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