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 #include "main/core.h"
  29 #include "glsl_symbol_table.h"
  30 #include "glsl_parser_extras.h"
  31 #include "ir.h"
  32 #include "program.h"
  33 #include "program/hash_table.h"
  34 #include "linker.h"
  35
  36 static ir_function_signature *
  37 find_matching_signature(const char *name, const exec_list *actual_parameters,
  38                         gl_shader **shader_list, unsigned num_shaders);
  39
  40 class call_link_visitor : public ir_hierarchical_visitor {
  41 public:
  42    call_link_visitor(gl_shader_program *prog, gl_shader *linked,
  43                      gl_shader **shader_list, unsigned num_shaders)
  44    {
  45       this->prog = prog;
  46       this->shader_list = shader_list;
  47       this->num_shaders = num_shaders;
  48       this->success = true;
  49       this->linked = linked;
  50
  51       this->locals = hash_table_ctor(0, hash_table_pointer_hash,
  52                                      hash_table_pointer_compare);
  53    }
  54
  55    ~call_link_visitor()
  56    {
  57       hash_table_dtor(this->locals);
  58    }
  59
  60    virtual ir_visitor_status visit(ir_variable *ir)
  61    {
  62       hash_table_insert(locals, ir, ir);
  63       return visit_continue;
  64    }
  65
  66    virtual ir_visitor_status visit_enter(ir_call *ir)
  67    {
  68       /* If ir is an ir_call from a function that was imported from another
  69        * shader callee will point to an ir_function_signature in the original
  70        * shader.  In this case the function signature MUST NOT BE MODIFIED.
  71        * Doing so will modify the original shader.  This may prevent that
  72        * shader from being linkable in other programs.
  73        */
  74       const ir_function_signature *const callee = ir->get_callee();
  75       assert(callee != NULL);
  76       const char *const name = callee->function_name();
  77
  78       /* Determine if the requested function signature already exists in the
  79        * final linked shader.  If it does, use it as the target of the call.
  80        */
  81       ir_function_signature *sig =
  82          find_matching_signature(name, &callee->parameters, &linked, 1);
  83       if (sig != NULL) {
  84          ir->set_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);
  93       if (sig == NULL) {
  94          /* FINISHME: Log the full signature of unresolved function.
  95           */
  96          linker_error_printf(this->prog, "unresolved reference to function "
  97                              "`%s'\n", 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       ir_function_signature *linked_sig =
 110          f->exact_matching_signature(&callee->parameters);
 111       if (linked_sig == NULL) {
 112          linked_sig = new(linked) ir_function_signature(callee->return_type);
 113          f->add_signature(linked_sig);
 114       }
 115
 116       /* At this point linked_sig and called may be the same.  If ir is an
 117        * ir_call from linked then linked_sig and callee will be
 118        * ir_function_signatures that have no definitions (is_defined is false).
 119        */
 120       assert(!linked_sig->is_defined);
 121       assert(linked_sig->body.is_empty());
 122
 123       /* Create an in-place clone of the function definition.  This multistep
 124        * process introduces some complexity here, but it has some advantages.
 125        * The parameter list and the and function body are cloned separately.
 126        * The clone of the parameter list is used to prime the hashtable used
 127        * to replace variable references in the cloned body.
 128        *
 129        * The big advantage is that the ir_function_signature does not change.
 130        * This means that we don't have to process the rest of the IR tree to
 131        * patch ir_call nodes.  In addition, there is no way to remove or
 132        * replace signature stored in a function.  One could easily be added,
 133        * but this avoids the need.
 134        */
 135       struct hash_table *ht = hash_table_ctor(0, hash_table_pointer_hash,
 136                                               hash_table_pointer_compare);
 137       exec_list formal_parameters;
 138       foreach_list_const(node, &sig->parameters) {
 139          const ir_instruction *const original = (ir_instruction *) node;
 140          assert(const_cast<ir_instruction *>(original)->as_variable());
 141
 142          ir_instruction *copy = original->clone(linked, ht);
 143          formal_parameters.push_tail(copy);
 144       }
 145
 146       linked_sig->replace_parameters(&formal_parameters);
 147
 148       foreach_list_const(node, &sig->body) {
 149          const ir_instruction *const original = (ir_instruction *) node;
 150
 151          ir_instruction *copy = original->clone(linked, ht);
 152          linked_sig->body.push_tail(copy);
 153       }
 154
 155       linked_sig->is_defined = true;
 156       hash_table_dtor(ht);
 157
 158       /* Patch references inside the function to things outside the function
 159        * (i.e., function calls and global variables).
 160        */
 161       linked_sig->accept(this);
 162
 163       ir->set_callee(linked_sig);
 164
 165       return visit_continue;
 166    }
 167
 168    virtual ir_visitor_status visit(ir_dereference_variable *ir)
 169    {
 170       if (hash_table_find(locals, ir->var) == NULL) {
 171          /* The non-function variable must be a global, so try to find the
 172           * variable in the shader's symbol table.  If the variable is not
 173           * found, then it's a global that *MUST* be defined in the original
 174           * shader.
 175           */
 176          ir_variable *var = linked->symbols->get_variable(ir->var->name);
 177          if (var == NULL) {
 178             /* Clone the ir_variable that the dereference already has and add
 179              * it to the linked shader.
 180              */
 181             var = ir->var->clone(linked, NULL);
 182             linked->symbols->add_variable(var);
 183             linked->ir->push_head(var);
 184          } else if (var->type->is_array()) {
 185             /* It is possible to have a global array declared in multiple
 186              * shaders without a size.  The array is implicitly sized by the
 187              * maximal access to it in *any* shader.  Because of this, we
 188              * need to track the maximal access to the array as linking pulls
 189              * more functions in that access the array.
 190              */
 191             var->max_array_access =
 192                MAX2(var->max_array_access, ir->var->max_array_access);
 193
 194             if (var->type->length == 0 && ir->var->type->length != 0)
 195                var->type = ir->var->type;
 196          }
 197
 198          ir->var = var;
 199       }
 200
 201       return visit_continue;
 202    }
 203
 204    /** Was function linking successful? */
 205    bool success;
 206
 207 private:
 208    /**
 209     * Shader program being linked
 210     *
 211     * This is only used for logging error messages.
 212     */
 213    gl_shader_program *prog;
 214
 215    /** List of shaders available for linking. */
 216    gl_shader **shader_list;
 217
 218    /** Number of shaders available for linking. */
 219    unsigned num_shaders;
 220
 221    /**
 222     * Final linked shader
 223     *
 224     * This is used two ways.  It is used to find global variables in the
 225     * linked shader that are accessed by the function.  It is also used to add
 226     * global variables from the shader where the function originated.
 227     */
 228    gl_shader *linked;
 229
 230    /**
 231     * Table of variables local to the function.
 232     */
 233    hash_table *locals;
 234 };
 235
 236
 237 /**
 238  * Searches a list of shaders for a particular function definition
 239  */
 240 ir_function_signature *
 241 find_matching_signature(const char *name, const exec_list *actual_parameters,
 242                         gl_shader **shader_list, unsigned num_shaders)
 243 {
 244    for (unsigned i = 0; i < num_shaders; i++) {
 245       ir_function *const f = shader_list[i]->symbols->get_function(name);
 246
 247       if (f == NULL)
 248          continue;
 249
 250       ir_function_signature *sig = f->matching_signature(actual_parameters);
 251
 252       if ((sig == NULL) || !sig->is_defined)
 253          continue;
 254
 255       return sig;
 256    }
 257
 258    return NULL;
 259 }
 260
 261
 262 bool
 263 link_function_calls(gl_shader_program *prog, gl_shader *main,
 264                     gl_shader **shader_list, unsigned num_shaders)
 265 {
 266    call_link_visitor v(prog, main, shader_list, num_shaders);
 267
 268    v.run(main->ir);
 269    return v.success;
 270 }