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