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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 opt_structure_splitting.cpp
     26  *
     27  * If a structure is only ever referenced by its components, then
     28  * split those components out to individual variables so they can be
     29  * handled normally by other optimization passes.
     30  *
     31  * This skips structures like uniforms, which need to be accessible as
     32  * structures for their access by the GL.
     33  */
     34 
     35 #include "ir.h"
     36 #include "ir_visitor.h"
     37 #include "ir_print_visitor.h"
     38 #include "ir_rvalue_visitor.h"
     39 #include "glsl_types.h"
     40 
     41 namespace {
     42 
     43 static bool debug = false;
     44 
     45 // XXX using variable_entry2 here to avoid collision (MSVC multiply-defined
     46 // function) with the variable_entry class seen in ir_variable_refcount.h
     47 // Perhaps we can use the one in ir_variable_refcount.h and make this class
     48 // here go away?
     49 class variable_entry2 : public exec_node
     50 {
     51 public:
     52    variable_entry2(ir_variable *var)
     53    {
     54       this->var = var;
     55       this->whole_structure_access = 0;
     56       this->declaration = false;
     57       this->components = NULL;
     58       this->mem_ctx = NULL;
     59    }
     60 
     61    ir_variable *var; /* The key: the variable's pointer. */
     62 
     63    /** Number of times the variable is referenced, including assignments. */
     64    unsigned whole_structure_access;
     65 
     66    /* If the variable had a decl we can work with in the instruction
     67     * stream.  We can't do splitting on function arguments, which
     68     * don't get this variable set.
     69     */
     70    bool declaration;
     71 
     72    ir_variable **components;
     73 
     74    /** ralloc_parent(this->var) -- the shader's ralloc context. */
     75    void *mem_ctx;
     76 };
     77 
     78 
     79 class ir_structure_reference_visitor : public ir_hierarchical_visitor {
     80 public:
     81    ir_structure_reference_visitor(void)
     82    {
     83       this->mem_ctx = ralloc_context(NULL);
     84       this->variable_list.make_empty();
     85    }
     86 
     87    ~ir_structure_reference_visitor(void)
     88    {
     89       ralloc_free(mem_ctx);
     90    }
     91 
     92    virtual ir_visitor_status visit(ir_variable *);
     93    virtual ir_visitor_status visit(ir_dereference_variable *);
     94    virtual ir_visitor_status visit_enter(ir_dereference_record *);
     95    virtual ir_visitor_status visit_enter(ir_assignment *);
     96    virtual ir_visitor_status visit_enter(ir_function_signature *);
     97 
     98    variable_entry2 *get_variable_entry2(ir_variable *var);
     99 
    100    /* List of variable_entry */
    101    exec_list variable_list;
    102 
    103    void *mem_ctx;
    104 };
    105 
    106 variable_entry2 *
    107 ir_structure_reference_visitor::get_variable_entry2(ir_variable *var)
    108 {
    109    assert(var);
    110 
    111    if (!var->type->is_record() || var->mode == ir_var_uniform)
    112       return NULL;
    113 
    114    foreach_iter(exec_list_iterator, iter, this->variable_list) {
    115       variable_entry2 *entry = (variable_entry2 *)iter.get();
    116       if (entry->var == var)
    117 	 return entry;
    118    }
    119 
    120    variable_entry2 *entry = new(mem_ctx) variable_entry2(var);
    121    this->variable_list.push_tail(entry);
    122    return entry;
    123 }
    124 
    125 
    126 ir_visitor_status
    127 ir_structure_reference_visitor::visit(ir_variable *ir)
    128 {
    129    variable_entry2 *entry = this->get_variable_entry2(ir);
    130 
    131    if (entry)
    132       entry->declaration = true;
    133 
    134    return visit_continue;
    135 }
    136 
    137 ir_visitor_status
    138 ir_structure_reference_visitor::visit(ir_dereference_variable *ir)
    139 {
    140    ir_variable *const var = ir->variable_referenced();
    141    variable_entry2 *entry = this->get_variable_entry2(var);
    142 
    143    if (entry)
    144       entry->whole_structure_access++;
    145 
    146    return visit_continue;
    147 }
    148 
    149 ir_visitor_status
    150 ir_structure_reference_visitor::visit_enter(ir_dereference_record *ir)
    151 {
    152    (void) ir;
    153    /* Don't descend into the ir_dereference_variable below. */
    154    return visit_continue_with_parent;
    155 }
    156 
    157 ir_visitor_status
    158 ir_structure_reference_visitor::visit_enter(ir_assignment *ir)
    159 {
    160    /* If there are no structure references yet, no need to bother with
    161     * processing the expression tree.
    162     */
    163    if (this->variable_list.is_empty())
    164       return visit_continue_with_parent;
    165 
    166    if (ir->lhs->as_dereference_variable() &&
    167        ir->rhs->as_dereference_variable() &&
    168        !ir->condition) {
    169       /* We'll split copies of a structure to copies of components, so don't
    170        * descend to the ir_dereference_variables.
    171        */
    172       return visit_continue_with_parent;
    173    }
    174    return visit_continue;
    175 }
    176 
    177 ir_visitor_status
    178 ir_structure_reference_visitor::visit_enter(ir_function_signature *ir)
    179 {
    180    /* We don't have logic for structure-splitting function arguments,
    181     * so just look at the body instructions and not the parameter
    182     * declarations.
    183     */
    184    visit_list_elements(this, &ir->body);
    185    return visit_continue_with_parent;
    186 }
    187 
    188 class ir_structure_splitting_visitor : public ir_rvalue_visitor {
    189 public:
    190    ir_structure_splitting_visitor(exec_list *vars)
    191    {
    192       this->variable_list = vars;
    193    }
    194 
    195    virtual ~ir_structure_splitting_visitor()
    196    {
    197    }
    198 
    199    virtual ir_visitor_status visit_leave(ir_assignment *);
    200 
    201    void split_deref(ir_dereference **deref);
    202    void handle_rvalue(ir_rvalue **rvalue);
    203    variable_entry2 *get_splitting_entry(ir_variable *var);
    204 
    205    exec_list *variable_list;
    206 };
    207 
    208 variable_entry2 *
    209 ir_structure_splitting_visitor::get_splitting_entry(ir_variable *var)
    210 {
    211    assert(var);
    212 
    213    if (!var->type->is_record())
    214       return NULL;
    215 
    216    foreach_iter(exec_list_iterator, iter, *this->variable_list) {
    217       variable_entry2 *entry = (variable_entry2 *)iter.get();
    218       if (entry->var == var) {
    219 	 return entry;
    220       }
    221    }
    222 
    223    return NULL;
    224 }
    225 
    226 void
    227 ir_structure_splitting_visitor::split_deref(ir_dereference **deref)
    228 {
    229    if ((*deref)->ir_type != ir_type_dereference_record)
    230       return;
    231 
    232    ir_dereference_record *deref_record = (ir_dereference_record *)*deref;
    233    ir_dereference_variable *deref_var = deref_record->record->as_dereference_variable();
    234    if (!deref_var)
    235       return;
    236 
    237    variable_entry2 *entry = get_splitting_entry(deref_var->var);
    238    if (!entry)
    239       return;
    240 
    241    unsigned int i;
    242    for (i = 0; i < entry->var->type->length; i++) {
    243       if (strcmp(deref_record->field,
    244 		 entry->var->type->fields.structure[i].name) == 0)
    245 	 break;
    246    }
    247    assert(i != entry->var->type->length);
    248 
    249    *deref = new(entry->mem_ctx) ir_dereference_variable(entry->components[i]);
    250 }
    251 
    252 void
    253 ir_structure_splitting_visitor::handle_rvalue(ir_rvalue **rvalue)
    254 {
    255    if (!*rvalue)
    256       return;
    257 
    258    ir_dereference *deref = (*rvalue)->as_dereference();
    259 
    260    if (!deref)
    261       return;
    262 
    263    split_deref(&deref);
    264    *rvalue = deref;
    265 }
    266 
    267 ir_visitor_status
    268 ir_structure_splitting_visitor::visit_leave(ir_assignment *ir)
    269 {
    270    ir_dereference_variable *lhs_deref = ir->lhs->as_dereference_variable();
    271    ir_dereference_variable *rhs_deref = ir->rhs->as_dereference_variable();
    272    variable_entry2 *lhs_entry = lhs_deref ? get_splitting_entry(lhs_deref->var) : NULL;
    273    variable_entry2 *rhs_entry = rhs_deref ? get_splitting_entry(rhs_deref->var) : NULL;
    274    const glsl_type *type = ir->rhs->type;
    275 
    276    if ((lhs_entry || rhs_entry) && !ir->condition) {
    277       for (unsigned int i = 0; i < type->length; i++) {
    278 	 ir_dereference *new_lhs, *new_rhs;
    279 	 void *mem_ctx = lhs_entry ? lhs_entry->mem_ctx : rhs_entry->mem_ctx;
    280 
    281 	 if (lhs_entry) {
    282 	    new_lhs = new(mem_ctx) ir_dereference_variable(lhs_entry->components[i]);
    283 	 } else {
    284 	    new_lhs = new(mem_ctx)
    285 	       ir_dereference_record(ir->lhs->clone(mem_ctx, NULL),
    286 				     type->fields.structure[i].name);
    287 	 }
    288 
    289 	 if (rhs_entry) {
    290 	    new_rhs = new(mem_ctx) ir_dereference_variable(rhs_entry->components[i]);
    291 	 } else {
    292 	    new_rhs = new(mem_ctx)
    293 	       ir_dereference_record(ir->rhs->clone(mem_ctx, NULL),
    294 				     type->fields.structure[i].name);
    295 	 }
    296 
    297 	 ir->insert_before(new(mem_ctx) ir_assignment(new_lhs,
    298 						      new_rhs,
    299 						      NULL));
    300       }
    301       ir->remove();
    302    } else {
    303       handle_rvalue(&ir->rhs);
    304       split_deref(&ir->lhs);
    305    }
    306 
    307    handle_rvalue(&ir->condition);
    308 
    309    return visit_continue;
    310 }
    311 
    312 } /* unnamed namespace */
    313 
    314 bool
    315 do_structure_splitting(exec_list *instructions)
    316 {
    317    ir_structure_reference_visitor refs;
    318 
    319    visit_list_elements(&refs, instructions);
    320 
    321    /* Trim out variables we can't split. */
    322    foreach_iter(exec_list_iterator, iter, refs.variable_list) {
    323       variable_entry2 *entry = (variable_entry2 *)iter.get();
    324 
    325       if (debug) {
    326 	 printf("structure %s@%p: decl %d, whole_access %d\n",
    327 		entry->var->name, (void *) entry->var, entry->declaration,
    328 		entry->whole_structure_access);
    329       }
    330 
    331       if (!entry->declaration || entry->whole_structure_access) {
    332 	 entry->remove();
    333       }
    334    }
    335 
    336    if (refs.variable_list.is_empty())
    337       return false;
    338 
    339    void *mem_ctx = ralloc_context(NULL);
    340 
    341    /* Replace the decls of the structures to be split with their split
    342     * components.
    343     */
    344    foreach_iter(exec_list_iterator, iter, refs.variable_list) {
    345       variable_entry2 *entry = (variable_entry2 *)iter.get();
    346       const struct glsl_type *type = entry->var->type;
    347 
    348       entry->mem_ctx = ralloc_parent(entry->var);
    349 
    350       entry->components = ralloc_array(mem_ctx,
    351 				       ir_variable *,
    352 				       type->length);
    353 
    354       for (unsigned int i = 0; i < entry->var->type->length; i++) {
    355 	 const char *name = ralloc_asprintf(mem_ctx, "%s_%s",
    356 					    entry->var->name,
    357 					    type->fields.structure[i].name);
    358 
    359 	 entry->components[i] =
    360 	    new(entry->mem_ctx) ir_variable(type->fields.structure[i].type,
    361 					    name,
    362 					    ir_var_temporary);
    363 	 entry->var->insert_before(entry->components[i]);
    364       }
    365 
    366       entry->var->remove();
    367    }
    368 
    369    ir_structure_splitting_visitor split(&refs.variable_list);
    370    visit_list_elements(&split, instructions);
    371 
    372    ralloc_free(mem_ctx);
    373 
    374    return true;
    375 }
    376