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      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 (at) 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, 1),
    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 }
    225