src/glsl/lower_vector.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 lower_vector.cpp
  26  * IR lowering pass to remove some types of ir_quadop_vector
  27  *
  28  * \author Ian Romanick <ian.d.romanick@intel.com>
  29  */
  30
  31 #include "ir.h"
  32 #include "ir_rvalue_visitor.h"
  33
  34 class lower_vector_visitor : public ir_rvalue_visitor {
  35 public:
  36    lower_vector_visitor() : progress(false)
  37    {
  38       /* empty */
  39    }
  40
  41    void handle_rvalue(ir_rvalue **rvalue);
  42
  43    /**
  44     * Should SWZ-like expressions be lowered?
  45     */
  46    bool dont_lower_swz;
  47
  48    bool progress;
  49 };
  50
  51 /**
  52  * Determine if an IR expression tree looks like an extended swizzle
  53  *
  54  * Extended swizzles consist of access of a single vector source (with possible
  55  * per component negation) and the constants -1, 0, or 1.
  56  */
  57 bool
  58 is_extended_swizzle(ir_expression *ir)
  59 {
  60    /* Track any variables that are accessed by this expression.
  61     */
  62    ir_variable *var = NULL;
  63
  64    assert(ir->operation == ir_quadop_vector);
  65
  66    for (unsigned i = 0; i < ir->type->vector_elements; i++) {
  67       ir_rvalue *op = ir->operands[i];
  68
  69       while (op != NULL) {
  70          switch (op->ir_type) {
  71          case ir_type_constant: {
  72             const ir_constant *const c = op->as_constant();
  73
  74             if (!c->is_one() && !c->is_zero() && !c->is_negative_one())
  75                return false;
  76
  77             op = NULL;
  78             break;
  79          }
  80
  81          case ir_type_dereference_variable: {
  82             ir_dereference_variable *const d = (ir_dereference_variable *) op;
  83
  84             if ((var != NULL) && (var != d->var))
  85                return false;
  86
  87             var = d->var;
  88             op = NULL;
  89             break;
  90          }
  91
  92          case ir_type_expression: {
  93             ir_expression *const ex = (ir_expression *) op;
  94
  95             if (ex->operation != ir_unop_neg)
  96                return false;
  97
  98             op = ex->operands[0];
  99             break;
 100          }
 101
 102          case ir_type_swizzle:
 103             op = ((ir_swizzle *) op)->val;
 104             break;
 105
 106          default:
 107             return false;
 108          }
 109       }
 110    }
 111
 112    return true;
 113 }
 114
 115 void
 116 lower_vector_visitor::handle_rvalue(ir_rvalue **rvalue)
 117 {
 118    if (!*rvalue)
 119       return;
 120
 121    ir_expression *expr = (*rvalue)->as_expression();
 122    if ((expr == NULL) || (expr->operation != ir_quadop_vector))
 123       return;
 124
 125    if (this->dont_lower_swz && is_extended_swizzle(expr))
 126       return;
 127
 128    /* FINISHME: Is this the right thing to use for the ralloc context?
 129     */
 130    void *const mem_ctx = expr;
 131
 132    assert(expr->type->vector_elements == expr->get_num_operands());
 133
 134    /* Generate a temporary with the same type as the ir_quadop_operation.
 135     */
 136    ir_variable *const temp =
 137       new(mem_ctx) ir_variable(expr->type, "vecop_tmp", ir_var_temporary);
 138
 139    this->base_ir->insert_before(temp);
 140
 141    /* Counter of the number of components collected so far.
 142     */
 143    unsigned assigned;
 144
 145    /* Write-mask in the destination that receives counted by 'assigned'.
 146     */
 147    unsigned write_mask;
 148
 149
 150    /* Generate upto four assignments to that variable.  Try to group component
 151     * assignments together:
 152     *
 153     * - All constant components can be assigned at once.
 154     * - All assigments of components from a single variable with the same
 155     *   unary operator can be assigned at once.
 156     */
 157    ir_constant_data d = { { 0 } };
 158
 159    assigned = 0;
 160    write_mask = 0;
 161    for (unsigned i = 0; i < expr->type->vector_elements; i++) {
 162       const ir_constant *const c = expr->operands[i]->as_constant();
 163
 164       if (c == NULL)
 165          continue;
 166
 167       switch (expr->type->base_type) {
 168       case GLSL_TYPE_UINT:  d.u[assigned] = c->value.u[0]; break;
 169       case GLSL_TYPE_INT:   d.i[assigned] = c->value.i[0]; break;
 170       case GLSL_TYPE_FLOAT: d.f[assigned] = c->value.f[0]; break;
 171       case GLSL_TYPE_BOOL:  d.b[assigned] = c->value.b[0]; break;
 172       default:              assert(!"Should not get here."); break;
 173       }
 174
 175       write_mask |= (1U << i);
 176       assigned++;
 177    }
 178
 179    assert((write_mask == 0) == (assigned == 0));
 180
 181    /* If there were constant values, generate an assignment.
 182     */
 183    if (assigned > 0) {
 184       ir_constant *const c =
 185          new(mem_ctx) ir_constant(glsl_type::get_instance(expr->type->base_type,
 186                                                           assigned, 0),
 187                                   &d);
 188       ir_dereference *const lhs = new(mem_ctx) ir_dereference_variable(temp);
 189       ir_assignment *const assign =
 190          new(mem_ctx) ir_assignment(lhs, c, NULL, write_mask);
 191
 192       this->base_ir->insert_before(assign);
 193    }
 194
 195    /* FINISHME: This should try to coalesce assignments.
 196     */
 197    for (unsigned i = 0; i < expr->type->vector_elements; i++) {
 198       if (expr->operands[i]->ir_type == ir_type_constant)
 199          continue;
 200
 201       ir_dereference *const lhs = new(mem_ctx) ir_dereference_variable(temp);
 202       ir_assignment *const assign =
 203          new(mem_ctx) ir_assignment(lhs, expr->operands[i], NULL, (1U << i));
 204
 205       this->base_ir->insert_before(assign);
 206       assigned++;
 207    }
 208
 209    assert(assigned == expr->type->vector_elements);
 210
 211    *rvalue = new(mem_ctx) ir_dereference_variable(temp);
 212    this->progress = true;
 213 }
 214
 215 bool
 216 lower_quadop_vector(exec_list *instructions, bool dont_lower_swz)
 217 {
 218    lower_vector_visitor v;
 219
 220    v.dont_lower_swz = dont_lower_swz;
 221    visit_list_elements(&v, instructions);
 222
 223    return v.progress;
 224 }