src/glsl/link_functions.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 #include "main/core.h"
  25 #include "glsl_symbol_table.h"
  26 #include "glsl_parser_extras.h"
  27 #include "ir.h"
  28 #include "program.h"
  29 #include "program/hash_table.h"
  30 #include "linker.h"
  31
  32 static ir_function_signature *
  33 find_matching_signature(const char *name, const exec_list *actual_parameters,
  34                         gl_shader **shader_list, unsigned num_shaders,
  35                         bool use_builtin);
  36
  37 namespace {
  38
  39 class call_link_visitor : public ir_hierarchical_visitor {
  40 public:
  41    call_link_visitor(gl_shader_program *prog, gl_shader *linked,
  42                      gl_shader **shader_list, unsigned num_shaders)
  43    {
  44       this->prog = prog;
  45       this->shader_list = shader_list;
  46       this->num_shaders = num_shaders;
  47       this->success = true;
  48       this->linked = linked;
  49
  50       this->locals = hash_table_ctor(0, hash_table_pointer_hash,
  51                                      hash_table_pointer_compare);
  52    }
  53
  54    ~call_link_visitor()
  55    {
  56       hash_table_dtor(this->locals);
  57    }
  58
  59    virtual ir_visitor_status visit(ir_variable *ir)
  60    {
  61       hash_table_insert(locals, ir, ir);
  62       return visit_continue;
  63    }
  64
  65    virtual ir_visitor_status visit_enter(ir_call *ir)
  66    {
  67       /* If ir is an ir_call from a function that was imported from another
  68        * shader callee will point to an ir_function_signature in the original
  69        * shader.  In this case the function signature MUST NOT BE MODIFIED.
  70        * Doing so will modify the original shader.  This may prevent that
  71        * shader from being linkable in other programs.
  72        */
  73       const ir_function_signature *const callee = ir->callee;
  74       assert(callee != NULL);
  75       const char *const name = callee->function_name();
  76
  77       /* Determine if the requested function signature already exists in the
  78        * final linked shader.  If it does, use it as the target of the call.
  79        */
  80       ir_function_signature *sig =
  81          find_matching_signature(name, &callee->parameters, &linked, 1,
  82                                  ir->use_builtin);
  83       if (sig != NULL) {
  84          ir->callee = sig;
  85          return visit_continue;
  86       }
  87
  88       /* Try to find the signature in one of the other shaders that is being
  89        * linked.  If it's not found there, return an error.
  90        */
  91       sig = find_matching_signature(name, &ir->actual_parameters, shader_list,
  92                                     num_shaders, ir->use_builtin);
  93       if (sig == NULL) {
  94          /* FINISHME: Log the full signature of unresolved function.
  95           */
  96          linker_error(this->prog, "unresolved reference to function `%s'\n",
  97                       name);
  98          this->success = false;
  99          return visit_stop;
 100       }
 101
 102       /* Find the prototype information in the linked shader.  Generate any
 103        * details that may be missing.
 104        */
 105       ir_function *f = linked->symbols->get_function(name);
 106       if (f == NULL) {
 107          f = new(linked) ir_function(name);
 108
 109          /* Add the new function to the linked IR.  Put it at the end
 110           * so that it comes after any global variable declarations
 111           * that it refers to.
 112           */
 113          linked->symbols->add_function(f);
 114          linked->ir->push_tail(f);
 115       }
 116
 117       ir_function_signature *linked_sig =
 118          f->exact_matching_signature(NULL, &callee->parameters);
 119       if ((linked_sig == NULL)
 120           || ((linked_sig != NULL)
 121               && (linked_sig->is_builtin() != ir->use_builtin))) {
 122          linked_sig = new(linked) ir_function_signature(callee->return_type);
 123          f->add_signature(linked_sig);
 124       }
 125
 126       /* At this point linked_sig and called may be the same.  If ir is an
 127        * ir_call from linked then linked_sig and callee will be
 128        * ir_function_signatures that have no definitions (is_defined is false).
 129        */
 130       assert(!linked_sig->is_defined);
 131       assert(linked_sig->body.is_empty());
 132
 133       /* Create an in-place clone of the function definition.  This multistep
 134        * process introduces some complexity here, but it has some advantages.
 135        * The parameter list and the and function body are cloned separately.
 136        * The clone of the parameter list is used to prime the hashtable used
 137        * to replace variable references in the cloned body.
 138        *
 139        * The big advantage is that the ir_function_signature does not change.
 140        * This means that we don't have to process the rest of the IR tree to
 141        * patch ir_call nodes.  In addition, there is no way to remove or
 142        * replace signature stored in a function.  One could easily be added,
 143        * but this avoids the need.
 144        */
 145       struct hash_table *ht = hash_table_ctor(0, hash_table_pointer_hash,
 146                                               hash_table_pointer_compare);
 147       exec_list formal_parameters;
 148       foreach_list_const(node, &sig->parameters) {
 149          const ir_instruction *const original = (ir_instruction *) node;
 150          assert(const_cast<ir_instruction *>(original)->as_variable());
 151
 152          ir_instruction *copy = original->clone(linked, ht);
 153          formal_parameters.push_tail(copy);
 154       }
 155
 156       linked_sig->replace_parameters(&formal_parameters);
 157
 158       foreach_list_const(node, &sig->body) {
 159          const ir_instruction *const original = (ir_instruction *) node;
 160
 161          ir_instruction *copy = original->clone(linked, ht);
 162          linked_sig->body.push_tail(copy);
 163       }
 164
 165       linked_sig->is_defined = true;
 166       hash_table_dtor(ht);
 167
 168       /* Patch references inside the function to things outside the function
 169        * (i.e., function calls and global variables).
 170        */
 171       linked_sig->accept(this);
 172
 173       ir->callee = linked_sig;
 174
 175       return visit_continue;
 176    }
 177
 178    virtual ir_visitor_status visit_leave(ir_call *ir)
 179    {
 180       /* Traverse list of function parameters, and for array parameters
 181        * propagate max_array_access. Otherwise arrays that are only referenced
 182        * from inside functions via function parameters will be incorrectly
 183        * optimized. This will lead to incorrect code being generated (or worse).
 184        * Do it when leaving the node so the children would propagate their
 185        * array accesses first.
 186        */
 187
 188       const exec_node *formal_param_node = ir->callee->parameters.get_head();
 189       if (formal_param_node) {
 190          const exec_node *actual_param_node = ir->actual_parameters.get_head();
 191          while (!actual_param_node->is_tail_sentinel()) {
 192             ir_variable *formal_param = (ir_variable *) formal_param_node;
 193             ir_rvalue *actual_param = (ir_rvalue *) actual_param_node;
 194
 195             formal_param_node = formal_param_node->get_next();
 196             actual_param_node = actual_param_node->get_next();
 197
 198             if (formal_param->type->is_array()) {
 199                ir_dereference_variable *deref = actual_param->as_dereference_variable();
 200                if (deref && deref->var && deref->var->type->is_array()) {
 201                   deref->var->max_array_access =
 202                      MAX2(formal_param->max_array_access, deref->var->max_array_access);
 203                }
 204             }
 205          }
 206       }
 207       return visit_continue;
 208    }
 209
 210    virtual ir_visitor_status visit(ir_dereference_variable *ir)
 211    {
 212       if (hash_table_find(locals, ir->var) == NULL) {
 213          /* The non-function variable must be a global, so try to find the
 214           * variable in the shader's symbol table.  If the variable is not
 215           * found, then it's a global that *MUST* be defined in the original
 216           * shader.
 217           */
 218          ir_variable *var = linked->symbols->get_variable(ir->var->name);
 219          if (var == NULL) {
 220             /* Clone the ir_variable that the dereference already has and add
 221              * it to the linked shader.
 222              */
 223             var = ir->var->clone(linked, NULL);
 224             linked->symbols->add_variable(var);
 225             linked->ir->push_head(var);
 226          } else if (var->type->is_array()) {
 227             /* It is possible to have a global array declared in multiple
 228              * shaders without a size.  The array is implicitly sized by the
 229              * maximal access to it in *any* shader.  Because of this, we
 230              * need to track the maximal access to the array as linking pulls
 231              * more functions in that access the array.
 232              */
 233             var->max_array_access =
 234                MAX2(var->max_array_access, ir->var->max_array_access);
 235
 236             if (var->type->length == 0 && ir->var->type->length != 0)
 237                var->type = ir->var->type;
 238          }
 239
 240          ir->var = var;
 241       }
 242
 243       return visit_continue;
 244    }
 245
 246    /** Was function linking successful? */
 247    bool success;
 248
 249 private:
 250    /**
 251     * Shader program being linked
 252     *
 253     * This is only used for logging error messages.
 254     */
 255    gl_shader_program *prog;
 256
 257    /** List of shaders available for linking. */
 258    gl_shader **shader_list;
 259
 260    /** Number of shaders available for linking. */
 261    unsigned num_shaders;
 262
 263    /**
 264     * Final linked shader
 265     *
 266     * This is used two ways.  It is used to find global variables in the
 267     * linked shader that are accessed by the function.  It is also used to add
 268     * global variables from the shader where the function originated.
 269     */
 270    gl_shader *linked;
 271
 272    /**
 273     * Table of variables local to the function.
 274     */
 275    hash_table *locals;
 276 };
 277
 278 } /* anonymous namespace */
 279
 280 /**
 281  * Searches a list of shaders for a particular function definition
 282  */
 283 ir_function_signature *
 284 find_matching_signature(const char *name, const exec_list *actual_parameters,
 285                         gl_shader **shader_list, unsigned num_shaders,
 286                         bool use_builtin)
 287 {
 288    for (unsigned i = 0; i < num_shaders; i++) {
 289       ir_function *const f = shader_list[i]->symbols->get_function(name);
 290
 291       if (f == NULL)
 292          continue;
 293
 294       ir_function_signature *sig =
 295          f->matching_signature(NULL, actual_parameters);
 296
 297       if ((sig == NULL) || !sig->is_defined)
 298          continue;
 299
 300       /* If this function expects to bind to a built-in function and the
 301        * signature that we found isn't a built-in, keep looking.  Also keep
 302        * looking if we expect a non-built-in but found a built-in.
 303        */
 304       if (use_builtin != sig->is_builtin())
 305             continue;
 306
 307       return sig;
 308    }
 309
 310    return NULL;
 311 }
 312
 313
 314 bool
 315 link_function_calls(gl_shader_program *prog, gl_shader *main,
 316                     gl_shader **shader_list, unsigned num_shaders)
 317 {
 318    call_link_visitor v(prog, main, shader_list, num_shaders);
 319
 320    v.run(main->ir);
 321    return v.success;
 322 }