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       if (sig->is_defined) {
 159          foreach_list_const(node, &sig->body) {
 160             const ir_instruction *const original = (ir_instruction *) node;
 161
 162             ir_instruction *copy = original->clone(linked, ht);
 163             linked_sig->body.push_tail(copy);
 164          }
 165
 166          linked_sig->is_defined = true;
 167       }
 168
 169       hash_table_dtor(ht);
 170
 171       /* Patch references inside the function to things outside the function
 172        * (i.e., function calls and global variables).
 173        */
 174       linked_sig->accept(this);
 175
 176       ir->callee = linked_sig;
 177
 178       return visit_continue;
 179    }
 180
 181    virtual ir_visitor_status visit_leave(ir_call *ir)
 182    {
 183       /* Traverse list of function parameters, and for array parameters
 184        * propagate max_array_access. Otherwise arrays that are only referenced
 185        * from inside functions via function parameters will be incorrectly
 186        * optimized. This will lead to incorrect code being generated (or worse).
 187        * Do it when leaving the node so the children would propagate their
 188        * array accesses first.
 189        */
 190
 191       const exec_node *formal_param_node = ir->callee->parameters.get_head();
 192       if (formal_param_node) {
 193          const exec_node *actual_param_node = ir->actual_parameters.get_head();
 194          while (!actual_param_node->is_tail_sentinel()) {
 195             ir_variable *formal_param = (ir_variable *) formal_param_node;
 196             ir_rvalue *actual_param = (ir_rvalue *) actual_param_node;
 197
 198             formal_param_node = formal_param_node->get_next();
 199             actual_param_node = actual_param_node->get_next();
 200
 201             if (formal_param->type->is_array()) {
 202                ir_dereference_variable *deref = actual_param->as_dereference_variable();
 203                if (deref && deref->var && deref->var->type->is_array()) {
 204                   deref->var->max_array_access =
 205                      MAX2(formal_param->max_array_access, deref->var->max_array_access);
 206                }
 207             }
 208          }
 209       }
 210       return visit_continue;
 211    }
 212
 213    virtual ir_visitor_status visit(ir_dereference_variable *ir)
 214    {
 215       if (hash_table_find(locals, ir->var) == NULL) {
 216          /* The non-function variable must be a global, so try to find the
 217           * variable in the shader's symbol table.  If the variable is not
 218           * found, then it's a global that *MUST* be defined in the original
 219           * shader.
 220           */
 221          ir_variable *var = linked->symbols->get_variable(ir->var->name);
 222          if (var == NULL) {
 223             /* Clone the ir_variable that the dereference already has and add
 224              * it to the linked shader.
 225              */
 226             var = ir->var->clone(linked, NULL);
 227             linked->symbols->add_variable(var);
 228             linked->ir->push_head(var);
 229          } else {
 230             if (var->type->is_array()) {
 231                /* It is possible to have a global array declared in multiple
 232                 * shaders without a size.  The array is implicitly sized by
 233                 * the maximal access to it in *any* shader.  Because of this,
 234                 * we need to track the maximal access to the array as linking
 235                 * pulls more functions in that access the array.
 236                 */
 237                var->max_array_access =
 238                   MAX2(var->max_array_access, ir->var->max_array_access);
 239
 240                if (var->type->length == 0 && ir->var->type->length != 0)
 241                   var->type = ir->var->type;
 242             }
 243             if (var->is_interface_instance()) {
 244                /* Similarly, we need implicit sizes of arrays within interface
 245                 * blocks to be sized by the maximal access in *any* shader.
 246                 */
 247                for (unsigned i = 0; i < var->get_interface_type()->length;
 248                     i++) {
 249                   var->max_ifc_array_access[i] =
 250                      MAX2(var->max_ifc_array_access[i],
 251                           ir->var->max_ifc_array_access[i]);
 252                }
 253             }
 254          }
 255
 256          ir->var = var;
 257       }
 258
 259       return visit_continue;
 260    }
 261
 262    /** Was function linking successful? */
 263    bool success;
 264
 265 private:
 266    /**
 267     * Shader program being linked
 268     *
 269     * This is only used for logging error messages.
 270     */
 271    gl_shader_program *prog;
 272
 273    /** List of shaders available for linking. */
 274    gl_shader **shader_list;
 275
 276    /** Number of shaders available for linking. */
 277    unsigned num_shaders;
 278
 279    /**
 280     * Final linked shader
 281     *
 282     * This is used two ways.  It is used to find global variables in the
 283     * linked shader that are accessed by the function.  It is also used to add
 284     * global variables from the shader where the function originated.
 285     */
 286    gl_shader *linked;
 287
 288    /**
 289     * Table of variables local to the function.
 290     */
 291    hash_table *locals;
 292 };
 293
 294 } /* anonymous namespace */
 295
 296 /**
 297  * Searches a list of shaders for a particular function definition
 298  */
 299 ir_function_signature *
 300 find_matching_signature(const char *name, const exec_list *actual_parameters,
 301                         gl_shader **shader_list, unsigned num_shaders,
 302                         bool use_builtin)
 303 {
 304    for (unsigned i = 0; i < num_shaders; i++) {
 305       ir_function *const f = shader_list[i]->symbols->get_function(name);
 306
 307       if (f == NULL)
 308          continue;
 309
 310       ir_function_signature *sig =
 311          f->matching_signature(NULL, actual_parameters);
 312
 313       if ((sig == NULL) ||
 314           (!sig->is_defined && !sig->is_intrinsic))
 315          continue;
 316
 317       /* If this function expects to bind to a built-in function and the
 318        * signature that we found isn't a built-in, keep looking.  Also keep
 319        * looking if we expect a non-built-in but found a built-in.
 320        */
 321       if (use_builtin != sig->is_builtin())
 322             continue;
 323
 324       return sig;
 325    }
 326
 327    return NULL;
 328 }
 329
 330
 331 bool
 332 link_function_calls(gl_shader_program *prog, gl_shader *main,
 333                     gl_shader **shader_list, unsigned num_shaders)
 334 {
 335    call_link_visitor v(prog, main, shader_list, num_shaders);
 336
 337    v.run(main->ir);
 338    return v.success;
 339 }