * Mark an entire variable as used.  Caller must ensure that the variable
 151  * represents a shader input or output.
 152  */
 153 void
 154 ir_set_program_inouts_visitor::mark_whole_variable(ir_variable *var)
 155 {
 156    const glsl_type *type = var->type;
 157    if (this->shader_stage == MESA_SHADER_GEOMETRY &&
 158        var->data.mode == ir_var_shader_in && type->is_array()) {
 159       type = type->fields.array;
 160    }
 161
 162    if (this->shader_stage == MESA_SHADER_TESS_CTRL &&
 163        var->data.mode == ir_var_shader_in) {
 164       assert(type->is_array());
 165       type = type->fields.array;
 166    }
 167
 168    if (this->shader_stage == MESA_SHADER_TESS_CTRL &&
 169        var->data.mode == ir_var_shader_out && !var->data.patch) {
 170       assert(type->is_array());
 171       type = type->fields.array;
 172    }
 173
 174    if (this->shader_stage == MESA_SHADER_TESS_EVAL &&
 175        var->data.mode == ir_var_shader_in && !var->data.patch) {
 176       assert(type->is_array());
 177       type = type->fields.array;
 178    }
 179
 180    mark(this->prog, var, 0, type->count_attribute_slots(),
 181         this->shader_stage == MESA_SHADER_FRAGMENT);
 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    if (!(type->is_matrix() ||
 263         (type->is_array() &&
 264          (type->fields.array->is_numeric() ||
 265           type->fields.array->is_boolean())))) {
 266       assert(!"Unexpected indexing in ir_set_program_inouts");
 267
 268       /* For safety in release builds, in case we ever encounter unexpected
 269        * indexing, give up and let the caller mark the whole variable as used.
 270        */
 271       return false;
 272    }
 273
 274    ir_constant *index_as_constant = index->as_constant();
 275    if (!index_as_constant)
 276       return false;
 277
 278    unsigned elem_width;
 279    unsigned num_elems;
 280    if (type->is_array()) {
 281       num_elems = type->length;
 282       if (type->fields.array->is_matrix())
 283          elem_width = type->fields.array->matrix_columns;
 284       else
 285          elem_width = 1;
 286    } else {
 287       num_elems = type->matrix_columns;
 288       elem_width = 1;
 289    }
 290
 291    if (index_as_constant->value.u[0] >= num_elems) {
 292       /* Constant index outside the bounds of the matrix/array.  This could
 293        * arise as a result of constant folding of a legal GLSL program.
 294        *
 295        * Even though the spec says that indexing outside the bounds of a
 296        * matrix/array results in undefined behaviour, we don't want to pass
 297        * out-of-range values to mark() (since this could result in slots that
 298        * don't exist being marked as used), so just let the caller mark the
 299        * whole variable as used.
 300        */
 301       return false;
 302    }
 303
 304    mark(this->prog, var, index_as_constant->value.u[0] * elem_width,
 305         elem_width, this->shader_stage == MESA_SHADER_FRAGMENT);
 306    return true;
 307 }
 308
 309 static bool
 310 is_multiple_vertices(gl_shader_stage stage, ir_variable *var)
 311 {
 312    if (var->data.patch)
 313       return false;
 314
 315    if (var->data.mode == ir_var_shader_in)
 316       return stage == MESA_SHADER_GEOMETRY ||
 317              stage == MESA_SHADER_TESS_CTRL ||
 318              stage == MESA_SHADER_TESS_EVAL;
 319    if (var->data.mode == ir_var_shader_out)
 320       return stage == MESA_SHADER_TESS_CTRL;
 321
 322    return false;
 323 }
 324
 325 ir_visitor_status
 326 ir_set_program_inouts_visitor::visit_enter(ir_dereference_array *ir)
 327 {
 328    /* Note: for geometry shader inputs, lower_named_interface_blocks may
 329     * create 2D arrays, so we need to be able to handle those.  2D arrays
 330     * shouldn't be able to crop up for any other reason.
 331     */
 332    if (ir_dereference_array * const inner_array =
 333        ir->array->as_dereference_array()) {
 334       /*          ir => foo[i][j]
 335        * inner_array => foo[i]
 336        */
 337       if (ir_dereference_variable * const deref_var =
 338           inner_array->array->as_dereference_variable()) {
 339          if (is_multiple_vertices(this->shader_stage, deref_var->var)) {
 340             /* foo is a geometry or tessellation shader input, so i is
 341              * the vertex, and j the part of the input we're accessing.
 342              */
 343             if (try_mark_partial_variable(deref_var->var, ir->array_index))
 344             {
 345                /* We've now taken care of foo and j, but i might contain a
 346                 * subexpression that accesses shader inputs.  So manually
 347                 * visit i and then continue with the parent.
 348                 */
 349                inner_array->array_index->accept(this);
 350                return visit_continue_with_parent;
 351             }
 352          }
 353       }
 354    } else if (ir_dereference_variable * const deref_var =
 355               ir->array->as_dereference_variable()) {
 356       /* ir => foo[i], where foo is a variable. */
 357       if (is_multiple_vertices(this->shader_stage, deref_var->var)) {
 358          /* foo is a geometry or tessellation shader input, so i is
 359           * the vertex, and we're accessing the entire input.
 360           */
 361          mark_whole_variable(deref_var->var);
 362          /* We've now taken care of foo, but i might contain a subexpression
 363           * that accesses shader inputs.  So manually visit i and then
 364           * continue with the parent.
 365           */
 366          ir->array_index->accept(this);
 367          return visit_continue_with_parent;
 368       } else if (is_shader_inout(deref_var->var)) {
 369          /* foo is a shader input/output, but not a geometry shader input,
 370           * so i is the part of the input we're accessing.
 371           */
 372          if (try_mark_partial_variable(deref_var->var, ir->array_index))
 373             return visit_continue_with_parent;
 374       }
 375    }
 376
 377    /* The expression is something we don't recognize.  Just visit its
 378     * subexpressions.
 379     */
 380    return visit_continue;
 381 }
 382
 383 ir_visitor_status
 384 ir_set_program_inouts_visitor::visit_enter(ir_function_signature *ir)
 385 {
 386    /* We don't want to descend into the function parameters and
 387     * consider them as shader inputs or outputs.
 388     */
 389    visit_list_elements(this, &ir->body);
 390    return visit_continue_with_parent;
 391 }
 392
 393 ir_visitor_status
 394 ir_set_program_inouts_visitor::visit_enter(ir_expression *ir)
 395 {
 396    if (this->shader_stage == MESA_SHADER_FRAGMENT &&
 397        (ir->operation == ir_unop_dFdy ||
 398         ir->operation == ir_unop_dFdy_coarse ||
 399         ir->operation == ir_unop_dFdy_fine)) {
 400       gl_fragment_program *fprog = (gl_fragment_program *) prog;
 401       fprog->UsesDFdy = true;
 402    }
 403    return visit_continue;
 404 }
 405
 406 ir_visitor_status
 407 ir_set_program_inouts_visitor::visit_enter(ir_discard *)
 408 {
 409    /* discards are only allowed in fragment shaders. */
 410    assert(this->shader_stage == MESA_SHADER_FRAGMENT);
 411
 412    gl_fragment_program *fprog = (gl_fragment_program *) prog;
 413    fprog->UsesKill = true;
 414
 415    return visit_continue;
 416 }
 417
 418 ir_visitor_status
 419 ir_set_program_inouts_visitor::visit_enter(ir_texture *ir)
 420 {
 421    if (ir->op == ir_tg4)
 422       prog->UsesGather = true;
 423    return visit_continue;
 424 }
 425
 426 void
 427 do_set_program_inouts(exec_list *instructions, struct gl_program *prog,
 428                       gl_shader_stage shader_stage)
 429 {
 430    ir_set_program_inouts_visitor v(prog, shader_stage);
 431
 432    prog->InputsRead = 0;
 433    prog->OutputsWritten = 0;
 434    prog->PatchInputsRead = 0;
 435    prog->PatchOutputsWritten = 0;
 436    prog->SystemValuesRead = 0;
 437    if (shader_stage == MESA_SHADER_FRAGMENT) {
 438       gl_fragment_program *fprog = (gl_fragment_program *) prog;
 439       memset(fprog->InterpQualifier, 0, sizeof(fprog->InterpQualifier));
 440       fprog->IsCentroid = 0;
 441       fprog->IsSample = 0;
 442       fprog->UsesDFdy = false;
 443       fprog->UsesKill = false;
 444    }
 445    visit_list_elements(&v, instructions);
 446 }