src/mesa/drivers/dri/i965/brw_fs_channel_expressions.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 brw_wm_channel_expressions.cpp
  26  *
  27  * Breaks vector operations down into operations on each component.
  28  *
  29  * The 965 fragment shader receives 8 or 16 pixels at a time, so each
  30  * channel of a vector is laid out as 1 or 2 8-float registers.  Each
  31  * ALU operation operates on one of those channel registers.  As a
  32  * result, there is no value to the 965 fragment shader in tracking
  33  * "vector" expressions in the sense of GLSL fragment shaders, when
  34  * doing a channel at a time may help in constant folding, algebraic
  35  * simplification, and reducing the liveness of channel registers.
  36  *
  37  * The exception to the desire to break everything down to floats is
  38  * texturing.  The texture sampler returns a writemasked masked
  39  * 4/8-register sequence containing the texture values.  We don't want
  40  * to dispatch to the sampler separately for each channel we need, so
  41  * we do retain the vector types in that case.
  42  */
  43
  44 extern "C" {
  45 #include "main/core.h"
  46 #include "brw_wm.h"
  47 }
  48 #include "../glsl/ir.h"
  49 #include "../glsl/ir_expression_flattening.h"
  50 #include "../glsl/glsl_types.h"
  51
  52 class ir_channel_expressions_visitor : public ir_hierarchical_visitor {
  53 public:
  54    ir_channel_expressions_visitor()
  55    {
  56       this->progress = false;
  57       this->mem_ctx = NULL;
  58    }
  59
  60    ir_visitor_status visit_leave(ir_assignment *);
  61
  62    ir_rvalue *get_element(ir_variable *var, unsigned int element);
  63    void assign(ir_assignment *ir, int elem, ir_rvalue *val);
  64
  65    bool progress;
  66    void *mem_ctx;
  67 };
  68
  69 static bool
  70 channel_expressions_predicate(ir_instruction *ir)
  71 {
  72    ir_expression *expr = ir->as_expression();
  73    unsigned int i;
  74
  75    if (!expr)
  76       return false;
  77
  78    for (i = 0; i < expr->get_num_operands(); i++) {
  79       if (expr->operands[i]->type->is_vector())
  80          return true;
  81    }
  82
  83    return false;
  84 }
  85
  86 GLboolean
  87 brw_do_channel_expressions(exec_list *instructions)
  88 {
  89    ir_channel_expressions_visitor v;
  90
  91    /* Pull out any matrix expression to a separate assignment to a
  92     * temp.  This will make our handling of the breakdown to
  93     * operations on the matrix's vector components much easier.
  94     */
  95    do_expression_flattening(instructions, channel_expressions_predicate);
  96
  97    visit_list_elements(&v, instructions);
  98
  99    return v.progress;
 100 }
 101
 102 ir_rvalue *
 103 ir_channel_expressions_visitor::get_element(ir_variable *var, unsigned int elem)
 104 {
 105    ir_dereference *deref;
 106
 107    if (var->type->is_scalar())
 108       return new(mem_ctx) ir_dereference_variable(var);
 109
 110    assert(elem < var->type->components());
 111    deref = new(mem_ctx) ir_dereference_variable(var);
 112    return new(mem_ctx) ir_swizzle(deref, elem, 0, 0, 0, 1);
 113 }
 114
 115 void
 116 ir_channel_expressions_visitor::assign(ir_assignment *ir, int elem, ir_rvalue *val)
 117 {
 118    ir_dereference *lhs = ir->lhs->clone(mem_ctx, NULL);
 119    ir_assignment *assign;
 120
 121    /* This assign-of-expression should have been generated by the
 122     * expression flattening visitor (since we never short circit to
 123     * not flatten, even for plain assignments of variables), so the
 124     * writemask is always full.
 125     */
 126    assert(ir->write_mask == (1 << ir->lhs->type->components()) - 1);
 127
 128    assign = new(mem_ctx) ir_assignment(lhs, val, NULL, (1 << elem));
 129    ir->insert_before(assign);
 130 }
 131
 132 ir_visitor_status
 133 ir_channel_expressions_visitor::visit_leave(ir_assignment *ir)
 134 {
 135    ir_expression *expr = ir->rhs->as_expression();
 136    bool found_vector = false;
 137    unsigned int i, vector_elements = 1;
 138    ir_variable *op_var[2];
 139
 140    if (!expr)
 141       return visit_continue;
 142
 143    if (!this->mem_ctx)
 144       this->mem_ctx = talloc_parent(ir);
 145
 146    for (i = 0; i < expr->get_num_operands(); i++) {
 147       if (expr->operands[i]->type->is_vector()) {
 148          found_vector = true;
 149          vector_elements = expr->operands[i]->type->vector_elements;
 150          break;
 151       }
 152    }
 153    if (!found_vector)
 154       return visit_continue;
 155
 156    /* Store the expression operands in temps so we can use them
 157     * multiple times.
 158     */
 159    for (i = 0; i < expr->get_num_operands(); i++) {
 160       ir_assignment *assign;
 161       ir_dereference *deref;
 162
 163       assert(!expr->operands[i]->type->is_matrix());
 164
 165       op_var[i] = new(mem_ctx) ir_variable(expr->operands[i]->type,
 166                                            "channel_expressions",
 167                                            ir_var_temporary);
 168       ir->insert_before(op_var[i]);
 169
 170       deref = new(mem_ctx) ir_dereference_variable(op_var[i]);
 171       assign = new(mem_ctx) ir_assignment(deref,
 172                                           expr->operands[i],
 173                                           NULL);
 174       ir->insert_before(assign);
 175    }
 176
 177    const glsl_type *element_type = glsl_type::get_instance(ir->lhs->type->base_type,
 178                                                            1, 1);
 179
 180    /* OK, time to break down this vector operation. */
 181    switch (expr->operation) {
 182    case ir_unop_bit_not:
 183    case ir_unop_logic_not:
 184    case ir_unop_neg:
 185    case ir_unop_abs:
 186    case ir_unop_sign:
 187    case ir_unop_rcp:
 188    case ir_unop_rsq:
 189    case ir_unop_sqrt:
 190    case ir_unop_exp:
 191    case ir_unop_log:
 192    case ir_unop_exp2:
 193    case ir_unop_log2:
 194    case ir_unop_f2i:
 195    case ir_unop_i2f:
 196    case ir_unop_f2b:
 197    case ir_unop_b2f:
 198    case ir_unop_i2b:
 199    case ir_unop_b2i:
 200    case ir_unop_u2f:
 201    case ir_unop_trunc:
 202    case ir_unop_ceil:
 203    case ir_unop_floor:
 204    case ir_unop_fract:
 205    case ir_unop_sin:
 206    case ir_unop_cos:
 207    case ir_unop_dFdx:
 208    case ir_unop_dFdy:
 209       for (i = 0; i < vector_elements; i++) {
 210          ir_rvalue *op0 = get_element(op_var[0], i);
 211
 212          assign(ir, i, new(mem_ctx) ir_expression(expr->operation,
 213                                                   element_type,
 214                                                   op0,
 215                                                   NULL));
 216       }
 217       break;
 218
 219    case ir_binop_add:
 220    case ir_binop_sub:
 221    case ir_binop_mul:
 222    case ir_binop_div:
 223    case ir_binop_mod:
 224    case ir_binop_min:
 225    case ir_binop_max:
 226    case ir_binop_pow:
 227    case ir_binop_lshift:
 228    case ir_binop_rshift:
 229    case ir_binop_bit_and:
 230    case ir_binop_bit_xor:
 231    case ir_binop_bit_or:
 232    case ir_binop_less:
 233    case ir_binop_greater:
 234    case ir_binop_lequal:
 235    case ir_binop_gequal:
 236    case ir_binop_equal:
 237    case ir_binop_nequal:
 238       for (i = 0; i < vector_elements; i++) {
 239          ir_rvalue *op0 = get_element(op_var[0], i);
 240          ir_rvalue *op1 = get_element(op_var[1], i);
 241
 242          assign(ir, i, new(mem_ctx) ir_expression(expr->operation,
 243                                                   element_type,
 244                                                   op0,
 245                                                   op1));
 246       }
 247       break;
 248
 249    case ir_unop_any: {
 250       ir_expression *temp;
 251       temp = new(mem_ctx) ir_expression(ir_binop_logic_or,
 252                                         element_type,
 253                                         get_element(op_var[0], 0),
 254                                         get_element(op_var[0], 1));
 255
 256       for (i = 2; i < vector_elements; i++) {
 257          temp = new(mem_ctx) ir_expression(ir_binop_logic_or,
 258                                            element_type,
 259                                            get_element(op_var[0], i),
 260                                            temp);
 261       }
 262       assign(ir, 0, temp);
 263       break;
 264    }
 265
 266    case ir_binop_dot: {
 267       ir_expression *last = NULL;
 268       for (i = 0; i < vector_elements; i++) {
 269          ir_rvalue *op0 = get_element(op_var[0], i);
 270          ir_rvalue *op1 = get_element(op_var[1], i);
 271          ir_expression *temp;
 272
 273          temp = new(mem_ctx) ir_expression(ir_binop_mul,
 274                                            element_type,
 275                                            op0,
 276                                            op1);
 277          if (last) {
 278             last = new(mem_ctx) ir_expression(ir_binop_add,
 279                                               element_type,
 280                                               temp,
 281                                               last);
 282          } else {
 283             last = temp;
 284          }
 285       }
 286       assign(ir, 0, last);
 287       break;
 288    }
 289
 290    case ir_binop_cross: {
 291       for (i = 0; i < vector_elements; i++) {
 292          int swiz0 = (i + 1) % 3;
 293          int swiz1 = (i + 2) % 3;
 294          ir_expression *temp1, *temp2;
 295
 296          temp1 = new(mem_ctx) ir_expression(ir_binop_mul,
 297                                             element_type,
 298                                             get_element(op_var[0], swiz0),
 299                                             get_element(op_var[1], swiz1));
 300
 301          temp2 = new(mem_ctx) ir_expression(ir_binop_mul,
 302                                             element_type,
 303                                             get_element(op_var[1], swiz0),
 304                                             get_element(op_var[0], swiz1));
 305
 306          temp2 = new(mem_ctx) ir_expression(ir_unop_neg,
 307                                             element_type,
 308                                             temp2,
 309                                             NULL);
 310
 311          assign(ir, i, new(mem_ctx) ir_expression(ir_binop_add,
 312                                                   element_type,
 313                                                   temp1, temp2));
 314       }
 315       break;
 316    }
 317
 318    case ir_binop_logic_and:
 319    case ir_binop_logic_xor:
 320    case ir_binop_logic_or:
 321       ir->print();
 322       printf("\n");
 323       assert(!"not reached: expression operates on scalars only");
 324       break;
 325    case ir_binop_all_equal:
 326    case ir_binop_any_nequal: {
 327       ir_expression *last = NULL;
 328       for (i = 0; i < vector_elements; i++) {
 329          ir_rvalue *op0 = get_element(op_var[0], i);
 330          ir_rvalue *op1 = get_element(op_var[1], i);
 331          ir_expression *temp;
 332          ir_expression_operation join;
 333
 334          if (expr->operation == ir_binop_all_equal)
 335             join = ir_binop_logic_and;
 336          else
 337             join = ir_binop_logic_or;
 338
 339          temp = new(mem_ctx) ir_expression(expr->operation,
 340                                            element_type,
 341                                            op0,
 342                                            op1);
 343          if (last) {
 344             last = new(mem_ctx) ir_expression(join,
 345                                               element_type,
 346                                               temp,
 347                                               last);
 348          } else {
 349             last = temp;
 350          }
 351       }
 352       assign(ir, 0, last);
 353       break;
 354    }
 355    case ir_unop_noise:
 356       assert(!"noise should have been broken down to function call");
 357       break;
 358    }
 359
 360    ir->remove();
 361    this->progress = true;
 362
 363    return visit_continue;
 364 }