glsl: Fail linking if assign_attribute_locations fails
[mesa.git] / src / glsl / linker.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 /**
25 * \file linker.cpp
26 * GLSL linker implementation
27 *
28 * Given a set of shaders that are to be linked to generate a final program,
29 * there are three distinct stages.
30 *
31 * In the first stage shaders are partitioned into groups based on the shader
32 * type. All shaders of a particular type (e.g., vertex shaders) are linked
33 * together.
34 *
35 * - Undefined references in each shader are resolve to definitions in
36 * another shader.
37 * - Types and qualifiers of uniforms, outputs, and global variables defined
38 * in multiple shaders with the same name are verified to be the same.
39 * - Initializers for uniforms and global variables defined
40 * in multiple shaders with the same name are verified to be the same.
41 *
42 * The result, in the terminology of the GLSL spec, is a set of shader
43 * executables for each processing unit.
44 *
45 * After the first stage is complete, a series of semantic checks are performed
46 * on each of the shader executables.
47 *
48 * - Each shader executable must define a \c main function.
49 * - Each vertex shader executable must write to \c gl_Position.
50 * - Each fragment shader executable must write to either \c gl_FragData or
51 * \c gl_FragColor.
52 *
53 * In the final stage individual shader executables are linked to create a
54 * complete exectuable.
55 *
56 * - Types of uniforms defined in multiple shader stages with the same name
57 * are verified to be the same.
58 * - Initializers for uniforms defined in multiple shader stages with the
59 * same name are verified to be the same.
60 * - Types and qualifiers of outputs defined in one stage are verified to
61 * be the same as the types and qualifiers of inputs defined with the same
62 * name in a later stage.
63 *
64 * \author Ian Romanick <ian.d.romanick@intel.com>
65 */
66 #include <cstdlib>
67 #include <cstdio>
68 #include <cstdarg>
69 #include <climits>
70
71 extern "C" {
72 #include <talloc.h>
73 }
74
75 #include "main/core.h"
76 #include "glsl_symbol_table.h"
77 #include "ir.h"
78 #include "program.h"
79 #include "program/hash_table.h"
80 #include "linker.h"
81 #include "ir_optimization.h"
82
83 /**
84 * Visitor that determines whether or not a variable is ever written.
85 */
86 class find_assignment_visitor : public ir_hierarchical_visitor {
87 public:
88 find_assignment_visitor(const char *name)
89 : name(name), found(false)
90 {
91 /* empty */
92 }
93
94 virtual ir_visitor_status visit_enter(ir_assignment *ir)
95 {
96 ir_variable *const var = ir->lhs->variable_referenced();
97
98 if (strcmp(name, var->name) == 0) {
99 found = true;
100 return visit_stop;
101 }
102
103 return visit_continue_with_parent;
104 }
105
106 virtual ir_visitor_status visit_enter(ir_call *ir)
107 {
108 exec_list_iterator sig_iter = ir->get_callee()->parameters.iterator();
109 foreach_iter(exec_list_iterator, iter, *ir) {
110 ir_rvalue *param_rval = (ir_rvalue *)iter.get();
111 ir_variable *sig_param = (ir_variable *)sig_iter.get();
112
113 if (sig_param->mode == ir_var_out ||
114 sig_param->mode == ir_var_inout) {
115 ir_variable *var = param_rval->variable_referenced();
116 if (var && strcmp(name, var->name) == 0) {
117 found = true;
118 return visit_stop;
119 }
120 }
121 sig_iter.next();
122 }
123
124 return visit_continue_with_parent;
125 }
126
127 bool variable_found()
128 {
129 return found;
130 }
131
132 private:
133 const char *name; /**< Find writes to a variable with this name. */
134 bool found; /**< Was a write to the variable found? */
135 };
136
137
138 /**
139 * Visitor that determines whether or not a variable is ever read.
140 */
141 class find_deref_visitor : public ir_hierarchical_visitor {
142 public:
143 find_deref_visitor(const char *name)
144 : name(name), found(false)
145 {
146 /* empty */
147 }
148
149 virtual ir_visitor_status visit(ir_dereference_variable *ir)
150 {
151 if (strcmp(this->name, ir->var->name) == 0) {
152 this->found = true;
153 return visit_stop;
154 }
155
156 return visit_continue;
157 }
158
159 bool variable_found() const
160 {
161 return this->found;
162 }
163
164 private:
165 const char *name; /**< Find writes to a variable with this name. */
166 bool found; /**< Was a write to the variable found? */
167 };
168
169
170 void
171 linker_error_printf(gl_shader_program *prog, const char *fmt, ...)
172 {
173 va_list ap;
174
175 prog->InfoLog = talloc_strdup_append(prog->InfoLog, "error: ");
176 va_start(ap, fmt);
177 prog->InfoLog = talloc_vasprintf_append(prog->InfoLog, fmt, ap);
178 va_end(ap);
179 }
180
181
182 void
183 invalidate_variable_locations(gl_shader *sh, enum ir_variable_mode mode,
184 int generic_base)
185 {
186 foreach_list(node, sh->ir) {
187 ir_variable *const var = ((ir_instruction *) node)->as_variable();
188
189 if ((var == NULL) || (var->mode != (unsigned) mode))
190 continue;
191
192 /* Only assign locations for generic attributes / varyings / etc.
193 */
194 if (var->location >= generic_base)
195 var->location = -1;
196 }
197 }
198
199
200 /**
201 * Determine the number of attribute slots required for a particular type
202 *
203 * This code is here because it implements the language rules of a specific
204 * GLSL version. Since it's a property of the language and not a property of
205 * types in general, it doesn't really belong in glsl_type.
206 */
207 unsigned
208 count_attribute_slots(const glsl_type *t)
209 {
210 /* From page 31 (page 37 of the PDF) of the GLSL 1.50 spec:
211 *
212 * "A scalar input counts the same amount against this limit as a vec4,
213 * so applications may want to consider packing groups of four
214 * unrelated float inputs together into a vector to better utilize the
215 * capabilities of the underlying hardware. A matrix input will use up
216 * multiple locations. The number of locations used will equal the
217 * number of columns in the matrix."
218 *
219 * The spec does not explicitly say how arrays are counted. However, it
220 * should be safe to assume the total number of slots consumed by an array
221 * is the number of entries in the array multiplied by the number of slots
222 * consumed by a single element of the array.
223 */
224
225 if (t->is_array())
226 return t->array_size() * count_attribute_slots(t->element_type());
227
228 if (t->is_matrix())
229 return t->matrix_columns;
230
231 return 1;
232 }
233
234
235 /**
236 * Verify that a vertex shader executable meets all semantic requirements
237 *
238 * \param shader Vertex shader executable to be verified
239 */
240 bool
241 validate_vertex_shader_executable(struct gl_shader_program *prog,
242 struct gl_shader *shader)
243 {
244 if (shader == NULL)
245 return true;
246
247 find_assignment_visitor find("gl_Position");
248 find.run(shader->ir);
249 if (!find.variable_found()) {
250 linker_error_printf(prog,
251 "vertex shader does not write to `gl_Position'\n");
252 return false;
253 }
254
255 return true;
256 }
257
258
259 /**
260 * Verify that a fragment shader executable meets all semantic requirements
261 *
262 * \param shader Fragment shader executable to be verified
263 */
264 bool
265 validate_fragment_shader_executable(struct gl_shader_program *prog,
266 struct gl_shader *shader)
267 {
268 if (shader == NULL)
269 return true;
270
271 find_assignment_visitor frag_color("gl_FragColor");
272 find_assignment_visitor frag_data("gl_FragData");
273
274 frag_color.run(shader->ir);
275 frag_data.run(shader->ir);
276
277 if (frag_color.variable_found() && frag_data.variable_found()) {
278 linker_error_printf(prog, "fragment shader writes to both "
279 "`gl_FragColor' and `gl_FragData'\n");
280 return false;
281 }
282
283 return true;
284 }
285
286
287 /**
288 * Generate a string describing the mode of a variable
289 */
290 static const char *
291 mode_string(const ir_variable *var)
292 {
293 switch (var->mode) {
294 case ir_var_auto:
295 return (var->read_only) ? "global constant" : "global variable";
296
297 case ir_var_uniform: return "uniform";
298 case ir_var_in: return "shader input";
299 case ir_var_out: return "shader output";
300 case ir_var_inout: return "shader inout";
301
302 case ir_var_temporary:
303 default:
304 assert(!"Should not get here.");
305 return "invalid variable";
306 }
307 }
308
309
310 /**
311 * Perform validation of global variables used across multiple shaders
312 */
313 bool
314 cross_validate_globals(struct gl_shader_program *prog,
315 struct gl_shader **shader_list,
316 unsigned num_shaders,
317 bool uniforms_only)
318 {
319 /* Examine all of the uniforms in all of the shaders and cross validate
320 * them.
321 */
322 glsl_symbol_table variables;
323 for (unsigned i = 0; i < num_shaders; i++) {
324 foreach_list(node, shader_list[i]->ir) {
325 ir_variable *const var = ((ir_instruction *) node)->as_variable();
326
327 if (var == NULL)
328 continue;
329
330 if (uniforms_only && (var->mode != ir_var_uniform))
331 continue;
332
333 /* Don't cross validate temporaries that are at global scope. These
334 * will eventually get pulled into the shaders 'main'.
335 */
336 if (var->mode == ir_var_temporary)
337 continue;
338
339 /* If a global with this name has already been seen, verify that the
340 * new instance has the same type. In addition, if the globals have
341 * initializers, the values of the initializers must be the same.
342 */
343 ir_variable *const existing = variables.get_variable(var->name);
344 if (existing != NULL) {
345 if (var->type != existing->type) {
346 /* Consider the types to be "the same" if both types are arrays
347 * of the same type and one of the arrays is implicitly sized.
348 * In addition, set the type of the linked variable to the
349 * explicitly sized array.
350 */
351 if (var->type->is_array()
352 && existing->type->is_array()
353 && (var->type->fields.array == existing->type->fields.array)
354 && ((var->type->length == 0)
355 || (existing->type->length == 0))) {
356 if (existing->type->length == 0)
357 existing->type = var->type;
358 } else {
359 linker_error_printf(prog, "%s `%s' declared as type "
360 "`%s' and type `%s'\n",
361 mode_string(var),
362 var->name, var->type->name,
363 existing->type->name);
364 return false;
365 }
366 }
367
368 /* FINISHME: Handle non-constant initializers.
369 */
370 if (var->constant_value != NULL) {
371 if (existing->constant_value != NULL) {
372 if (!var->constant_value->has_value(existing->constant_value)) {
373 linker_error_printf(prog, "initializers for %s "
374 "`%s' have differing values\n",
375 mode_string(var), var->name);
376 return false;
377 }
378 } else
379 /* If the first-seen instance of a particular uniform did not
380 * have an initializer but a later instance does, copy the
381 * initializer to the version stored in the symbol table.
382 */
383 /* FINISHME: This is wrong. The constant_value field should
384 * FINISHME: not be modified! Imagine a case where a shader
385 * FINISHME: without an initializer is linked in two different
386 * FINISHME: programs with shaders that have differing
387 * FINISHME: initializers. Linking with the first will
388 * FINISHME: modify the shader, and linking with the second
389 * FINISHME: will fail.
390 */
391 existing->constant_value =
392 var->constant_value->clone(talloc_parent(existing), NULL);
393 }
394 } else
395 variables.add_variable(var->name, var);
396 }
397 }
398
399 return true;
400 }
401
402
403 /**
404 * Perform validation of uniforms used across multiple shader stages
405 */
406 bool
407 cross_validate_uniforms(struct gl_shader_program *prog)
408 {
409 return cross_validate_globals(prog, prog->_LinkedShaders,
410 prog->_NumLinkedShaders, true);
411 }
412
413
414 /**
415 * Validate that outputs from one stage match inputs of another
416 */
417 bool
418 cross_validate_outputs_to_inputs(struct gl_shader_program *prog,
419 gl_shader *producer, gl_shader *consumer)
420 {
421 glsl_symbol_table parameters;
422 /* FINISHME: Figure these out dynamically. */
423 const char *const producer_stage = "vertex";
424 const char *const consumer_stage = "fragment";
425
426 /* Find all shader outputs in the "producer" stage.
427 */
428 foreach_list(node, producer->ir) {
429 ir_variable *const var = ((ir_instruction *) node)->as_variable();
430
431 /* FINISHME: For geometry shaders, this should also look for inout
432 * FINISHME: variables.
433 */
434 if ((var == NULL) || (var->mode != ir_var_out))
435 continue;
436
437 parameters.add_variable(var->name, var);
438 }
439
440
441 /* Find all shader inputs in the "consumer" stage. Any variables that have
442 * matching outputs already in the symbol table must have the same type and
443 * qualifiers.
444 */
445 foreach_list(node, consumer->ir) {
446 ir_variable *const input = ((ir_instruction *) node)->as_variable();
447
448 /* FINISHME: For geometry shaders, this should also look for inout
449 * FINISHME: variables.
450 */
451 if ((input == NULL) || (input->mode != ir_var_in))
452 continue;
453
454 ir_variable *const output = parameters.get_variable(input->name);
455 if (output != NULL) {
456 /* Check that the types match between stages.
457 */
458 if (input->type != output->type) {
459 linker_error_printf(prog,
460 "%s shader output `%s' declared as "
461 "type `%s', but %s shader input declared "
462 "as type `%s'\n",
463 producer_stage, output->name,
464 output->type->name,
465 consumer_stage, input->type->name);
466 return false;
467 }
468
469 /* Check that all of the qualifiers match between stages.
470 */
471 if (input->centroid != output->centroid) {
472 linker_error_printf(prog,
473 "%s shader output `%s' %s centroid qualifier, "
474 "but %s shader input %s centroid qualifier\n",
475 producer_stage,
476 output->name,
477 (output->centroid) ? "has" : "lacks",
478 consumer_stage,
479 (input->centroid) ? "has" : "lacks");
480 return false;
481 }
482
483 if (input->invariant != output->invariant) {
484 linker_error_printf(prog,
485 "%s shader output `%s' %s invariant qualifier, "
486 "but %s shader input %s invariant qualifier\n",
487 producer_stage,
488 output->name,
489 (output->invariant) ? "has" : "lacks",
490 consumer_stage,
491 (input->invariant) ? "has" : "lacks");
492 return false;
493 }
494
495 if (input->interpolation != output->interpolation) {
496 linker_error_printf(prog,
497 "%s shader output `%s' specifies %s "
498 "interpolation qualifier, "
499 "but %s shader input specifies %s "
500 "interpolation qualifier\n",
501 producer_stage,
502 output->name,
503 output->interpolation_string(),
504 consumer_stage,
505 input->interpolation_string());
506 return false;
507 }
508 }
509 }
510
511 return true;
512 }
513
514
515 /**
516 * Populates a shaders symbol table with all global declarations
517 */
518 static void
519 populate_symbol_table(gl_shader *sh)
520 {
521 sh->symbols = new(sh) glsl_symbol_table;
522
523 foreach_list(node, sh->ir) {
524 ir_instruction *const inst = (ir_instruction *) node;
525 ir_variable *var;
526 ir_function *func;
527
528 if ((func = inst->as_function()) != NULL) {
529 sh->symbols->add_function(func->name, func);
530 } else if ((var = inst->as_variable()) != NULL) {
531 sh->symbols->add_variable(var->name, var);
532 }
533 }
534 }
535
536
537 /**
538 * Remap variables referenced in an instruction tree
539 *
540 * This is used when instruction trees are cloned from one shader and placed in
541 * another. These trees will contain references to \c ir_variable nodes that
542 * do not exist in the target shader. This function finds these \c ir_variable
543 * references and replaces the references with matching variables in the target
544 * shader.
545 *
546 * If there is no matching variable in the target shader, a clone of the
547 * \c ir_variable is made and added to the target shader. The new variable is
548 * added to \b both the instruction stream and the symbol table.
549 *
550 * \param inst IR tree that is to be processed.
551 * \param symbols Symbol table containing global scope symbols in the
552 * linked shader.
553 * \param instructions Instruction stream where new variable declarations
554 * should be added.
555 */
556 void
557 remap_variables(ir_instruction *inst, struct gl_shader *target,
558 hash_table *temps)
559 {
560 class remap_visitor : public ir_hierarchical_visitor {
561 public:
562 remap_visitor(struct gl_shader *target,
563 hash_table *temps)
564 {
565 this->target = target;
566 this->symbols = target->symbols;
567 this->instructions = target->ir;
568 this->temps = temps;
569 }
570
571 virtual ir_visitor_status visit(ir_dereference_variable *ir)
572 {
573 if (ir->var->mode == ir_var_temporary) {
574 ir_variable *var = (ir_variable *) hash_table_find(temps, ir->var);
575
576 assert(var != NULL);
577 ir->var = var;
578 return visit_continue;
579 }
580
581 ir_variable *const existing =
582 this->symbols->get_variable(ir->var->name);
583 if (existing != NULL)
584 ir->var = existing;
585 else {
586 ir_variable *copy = ir->var->clone(this->target, NULL);
587
588 this->symbols->add_variable(copy->name, copy);
589 this->instructions->push_head(copy);
590 ir->var = copy;
591 }
592
593 return visit_continue;
594 }
595
596 private:
597 struct gl_shader *target;
598 glsl_symbol_table *symbols;
599 exec_list *instructions;
600 hash_table *temps;
601 };
602
603 remap_visitor v(target, temps);
604
605 inst->accept(&v);
606 }
607
608
609 /**
610 * Move non-declarations from one instruction stream to another
611 *
612 * The intended usage pattern of this function is to pass the pointer to the
613 * head sentinel of a list (i.e., a pointer to the list cast to an \c exec_node
614 * pointer) for \c last and \c false for \c make_copies on the first
615 * call. Successive calls pass the return value of the previous call for
616 * \c last and \c true for \c make_copies.
617 *
618 * \param instructions Source instruction stream
619 * \param last Instruction after which new instructions should be
620 * inserted in the target instruction stream
621 * \param make_copies Flag selecting whether instructions in \c instructions
622 * should be copied (via \c ir_instruction::clone) into the
623 * target list or moved.
624 *
625 * \return
626 * The new "last" instruction in the target instruction stream. This pointer
627 * is suitable for use as the \c last parameter of a later call to this
628 * function.
629 */
630 exec_node *
631 move_non_declarations(exec_list *instructions, exec_node *last,
632 bool make_copies, gl_shader *target)
633 {
634 hash_table *temps = NULL;
635
636 if (make_copies)
637 temps = hash_table_ctor(0, hash_table_pointer_hash,
638 hash_table_pointer_compare);
639
640 foreach_list_safe(node, instructions) {
641 ir_instruction *inst = (ir_instruction *) node;
642
643 if (inst->as_function())
644 continue;
645
646 ir_variable *var = inst->as_variable();
647 if ((var != NULL) && (var->mode != ir_var_temporary))
648 continue;
649
650 assert(inst->as_assignment()
651 || ((var != NULL) && (var->mode == ir_var_temporary)));
652
653 if (make_copies) {
654 inst = inst->clone(target, NULL);
655
656 if (var != NULL)
657 hash_table_insert(temps, inst, var);
658 else
659 remap_variables(inst, target, temps);
660 } else {
661 inst->remove();
662 }
663
664 last->insert_after(inst);
665 last = inst;
666 }
667
668 if (make_copies)
669 hash_table_dtor(temps);
670
671 return last;
672 }
673
674 /**
675 * Get the function signature for main from a shader
676 */
677 static ir_function_signature *
678 get_main_function_signature(gl_shader *sh)
679 {
680 ir_function *const f = sh->symbols->get_function("main");
681 if (f != NULL) {
682 exec_list void_parameters;
683
684 /* Look for the 'void main()' signature and ensure that it's defined.
685 * This keeps the linker from accidentally pick a shader that just
686 * contains a prototype for main.
687 *
688 * We don't have to check for multiple definitions of main (in multiple
689 * shaders) because that would have already been caught above.
690 */
691 ir_function_signature *sig = f->matching_signature(&void_parameters);
692 if ((sig != NULL) && sig->is_defined) {
693 return sig;
694 }
695 }
696
697 return NULL;
698 }
699
700
701 /**
702 * Combine a group of shaders for a single stage to generate a linked shader
703 *
704 * \note
705 * If this function is supplied a single shader, it is cloned, and the new
706 * shader is returned.
707 */
708 static struct gl_shader *
709 link_intrastage_shaders(GLcontext *ctx,
710 struct gl_shader_program *prog,
711 struct gl_shader **shader_list,
712 unsigned num_shaders)
713 {
714 /* Check that global variables defined in multiple shaders are consistent.
715 */
716 if (!cross_validate_globals(prog, shader_list, num_shaders, false))
717 return NULL;
718
719 /* Check that there is only a single definition of each function signature
720 * across all shaders.
721 */
722 for (unsigned i = 0; i < (num_shaders - 1); i++) {
723 foreach_list(node, shader_list[i]->ir) {
724 ir_function *const f = ((ir_instruction *) node)->as_function();
725
726 if (f == NULL)
727 continue;
728
729 for (unsigned j = i + 1; j < num_shaders; j++) {
730 ir_function *const other =
731 shader_list[j]->symbols->get_function(f->name);
732
733 /* If the other shader has no function (and therefore no function
734 * signatures) with the same name, skip to the next shader.
735 */
736 if (other == NULL)
737 continue;
738
739 foreach_iter (exec_list_iterator, iter, *f) {
740 ir_function_signature *sig =
741 (ir_function_signature *) iter.get();
742
743 if (!sig->is_defined || sig->is_builtin)
744 continue;
745
746 ir_function_signature *other_sig =
747 other->exact_matching_signature(& sig->parameters);
748
749 if ((other_sig != NULL) && other_sig->is_defined
750 && !other_sig->is_builtin) {
751 linker_error_printf(prog,
752 "function `%s' is multiply defined",
753 f->name);
754 return NULL;
755 }
756 }
757 }
758 }
759 }
760
761 /* Find the shader that defines main, and make a clone of it.
762 *
763 * Starting with the clone, search for undefined references. If one is
764 * found, find the shader that defines it. Clone the reference and add
765 * it to the shader. Repeat until there are no undefined references or
766 * until a reference cannot be resolved.
767 */
768 gl_shader *main = NULL;
769 for (unsigned i = 0; i < num_shaders; i++) {
770 if (get_main_function_signature(shader_list[i]) != NULL) {
771 main = shader_list[i];
772 break;
773 }
774 }
775
776 if (main == NULL) {
777 linker_error_printf(prog, "%s shader lacks `main'\n",
778 (shader_list[0]->Type == GL_VERTEX_SHADER)
779 ? "vertex" : "fragment");
780 return NULL;
781 }
782
783 gl_shader *const linked = ctx->Driver.NewShader(NULL, 0, main->Type);
784 linked->ir = new(linked) exec_list;
785 clone_ir_list(linked, linked->ir, main->ir);
786
787 populate_symbol_table(linked);
788
789 /* The a pointer to the main function in the final linked shader (i.e., the
790 * copy of the original shader that contained the main function).
791 */
792 ir_function_signature *const main_sig = get_main_function_signature(linked);
793
794 /* Move any instructions other than variable declarations or function
795 * declarations into main.
796 */
797 exec_node *insertion_point =
798 move_non_declarations(linked->ir, (exec_node *) &main_sig->body, false,
799 linked);
800
801 for (unsigned i = 0; i < num_shaders; i++) {
802 if (shader_list[i] == main)
803 continue;
804
805 insertion_point = move_non_declarations(shader_list[i]->ir,
806 insertion_point, true, linked);
807 }
808
809 /* Resolve initializers for global variables in the linked shader.
810 */
811 unsigned num_linking_shaders = num_shaders;
812 for (unsigned i = 0; i < num_shaders; i++)
813 num_linking_shaders += shader_list[i]->num_builtins_to_link;
814
815 gl_shader **linking_shaders =
816 (gl_shader **) calloc(num_linking_shaders, sizeof(gl_shader *));
817
818 memcpy(linking_shaders, shader_list,
819 sizeof(linking_shaders[0]) * num_shaders);
820
821 unsigned idx = num_shaders;
822 for (unsigned i = 0; i < num_shaders; i++) {
823 memcpy(&linking_shaders[idx], shader_list[i]->builtins_to_link,
824 sizeof(linking_shaders[0]) * shader_list[i]->num_builtins_to_link);
825 idx += shader_list[i]->num_builtins_to_link;
826 }
827
828 assert(idx == num_linking_shaders);
829
830 link_function_calls(prog, linked, linking_shaders, num_linking_shaders);
831
832 free(linking_shaders);
833
834 return linked;
835 }
836
837
838 struct uniform_node {
839 exec_node link;
840 struct gl_uniform *u;
841 unsigned slots;
842 };
843
844 /**
845 * Update the sizes of linked shader uniform arrays to the maximum
846 * array index used.
847 *
848 * From page 81 (page 95 of the PDF) of the OpenGL 2.1 spec:
849 *
850 * If one or more elements of an array are active,
851 * GetActiveUniform will return the name of the array in name,
852 * subject to the restrictions listed above. The type of the array
853 * is returned in type. The size parameter contains the highest
854 * array element index used, plus one. The compiler or linker
855 * determines the highest index used. There will be only one
856 * active uniform reported by the GL per uniform array.
857
858 */
859 static void
860 update_array_sizes(struct gl_shader_program *prog)
861 {
862 for (unsigned i = 0; i < prog->_NumLinkedShaders; i++) {
863 foreach_list(node, prog->_LinkedShaders[i]->ir) {
864 ir_variable *const var = ((ir_instruction *) node)->as_variable();
865
866 if ((var == NULL) || (var->mode != ir_var_uniform &&
867 var->mode != ir_var_in &&
868 var->mode != ir_var_out) ||
869 !var->type->is_array())
870 continue;
871
872 unsigned int size = var->max_array_access;
873 for (unsigned j = 0; j < prog->_NumLinkedShaders; j++) {
874 foreach_list(node2, prog->_LinkedShaders[j]->ir) {
875 ir_variable *other_var = ((ir_instruction *) node2)->as_variable();
876 if (!other_var)
877 continue;
878
879 if (strcmp(var->name, other_var->name) == 0 &&
880 other_var->max_array_access > size) {
881 size = other_var->max_array_access;
882 }
883 }
884 }
885
886 if (size + 1 != var->type->fields.array->length) {
887 var->type = glsl_type::get_array_instance(var->type->fields.array,
888 size + 1);
889 /* FINISHME: We should update the types of array
890 * dereferences of this variable now.
891 */
892 }
893 }
894 }
895 }
896
897 static void
898 add_uniform(void *mem_ctx, exec_list *uniforms, struct hash_table *ht,
899 const char *name, const glsl_type *type, GLenum shader_type,
900 unsigned *next_shader_pos, unsigned *total_uniforms)
901 {
902 if (type->is_record()) {
903 for (unsigned int i = 0; i < type->length; i++) {
904 const glsl_type *field_type = type->fields.structure[i].type;
905 char *field_name = talloc_asprintf(mem_ctx, "%s.%s", name,
906 type->fields.structure[i].name);
907
908 add_uniform(mem_ctx, uniforms, ht, field_name, field_type,
909 shader_type, next_shader_pos, total_uniforms);
910 }
911 } else {
912 uniform_node *n = (uniform_node *) hash_table_find(ht, name);
913 unsigned int vec4_slots;
914 const glsl_type *array_elem_type = NULL;
915
916 if (type->is_array()) {
917 array_elem_type = type->fields.array;
918 /* Array of structures. */
919 if (array_elem_type->is_record()) {
920 for (unsigned int i = 0; i < type->length; i++) {
921 char *elem_name = talloc_asprintf(mem_ctx, "%s[%d]", name, i);
922 add_uniform(mem_ctx, uniforms, ht, elem_name, array_elem_type,
923 shader_type, next_shader_pos, total_uniforms);
924 }
925 return;
926 }
927 }
928
929 /* Fix the storage size of samplers at 1 vec4 each. Be sure to pad out
930 * vectors to vec4 slots.
931 */
932 if (type->is_array()) {
933 if (array_elem_type->is_sampler())
934 vec4_slots = type->length;
935 else
936 vec4_slots = type->length * array_elem_type->matrix_columns;
937 } else if (type->is_sampler()) {
938 vec4_slots = 1;
939 } else {
940 vec4_slots = type->matrix_columns;
941 }
942
943 if (n == NULL) {
944 n = (uniform_node *) calloc(1, sizeof(struct uniform_node));
945 n->u = (gl_uniform *) calloc(1, sizeof(struct gl_uniform));
946 n->slots = vec4_slots;
947
948 n->u->Name = strdup(name);
949 n->u->Type = type;
950 n->u->VertPos = -1;
951 n->u->FragPos = -1;
952 n->u->GeomPos = -1;
953 (*total_uniforms)++;
954
955 hash_table_insert(ht, n, name);
956 uniforms->push_tail(& n->link);
957 }
958
959 switch (shader_type) {
960 case GL_VERTEX_SHADER:
961 n->u->VertPos = *next_shader_pos;
962 break;
963 case GL_FRAGMENT_SHADER:
964 n->u->FragPos = *next_shader_pos;
965 break;
966 case GL_GEOMETRY_SHADER:
967 n->u->GeomPos = *next_shader_pos;
968 break;
969 }
970
971 (*next_shader_pos) += vec4_slots;
972 }
973 }
974
975 void
976 assign_uniform_locations(struct gl_shader_program *prog)
977 {
978 /* */
979 exec_list uniforms;
980 unsigned total_uniforms = 0;
981 hash_table *ht = hash_table_ctor(32, hash_table_string_hash,
982 hash_table_string_compare);
983 void *mem_ctx = talloc_new(NULL);
984
985 for (unsigned i = 0; i < prog->_NumLinkedShaders; i++) {
986 unsigned next_position = 0;
987
988 foreach_list(node, prog->_LinkedShaders[i]->ir) {
989 ir_variable *const var = ((ir_instruction *) node)->as_variable();
990
991 if ((var == NULL) || (var->mode != ir_var_uniform))
992 continue;
993
994 if (strncmp(var->name, "gl_", 3) == 0) {
995 /* At the moment, we don't allocate uniform locations for
996 * builtin uniforms. It's permitted by spec, and we'll
997 * likely switch to doing that at some point, but not yet.
998 */
999 continue;
1000 }
1001
1002 var->location = next_position;
1003 add_uniform(mem_ctx, &uniforms, ht, var->name, var->type,
1004 prog->_LinkedShaders[i]->Type,
1005 &next_position, &total_uniforms);
1006 }
1007 }
1008
1009 talloc_free(mem_ctx);
1010
1011 gl_uniform_list *ul = (gl_uniform_list *)
1012 calloc(1, sizeof(gl_uniform_list));
1013
1014 ul->Size = total_uniforms;
1015 ul->NumUniforms = total_uniforms;
1016 ul->Uniforms = (gl_uniform *) calloc(total_uniforms, sizeof(gl_uniform));
1017
1018 unsigned idx = 0;
1019 uniform_node *next;
1020 for (uniform_node *node = (uniform_node *) uniforms.head
1021 ; node->link.next != NULL
1022 ; node = next) {
1023 next = (uniform_node *) node->link.next;
1024
1025 node->link.remove();
1026 memcpy(&ul->Uniforms[idx], node->u, sizeof(gl_uniform));
1027 idx++;
1028
1029 free(node->u);
1030 free(node);
1031 }
1032
1033 hash_table_dtor(ht);
1034
1035 prog->Uniforms = ul;
1036 }
1037
1038
1039 /**
1040 * Find a contiguous set of available bits in a bitmask
1041 *
1042 * \param used_mask Bits representing used (1) and unused (0) locations
1043 * \param needed_count Number of contiguous bits needed.
1044 *
1045 * \return
1046 * Base location of the available bits on success or -1 on failure.
1047 */
1048 int
1049 find_available_slots(unsigned used_mask, unsigned needed_count)
1050 {
1051 unsigned needed_mask = (1 << needed_count) - 1;
1052 const int max_bit_to_test = (8 * sizeof(used_mask)) - needed_count;
1053
1054 /* The comparison to 32 is redundant, but without it GCC emits "warning:
1055 * cannot optimize possibly infinite loops" for the loop below.
1056 */
1057 if ((needed_count == 0) || (max_bit_to_test < 0) || (max_bit_to_test > 32))
1058 return -1;
1059
1060 for (int i = 0; i <= max_bit_to_test; i++) {
1061 if ((needed_mask & ~used_mask) == needed_mask)
1062 return i;
1063
1064 needed_mask <<= 1;
1065 }
1066
1067 return -1;
1068 }
1069
1070
1071 bool
1072 assign_attribute_locations(gl_shader_program *prog, unsigned max_attribute_index)
1073 {
1074 /* Mark invalid attribute locations as being used.
1075 */
1076 unsigned used_locations = (max_attribute_index >= 32)
1077 ? ~0 : ~((1 << max_attribute_index) - 1);
1078
1079 gl_shader *const sh = prog->_LinkedShaders[0];
1080 assert(sh->Type == GL_VERTEX_SHADER);
1081
1082 /* Operate in a total of four passes.
1083 *
1084 * 1. Invalidate the location assignments for all vertex shader inputs.
1085 *
1086 * 2. Assign locations for inputs that have user-defined (via
1087 * glBindVertexAttribLocation) locatoins.
1088 *
1089 * 3. Sort the attributes without assigned locations by number of slots
1090 * required in decreasing order. Fragmentation caused by attribute
1091 * locations assigned by the application may prevent large attributes
1092 * from having enough contiguous space.
1093 *
1094 * 4. Assign locations to any inputs without assigned locations.
1095 */
1096
1097 invalidate_variable_locations(sh, ir_var_in, VERT_ATTRIB_GENERIC0);
1098
1099 if (prog->Attributes != NULL) {
1100 for (unsigned i = 0; i < prog->Attributes->NumParameters; i++) {
1101 ir_variable *const var =
1102 sh->symbols->get_variable(prog->Attributes->Parameters[i].Name);
1103
1104 /* Note: attributes that occupy multiple slots, such as arrays or
1105 * matrices, may appear in the attrib array multiple times.
1106 */
1107 if ((var == NULL) || (var->location != -1))
1108 continue;
1109
1110 /* From page 61 of the OpenGL 4.0 spec:
1111 *
1112 * "LinkProgram will fail if the attribute bindings assigned by
1113 * BindAttribLocation do not leave not enough space to assign a
1114 * location for an active matrix attribute or an active attribute
1115 * array, both of which require multiple contiguous generic
1116 * attributes."
1117 *
1118 * Previous versions of the spec contain similar language but omit the
1119 * bit about attribute arrays.
1120 *
1121 * Page 61 of the OpenGL 4.0 spec also says:
1122 *
1123 * "It is possible for an application to bind more than one
1124 * attribute name to the same location. This is referred to as
1125 * aliasing. This will only work if only one of the aliased
1126 * attributes is active in the executable program, or if no path
1127 * through the shader consumes more than one attribute of a set
1128 * of attributes aliased to the same location. A link error can
1129 * occur if the linker determines that every path through the
1130 * shader consumes multiple aliased attributes, but
1131 * implementations are not required to generate an error in this
1132 * case."
1133 *
1134 * These two paragraphs are either somewhat contradictory, or I don't
1135 * fully understand one or both of them.
1136 */
1137 /* FINISHME: The code as currently written does not support attribute
1138 * FINISHME: location aliasing (see comment above).
1139 */
1140 const int attr = prog->Attributes->Parameters[i].StateIndexes[0];
1141 const unsigned slots = count_attribute_slots(var->type);
1142
1143 /* Mask representing the contiguous slots that will be used by this
1144 * attribute.
1145 */
1146 const unsigned use_mask = (1 << slots) - 1;
1147
1148 /* Generate a link error if the set of bits requested for this
1149 * attribute overlaps any previously allocated bits.
1150 */
1151 if ((~(use_mask << attr) & used_locations) != used_locations) {
1152 linker_error_printf(prog,
1153 "insufficient contiguous attribute locations "
1154 "available for vertex shader input `%s'",
1155 var->name);
1156 return false;
1157 }
1158
1159 var->location = VERT_ATTRIB_GENERIC0 + attr;
1160 used_locations |= (use_mask << attr);
1161 }
1162 }
1163
1164 /* Temporary storage for the set of attributes that need locations assigned.
1165 */
1166 struct temp_attr {
1167 unsigned slots;
1168 ir_variable *var;
1169
1170 /* Used below in the call to qsort. */
1171 static int compare(const void *a, const void *b)
1172 {
1173 const temp_attr *const l = (const temp_attr *) a;
1174 const temp_attr *const r = (const temp_attr *) b;
1175
1176 /* Reversed because we want a descending order sort below. */
1177 return r->slots - l->slots;
1178 }
1179 } to_assign[16];
1180
1181 unsigned num_attr = 0;
1182
1183 foreach_list(node, sh->ir) {
1184 ir_variable *const var = ((ir_instruction *) node)->as_variable();
1185
1186 if ((var == NULL) || (var->mode != ir_var_in))
1187 continue;
1188
1189 /* The location was explicitly assigned, nothing to do here.
1190 */
1191 if (var->location != -1)
1192 continue;
1193
1194 to_assign[num_attr].slots = count_attribute_slots(var->type);
1195 to_assign[num_attr].var = var;
1196 num_attr++;
1197 }
1198
1199 /* If all of the attributes were assigned locations by the application (or
1200 * are built-in attributes with fixed locations), return early. This should
1201 * be the common case.
1202 */
1203 if (num_attr == 0)
1204 return true;
1205
1206 qsort(to_assign, num_attr, sizeof(to_assign[0]), temp_attr::compare);
1207
1208 /* VERT_ATTRIB_GENERIC0 is a psdueo-alias for VERT_ATTRIB_POS. It can only
1209 * be explicitly assigned by via glBindAttribLocation. Mark it as reserved
1210 * to prevent it from being automatically allocated below.
1211 */
1212 find_deref_visitor find("gl_Vertex");
1213 find.run(sh->ir);
1214 if (find.variable_found())
1215 used_locations |= (1 << 0);
1216
1217 for (unsigned i = 0; i < num_attr; i++) {
1218 /* Mask representing the contiguous slots that will be used by this
1219 * attribute.
1220 */
1221 const unsigned use_mask = (1 << to_assign[i].slots) - 1;
1222
1223 int location = find_available_slots(used_locations, to_assign[i].slots);
1224
1225 if (location < 0) {
1226 linker_error_printf(prog,
1227 "insufficient contiguous attribute locations "
1228 "available for vertex shader input `%s'",
1229 to_assign[i].var->name);
1230 return false;
1231 }
1232
1233 to_assign[i].var->location = VERT_ATTRIB_GENERIC0 + location;
1234 used_locations |= (use_mask << location);
1235 }
1236
1237 return true;
1238 }
1239
1240
1241 /**
1242 * Demote shader outputs that are not read to being just plain global variables
1243 */
1244 void
1245 demote_unread_shader_outputs(gl_shader *sh)
1246 {
1247 foreach_list(node, sh->ir) {
1248 ir_variable *const var = ((ir_instruction *) node)->as_variable();
1249
1250 if ((var == NULL) || (var->mode != ir_var_out))
1251 continue;
1252
1253 /* An 'out' variable is only really a shader output if its value is read
1254 * by the following stage.
1255 */
1256 if (var->location == -1) {
1257 var->mode = ir_var_auto;
1258 }
1259 }
1260 }
1261
1262
1263 void
1264 assign_varying_locations(struct gl_shader_program *prog,
1265 gl_shader *producer, gl_shader *consumer)
1266 {
1267 /* FINISHME: Set dynamically when geometry shader support is added. */
1268 unsigned output_index = VERT_RESULT_VAR0;
1269 unsigned input_index = FRAG_ATTRIB_VAR0;
1270
1271 /* Operate in a total of three passes.
1272 *
1273 * 1. Assign locations for any matching inputs and outputs.
1274 *
1275 * 2. Mark output variables in the producer that do not have locations as
1276 * not being outputs. This lets the optimizer eliminate them.
1277 *
1278 * 3. Mark input variables in the consumer that do not have locations as
1279 * not being inputs. This lets the optimizer eliminate them.
1280 */
1281
1282 invalidate_variable_locations(producer, ir_var_out, VERT_RESULT_VAR0);
1283 invalidate_variable_locations(consumer, ir_var_in, FRAG_ATTRIB_VAR0);
1284
1285 foreach_list(node, producer->ir) {
1286 ir_variable *const output_var = ((ir_instruction *) node)->as_variable();
1287
1288 if ((output_var == NULL) || (output_var->mode != ir_var_out)
1289 || (output_var->location != -1))
1290 continue;
1291
1292 ir_variable *const input_var =
1293 consumer->symbols->get_variable(output_var->name);
1294
1295 if ((input_var == NULL) || (input_var->mode != ir_var_in))
1296 continue;
1297
1298 assert(input_var->location == -1);
1299
1300 output_var->location = output_index;
1301 input_var->location = input_index;
1302
1303 /* FINISHME: Support for "varying" records in GLSL 1.50. */
1304 assert(!output_var->type->is_record());
1305
1306 if (output_var->type->is_array()) {
1307 const unsigned slots = output_var->type->length
1308 * output_var->type->fields.array->matrix_columns;
1309
1310 output_index += slots;
1311 input_index += slots;
1312 } else {
1313 const unsigned slots = output_var->type->matrix_columns;
1314
1315 output_index += slots;
1316 input_index += slots;
1317 }
1318 }
1319
1320 demote_unread_shader_outputs(producer);
1321
1322 foreach_list(node, consumer->ir) {
1323 ir_variable *const var = ((ir_instruction *) node)->as_variable();
1324
1325 if ((var == NULL) || (var->mode != ir_var_in))
1326 continue;
1327
1328 if (var->location == -1) {
1329 if (prog->Version <= 120) {
1330 /* On page 25 (page 31 of the PDF) of the GLSL 1.20 spec:
1331 *
1332 * Only those varying variables used (i.e. read) in
1333 * the fragment shader executable must be written to
1334 * by the vertex shader executable; declaring
1335 * superfluous varying variables in a vertex shader is
1336 * permissible.
1337 *
1338 * We interpret this text as meaning that the VS must
1339 * write the variable for the FS to read it. See
1340 * "glsl1-varying read but not written" in piglit.
1341 */
1342
1343 linker_error_printf(prog, "fragment shader varying %s not written "
1344 "by vertex shader\n.", var->name);
1345 prog->LinkStatus = false;
1346 }
1347
1348 /* An 'in' variable is only really a shader input if its
1349 * value is written by the previous stage.
1350 */
1351 var->mode = ir_var_auto;
1352 }
1353 }
1354 }
1355
1356
1357 void
1358 link_shaders(GLcontext *ctx, struct gl_shader_program *prog)
1359 {
1360 prog->LinkStatus = false;
1361 prog->Validated = false;
1362 prog->_Used = false;
1363
1364 if (prog->InfoLog != NULL)
1365 talloc_free(prog->InfoLog);
1366
1367 prog->InfoLog = talloc_strdup(NULL, "");
1368
1369 /* Separate the shaders into groups based on their type.
1370 */
1371 struct gl_shader **vert_shader_list;
1372 unsigned num_vert_shaders = 0;
1373 struct gl_shader **frag_shader_list;
1374 unsigned num_frag_shaders = 0;
1375
1376 vert_shader_list = (struct gl_shader **)
1377 calloc(2 * prog->NumShaders, sizeof(struct gl_shader *));
1378 frag_shader_list = &vert_shader_list[prog->NumShaders];
1379
1380 unsigned min_version = UINT_MAX;
1381 unsigned max_version = 0;
1382 for (unsigned i = 0; i < prog->NumShaders; i++) {
1383 min_version = MIN2(min_version, prog->Shaders[i]->Version);
1384 max_version = MAX2(max_version, prog->Shaders[i]->Version);
1385
1386 switch (prog->Shaders[i]->Type) {
1387 case GL_VERTEX_SHADER:
1388 vert_shader_list[num_vert_shaders] = prog->Shaders[i];
1389 num_vert_shaders++;
1390 break;
1391 case GL_FRAGMENT_SHADER:
1392 frag_shader_list[num_frag_shaders] = prog->Shaders[i];
1393 num_frag_shaders++;
1394 break;
1395 case GL_GEOMETRY_SHADER:
1396 /* FINISHME: Support geometry shaders. */
1397 assert(prog->Shaders[i]->Type != GL_GEOMETRY_SHADER);
1398 break;
1399 }
1400 }
1401
1402 /* Previous to GLSL version 1.30, different compilation units could mix and
1403 * match shading language versions. With GLSL 1.30 and later, the versions
1404 * of all shaders must match.
1405 */
1406 assert(min_version >= 100);
1407 assert(max_version <= 130);
1408 if ((max_version >= 130 || min_version == 100)
1409 && min_version != max_version) {
1410 linker_error_printf(prog, "all shaders must use same shading "
1411 "language version\n");
1412 goto done;
1413 }
1414
1415 prog->Version = max_version;
1416
1417 for (unsigned int i = 0; i < prog->_NumLinkedShaders; i++) {
1418 ctx->Driver.DeleteShader(ctx, prog->_LinkedShaders[i]);
1419 }
1420
1421 /* Link all shaders for a particular stage and validate the result.
1422 */
1423 prog->_NumLinkedShaders = 0;
1424 if (num_vert_shaders > 0) {
1425 gl_shader *const sh =
1426 link_intrastage_shaders(ctx, prog, vert_shader_list, num_vert_shaders);
1427
1428 if (sh == NULL)
1429 goto done;
1430
1431 if (!validate_vertex_shader_executable(prog, sh))
1432 goto done;
1433
1434 prog->_LinkedShaders[prog->_NumLinkedShaders] = sh;
1435 prog->_NumLinkedShaders++;
1436 }
1437
1438 if (num_frag_shaders > 0) {
1439 gl_shader *const sh =
1440 link_intrastage_shaders(ctx, prog, frag_shader_list, num_frag_shaders);
1441
1442 if (sh == NULL)
1443 goto done;
1444
1445 if (!validate_fragment_shader_executable(prog, sh))
1446 goto done;
1447
1448 prog->_LinkedShaders[prog->_NumLinkedShaders] = sh;
1449 prog->_NumLinkedShaders++;
1450 }
1451
1452 /* Here begins the inter-stage linking phase. Some initial validation is
1453 * performed, then locations are assigned for uniforms, attributes, and
1454 * varyings.
1455 */
1456 if (cross_validate_uniforms(prog)) {
1457 /* Validate the inputs of each stage with the output of the preceeding
1458 * stage.
1459 */
1460 for (unsigned i = 1; i < prog->_NumLinkedShaders; i++) {
1461 if (!cross_validate_outputs_to_inputs(prog,
1462 prog->_LinkedShaders[i - 1],
1463 prog->_LinkedShaders[i]))
1464 goto done;
1465 }
1466
1467 prog->LinkStatus = true;
1468 }
1469
1470 /* Do common optimization before assigning storage for attributes,
1471 * uniforms, and varyings. Later optimization could possibly make
1472 * some of that unused.
1473 */
1474 for (unsigned i = 0; i < prog->_NumLinkedShaders; i++) {
1475 while (do_common_optimization(prog->_LinkedShaders[i]->ir, true, 32))
1476 ;
1477 }
1478
1479 update_array_sizes(prog);
1480
1481 assign_uniform_locations(prog);
1482
1483 if (prog->_NumLinkedShaders && prog->_LinkedShaders[0]->Type == GL_VERTEX_SHADER) {
1484 /* FINISHME: The value of the max_attribute_index parameter is
1485 * FINISHME: implementation dependent based on the value of
1486 * FINISHME: GL_MAX_VERTEX_ATTRIBS. GL_MAX_VERTEX_ATTRIBS must be
1487 * FINISHME: at least 16, so hardcode 16 for now.
1488 */
1489 if (!assign_attribute_locations(prog, 16)) {
1490 prog->LinkStatus = false;
1491 goto done;
1492 }
1493
1494 if (prog->_NumLinkedShaders == 1)
1495 demote_unread_shader_outputs(prog->_LinkedShaders[0]);
1496 }
1497
1498 for (unsigned i = 1; i < prog->_NumLinkedShaders; i++)
1499 assign_varying_locations(prog,
1500 prog->_LinkedShaders[i - 1],
1501 prog->_LinkedShaders[i]);
1502
1503 /* FINISHME: Assign fragment shader output locations. */
1504
1505 done:
1506 free(vert_shader_list);
1507 }