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 <cstdlib>
  25 #include <cstdio>
  26 #include <cstdarg>
  27
  28 extern "C" {
  29 #include <talloc.h>
  30 }
  31
  32 #include "main/mtypes.h"
  33 #include "glsl_symbol_table.h"
  34 #include "glsl_parser_extras.h"
  35 #include "ir.h"
  36 #include "program.h"
  37 #include "hash_table.h"
  38 #include "linker.h"
  39
  40 static ir_function_signature *
  41 find_matching_signature(const char *name, const exec_list *actual_parameters,
  42                         gl_shader **shader_list, unsigned num_shaders);
  43
  44 class call_link_visitor : public ir_hierarchical_visitor {
  45 public:
  46    call_link_visitor(gl_shader_program *prog, gl_shader *linked,
  47                      gl_shader **shader_list, unsigned num_shaders)
  48    {
  49       this->prog = prog;
  50       this->shader_list = shader_list;
  51       this->num_shaders = num_shaders;
  52       this->success = true;
  53       this->linked = linked;
  54
  55       this->locals = hash_table_ctor(0, hash_table_pointer_hash,
  56                                      hash_table_pointer_compare);
  57    }
  58
  59    ~call_link_visitor()
  60    {
  61       hash_table_dtor(this->locals);
  62    }
  63
  64    virtual ir_visitor_status visit(ir_variable *ir)
  65    {
  66       hash_table_insert(locals, ir, ir);
  67       return visit_continue;
  68    }
  69
  70    virtual ir_visitor_status visit_enter(ir_call *ir)
  71    {
  72       /* If ir is an ir_call from a function that was imported from another
  73        * shader callee will point to an ir_function_signature in the original
  74        * shader.  In this case the function signature MUST NOT BE MODIFIED.
  75        * Doing so will modify the original shader.  This may prevent that
  76        * shader from being linkable in other programs.
  77        */
  78       const ir_function_signature *const callee = ir->get_callee();
  79       assert(callee != NULL);
  80       const char *const name = callee->function_name();
  81
  82       /* Determine if the requested function signature already exists in the
  83        * final linked shader.  If it does, use it as the target of the call.
  84        */
  85       ir_function_signature *sig =
  86          find_matching_signature(name, &callee->parameters, &linked, 1);
  87       if (sig != NULL) {
  88          ir->set_callee(sig);
  89          return visit_continue;
  90       }
  91
  92       /* Try to find the signature in one of the other shaders that is being
  93        * linked.  If it's not found there, return an error.
  94        */
  95       sig = find_matching_signature(name, &ir->actual_parameters, shader_list,
  96                                     num_shaders);
  97       if (sig == NULL) {
  98          /* FINISHME: Log the full signature of unresolved function.
  99           */
 100          linker_error_printf(this->prog, "unresolved reference to function "
 101                              "`%s'\n", name);
 102          this->success = false;
 103          return visit_stop;
 104       }
 105
 106       /* Find the prototype information in the linked shader.  Generate any
 107        * details that may be missing.
 108        */
 109       ir_function *f = linked->symbols->get_function(name);
 110       if (f == NULL)
 111          f = new(linked) ir_function(name);
 112
 113       ir_function_signature *linked_sig =
 114          f->matching_signature(&callee->parameters);
 115       if (linked_sig == NULL) {
 116          linked_sig = new(linked) ir_function_signature(callee->return_type);
 117          f->add_signature(linked_sig);
 118       }
 119
 120       /* At this point linked_sig and called may be the same.  If ir is an
 121        * ir_call from linked then linked_sig and callee will be
 122        * ir_function_signatures that have no definitions (is_defined is false).
 123        */
 124       assert(!linked_sig->is_defined);
 125       assert(linked_sig->body.is_empty());
 126
 127       /* Create an in-place clone of the function definition.  This multistep
 128        * process introduces some complexity here, but it has some advantages.
 129        * The parameter list and the and function body are cloned separately.
 130        * The clone of the parameter list is used to prime the hashtable used
 131        * to replace variable references in the cloned body.
 132        *
 133        * The big advantage is that the ir_function_signature does not change.
 134        * This means that we don't have to process the rest of the IR tree to
 135        * patch ir_call nodes.  In addition, there is no way to remove or
 136        * replace signature stored in a function.  One could easily be added,
 137        * but this avoids the need.
 138        */
 139       struct hash_table *ht = hash_table_ctor(0, hash_table_pointer_hash,
 140                                               hash_table_pointer_compare);
 141       exec_list formal_parameters;
 142       foreach_list_const(node, &sig->parameters) {
 143          const ir_instruction *const original = (ir_instruction *) node;
 144          assert(const_cast<ir_instruction *>(original)->as_variable());
 145
 146          ir_instruction *copy = original->clone(ht);
 147          formal_parameters.push_tail(copy);
 148       }
 149
 150       linked_sig->replace_parameters(&formal_parameters);
 151
 152       foreach_list_const(node, &sig->body) {
 153          const ir_instruction *const original = (ir_instruction *) node;
 154
 155          ir_instruction *copy = original->clone(ht);
 156          linked_sig->body.push_tail(copy);
 157       }
 158
 159       linked_sig->is_defined = true;
 160       hash_table_dtor(ht);
 161
 162       /* Patch references inside the function to things outside the function
 163        * (i.e., function calls and global variables).
 164        */
 165       linked_sig->accept(this);
 166
 167       return visit_continue;
 168    }
 169
 170    virtual ir_visitor_status visit(ir_dereference_variable *ir)
 171    {
 172       if (hash_table_find(locals, ir->var) == NULL) {
 173          /* The non-function variable must be a global, so try to find the
 174           * variable in the shader's symbol table.  If the variable is not
 175           * found, then it's a global that *MUST* be defined in the original
 176           * shader.
 177           */
 178          ir_variable *var = linked->symbols->get_variable(ir->var->name);
 179          if (var == NULL) {
 180             /* Clone the ir_variable that the dereference already has and add
 181              * it to the linked shader.
 182              */
 183             var = ir->var->clone(NULL);
 184             linked->symbols->add_variable(var->name, var);
 185             linked->ir->push_head(var);
 186          }
 187
 188          ir->var = var;
 189       }
 190
 191       return visit_continue;
 192    }
 193
 194    /** Was function linking successful? */
 195    bool success;
 196
 197 private:
 198    /**
 199     * Shader program being linked
 200     *
 201     * This is only used for logging error messages.
 202     */
 203    gl_shader_program *prog;
 204
 205    /** List of shaders available for linking. */
 206    gl_shader **shader_list;
 207
 208    /** Number of shaders available for linking. */
 209    unsigned num_shaders;
 210
 211    /**
 212     * Final linked shader
 213     *
 214     * This is used two ways.  It is used to find global variables in the
 215     * linked shader that are accessed by the function.  It is also used to add
 216     * global variables from the shader where the function originated.
 217     */
 218    gl_shader *linked;
 219
 220    /**
 221     * Table of variables local to the function.
 222     */
 223    hash_table *locals;
 224 };
 225
 226
 227 /**
 228  * Searches a list of shaders for a particular function definition
 229  */
 230 ir_function_signature *
 231 find_matching_signature(const char *name, const exec_list *actual_parameters,
 232                         gl_shader **shader_list, unsigned num_shaders)
 233 {
 234    for (unsigned i = 0; i < num_shaders; i++) {
 235       ir_function *const f = shader_list[i]->symbols->get_function(name);
 236
 237       if (f == NULL)
 238          continue;
 239
 240       ir_function_signature *sig = f->matching_signature(actual_parameters);
 241
 242       if ((sig == NULL) || !sig->is_defined)
 243          continue;
 244
 245       return sig;
 246    }
 247
 248    return NULL;
 249 }
 250
 251
 252 bool
 253 link_function_calls(gl_shader_program *prog, gl_shader *main,
 254                     gl_shader **shader_list, unsigned num_shaders)
 255 {
 256    call_link_visitor v(prog, main, shader_list, num_shaders);
 257
 258    v.run(main->ir);
 259    return v.success;
 260 }