svn merge ^/branches/released .

1 files changed, 1713 insertions, 1713 deletions

diff --git a/mesalib/src/glsl/linker.cpp b/mesalib/src/glsl/linker.cpp
index 46cd1950c..a9a2a5e20 100644
--- a/mesalib/src/glsl/linker.cpp
+++ b/mesalib/src/glsl/linker.cpp
@@ -1,1713 +1,1713 @@
-/*
- * Copyright © 2010 Intel Corporation
- *
- * Permission is hereby granted, free of charge, to any person obtaining a
- * copy of this software and associated documentation files (the "Software"),
- * to deal in the Software without restriction, including without limitation
- * the rights to use, copy, modify, merge, publish, distribute, sublicense,
- * and/or sell copies of the Software, and to permit persons to whom the
- * Software is furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice (including the next
- * paragraph) shall be included in all copies or substantial portions of the
- * Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
- * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
- * DEALINGS IN THE SOFTWARE.
- */
-
-/**
- * \file linker.cpp
- * GLSL linker implementation
- *
- * Given a set of shaders that are to be linked to generate a final program,
- * there are three distinct stages.
- *
- * In the first stage shaders are partitioned into groups based on the shader
- * type.  All shaders of a particular type (e.g., vertex shaders) are linked
- * together.
- *
- *   - Undefined references in each shader are resolve to definitions in
- *     another shader.
- *   - Types and qualifiers of uniforms, outputs, and global variables defined
- *     in multiple shaders with the same name are verified to be the same.
- *   - Initializers for uniforms and global variables defined
- *     in multiple shaders with the same name are verified to be the same.
- *
- * The result, in the terminology of the GLSL spec, is a set of shader
- * executables for each processing unit.
- *
- * After the first stage is complete, a series of semantic checks are performed
- * on each of the shader executables.
- *
- *   - Each shader executable must define a \c main function.
- *   - Each vertex shader executable must write to \c gl_Position.
- *   - Each fragment shader executable must write to either \c gl_FragData or
- *     \c gl_FragColor.
- *
- * In the final stage individual shader executables are linked to create a
- * complete exectuable.
- *
- *   - Types of uniforms defined in multiple shader stages with the same name
- *     are verified to be the same.
- *   - Initializers for uniforms defined in multiple shader stages with the
- *     same name are verified to be the same.
- *   - Types and qualifiers of outputs defined in one stage are verified to
- *     be the same as the types and qualifiers of inputs defined with the same
- *     name in a later stage.
- *
- * \author Ian Romanick <ian.d.romanick@intel.com>
- */
-#include <cstdlib>
-#include <cstdio>
-#include <cstdarg>
-#include <climits>
-
-#include "main/core.h"
-#include "glsl_symbol_table.h"
-#include "ir.h"
-#include "program.h"
-#include "program/hash_table.h"
-#include "linker.h"
-#include "ir_optimization.h"
-
-extern "C" {
-#include "main/shaderobj.h"
-}
-
-/**
- * Visitor that determines whether or not a variable is ever written.
- */
-class find_assignment_visitor : public ir_hierarchical_visitor {
-public:
-   find_assignment_visitor(const char *name)
-      : name(name), found(false)
-   {
-      /* empty */
-   }
-
-   virtual ir_visitor_status visit_enter(ir_assignment *ir)
-   {
-      ir_variable *const var = ir->lhs->variable_referenced();
-
-      if (strcmp(name, var->name) == 0) {
-	 found = true;
-	 return visit_stop;
-      }
-
-      return visit_continue_with_parent;
-   }
-
-   virtual ir_visitor_status visit_enter(ir_call *ir)
-   {
-      exec_list_iterator sig_iter = ir->get_callee()->parameters.iterator();
-      foreach_iter(exec_list_iterator, iter, *ir) {
-	 ir_rvalue *param_rval = (ir_rvalue *)iter.get();
-	 ir_variable *sig_param = (ir_variable *)sig_iter.get();
-
-	 if (sig_param->mode == ir_var_out ||
-	     sig_param->mode == ir_var_inout) {
-	    ir_variable *var = param_rval->variable_referenced();
-	    if (var && strcmp(name, var->name) == 0) {
-	       found = true;
-	       return visit_stop;
-	    }
-	 }
-	 sig_iter.next();
-      }
-
-      return visit_continue_with_parent;
-   }
-
-   bool variable_found()
-   {
-      return found;
-   }
-
-private:
-   const char *name;       /**< Find writes to a variable with this name. */
-   bool found;             /**< Was a write to the variable found? */
-};
-
-
-/**
- * Visitor that determines whether or not a variable is ever read.
- */
-class find_deref_visitor : public ir_hierarchical_visitor {
-public:
-   find_deref_visitor(const char *name)
-      : name(name), found(false)
-   {
-      /* empty */
-   }
-
-   virtual ir_visitor_status visit(ir_dereference_variable *ir)
-   {
-      if (strcmp(this->name, ir->var->name) == 0) {
-	 this->found = true;
-	 return visit_stop;
-      }
-
-      return visit_continue;
-   }
-
-   bool variable_found() const
-   {
-      return this->found;
-   }
-
-private:
-   const char *name;       /**< Find writes to a variable with this name. */
-   bool found;             /**< Was a write to the variable found? */
-};
-
-
-void
-linker_error_printf(gl_shader_program *prog, const char *fmt, ...)
-{
-   va_list ap;
-
-   ralloc_strcat(&prog->InfoLog, "error: ");
-   va_start(ap, fmt);
-   ralloc_vasprintf_append(&prog->InfoLog, fmt, ap);
-   va_end(ap);
-}
-
-
-void
-invalidate_variable_locations(gl_shader *sh, enum ir_variable_mode mode,
-			      int generic_base)
-{
-   foreach_list(node, sh->ir) {
-      ir_variable *const var = ((ir_instruction *) node)->as_variable();
-
-      if ((var == NULL) || (var->mode != (unsigned) mode))
-	 continue;
-
-      /* Only assign locations for generic attributes / varyings / etc.
-       */
-      if ((var->location >= generic_base) && !var->explicit_location)
-	  var->location = -1;
-   }
-}
-
-
-/**
- * Determine the number of attribute slots required for a particular type
- *
- * This code is here because it implements the language rules of a specific
- * GLSL version.  Since it's a property of the language and not a property of
- * types in general, it doesn't really belong in glsl_type.
- */
-unsigned
-count_attribute_slots(const glsl_type *t)
-{
-   /* From page 31 (page 37 of the PDF) of the GLSL 1.50 spec:
-    *
-    *     "A scalar input counts the same amount against this limit as a vec4,
-    *     so applications may want to consider packing groups of four
-    *     unrelated float inputs together into a vector to better utilize the
-    *     capabilities of the underlying hardware. A matrix input will use up
-    *     multiple locations.  The number of locations used will equal the
-    *     number of columns in the matrix."
-    *
-    * The spec does not explicitly say how arrays are counted.  However, it
-    * should be safe to assume the total number of slots consumed by an array
-    * is the number of entries in the array multiplied by the number of slots
-    * consumed by a single element of the array.
-    */
-
-   if (t->is_array())
-      return t->array_size() * count_attribute_slots(t->element_type());
-
-   if (t->is_matrix())
-      return t->matrix_columns;
-
-   return 1;
-}
-
-
-/**
- * Verify that a vertex shader executable meets all semantic requirements
- *
- * \param shader  Vertex shader executable to be verified
- */
-bool
-validate_vertex_shader_executable(struct gl_shader_program *prog,
-				  struct gl_shader *shader)
-{
-   if (shader == NULL)
-      return true;
-
-   find_assignment_visitor find("gl_Position");
-   find.run(shader->ir);
-   if (!find.variable_found()) {
-      linker_error_printf(prog,
-			  "vertex shader does not write to `gl_Position'\n");
-      return false;
-   }
-
-   return true;
-}
-
-
-/**
- * Verify that a fragment shader executable meets all semantic requirements
- *
- * \param shader  Fragment shader executable to be verified
- */
-bool
-validate_fragment_shader_executable(struct gl_shader_program *prog,
-				    struct gl_shader *shader)
-{
-   if (shader == NULL)
-      return true;
-
-   find_assignment_visitor frag_color("gl_FragColor");
-   find_assignment_visitor frag_data("gl_FragData");
-
-   frag_color.run(shader->ir);
-   frag_data.run(shader->ir);
-
-   if (frag_color.variable_found() && frag_data.variable_found()) {
-      linker_error_printf(prog,  "fragment shader writes to both "
-			  "`gl_FragColor' and `gl_FragData'\n");
-      return false;
-   }
-
-   return true;
-}
-
-
-/**
- * Generate a string describing the mode of a variable
- */
-static const char *
-mode_string(const ir_variable *var)
-{
-   switch (var->mode) {
-   case ir_var_auto:
-      return (var->read_only) ? "global constant" : "global variable";
-
-   case ir_var_uniform: return "uniform";
-   case ir_var_in:      return "shader input";
-   case ir_var_out:     return "shader output";
-   case ir_var_inout:   return "shader inout";
-
-   case ir_var_const_in:
-   case ir_var_temporary:
-   default:
-      assert(!"Should not get here.");
-      return "invalid variable";
-   }
-}
-
-
-/**
- * Perform validation of global variables used across multiple shaders
- */
-bool
-cross_validate_globals(struct gl_shader_program *prog,
-		       struct gl_shader **shader_list,
-		       unsigned num_shaders,
-		       bool uniforms_only)
-{
-   /* Examine all of the uniforms in all of the shaders and cross validate
-    * them.
-    */
-   glsl_symbol_table variables;
-   for (unsigned i = 0; i < num_shaders; i++) {
-      if (shader_list[i] == NULL)
-	 continue;
-
-      foreach_list(node, shader_list[i]->ir) {
-	 ir_variable *const var = ((ir_instruction *) node)->as_variable();
-
-	 if (var == NULL)
-	    continue;
-
-	 if (uniforms_only && (var->mode != ir_var_uniform))
-	    continue;
-
-	 /* Don't cross validate temporaries that are at global scope.  These
-	  * will eventually get pulled into the shaders 'main'.
-	  */
-	 if (var->mode == ir_var_temporary)
-	    continue;
-
-	 /* If a global with this name has already been seen, verify that the
-	  * new instance has the same type.  In addition, if the globals have
-	  * initializers, the values of the initializers must be the same.
-	  */
-	 ir_variable *const existing = variables.get_variable(var->name);
-	 if (existing != NULL) {
-	    if (var->type != existing->type) {
-	       /* Consider the types to be "the same" if both types are arrays
-		* of the same type and one of the arrays is implicitly sized.
-		* In addition, set the type of the linked variable to the
-		* explicitly sized array.
-		*/
-	       if (var->type->is_array()
-		   && existing->type->is_array()
-		   && (var->type->fields.array == existing->type->fields.array)
-		   && ((var->type->length == 0)
-		       || (existing->type->length == 0))) {
-		  if (var->type->length != 0) {
-		     existing->type = var->type;
-		  }
-	       } else {
-		  linker_error_printf(prog, "%s `%s' declared as type "
-				      "`%s' and type `%s'\n",
-				      mode_string(var),
-				      var->name, var->type->name,
-				      existing->type->name);
-		  return false;
-	       }
-	    }
-
-	    if (var->explicit_location) {
-	       if (existing->explicit_location
-		   && (var->location != existing->location)) {
-		     linker_error_printf(prog, "explicit locations for %s "
-					 "`%s' have differing values\n",
-					 mode_string(var), var->name);
-		     return false;
-	       }
-
-	       existing->location = var->location;
-	       existing->explicit_location = true;
-	    }
-
-        /* Validate layout qualifiers for gl_FragDepth.
-         *
-         * From the AMD_conservative_depth spec:
-         *    "If gl_FragDepth is redeclared in any fragment shader in
-         *    a program, it must be redeclared in all fragment shaders in that
-         *    program that have static assignments to gl_FragDepth. All
-         *    redeclarations of gl_FragDepth in all fragment shaders in
-         *    a single program must have the same set of qualifiers."
-         */
-        if (strcmp(var->name, "gl_FragDepth") == 0) {
-           bool layout_declared = var->depth_layout != ir_depth_layout_none;
-           bool layout_differs = var->depth_layout != existing->depth_layout;
-           if (layout_declared && layout_differs) {
-              linker_error_printf(prog,
-                 "All redeclarations of gl_FragDepth in all fragment shaders "
-                 "in a single program must have the same set of qualifiers.");
-           }
-           if (var->used && layout_differs) {
-              linker_error_printf(prog,
-                    "If gl_FragDepth is redeclared with a layout qualifier in"
-                    "any fragment shader, it must be redeclared with the same"
-                    "layout qualifier in all fragment shaders that have"
-                    "assignments to gl_FragDepth");
-           }
-        }
-
-	    /* FINISHME: Handle non-constant initializers.
-	     */
-	    if (var->constant_value != NULL) {
-	       if (existing->constant_value != NULL) {
-		  if (!var->constant_value->has_value(existing->constant_value)) {
-		     linker_error_printf(prog, "initializers for %s "
-					 "`%s' have differing values\n",
-					 mode_string(var), var->name);
-		     return false;
-		  }
-	       } else
-		  /* If the first-seen instance of a particular uniform did not
-		   * have an initializer but a later instance does, copy the
-		   * initializer to the version stored in the symbol table.
-		   */
-		  /* FINISHME: This is wrong.  The constant_value field should
-		   * FINISHME: not be modified!  Imagine a case where a shader
-		   * FINISHME: without an initializer is linked in two different
-		   * FINISHME: programs with shaders that have differing
-		   * FINISHME: initializers.  Linking with the first will
-		   * FINISHME: modify the shader, and linking with the second
-		   * FINISHME: will fail.
-		   */
-		  existing->constant_value =
-		     var->constant_value->clone(ralloc_parent(existing), NULL);
-	    }
-
-	    if (existing->invariant != var->invariant) {
-	       linker_error_printf(prog, "declarations for %s `%s' have "
-	                           "mismatching invariant qualifiers\n",
-	                           mode_string(var), var->name);
-	       return false;
-	    }
-            if (existing->centroid != var->centroid) {
-               linker_error_printf(prog, "declarations for %s `%s' have "
-                                   "mismatching centroid qualifiers\n",
-                                   mode_string(var), var->name);
-               return false;
-            }
-	 } else
-	    variables.add_variable(var);
-      }
-   }
-
-   return true;
-}
-
-
-/**
- * Perform validation of uniforms used across multiple shader stages
- */
-bool
-cross_validate_uniforms(struct gl_shader_program *prog)
-{
-   return cross_validate_globals(prog, prog->_LinkedShaders,
-				 MESA_SHADER_TYPES, true);
-}
-
-
-/**
- * Validate that outputs from one stage match inputs of another
- */
-bool
-cross_validate_outputs_to_inputs(struct gl_shader_program *prog,
-				 gl_shader *producer, gl_shader *consumer)
-{
-   glsl_symbol_table parameters;
-   /* FINISHME: Figure these out dynamically. */
-   const char *const producer_stage = "vertex";
-   const char *const consumer_stage = "fragment";
-
-   /* Find all shader outputs in the "producer" stage.
-    */
-   foreach_list(node, producer->ir) {
-      ir_variable *const var = ((ir_instruction *) node)->as_variable();
-
-      /* FINISHME: For geometry shaders, this should also look for inout
-       * FINISHME: variables.
-       */
-      if ((var == NULL) || (var->mode != ir_var_out))
-	 continue;
-
-      parameters.add_variable(var);
-   }
-
-
-   /* Find all shader inputs in the "consumer" stage.  Any variables that have
-    * matching outputs already in the symbol table must have the same type and
-    * qualifiers.
-    */
-   foreach_list(node, consumer->ir) {
-      ir_variable *const input = ((ir_instruction *) node)->as_variable();
-
-      /* FINISHME: For geometry shaders, this should also look for inout
-       * FINISHME: variables.
-       */
-      if ((input == NULL) || (input->mode != ir_var_in))
-	 continue;
-
-      ir_variable *const output = parameters.get_variable(input->name);
-      if (output != NULL) {
-	 /* Check that the types match between stages.
-	  */
-	 if (input->type != output->type) {
-	    /* There is a bit of a special case for gl_TexCoord.  This
-	     * built-in is unsized by default.  Appliations that variable
-	     * access it must redeclare it with a size.  There is some
-	     * language in the GLSL spec that implies the fragment shader
-	     * and vertex shader do not have to agree on this size.  Other
-	     * driver behave this way, and one or two applications seem to
-	     * rely on it.
-	     *
-	     * Neither declaration needs to be modified here because the array
-	     * sizes are fixed later when update_array_sizes is called.
-	     *
-	     * From page 48 (page 54 of the PDF) of the GLSL 1.10 spec:
-	     *
-	     *     "Unlike user-defined varying variables, the built-in
-	     *     varying variables don't have a strict one-to-one
-	     *     correspondence between the vertex language and the
-	     *     fragment language."
-	     */
-	    if (!output->type->is_array()
-		|| (strncmp("gl_", output->name, 3) != 0)) {
-	       linker_error_printf(prog,
-				   "%s shader output `%s' declared as "
-				   "type `%s', but %s shader input declared "
-				   "as type `%s'\n",
-				   producer_stage, output->name,
-				   output->type->name,
-				   consumer_stage, input->type->name);
-	       return false;
-	    }
-	 }
-
-	 /* Check that all of the qualifiers match between stages.
-	  */
-	 if (input->centroid != output->centroid) {
-	    linker_error_printf(prog,
-				"%s shader output `%s' %s centroid qualifier, "
-				"but %s shader input %s centroid qualifier\n",
-				producer_stage,
-				output->name,
-				(output->centroid) ? "has" : "lacks",
-				consumer_stage,
-				(input->centroid) ? "has" : "lacks");
-	    return false;
-	 }
-
-	 if (input->invariant != output->invariant) {
-	    linker_error_printf(prog,
-				"%s shader output `%s' %s invariant qualifier, "
-				"but %s shader input %s invariant qualifier\n",
-				producer_stage,
-				output->name,
-				(output->invariant) ? "has" : "lacks",
-				consumer_stage,
-				(input->invariant) ? "has" : "lacks");
-	    return false;
-	 }
-
-	 if (input->interpolation != output->interpolation) {
-	    linker_error_printf(prog,
-				"%s shader output `%s' specifies %s "
-				"interpolation qualifier, "
-				"but %s shader input specifies %s "
-				"interpolation qualifier\n",
-				producer_stage,
-				output->name,
-				output->interpolation_string(),
-				consumer_stage,
-				input->interpolation_string());
-	    return false;
-	 }
-      }
-   }
-
-   return true;
-}
-
-
-/**
- * Populates a shaders symbol table with all global declarations
- */
-static void
-populate_symbol_table(gl_shader *sh)
-{
-   sh->symbols = new(sh) glsl_symbol_table;
-
-   foreach_list(node, sh->ir) {
-      ir_instruction *const inst = (ir_instruction *) node;
-      ir_variable *var;
-      ir_function *func;
-
-      if ((func = inst->as_function()) != NULL) {
-	 sh->symbols->add_function(func);
-      } else if ((var = inst->as_variable()) != NULL) {
-	 sh->symbols->add_variable(var);
-      }
-   }
-}
-
-
-/**
- * Remap variables referenced in an instruction tree
- *
- * This is used when instruction trees are cloned from one shader and placed in
- * another.  These trees will contain references to \c ir_variable nodes that
- * do not exist in the target shader.  This function finds these \c ir_variable
- * references and replaces the references with matching variables in the target
- * shader.
- *
- * If there is no matching variable in the target shader, a clone of the
- * \c ir_variable is made and added to the target shader.  The new variable is
- * added to \b both the instruction stream and the symbol table.
- *
- * \param inst         IR tree that is to be processed.
- * \param symbols      Symbol table containing global scope symbols in the
- *                     linked shader.
- * \param instructions Instruction stream where new variable declarations
- *                     should be added.
- */
-void
-remap_variables(ir_instruction *inst, struct gl_shader *target,
-		hash_table *temps)
-{
-   class remap_visitor : public ir_hierarchical_visitor {
-   public:
-	 remap_visitor(struct gl_shader *target,
-		    hash_table *temps)
-      {
-	 this->target = target;
-	 this->symbols = target->symbols;
-	 this->instructions = target->ir;
-	 this->temps = temps;
-      }
-
-      virtual ir_visitor_status visit(ir_dereference_variable *ir)
-      {
-	 if (ir->var->mode == ir_var_temporary) {
-	    ir_variable *var = (ir_variable *) hash_table_find(temps, ir->var);
-
-	    assert(var != NULL);
-	    ir->var = var;
-	    return visit_continue;
-	 }
-
-	 ir_variable *const existing =
-	    this->symbols->get_variable(ir->var->name);
-	 if (existing != NULL)
-	    ir->var = existing;
-	 else {
-	    ir_variable *copy = ir->var->clone(this->target, NULL);
-
-	    this->symbols->add_variable(copy);
-	    this->instructions->push_head(copy);
-	    ir->var = copy;
-	 }
-
-	 return visit_continue;
-      }
-
-   private:
-      struct gl_shader *target;
-      glsl_symbol_table *symbols;
-      exec_list *instructions;
-      hash_table *temps;
-   };
-
-   remap_visitor v(target, temps);
-
-   inst->accept(&v);
-}
-
-
-/**
- * Move non-declarations from one instruction stream to another
- *
- * The intended usage pattern of this function is to pass the pointer to the
- * head sentinel of a list (i.e., a pointer to the list cast to an \c exec_node
- * pointer) for \c last and \c false for \c make_copies on the first
- * call.  Successive calls pass the return value of the previous call for
- * \c last and \c true for \c make_copies.
- *
- * \param instructions Source instruction stream
- * \param last         Instruction after which new instructions should be
- *                     inserted in the target instruction stream
- * \param make_copies  Flag selecting whether instructions in \c instructions
- *                     should be copied (via \c ir_instruction::clone) into the
- *                     target list or moved.
- *
- * \return
- * The new "last" instruction in the target instruction stream.  This pointer
- * is suitable for use as the \c last parameter of a later call to this
- * function.
- */
-exec_node *
-move_non_declarations(exec_list *instructions, exec_node *last,
-		      bool make_copies, gl_shader *target)
-{
-   hash_table *temps = NULL;
-
-   if (make_copies)
-      temps = hash_table_ctor(0, hash_table_pointer_hash,
-			      hash_table_pointer_compare);
-
-   foreach_list_safe(node, instructions) {
-      ir_instruction *inst = (ir_instruction *) node;
-
-      if (inst->as_function())
-	 continue;
-
-      ir_variable *var = inst->as_variable();
-      if ((var != NULL) && (var->mode != ir_var_temporary))
-	 continue;
-
-      assert(inst->as_assignment()
-	     || ((var != NULL) && (var->mode == ir_var_temporary)));
-
-      if (make_copies) {
-	 inst = inst->clone(target, NULL);
-
-	 if (var != NULL)
-	    hash_table_insert(temps, inst, var);
-	 else
-	    remap_variables(inst, target, temps);
-      } else {
-	 inst->remove();
-      }
-
-      last->insert_after(inst);
-      last = inst;
-   }
-
-   if (make_copies)
-      hash_table_dtor(temps);
-
-   return last;
-}
-
-/**
- * Get the function signature for main from a shader
- */
-static ir_function_signature *
-get_main_function_signature(gl_shader *sh)
-{
-   ir_function *const f = sh->symbols->get_function("main");
-   if (f != NULL) {
-      exec_list void_parameters;
-
-      /* Look for the 'void main()' signature and ensure that it's defined.
-       * This keeps the linker from accidentally pick a shader that just
-       * contains a prototype for main.
-       *
-       * We don't have to check for multiple definitions of main (in multiple
-       * shaders) because that would have already been caught above.
-       */
-      ir_function_signature *sig = f->matching_signature(&void_parameters);
-      if ((sig != NULL) && sig->is_defined) {
-	 return sig;
-      }
-   }
-
-   return NULL;
-}
-
-
-/**
- * Combine a group of shaders for a single stage to generate a linked shader
- *
- * \note
- * If this function is supplied a single shader, it is cloned, and the new
- * shader is returned.
- */
-static struct gl_shader *
-link_intrastage_shaders(void *mem_ctx,
-			struct gl_context *ctx,
-			struct gl_shader_program *prog,
-			struct gl_shader **shader_list,
-			unsigned num_shaders)
-{
-   /* Check that global variables defined in multiple shaders are consistent.
-    */
-   if (!cross_validate_globals(prog, shader_list, num_shaders, false))
-      return NULL;
-
-   /* Check that there is only a single definition of each function signature
-    * across all shaders.
-    */
-   for (unsigned i = 0; i < (num_shaders - 1); i++) {
-      foreach_list(node, shader_list[i]->ir) {
-	 ir_function *const f = ((ir_instruction *) node)->as_function();
-
-	 if (f == NULL)
-	    continue;
-
-	 for (unsigned j = i + 1; j < num_shaders; j++) {
-	    ir_function *const other =
-	       shader_list[j]->symbols->get_function(f->name);
-
-	    /* If the other shader has no function (and therefore no function
-	     * signatures) with the same name, skip to the next shader.
-	     */
-	    if (other == NULL)
-	       continue;
-
-	    foreach_iter (exec_list_iterator, iter, *f) {
-	       ir_function_signature *sig =
-		  (ir_function_signature *) iter.get();
-
-	       if (!sig->is_defined || sig->is_builtin)
-		  continue;
-
-	       ir_function_signature *other_sig =
-		  other->exact_matching_signature(& sig->parameters);
-
-	       if ((other_sig != NULL) && other_sig->is_defined
-		   && !other_sig->is_builtin) {
-		  linker_error_printf(prog,
-				      "function `%s' is multiply defined",
-				      f->name);
-		  return NULL;
-	       }
-	    }
-	 }
-      }
-   }
-
-   /* Find the shader that defines main, and make a clone of it.
-    *
-    * Starting with the clone, search for undefined references.  If one is
-    * found, find the shader that defines it.  Clone the reference and add
-    * it to the shader.  Repeat until there are no undefined references or
-    * until a reference cannot be resolved.
-    */
-   gl_shader *main = NULL;
-   for (unsigned i = 0; i < num_shaders; i++) {
-      if (get_main_function_signature(shader_list[i]) != NULL) {
-	 main = shader_list[i];
-	 break;
-      }
-   }
-
-   if (main == NULL) {
-      linker_error_printf(prog, "%s shader lacks `main'\n",
-			  (shader_list[0]->Type == GL_VERTEX_SHADER)
-			  ? "vertex" : "fragment");
-      return NULL;
-   }
-
-   gl_shader *linked = ctx->Driver.NewShader(NULL, 0, main->Type);
-   linked->ir = new(linked) exec_list;
-   clone_ir_list(mem_ctx, linked->ir, main->ir);
-
-   populate_symbol_table(linked);
-
-   /* The a pointer to the main function in the final linked shader (i.e., the
-    * copy of the original shader that contained the main function).
-    */
-   ir_function_signature *const main_sig = get_main_function_signature(linked);
-
-   /* Move any instructions other than variable declarations or function
-    * declarations into main.
-    */
-   exec_node *insertion_point =
-      move_non_declarations(linked->ir, (exec_node *) &main_sig->body, false,
-			    linked);
-
-   for (unsigned i = 0; i < num_shaders; i++) {
-      if (shader_list[i] == main)
-	 continue;
-
-      insertion_point = move_non_declarations(shader_list[i]->ir,
-					      insertion_point, true, linked);
-   }
-
-   /* Resolve initializers for global variables in the linked shader.
-    */
-   unsigned num_linking_shaders = num_shaders;
-   for (unsigned i = 0; i < num_shaders; i++)
-      num_linking_shaders += shader_list[i]->num_builtins_to_link;
-
-   gl_shader **linking_shaders =
-      (gl_shader **) calloc(num_linking_shaders, sizeof(gl_shader *));
-
-   memcpy(linking_shaders, shader_list,
-	  sizeof(linking_shaders[0]) * num_shaders);
-
-   unsigned idx = num_shaders;
-   for (unsigned i = 0; i < num_shaders; i++) {
-      memcpy(&linking_shaders[idx], shader_list[i]->builtins_to_link,
-	     sizeof(linking_shaders[0]) * shader_list[i]->num_builtins_to_link);
-      idx += shader_list[i]->num_builtins_to_link;
-   }
-
-   assert(idx == num_linking_shaders);
-
-   if (!link_function_calls(prog, linked, linking_shaders,
-			    num_linking_shaders)) {
-      ctx->Driver.DeleteShader(ctx, linked);
-      linked = NULL;
-   }
-
-   free(linking_shaders);
-
-   /* Make a pass over all variable declarations to ensure that arrays with
-    * unspecified sizes have a size specified.  The size is inferred from the
-    * max_array_access field.
-    */
-   if (linked != NULL) {
-      class array_sizing_visitor : public ir_hierarchical_visitor {
-      public:
-	 virtual ir_visitor_status visit(ir_variable *var)
-	 {
-	    if (var->type->is_array() && (var->type->length == 0)) {
-	       const glsl_type *type =
-		  glsl_type::get_array_instance(var->type->fields.array,
-						var->max_array_access);
-
-	       assert(type != NULL);
-	       var->type = type;
-	    }
-
-	    return visit_continue;
-	 }
-      } v;
-
-      v.run(linked->ir);
-   }
-
-   return linked;
-}
-
-
-struct uniform_node {
-   exec_node link;
-   struct gl_uniform *u;
-   unsigned slots;
-};
-
-/**
- * Update the sizes of linked shader uniform arrays to the maximum
- * array index used.
- *
- * From page 81 (page 95 of the PDF) of the OpenGL 2.1 spec:
- *
- *     If one or more elements of an array are active,
- *     GetActiveUniform will return the name of the array in name,
- *     subject to the restrictions listed above. The type of the array
- *     is returned in type. The size parameter contains the highest
- *     array element index used, plus one. The compiler or linker
- *     determines the highest index used.  There will be only one
- *     active uniform reported by the GL per uniform array.
-
- */
-static void
-update_array_sizes(struct gl_shader_program *prog)
-{
-   for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {
-	 if (prog->_LinkedShaders[i] == NULL)
-	    continue;
-
-      foreach_list(node, prog->_LinkedShaders[i]->ir) {
-	 ir_variable *const var = ((ir_instruction *) node)->as_variable();
-
-	 if ((var == NULL) || (var->mode != ir_var_uniform &&
-			       var->mode != ir_var_in &&
-			       var->mode != ir_var_out) ||
-	     !var->type->is_array())
-	    continue;
-
-	 unsigned int size = var->max_array_access;
-	 for (unsigned j = 0; j < MESA_SHADER_TYPES; j++) {
-	       if (prog->_LinkedShaders[j] == NULL)
-		  continue;
-
-	    foreach_list(node2, prog->_LinkedShaders[j]->ir) {
-	       ir_variable *other_var = ((ir_instruction *) node2)->as_variable();
-	       if (!other_var)
-		  continue;
-
-	       if (strcmp(var->name, other_var->name) == 0 &&
-		   other_var->max_array_access > size) {
-		  size = other_var->max_array_access;
-	       }
-	    }
-	 }
-
-	 if (size + 1 != var->type->fields.array->length) {
-	    var->type = glsl_type::get_array_instance(var->type->fields.array,
-						      size + 1);
-	    /* FINISHME: We should update the types of array
-	     * dereferences of this variable now.
-	     */
-	 }
-      }
-   }
-}
-
-static void
-add_uniform(void *mem_ctx, exec_list *uniforms, struct hash_table *ht,
-	    const char *name, const glsl_type *type, GLenum shader_type,
-	    unsigned *next_shader_pos, unsigned *total_uniforms)
-{
-   if (type->is_record()) {
-      for (unsigned int i = 0; i < type->length; i++) {
-	 const glsl_type *field_type = type->fields.structure[i].type;
-	 char *field_name = ralloc_asprintf(mem_ctx, "%s.%s", name,
-					    type->fields.structure[i].name);
-
-	 add_uniform(mem_ctx, uniforms, ht, field_name, field_type,
-		     shader_type, next_shader_pos, total_uniforms);
-      }
-   } else {
-      uniform_node *n = (uniform_node *) hash_table_find(ht, name);
-      unsigned int vec4_slots;
-      const glsl_type *array_elem_type = NULL;
-
-      if (type->is_array()) {
-	 array_elem_type = type->fields.array;
-	 /* Array of structures. */
-	 if (array_elem_type->is_record()) {
-	    for (unsigned int i = 0; i < type->length; i++) {
-	       char *elem_name = ralloc_asprintf(mem_ctx, "%s[%d]", name, i);
-	       add_uniform(mem_ctx, uniforms, ht, elem_name, array_elem_type,
-			   shader_type, next_shader_pos, total_uniforms);
-	    }
-	    return;
-	 }
-      }
-
-      /* Fix the storage size of samplers at 1 vec4 each. Be sure to pad out
-       * vectors to vec4 slots.
-       */
-      if (type->is_array()) {
-	 if (array_elem_type->is_sampler())
-	    vec4_slots = type->length;
-	 else
-	    vec4_slots = type->length * array_elem_type->matrix_columns;
-      } else if (type->is_sampler()) {
-	 vec4_slots = 1;
-      } else {
-	 vec4_slots = type->matrix_columns;
-      }
-
-      if (n == NULL) {
-	 n = (uniform_node *) calloc(1, sizeof(struct uniform_node));
-	 n->u = (gl_uniform *) calloc(1, sizeof(struct gl_uniform));
-	 n->slots = vec4_slots;
-
-	 n->u->Name = strdup(name);
-	 n->u->Type = type;
-	 n->u->VertPos = -1;
-	 n->u->FragPos = -1;
-	 n->u->GeomPos = -1;
-	 (*total_uniforms)++;
-
-	 hash_table_insert(ht, n, name);
-	 uniforms->push_tail(& n->link);
-      }
-
-      switch (shader_type) {
-      case GL_VERTEX_SHADER:
-	 n->u->VertPos = *next_shader_pos;
-	 break;
-      case GL_FRAGMENT_SHADER:
-	 n->u->FragPos = *next_shader_pos;
-	 break;
-      case GL_GEOMETRY_SHADER:
-	 n->u->GeomPos = *next_shader_pos;
-	 break;
-      }
-
-      (*next_shader_pos) += vec4_slots;
-   }
-}
-
-void
-assign_uniform_locations(struct gl_shader_program *prog)
-{
-   /* */
-   exec_list uniforms;
-   unsigned total_uniforms = 0;
-   hash_table *ht = hash_table_ctor(32, hash_table_string_hash,
-				    hash_table_string_compare);
-   void *mem_ctx = ralloc_context(NULL);
-
-   for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {
-      if (prog->_LinkedShaders[i] == NULL)
-	 continue;
-
-      unsigned next_position = 0;
-
-      foreach_list(node, prog->_LinkedShaders[i]->ir) {
-	 ir_variable *const var = ((ir_instruction *) node)->as_variable();
-
-	 if ((var == NULL) || (var->mode != ir_var_uniform))
-	    continue;
-
-	 if (strncmp(var->name, "gl_", 3) == 0) {
-	    /* At the moment, we don't allocate uniform locations for
-	     * builtin uniforms.  It's permitted by spec, and we'll
-	     * likely switch to doing that at some point, but not yet.
-	     */
-	    continue;
-	 }
-
-	 var->location = next_position;
-	 add_uniform(mem_ctx, &uniforms, ht, var->name, var->type,
-		     prog->_LinkedShaders[i]->Type,
-		     &next_position, &total_uniforms);
-      }
-   }
-
-   ralloc_free(mem_ctx);
-
-   gl_uniform_list *ul = (gl_uniform_list *)
-      calloc(1, sizeof(gl_uniform_list));
-
-   ul->Size = total_uniforms;
-   ul->NumUniforms = total_uniforms;
-   ul->Uniforms = (gl_uniform *) calloc(total_uniforms, sizeof(gl_uniform));
-
-   unsigned idx = 0;
-   uniform_node *next;
-   for (uniform_node *node = (uniform_node *) uniforms.head
-	   ; node->link.next != NULL
-	   ; node = next) {
-      next = (uniform_node *) node->link.next;
-
-      node->link.remove();
-      memcpy(&ul->Uniforms[idx], node->u, sizeof(gl_uniform));
-      idx++;
-
-      free(node->u);
-      free(node);
-   }
-
-   hash_table_dtor(ht);
-
-   prog->Uniforms = ul;
-}
-
-
-/**
- * Find a contiguous set of available bits in a bitmask
- *
- * \param used_mask     Bits representing used (1) and unused (0) locations
- * \param needed_count  Number of contiguous bits needed.
- *
- * \return
- * Base location of the available bits on success or -1 on failure.
- */
-int
-find_available_slots(unsigned used_mask, unsigned needed_count)
-{
-   unsigned needed_mask = (1 << needed_count) - 1;
-   const int max_bit_to_test = (8 * sizeof(used_mask)) - needed_count;
-
-   /* The comparison to 32 is redundant, but without it GCC emits "warning:
-    * cannot optimize possibly infinite loops" for the loop below.
-    */
-   if ((needed_count == 0) || (max_bit_to_test < 0) || (max_bit_to_test > 32))
-      return -1;
-
-   for (int i = 0; i <= max_bit_to_test; i++) {
-      if ((needed_mask & ~used_mask) == needed_mask)
-	 return i;
-
-      needed_mask <<= 1;
-   }
-
-   return -1;
-}
-
-
-bool
-assign_attribute_locations(gl_shader_program *prog, unsigned max_attribute_index)
-{
-   /* Mark invalid attribute locations as being used.
-    */
-   unsigned used_locations = (max_attribute_index >= 32)
-      ? ~0 : ~((1 << max_attribute_index) - 1);
-
-   gl_shader *const sh = prog->_LinkedShaders[0];
-   assert(sh->Type == GL_VERTEX_SHADER);
-
-   /* Operate in a total of four passes.
-    *
-    * 1. Invalidate the location assignments for all vertex shader inputs.
-    *
-    * 2. Assign locations for inputs that have user-defined (via
-    *    glBindVertexAttribLocation) locatoins.
-    *
-    * 3. Sort the attributes without assigned locations by number of slots
-    *    required in decreasing order.  Fragmentation caused by attribute
-    *    locations assigned by the application may prevent large attributes
-    *    from having enough contiguous space.
-    *
-    * 4. Assign locations to any inputs without assigned locations.
-    */
-
-   invalidate_variable_locations(sh, ir_var_in, VERT_ATTRIB_GENERIC0);
-
-   if (prog->Attributes != NULL) {
-      for (unsigned i = 0; i < prog->Attributes->NumParameters; i++) {
-	 ir_variable *const var =
-	    sh->symbols->get_variable(prog->Attributes->Parameters[i].Name);
-
-	 /* Note: attributes that occupy multiple slots, such as arrays or
-	  * matrices, may appear in the attrib array multiple times.
-	  */
-	 if ((var == NULL) || (var->location != -1))
-	    continue;
-
-	 /* From page 61 of the OpenGL 4.0 spec:
-	  *
-	  *     "LinkProgram will fail if the attribute bindings assigned by
-	  *     BindAttribLocation do not leave not enough space to assign a
-	  *     location for an active matrix attribute or an active attribute
-	  *     array, both of which require multiple contiguous generic
-	  *     attributes."
-	  *
-	  * Previous versions of the spec contain similar language but omit the
-	  * bit about attribute arrays.
-	  *
-	  * Page 61 of the OpenGL 4.0 spec also says:
-	  *
-	  *     "It is possible for an application to bind more than one
-	  *     attribute name to the same location. This is referred to as
-	  *     aliasing. This will only work if only one of the aliased
-	  *     attributes is active in the executable program, or if no path
-	  *     through the shader consumes more than one attribute of a set
-	  *     of attributes aliased to the same location. A link error can
-	  *     occur if the linker determines that every path through the
-	  *     shader consumes multiple aliased attributes, but
-	  *     implementations are not required to generate an error in this
-	  *     case."
-	  *
-	  * These two paragraphs are either somewhat contradictory, or I don't
-	  * fully understand one or both of them.
-	  */
-	 /* FINISHME: The code as currently written does not support attribute
-	  * FINISHME: location aliasing (see comment above).
-	  */
-	 const int attr = prog->Attributes->Parameters[i].StateIndexes[0];
-	 const unsigned slots = count_attribute_slots(var->type);
-
-	 /* Mask representing the contiguous slots that will be used by this
-	  * attribute.
-	  */
-	 const unsigned use_mask = (1 << slots) - 1;
-
-	 /* Generate a link error if the set of bits requested for this
-	  * attribute overlaps any previously allocated bits.
-	  */
-	 if ((~(use_mask << attr) & used_locations) != used_locations) {
-	    linker_error_printf(prog,
-				"insufficient contiguous attribute locations "
-				"available for vertex shader input `%s'",
-				var->name);
-	    return false;
-	 }
-
-	 var->location = VERT_ATTRIB_GENERIC0 + attr;
-	 used_locations |= (use_mask << attr);
-      }
-   }
-
-   /* Temporary storage for the set of attributes that need locations assigned.
-    */
-   struct temp_attr {
-      unsigned slots;
-      ir_variable *var;
-
-      /* Used below in the call to qsort. */
-      static int compare(const void *a, const void *b)
-      {
-	 const temp_attr *const l = (const temp_attr *) a;
-	 const temp_attr *const r = (const temp_attr *) b;
-
-	 /* Reversed because we want a descending order sort below. */
-	 return r->slots - l->slots;
-      }
-   } to_assign[16];
-
-   unsigned num_attr = 0;
-
-   foreach_list(node, sh->ir) {
-      ir_variable *const var = ((ir_instruction *) node)->as_variable();
-
-      if ((var == NULL) || (var->mode != ir_var_in))
-	 continue;
-
-      if (var->explicit_location) {
-	 const unsigned slots = count_attribute_slots(var->type);
-	 const unsigned use_mask = (1 << slots) - 1;
-	 const int attr = var->location - VERT_ATTRIB_GENERIC0;
-
-	 if ((var->location >= (int)(max_attribute_index + VERT_ATTRIB_GENERIC0))
-	     || (var->location < 0)) {
-	    linker_error_printf(prog,
-				"invalid explicit location %d specified for "
-				"`%s'\n",
-				(var->location < 0) ? var->location : attr,
-				var->name);
-	    return false;
-	 } else if (var->location >= VERT_ATTRIB_GENERIC0) {
-	    used_locations |= (use_mask << attr);
-	 }
-      }
-
-      /* The location was explicitly assigned, nothing to do here.
-       */
-      if (var->location != -1)
-	 continue;
-
-      to_assign[num_attr].slots = count_attribute_slots(var->type);
-      to_assign[num_attr].var = var;
-      num_attr++;
-   }
-
-   /* If all of the attributes were assigned locations by the application (or
-    * are built-in attributes with fixed locations), return early.  This should
-    * be the common case.
-    */
-   if (num_attr == 0)
-      return true;
-
-   qsort(to_assign, num_attr, sizeof(to_assign[0]), temp_attr::compare);
-
-   /* VERT_ATTRIB_GENERIC0 is a psdueo-alias for VERT_ATTRIB_POS.  It can only
-    * be explicitly assigned by via glBindAttribLocation.  Mark it as reserved
-    * to prevent it from being automatically allocated below.
-    */
-   find_deref_visitor find("gl_Vertex");
-   find.run(sh->ir);
-   if (find.variable_found())
-      used_locations |= (1 << 0);
-
-   for (unsigned i = 0; i < num_attr; i++) {
-      /* Mask representing the contiguous slots that will be used by this
-       * attribute.
-       */
-      const unsigned use_mask = (1 << to_assign[i].slots) - 1;
-
-      int location = find_available_slots(used_locations, to_assign[i].slots);
-
-      if (location < 0) {
-	 linker_error_printf(prog,
-			     "insufficient contiguous attribute locations "
-			     "available for vertex shader input `%s'",
-			     to_assign[i].var->name);
-	 return false;
-      }
-
-      to_assign[i].var->location = VERT_ATTRIB_GENERIC0 + location;
-      used_locations |= (use_mask << location);
-   }
-
-   return true;
-}
-
-
-/**
- * Demote shader inputs and outputs that are not used in other stages
- */
-void
-demote_shader_inputs_and_outputs(gl_shader *sh, enum ir_variable_mode mode)
-{
-   foreach_list(node, sh->ir) {
-      ir_variable *const var = ((ir_instruction *) node)->as_variable();
-
-      if ((var == NULL) || (var->mode != int(mode)))
-	 continue;
-
-      /* A shader 'in' or 'out' variable is only really an input or output if
-       * its value is used by other shader stages.  This will cause the variable
-       * to have a location assigned.
-       */
-      if (var->location == -1) {
-	 var->mode = ir_var_auto;
-      }
-   }
-}
-
-
-void
-assign_varying_locations(struct gl_shader_program *prog,
-			 gl_shader *producer, gl_shader *consumer)
-{
-   /* FINISHME: Set dynamically when geometry shader support is added. */
-   unsigned output_index = VERT_RESULT_VAR0;
-   unsigned input_index = FRAG_ATTRIB_VAR0;
-
-   /* Operate in a total of three passes.
-    *
-    * 1. Assign locations for any matching inputs and outputs.
-    *
-    * 2. Mark output variables in the producer that do not have locations as
-    *    not being outputs.  This lets the optimizer eliminate them.
-    *
-    * 3. Mark input variables in the consumer that do not have locations as
-    *    not being inputs.  This lets the optimizer eliminate them.
-    */
-
-   invalidate_variable_locations(producer, ir_var_out, VERT_RESULT_VAR0);
-   invalidate_variable_locations(consumer, ir_var_in, FRAG_ATTRIB_VAR0);
-
-   foreach_list(node, producer->ir) {
-      ir_variable *const output_var = ((ir_instruction *) node)->as_variable();
-
-      if ((output_var == NULL) || (output_var->mode != ir_var_out)
-	  || (output_var->location != -1))
-	 continue;
-
-      ir_variable *const input_var =
-	 consumer->symbols->get_variable(output_var->name);
-
-      if ((input_var == NULL) || (input_var->mode != ir_var_in))
-	 continue;
-
-      assert(input_var->location == -1);
-
-      output_var->location = output_index;
-      input_var->location = input_index;
-
-      /* FINISHME: Support for "varying" records in GLSL 1.50. */
-      assert(!output_var->type->is_record());
-
-      if (output_var->type->is_array()) {
-	 const unsigned slots = output_var->type->length
-	    * output_var->type->fields.array->matrix_columns;
-
-	 output_index += slots;
-	 input_index += slots;
-      } else {
-	 const unsigned slots = output_var->type->matrix_columns;
-
-	 output_index += slots;
-	 input_index += slots;
-      }
-   }
-
-   foreach_list(node, consumer->ir) {
-      ir_variable *const var = ((ir_instruction *) node)->as_variable();
-
-      if ((var == NULL) || (var->mode != ir_var_in))
-	 continue;
-
-      if (var->location == -1) {
-	 if (prog->Version <= 120) {
-	    /* On page 25 (page 31 of the PDF) of the GLSL 1.20 spec:
-	     *
-	     *     Only those varying variables used (i.e. read) in
-	     *     the fragment shader executable must be written to
-	     *     by the vertex shader executable; declaring
-	     *     superfluous varying variables in a vertex shader is
-	     *     permissible.
-	     *
-	     * We interpret this text as meaning that the VS must
-	     * write the variable for the FS to read it.  See
-	     * "glsl1-varying read but not written" in piglit.
-	     */
-
-	    linker_error_printf(prog, "fragment shader varying %s not written "
-				"by vertex shader\n.", var->name);
-	    prog->LinkStatus = false;
-	 }
-
-	 /* An 'in' variable is only really a shader input if its
-	  * value is written by the previous stage.
-	  */
-	 var->mode = ir_var_auto;
-      }
-   }
-}
-
-
-void
-link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
-{
-   void *mem_ctx = ralloc_context(NULL); // temporary linker context
-
-   prog->LinkStatus = false;
-   prog->Validated = false;
-   prog->_Used = false;
-
-   if (prog->InfoLog != NULL)
-      ralloc_free(prog->InfoLog);
-
-   prog->InfoLog = ralloc_strdup(NULL, "");
-
-   /* Separate the shaders into groups based on their type.
-    */
-   struct gl_shader **vert_shader_list;
-   unsigned num_vert_shaders = 0;
-   struct gl_shader **frag_shader_list;
-   unsigned num_frag_shaders = 0;
-
-   vert_shader_list = (struct gl_shader **)
-      calloc(2 * prog->NumShaders, sizeof(struct gl_shader *));
-   frag_shader_list =  &vert_shader_list[prog->NumShaders];
-
-   unsigned min_version = UINT_MAX;
-   unsigned max_version = 0;
-   for (unsigned i = 0; i < prog->NumShaders; i++) {
-      min_version = MIN2(min_version, prog->Shaders[i]->Version);
-      max_version = MAX2(max_version, prog->Shaders[i]->Version);
-
-      switch (prog->Shaders[i]->Type) {
-      case GL_VERTEX_SHADER:
-	 vert_shader_list[num_vert_shaders] = prog->Shaders[i];
-	 num_vert_shaders++;
-	 break;
-      case GL_FRAGMENT_SHADER:
-	 frag_shader_list[num_frag_shaders] = prog->Shaders[i];
-	 num_frag_shaders++;
-	 break;
-      case GL_GEOMETRY_SHADER:
-	 /* FINISHME: Support geometry shaders. */
-	 assert(prog->Shaders[i]->Type != GL_GEOMETRY_SHADER);
-	 break;
-      }
-   }
-
-   /* Previous to GLSL version 1.30, different compilation units could mix and
-    * match shading language versions.  With GLSL 1.30 and later, the versions
-    * of all shaders must match.
-    */
-   assert(min_version >= 100);
-   assert(max_version <= 130);
-   if ((max_version >= 130 || min_version == 100)
-       && min_version != max_version) {
-      linker_error_printf(prog, "all shaders must use same shading "
-			  "language version\n");
-      goto done;
-   }
-
-   prog->Version = max_version;
-
-   for (unsigned int i = 0; i < MESA_SHADER_TYPES; i++) {
-      if (prog->_LinkedShaders[i] != NULL)
-	 ctx->Driver.DeleteShader(ctx, prog->_LinkedShaders[i]);
-
-      prog->_LinkedShaders[i] = NULL;
-   }
-
-   /* Link all shaders for a particular stage and validate the result.
-    */
-   if (num_vert_shaders > 0) {
-      gl_shader *const sh =
-	 link_intrastage_shaders(mem_ctx, ctx, prog, vert_shader_list,
-				 num_vert_shaders);
-
-      if (sh == NULL)
-	 goto done;
-
-      if (!validate_vertex_shader_executable(prog, sh))
-	 goto done;
-
-      _mesa_reference_shader(ctx, &prog->_LinkedShaders[MESA_SHADER_VERTEX],
-			     sh);
-   }
-
-   if (num_frag_shaders > 0) {
-      gl_shader *const sh =
-	 link_intrastage_shaders(mem_ctx, ctx, prog, frag_shader_list,
-				 num_frag_shaders);
-
-      if (sh == NULL)
-	 goto done;
-
-      if (!validate_fragment_shader_executable(prog, sh))
-	 goto done;
-
-      _mesa_reference_shader(ctx, &prog->_LinkedShaders[MESA_SHADER_FRAGMENT],
-			     sh);
-   }
-
-   /* Here begins the inter-stage linking phase.  Some initial validation is
-    * performed, then locations are assigned for uniforms, attributes, and
-    * varyings.
-    */
-   if (cross_validate_uniforms(prog)) {
-      unsigned prev;
-
-      for (prev = 0; prev < MESA_SHADER_TYPES; prev++) {
-	 if (prog->_LinkedShaders[prev] != NULL)
-	    break;
-      }
-
-      /* Validate the inputs of each stage with the output of the preceeding
-       * stage.
-       */
-      for (unsigned i = prev + 1; i < MESA_SHADER_TYPES; i++) {
-	 if (prog->_LinkedShaders[i] == NULL)
-	    continue;
-
-	 if (!cross_validate_outputs_to_inputs(prog,
-					       prog->_LinkedShaders[prev],
-					       prog->_LinkedShaders[i]))
-	    goto done;
-
-	 prev = i;
-      }
-
-      prog->LinkStatus = true;
-   }
-
-   /* Do common optimization before assigning storage for attributes,
-    * uniforms, and varyings.  Later optimization could possibly make
-    * some of that unused.
-    */
-   for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {
-      if (prog->_LinkedShaders[i] == NULL)
-	 continue;
-
-      while (do_common_optimization(prog->_LinkedShaders[i]->ir, true, 32))
-	 ;
-   }
-
-   update_array_sizes(prog);
-
-   assign_uniform_locations(prog);
-
-   if (prog->_LinkedShaders[MESA_SHADER_VERTEX] != NULL) {
-      /* FINISHME: The value of the max_attribute_index parameter is
-       * FINISHME: implementation dependent based on the value of
-       * FINISHME: GL_MAX_VERTEX_ATTRIBS.  GL_MAX_VERTEX_ATTRIBS must be
-       * FINISHME: at least 16, so hardcode 16 for now.
-       */
-      if (!assign_attribute_locations(prog, 16)) {
-	 prog->LinkStatus = false;
-	 goto done;
-      }
-   }
-
-   unsigned prev;
-   for (prev = 0; prev < MESA_SHADER_TYPES; prev++) {
-      if (prog->_LinkedShaders[prev] != NULL)
-	 break;
-   }
-
-   for (unsigned i = prev + 1; i < MESA_SHADER_TYPES; i++) {
-      if (prog->_LinkedShaders[i] == NULL)
-	 continue;
-
-      assign_varying_locations(prog,
-			       prog->_LinkedShaders[prev],
-			       prog->_LinkedShaders[i]);
-      prev = i;
-   }
-
-   if (prog->_LinkedShaders[MESA_SHADER_VERTEX] != NULL) {
-      demote_shader_inputs_and_outputs(prog->_LinkedShaders[MESA_SHADER_VERTEX],
-				       ir_var_out);
-   }
-
-   if (prog->_LinkedShaders[MESA_SHADER_GEOMETRY] != NULL) {
-      gl_shader *const sh = prog->_LinkedShaders[MESA_SHADER_GEOMETRY];
-
-      demote_shader_inputs_and_outputs(sh, ir_var_in);
-      demote_shader_inputs_and_outputs(sh, ir_var_inout);
-      demote_shader_inputs_and_outputs(sh, ir_var_out);
-   }
-
-   if (prog->_LinkedShaders[MESA_SHADER_FRAGMENT] != NULL) {
-      gl_shader *const sh = prog->_LinkedShaders[MESA_SHADER_FRAGMENT];
-
-      demote_shader_inputs_and_outputs(sh, ir_var_in);
-   }
-
-   /* OpenGL ES requires that a vertex shader and a fragment shader both be
-    * present in a linked program.  By checking for use of shading language
-    * version 1.00, we also catch the GL_ARB_ES2_compatibility case.
-    */
-   if (ctx->API == API_OPENGLES2 || prog->Version == 100) {
-      if (prog->_LinkedShaders[MESA_SHADER_VERTEX] == NULL) {
-	 linker_error_printf(prog, "program lacks a vertex shader\n");
-	 prog->LinkStatus = false;
-      } else if (prog->_LinkedShaders[MESA_SHADER_FRAGMENT] == NULL) {
-	 linker_error_printf(prog, "program lacks a fragment shader\n");
-	 prog->LinkStatus = false;
-      }
-   }
-
-   /* FINISHME: Assign fragment shader output locations. */
-
-done:
-   free(vert_shader_list);
-
-   for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {
-      if (prog->_LinkedShaders[i] == NULL)
-	 continue;
-
-      /* Retain any live IR, but trash the rest. */
-      reparent_ir(prog->_LinkedShaders[i]->ir, prog->_LinkedShaders[i]->ir);
-   }
-
-   ralloc_free(mem_ctx);
-}
+/*

+ * Copyright © 2010 Intel Corporation

+ *

+ * Permission is hereby granted, free of charge, to any person obtaining a

+ * copy of this software and associated documentation files (the "Software"),

+ * to deal in the Software without restriction, including without limitation

+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,

+ * and/or sell copies of the Software, and to permit persons to whom the

+ * Software is furnished to do so, subject to the following conditions:

+ *

+ * The above copyright notice and this permission notice (including the next

+ * paragraph) shall be included in all copies or substantial portions of the

+ * Software.

+ *

+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

+ * DEALINGS IN THE SOFTWARE.

+ */

+

+/**

+ * \file linker.cpp

+ * GLSL linker implementation

+ *

+ * Given a set of shaders that are to be linked to generate a final program,

+ * there are three distinct stages.

+ *

+ * In the first stage shaders are partitioned into groups based on the shader

+ * type.  All shaders of a particular type (e.g., vertex shaders) are linked

+ * together.

+ *

+ *   - Undefined references in each shader are resolve to definitions in

+ *     another shader.

+ *   - Types and qualifiers of uniforms, outputs, and global variables defined

+ *     in multiple shaders with the same name are verified to be the same.

+ *   - Initializers for uniforms and global variables defined

+ *     in multiple shaders with the same name are verified to be the same.

+ *

+ * The result, in the terminology of the GLSL spec, is a set of shader

+ * executables for each processing unit.

+ *

+ * After the first stage is complete, a series of semantic checks are performed

+ * on each of the shader executables.

+ *

+ *   - Each shader executable must define a \c main function.

+ *   - Each vertex shader executable must write to \c gl_Position.

+ *   - Each fragment shader executable must write to either \c gl_FragData or

+ *     \c gl_FragColor.

+ *

+ * In the final stage individual shader executables are linked to create a

+ * complete exectuable.

+ *

+ *   - Types of uniforms defined in multiple shader stages with the same name

+ *     are verified to be the same.

+ *   - Initializers for uniforms defined in multiple shader stages with the

+ *     same name are verified to be the same.

+ *   - Types and qualifiers of outputs defined in one stage are verified to

+ *     be the same as the types and qualifiers of inputs defined with the same

+ *     name in a later stage.

+ *

+ * \author Ian Romanick <ian.d.romanick@intel.com>

+ */

+#include <cstdlib>

+#include <cstdio>

+#include <cstdarg>

+#include <climits>

+

+#include "main/core.h"

+#include "glsl_symbol_table.h"

+#include "ir.h"

+#include "program.h"

+#include "program/hash_table.h"

+#include "linker.h"

+#include "ir_optimization.h"

+

+extern "C" {

+#include "main/shaderobj.h"

+}

+

+/**

+ * Visitor that determines whether or not a variable is ever written.

+ */

+class find_assignment_visitor : public ir_hierarchical_visitor {

+public:

+   find_assignment_visitor(const char *name)

+      : name(name), found(false)

+   {

+      /* empty */

+   }

+

+   virtual ir_visitor_status visit_enter(ir_assignment *ir)

+   {

+      ir_variable *const var = ir->lhs->variable_referenced();

+

+      if (strcmp(name, var->name) == 0) {

+	 found = true;

+	 return visit_stop;

+      }

+

+      return visit_continue_with_parent;

+   }

+

+   virtual ir_visitor_status visit_enter(ir_call *ir)

+   {

+      exec_list_iterator sig_iter = ir->get_callee()->parameters.iterator();

+      foreach_iter(exec_list_iterator, iter, *ir) {

+	 ir_rvalue *param_rval = (ir_rvalue *)iter.get();

+	 ir_variable *sig_param = (ir_variable *)sig_iter.get();

+

+	 if (sig_param->mode == ir_var_out ||

+	     sig_param->mode == ir_var_inout) {

+	    ir_variable *var = param_rval->variable_referenced();

+	    if (var && strcmp(name, var->name) == 0) {

+	       found = true;

+	       return visit_stop;

+	    }

+	 }

+	 sig_iter.next();

+      }

+

+      return visit_continue_with_parent;

+   }

+

+   bool variable_found()

+   {

+      return found;

+   }

+

+private:

+   const char *name;       /**< Find writes to a variable with this name. */

+   bool found;             /**< Was a write to the variable found? */

+};

+

+

+/**

+ * Visitor that determines whether or not a variable is ever read.

+ */

+class find_deref_visitor : public ir_hierarchical_visitor {

+public:

+   find_deref_visitor(const char *name)

+      : name(name), found(false)

+   {

+      /* empty */

+   }

+

+   virtual ir_visitor_status visit(ir_dereference_variable *ir)

+   {

+      if (strcmp(this->name, ir->var->name) == 0) {

+	 this->found = true;

+	 return visit_stop;

+      }

+

+      return visit_continue;

+   }

+

+   bool variable_found() const

+   {

+      return this->found;

+   }

+

+private:

+   const char *name;       /**< Find writes to a variable with this name. */

+   bool found;             /**< Was a write to the variable found? */

+};

+

+

+void

+linker_error_printf(gl_shader_program *prog, const char *fmt, ...)

+{

+   va_list ap;

+

+   ralloc_strcat(&prog->InfoLog, "error: ");

+   va_start(ap, fmt);

+   ralloc_vasprintf_append(&prog->InfoLog, fmt, ap);

+   va_end(ap);

+}

+

+

+void

+invalidate_variable_locations(gl_shader *sh, enum ir_variable_mode mode,

+			      int generic_base)

+{

+   foreach_list(node, sh->ir) {

+      ir_variable *const var = ((ir_instruction *) node)->as_variable();

+

+      if ((var == NULL) || (var->mode != (unsigned) mode))

+	 continue;

+

+      /* Only assign locations for generic attributes / varyings / etc.

+       */

+      if ((var->location >= generic_base) && !var->explicit_location)

+	  var->location = -1;

+   }

+}

+

+

+/**

+ * Determine the number of attribute slots required for a particular type

+ *

+ * This code is here because it implements the language rules of a specific

+ * GLSL version.  Since it's a property of the language and not a property of

+ * types in general, it doesn't really belong in glsl_type.

+ */

+unsigned

+count_attribute_slots(const glsl_type *t)

+{

+   /* From page 31 (page 37 of the PDF) of the GLSL 1.50 spec:

+    *

+    *     "A scalar input counts the same amount against this limit as a vec4,

+    *     so applications may want to consider packing groups of four

+    *     unrelated float inputs together into a vector to better utilize the

+    *     capabilities of the underlying hardware. A matrix input will use up

+    *     multiple locations.  The number of locations used will equal the

+    *     number of columns in the matrix."

+    *

+    * The spec does not explicitly say how arrays are counted.  However, it

+    * should be safe to assume the total number of slots consumed by an array

+    * is the number of entries in the array multiplied by the number of slots

+    * consumed by a single element of the array.

+    */

+

+   if (t->is_array())

+      return t->array_size() * count_attribute_slots(t->element_type());

+

+   if (t->is_matrix())

+      return t->matrix_columns;

+

+   return 1;

+}

+

+

+/**

+ * Verify that a vertex shader executable meets all semantic requirements

+ *

+ * \param shader  Vertex shader executable to be verified

+ */

+bool

+validate_vertex_shader_executable(struct gl_shader_program *prog,

+				  struct gl_shader *shader)

+{

+   if (shader == NULL)

+      return true;

+

+   find_assignment_visitor find("gl_Position");

+   find.run(shader->ir);

+   if (!find.variable_found()) {

+      linker_error_printf(prog,

+			  "vertex shader does not write to `gl_Position'\n");

+      return false;

+   }

+

+   return true;

+}

+

+

+/**

+ * Verify that a fragment shader executable meets all semantic requirements

+ *

+ * \param shader  Fragment shader executable to be verified

+ */

+bool

+validate_fragment_shader_executable(struct gl_shader_program *prog,

+				    struct gl_shader *shader)

+{

+   if (shader == NULL)

+      return true;

+

+   find_assignment_visitor frag_color("gl_FragColor");

+   find_assignment_visitor frag_data("gl_FragData");

+

+   frag_color.run(shader->ir);

+   frag_data.run(shader->ir);

+

+   if (frag_color.variable_found() && frag_data.variable_found()) {

+      linker_error_printf(prog,  "fragment shader writes to both "

+			  "`gl_FragColor' and `gl_FragData'\n");

+      return false;

+   }

+

+   return true;

+}

+

+

+/**

+ * Generate a string describing the mode of a variable

+ */

+static const char *

+mode_string(const ir_variable *var)

+{

+   switch (var->mode) {

+   case ir_var_auto:

+      return (var->read_only) ? "global constant" : "global variable";

+

+   case ir_var_uniform: return "uniform";

+   case ir_var_in:      return "shader input";

+   case ir_var_out:     return "shader output";

+   case ir_var_inout:   return "shader inout";

+

+   case ir_var_const_in:

+   case ir_var_temporary:

+   default:

+      assert(!"Should not get here.");

+      return "invalid variable";

+   }

+}

+

+

+/**

+ * Perform validation of global variables used across multiple shaders

+ */

+bool

+cross_validate_globals(struct gl_shader_program *prog,

+		       struct gl_shader **shader_list,

+		       unsigned num_shaders,

+		       bool uniforms_only)

+{

+   /* Examine all of the uniforms in all of the shaders and cross validate

+    * them.

+    */

+   glsl_symbol_table variables;

+   for (unsigned i = 0; i < num_shaders; i++) {

+      if (shader_list[i] == NULL)

+	 continue;

+

+      foreach_list(node, shader_list[i]->ir) {

+	 ir_variable *const var = ((ir_instruction *) node)->as_variable();

+

+	 if (var == NULL)

+	    continue;

+

+	 if (uniforms_only && (var->mode != ir_var_uniform))

+	    continue;

+

+	 /* Don't cross validate temporaries that are at global scope.  These

+	  * will eventually get pulled into the shaders 'main'.

+	  */

+	 if (var->mode == ir_var_temporary)

+	    continue;

+

+	 /* If a global with this name has already been seen, verify that the

+	  * new instance has the same type.  In addition, if the globals have

+	  * initializers, the values of the initializers must be the same.

+	  */

+	 ir_variable *const existing = variables.get_variable(var->name);

+	 if (existing != NULL) {

+	    if (var->type != existing->type) {

+	       /* Consider the types to be "the same" if both types are arrays

+		* of the same type and one of the arrays is implicitly sized.

+		* In addition, set the type of the linked variable to the

+		* explicitly sized array.

+		*/

+	       if (var->type->is_array()

+		   && existing->type->is_array()

+		   && (var->type->fields.array == existing->type->fields.array)

+		   && ((var->type->length == 0)

+		       || (existing->type->length == 0))) {

+		  if (var->type->length != 0) {

+		     existing->type = var->type;

+		  }

+	       } else {

+		  linker_error_printf(prog, "%s `%s' declared as type "

+				      "`%s' and type `%s'\n",

+				      mode_string(var),

+				      var->name, var->type->name,

+				      existing->type->name);

+		  return false;

+	       }

+	    }

+

+	    if (var->explicit_location) {

+	       if (existing->explicit_location

+		   && (var->location != existing->location)) {

+		     linker_error_printf(prog, "explicit locations for %s "

+					 "`%s' have differing values\n",

+					 mode_string(var), var->name);

+		     return false;

+	       }

+

+	       existing->location = var->location;

+	       existing->explicit_location = true;

+	    }

+

+        /* Validate layout qualifiers for gl_FragDepth.

+         *

+         * From the AMD_conservative_depth spec:

+         *    "If gl_FragDepth is redeclared in any fragment shader in

+         *    a program, it must be redeclared in all fragment shaders in that

+         *    program that have static assignments to gl_FragDepth. All

+         *    redeclarations of gl_FragDepth in all fragment shaders in

+         *    a single program must have the same set of qualifiers."

+         */

+        if (strcmp(var->name, "gl_FragDepth") == 0) {

+           bool layout_declared = var->depth_layout != ir_depth_layout_none;

+           bool layout_differs = var->depth_layout != existing->depth_layout;

+           if (layout_declared && layout_differs) {

+              linker_error_printf(prog,

+                 "All redeclarations of gl_FragDepth in all fragment shaders "

+                 "in a single program must have the same set of qualifiers.");

+           }

+           if (var->used && layout_differs) {

+              linker_error_printf(prog,

+                    "If gl_FragDepth is redeclared with a layout qualifier in"

+                    "any fragment shader, it must be redeclared with the same"

+                    "layout qualifier in all fragment shaders that have"

+                    "assignments to gl_FragDepth");

+           }

+        }

+

+	    /* FINISHME: Handle non-constant initializers.

+	     */

+	    if (var->constant_value != NULL) {

+	       if (existing->constant_value != NULL) {

+		  if (!var->constant_value->has_value(existing->constant_value)) {

+		     linker_error_printf(prog, "initializers for %s "

+					 "`%s' have differing values\n",

+					 mode_string(var), var->name);

+		     return false;

+		  }

+	       } else

+		  /* If the first-seen instance of a particular uniform did not

+		   * have an initializer but a later instance does, copy the

+		   * initializer to the version stored in the symbol table.

+		   */

+		  /* FINISHME: This is wrong.  The constant_value field should

+		   * FINISHME: not be modified!  Imagine a case where a shader

+		   * FINISHME: without an initializer is linked in two different

+		   * FINISHME: programs with shaders that have differing

+		   * FINISHME: initializers.  Linking with the first will

+		   * FINISHME: modify the shader, and linking with the second

+		   * FINISHME: will fail.

+		   */

+		  existing->constant_value =

+		     var->constant_value->clone(ralloc_parent(existing), NULL);

+	    }

+

+	    if (existing->invariant != var->invariant) {

+	       linker_error_printf(prog, "declarations for %s `%s' have "

+	                           "mismatching invariant qualifiers\n",

+	                           mode_string(var), var->name);

+	       return false;

+	    }

+            if (existing->centroid != var->centroid) {

+               linker_error_printf(prog, "declarations for %s `%s' have "

+                                   "mismatching centroid qualifiers\n",

+                                   mode_string(var), var->name);

+               return false;

+            }

+	 } else

+	    variables.add_variable(var);

+      }

+   }

+

+   return true;

+}

+

+

+/**

+ * Perform validation of uniforms used across multiple shader stages

+ */

+bool

+cross_validate_uniforms(struct gl_shader_program *prog)

+{

+   return cross_validate_globals(prog, prog->_LinkedShaders,

+				 MESA_SHADER_TYPES, true);

+}

+

+

+/**

+ * Validate that outputs from one stage match inputs of another

+ */

+bool

+cross_validate_outputs_to_inputs(struct gl_shader_program *prog,

+				 gl_shader *producer, gl_shader *consumer)

+{

+   glsl_symbol_table parameters;

+   /* FINISHME: Figure these out dynamically. */

+   const char *const producer_stage = "vertex";

+   const char *const consumer_stage = "fragment";

+

+   /* Find all shader outputs in the "producer" stage.

+    */

+   foreach_list(node, producer->ir) {

+      ir_variable *const var = ((ir_instruction *) node)->as_variable();

+

+      /* FINISHME: For geometry shaders, this should also look for inout

+       * FINISHME: variables.

+       */

+      if ((var == NULL) || (var->mode != ir_var_out))

+	 continue;

+

+      parameters.add_variable(var);

+   }

+

+

+   /* Find all shader inputs in the "consumer" stage.  Any variables that have

+    * matching outputs already in the symbol table must have the same type and

+    * qualifiers.

+    */

+   foreach_list(node, consumer->ir) {

+      ir_variable *const input = ((ir_instruction *) node)->as_variable();

+

+      /* FINISHME: For geometry shaders, this should also look for inout

+       * FINISHME: variables.

+       */

+      if ((input == NULL) || (input->mode != ir_var_in))

+	 continue;

+

+      ir_variable *const output = parameters.get_variable(input->name);

+      if (output != NULL) {

+	 /* Check that the types match between stages.

+	  */

+	 if (input->type != output->type) {

+	    /* There is a bit of a special case for gl_TexCoord.  This

+	     * built-in is unsized by default.  Appliations that variable

+	     * access it must redeclare it with a size.  There is some

+	     * language in the GLSL spec that implies the fragment shader

+	     * and vertex shader do not have to agree on this size.  Other

+	     * driver behave this way, and one or two applications seem to

+	     * rely on it.

+	     *

+	     * Neither declaration needs to be modified here because the array

+	     * sizes are fixed later when update_array_sizes is called.

+	     *

+	     * From page 48 (page 54 of the PDF) of the GLSL 1.10 spec:

+	     *

+	     *     "Unlike user-defined varying variables, the built-in

+	     *     varying variables don't have a strict one-to-one

+	     *     correspondence between the vertex language and the

+	     *     fragment language."

+	     */

+	    if (!output->type->is_array()

+		|| (strncmp("gl_", output->name, 3) != 0)) {

+	       linker_error_printf(prog,

+				   "%s shader output `%s' declared as "

+				   "type `%s', but %s shader input declared "

+				   "as type `%s'\n",

+				   producer_stage, output->name,

+				   output->type->name,

+				   consumer_stage, input->type->name);

+	       return false;

+	    }

+	 }

+

+	 /* Check that all of the qualifiers match between stages.

+	  */

+	 if (input->centroid != output->centroid) {

+	    linker_error_printf(prog,

+				"%s shader output `%s' %s centroid qualifier, "

+				"but %s shader input %s centroid qualifier\n",

+				producer_stage,

+				output->name,

+				(output->centroid) ? "has" : "lacks",

+				consumer_stage,

+				(input->centroid) ? "has" : "lacks");

+	    return false;

+	 }

+

+	 if (input->invariant != output->invariant) {

+	    linker_error_printf(prog,

+				"%s shader output `%s' %s invariant qualifier, "

+				"but %s shader input %s invariant qualifier\n",

+				producer_stage,

+				output->name,

+				(output->invariant) ? "has" : "lacks",

+				consumer_stage,

+				(input->invariant) ? "has" : "lacks");

+	    return false;

+	 }

+

+	 if (input->interpolation != output->interpolation) {

+	    linker_error_printf(prog,

+				"%s shader output `%s' specifies %s "

+				"interpolation qualifier, "

+				"but %s shader input specifies %s "

+				"interpolation qualifier\n",

+				producer_stage,

+				output->name,

+				output->interpolation_string(),

+				consumer_stage,

+				input->interpolation_string());

+	    return false;

+	 }

+      }

+   }

+

+   return true;

+}

+

+

+/**

+ * Populates a shaders symbol table with all global declarations

+ */

+static void

+populate_symbol_table(gl_shader *sh)

+{

+   sh->symbols = new(sh) glsl_symbol_table;

+

+   foreach_list(node, sh->ir) {

+      ir_instruction *const inst = (ir_instruction *) node;

+      ir_variable *var;

+      ir_function *func;

+

+      if ((func = inst->as_function()) != NULL) {

+	 sh->symbols->add_function(func);

+      } else if ((var = inst->as_variable()) != NULL) {

+	 sh->symbols->add_variable(var);

+      }

+   }

+}

+

+

+/**

+ * Remap variables referenced in an instruction tree

+ *

+ * This is used when instruction trees are cloned from one shader and placed in

+ * another.  These trees will contain references to \c ir_variable nodes that

+ * do not exist in the target shader.  This function finds these \c ir_variable

+ * references and replaces the references with matching variables in the target

+ * shader.

+ *

+ * If there is no matching variable in the target shader, a clone of the

+ * \c ir_variable is made and added to the target shader.  The new variable is

+ * added to \b both the instruction stream and the symbol table.

+ *

+ * \param inst         IR tree that is to be processed.

+ * \param symbols      Symbol table containing global scope symbols in the

+ *                     linked shader.

+ * \param instructions Instruction stream where new variable declarations

+ *                     should be added.

+ */

+void

+remap_variables(ir_instruction *inst, struct gl_shader *target,

+		hash_table *temps)

+{

+   class remap_visitor : public ir_hierarchical_visitor {

+   public:

+	 remap_visitor(struct gl_shader *target,

+		    hash_table *temps)

+      {

+	 this->target = target;

+	 this->symbols = target->symbols;

+	 this->instructions = target->ir;

+	 this->temps = temps;

+      }

+

+      virtual ir_visitor_status visit(ir_dereference_variable *ir)

+      {

+	 if (ir->var->mode == ir_var_temporary) {

+	    ir_variable *var = (ir_variable *) hash_table_find(temps, ir->var);

+

+	    assert(var != NULL);

+	    ir->var = var;

+	    return visit_continue;

+	 }

+

+	 ir_variable *const existing =

+	    this->symbols->get_variable(ir->var->name);

+	 if (existing != NULL)

+	    ir->var = existing;

+	 else {

+	    ir_variable *copy = ir->var->clone(this->target, NULL);

+

+	    this->symbols->add_variable(copy);

+	    this->instructions->push_head(copy);

+	    ir->var = copy;

+	 }

+

+	 return visit_continue;

+      }

+

+   private:

+      struct gl_shader *target;

+      glsl_symbol_table *symbols;

+      exec_list *instructions;

+      hash_table *temps;

+   };

+

+   remap_visitor v(target, temps);

+

+   inst->accept(&v);

+}

+

+

+/**

+ * Move non-declarations from one instruction stream to another

+ *

+ * The intended usage pattern of this function is to pass the pointer to the

+ * head sentinel of a list (i.e., a pointer to the list cast to an \c exec_node

+ * pointer) for \c last and \c false for \c make_copies on the first

+ * call.  Successive calls pass the return value of the previous call for

+ * \c last and \c true for \c make_copies.

+ *

+ * \param instructions Source instruction stream

+ * \param last         Instruction after which new instructions should be

+ *                     inserted in the target instruction stream

+ * \param make_copies  Flag selecting whether instructions in \c instructions

+ *                     should be copied (via \c ir_instruction::clone) into the

+ *                     target list or moved.

+ *

+ * \return

+ * The new "last" instruction in the target instruction stream.  This pointer

+ * is suitable for use as the \c last parameter of a later call to this

+ * function.

+ */

+exec_node *

+move_non_declarations(exec_list *instructions, exec_node *last,

+		      bool make_copies, gl_shader *target)

+{

+   hash_table *temps = NULL;

+

+   if (make_copies)

+      temps = hash_table_ctor(0, hash_table_pointer_hash,

+			      hash_table_pointer_compare);

+

+   foreach_list_safe(node, instructions) {

+      ir_instruction *inst = (ir_instruction *) node;

+

+      if (inst->as_function())

+	 continue;

+

+      ir_variable *var = inst->as_variable();

+      if ((var != NULL) && (var->mode != ir_var_temporary))

+	 continue;

+

+      assert(inst->as_assignment()

+	     || ((var != NULL) && (var->mode == ir_var_temporary)));

+

+      if (make_copies) {

+	 inst = inst->clone(target, NULL);

+

+	 if (var != NULL)

+	    hash_table_insert(temps, inst, var);

+	 else

+	    remap_variables(inst, target, temps);

+      } else {

+	 inst->remove();

+      }

+

+      last->insert_after(inst);

+      last = inst;

+   }

+

+   if (make_copies)

+      hash_table_dtor(temps);

+

+   return last;

+}

+

+/**

+ * Get the function signature for main from a shader

+ */

+static ir_function_signature *

+get_main_function_signature(gl_shader *sh)

+{

+   ir_function *const f = sh->symbols->get_function("main");

+   if (f != NULL) {

+      exec_list void_parameters;

+

+      /* Look for the 'void main()' signature and ensure that it's defined.

+       * This keeps the linker from accidentally pick a shader that just

+       * contains a prototype for main.

+       *

+       * We don't have to check for multiple definitions of main (in multiple

+       * shaders) because that would have already been caught above.

+       */

+      ir_function_signature *sig = f->matching_signature(&void_parameters);

+      if ((sig != NULL) && sig->is_defined) {

+	 return sig;

+      }

+   }

+

+   return NULL;

+}

+

+

+/**

+ * Combine a group of shaders for a single stage to generate a linked shader

+ *

+ * \note

+ * If this function is supplied a single shader, it is cloned, and the new

+ * shader is returned.

+ */

+static struct gl_shader *

+link_intrastage_shaders(void *mem_ctx,

+			struct gl_context *ctx,

+			struct gl_shader_program *prog,

+			struct gl_shader **shader_list,

+			unsigned num_shaders)

+{

+   /* Check that global variables defined in multiple shaders are consistent.

+    */

+   if (!cross_validate_globals(prog, shader_list, num_shaders, false))

+      return NULL;

+

+   /* Check that there is only a single definition of each function signature

+    * across all shaders.

+    */

+   for (unsigned i = 0; i < (num_shaders - 1); i++) {

+      foreach_list(node, shader_list[i]->ir) {

+	 ir_function *const f = ((ir_instruction *) node)->as_function();

+

+	 if (f == NULL)

+	    continue;

+

+	 for (unsigned j = i + 1; j < num_shaders; j++) {

+	    ir_function *const other =

+	       shader_list[j]->symbols->get_function(f->name);

+

+	    /* If the other shader has no function (and therefore no function

+	     * signatures) with the same name, skip to the next shader.

+	     */

+	    if (other == NULL)

+	       continue;

+

+	    foreach_iter (exec_list_iterator, iter, *f) {

+	       ir_function_signature *sig =

+		  (ir_function_signature *) iter.get();

+

+	       if (!sig->is_defined || sig->is_builtin)

+		  continue;

+

+	       ir_function_signature *other_sig =

+		  other->exact_matching_signature(& sig->parameters);

+

+	       if ((other_sig != NULL) && other_sig->is_defined

+		   && !other_sig->is_builtin) {

+		  linker_error_printf(prog,

+				      "function `%s' is multiply defined",

+				      f->name);

+		  return NULL;

+	       }

+	    }

+	 }

+      }

+   }

+

+   /* Find the shader that defines main, and make a clone of it.

+    *

+    * Starting with the clone, search for undefined references.  If one is

+    * found, find the shader that defines it.  Clone the reference and add

+    * it to the shader.  Repeat until there are no undefined references or

+    * until a reference cannot be resolved.

+    */

+   gl_shader *main = NULL;

+   for (unsigned i = 0; i < num_shaders; i++) {

+      if (get_main_function_signature(shader_list[i]) != NULL) {

+	 main = shader_list[i];

+	 break;

+      }

+   }

+

+   if (main == NULL) {

+      linker_error_printf(prog, "%s shader lacks `main'\n",

+			  (shader_list[0]->Type == GL_VERTEX_SHADER)

+			  ? "vertex" : "fragment");

+      return NULL;

+   }

+

+   gl_shader *linked = ctx->Driver.NewShader(NULL, 0, main->Type);

+   linked->ir = new(linked) exec_list;

+   clone_ir_list(mem_ctx, linked->ir, main->ir);

+

+   populate_symbol_table(linked);

+

+   /* The a pointer to the main function in the final linked shader (i.e., the

+    * copy of the original shader that contained the main function).

+    */

+   ir_function_signature *const main_sig = get_main_function_signature(linked);

+

+   /* Move any instructions other than variable declarations or function

+    * declarations into main.

+    */

+   exec_node *insertion_point =

+      move_non_declarations(linked->ir, (exec_node *) &main_sig->body, false,

+			    linked);

+

+   for (unsigned i = 0; i < num_shaders; i++) {

+      if (shader_list[i] == main)

+	 continue;

+

+      insertion_point = move_non_declarations(shader_list[i]->ir,

+					      insertion_point, true, linked);

+   }

+

+   /* Resolve initializers for global variables in the linked shader.

+    */

+   unsigned num_linking_shaders = num_shaders;

+   for (unsigned i = 0; i < num_shaders; i++)

+      num_linking_shaders += shader_list[i]->num_builtins_to_link;

+

+   gl_shader **linking_shaders =

+      (gl_shader **) calloc(num_linking_shaders, sizeof(gl_shader *));

+

+   memcpy(linking_shaders, shader_list,

+	  sizeof(linking_shaders[0]) * num_shaders);

+

+   unsigned idx = num_shaders;

+   for (unsigned i = 0; i < num_shaders; i++) {

+      memcpy(&linking_shaders[idx], shader_list[i]->builtins_to_link,

+	     sizeof(linking_shaders[0]) * shader_list[i]->num_builtins_to_link);

+      idx += shader_list[i]->num_builtins_to_link;

+   }

+

+   assert(idx == num_linking_shaders);

+

+   if (!link_function_calls(prog, linked, linking_shaders,

+			    num_linking_shaders)) {

+      ctx->Driver.DeleteShader(ctx, linked);

+      linked = NULL;

+   }

+

+   free(linking_shaders);

+

+   /* Make a pass over all variable declarations to ensure that arrays with

+    * unspecified sizes have a size specified.  The size is inferred from the

+    * max_array_access field.

+    */

+   if (linked != NULL) {

+      class array_sizing_visitor : public ir_hierarchical_visitor {

+      public:

+	 virtual ir_visitor_status visit(ir_variable *var)

+	 {

+	    if (var->type->is_array() && (var->type->length == 0)) {

+	       const glsl_type *type =

+		  glsl_type::get_array_instance(var->type->fields.array,

+						var->max_array_access + 1);

+

+	       assert(type != NULL);

+	       var->type = type;

+	    }

+

+	    return visit_continue;

+	 }

+      } v;

+

+      v.run(linked->ir);

+   }

+

+   return linked;

+}

+

+

+struct uniform_node {

+   exec_node link;

+   struct gl_uniform *u;

+   unsigned slots;

+};

+

+/**

+ * Update the sizes of linked shader uniform arrays to the maximum

+ * array index used.

+ *

+ * From page 81 (page 95 of the PDF) of the OpenGL 2.1 spec:

+ *

+ *     If one or more elements of an array are active,

+ *     GetActiveUniform will return the name of the array in name,

+ *     subject to the restrictions listed above. The type of the array

+ *     is returned in type. The size parameter contains the highest

+ *     array element index used, plus one. The compiler or linker

+ *     determines the highest index used.  There will be only one

+ *     active uniform reported by the GL per uniform array.

+

+ */

+static void

+update_array_sizes(struct gl_shader_program *prog)

+{

+   for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {

+	 if (prog->_LinkedShaders[i] == NULL)

+	    continue;

+

+      foreach_list(node, prog->_LinkedShaders[i]->ir) {

+	 ir_variable *const var = ((ir_instruction *) node)->as_variable();

+

+	 if ((var == NULL) || (var->mode != ir_var_uniform &&

+			       var->mode != ir_var_in &&

+			       var->mode != ir_var_out) ||

+	     !var->type->is_array())

+	    continue;

+

+	 unsigned int size = var->max_array_access;

+	 for (unsigned j = 0; j < MESA_SHADER_TYPES; j++) {

+	       if (prog->_LinkedShaders[j] == NULL)

+		  continue;

+

+	    foreach_list(node2, prog->_LinkedShaders[j]->ir) {

+	       ir_variable *other_var = ((ir_instruction *) node2)->as_variable();

+	       if (!other_var)

+		  continue;

+

+	       if (strcmp(var->name, other_var->name) == 0 &&

+		   other_var->max_array_access > size) {

+		  size = other_var->max_array_access;

+	       }

+	    }

+	 }

+

+	 if (size + 1 != var->type->fields.array->length) {

+	    var->type = glsl_type::get_array_instance(var->type->fields.array,

+						      size + 1);

+	    /* FINISHME: We should update the types of array

+	     * dereferences of this variable now.

+	     */

+	 }

+      }

+   }

+}

+

+static void

+add_uniform(void *mem_ctx, exec_list *uniforms, struct hash_table *ht,

+	    const char *name, const glsl_type *type, GLenum shader_type,

+	    unsigned *next_shader_pos, unsigned *total_uniforms)

+{

+   if (type->is_record()) {

+      for (unsigned int i = 0; i < type->length; i++) {

+	 const glsl_type *field_type = type->fields.structure[i].type;

+	 char *field_name = ralloc_asprintf(mem_ctx, "%s.%s", name,

+					    type->fields.structure[i].name);

+

+	 add_uniform(mem_ctx, uniforms, ht, field_name, field_type,

+		     shader_type, next_shader_pos, total_uniforms);

+      }

+   } else {

+      uniform_node *n = (uniform_node *) hash_table_find(ht, name);

+      unsigned int vec4_slots;

+      const glsl_type *array_elem_type = NULL;

+

+      if (type->is_array()) {

+	 array_elem_type = type->fields.array;

+	 /* Array of structures. */

+	 if (array_elem_type->is_record()) {

+	    for (unsigned int i = 0; i < type->length; i++) {

+	       char *elem_name = ralloc_asprintf(mem_ctx, "%s[%d]", name, i);

+	       add_uniform(mem_ctx, uniforms, ht, elem_name, array_elem_type,

+			   shader_type, next_shader_pos, total_uniforms);

+	    }

+	    return;

+	 }

+      }

+

+      /* Fix the storage size of samplers at 1 vec4 each. Be sure to pad out

+       * vectors to vec4 slots.

+       */

+      if (type->is_array()) {

+	 if (array_elem_type->is_sampler())

+	    vec4_slots = type->length;

+	 else

+	    vec4_slots = type->length * array_elem_type->matrix_columns;

+      } else if (type->is_sampler()) {

+	 vec4_slots = 1;

+      } else {

+	 vec4_slots = type->matrix_columns;

+      }

+

+      if (n == NULL) {

+	 n = (uniform_node *) calloc(1, sizeof(struct uniform_node));

+	 n->u = (gl_uniform *) calloc(1, sizeof(struct gl_uniform));

+	 n->slots = vec4_slots;

+

+	 n->u->Name = strdup(name);

+	 n->u->Type = type;

+	 n->u->VertPos = -1;

+	 n->u->FragPos = -1;

+	 n->u->GeomPos = -1;

+	 (*total_uniforms)++;

+

+	 hash_table_insert(ht, n, name);

+	 uniforms->push_tail(& n->link);

+      }

+

+      switch (shader_type) {

+      case GL_VERTEX_SHADER:

+	 n->u->VertPos = *next_shader_pos;

+	 break;

+      case GL_FRAGMENT_SHADER:

+	 n->u->FragPos = *next_shader_pos;

+	 break;

+      case GL_GEOMETRY_SHADER:

+	 n->u->GeomPos = *next_shader_pos;

+	 break;

+      }

+

+      (*next_shader_pos) += vec4_slots;

+   }

+}

+

+void

+assign_uniform_locations(struct gl_shader_program *prog)

+{

+   /* */

+   exec_list uniforms;

+   unsigned total_uniforms = 0;

+   hash_table *ht = hash_table_ctor(32, hash_table_string_hash,

+				    hash_table_string_compare);

+   void *mem_ctx = ralloc_context(NULL);

+

+   for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {

+      if (prog->_LinkedShaders[i] == NULL)

+	 continue;

+

+      unsigned next_position = 0;

+

+      foreach_list(node, prog->_LinkedShaders[i]->ir) {

+	 ir_variable *const var = ((ir_instruction *) node)->as_variable();

+

+	 if ((var == NULL) || (var->mode != ir_var_uniform))

+	    continue;

+

+	 if (strncmp(var->name, "gl_", 3) == 0) {

+	    /* At the moment, we don't allocate uniform locations for

+	     * builtin uniforms.  It's permitted by spec, and we'll

+	     * likely switch to doing that at some point, but not yet.

+	     */

+	    continue;

+	 }

+

+	 var->location = next_position;

+	 add_uniform(mem_ctx, &uniforms, ht, var->name, var->type,

+		     prog->_LinkedShaders[i]->Type,

+		     &next_position, &total_uniforms);

+      }

+   }

+

+   ralloc_free(mem_ctx);

+

+   gl_uniform_list *ul = (gl_uniform_list *)

+      calloc(1, sizeof(gl_uniform_list));

+

+   ul->Size = total_uniforms;

+   ul->NumUniforms = total_uniforms;

+   ul->Uniforms = (gl_uniform *) calloc(total_uniforms, sizeof(gl_uniform));

+

+   unsigned idx = 0;

+   uniform_node *next;

+   for (uniform_node *node = (uniform_node *) uniforms.head

+	   ; node->link.next != NULL

+	   ; node = next) {

+      next = (uniform_node *) node->link.next;

+

+      node->link.remove();

+      memcpy(&ul->Uniforms[idx], node->u, sizeof(gl_uniform));

+      idx++;

+

+      free(node->u);

+      free(node);

+   }

+

+   hash_table_dtor(ht);

+

+   prog->Uniforms = ul;

+}

+

+

+/**

+ * Find a contiguous set of available bits in a bitmask

+ *

+ * \param used_mask     Bits representing used (1) and unused (0) locations

+ * \param needed_count  Number of contiguous bits needed.

+ *

+ * \return

+ * Base location of the available bits on success or -1 on failure.

+ */

+int

+find_available_slots(unsigned used_mask, unsigned needed_count)

+{

+   unsigned needed_mask = (1 << needed_count) - 1;

+   const int max_bit_to_test = (8 * sizeof(used_mask)) - needed_count;

+

+   /* The comparison to 32 is redundant, but without it GCC emits "warning:

+    * cannot optimize possibly infinite loops" for the loop below.

+    */

+   if ((needed_count == 0) || (max_bit_to_test < 0) || (max_bit_to_test > 32))

+      return -1;

+

+   for (int i = 0; i <= max_bit_to_test; i++) {

+      if ((needed_mask & ~used_mask) == needed_mask)

+	 return i;

+

+      needed_mask <<= 1;

+   }

+

+   return -1;

+}

+

+

+bool

+assign_attribute_locations(gl_shader_program *prog, unsigned max_attribute_index)

+{

+   /* Mark invalid attribute locations as being used.

+    */

+   unsigned used_locations = (max_attribute_index >= 32)

+      ? ~0 : ~((1 << max_attribute_index) - 1);

+

+   gl_shader *const sh = prog->_LinkedShaders[0];

+   assert(sh->Type == GL_VERTEX_SHADER);

+

+   /* Operate in a total of four passes.

+    *

+    * 1. Invalidate the location assignments for all vertex shader inputs.

+    *

+    * 2. Assign locations for inputs that have user-defined (via

+    *    glBindVertexAttribLocation) locatoins.

+    *

+    * 3. Sort the attributes without assigned locations by number of slots

+    *    required in decreasing order.  Fragmentation caused by attribute

+    *    locations assigned by the application may prevent large attributes

+    *    from having enough contiguous space.

+    *

+    * 4. Assign locations to any inputs without assigned locations.

+    */

+

+   invalidate_variable_locations(sh, ir_var_in, VERT_ATTRIB_GENERIC0);

+

+   if (prog->Attributes != NULL) {

+      for (unsigned i = 0; i < prog->Attributes->NumParameters; i++) {

+	 ir_variable *const var =

+	    sh->symbols->get_variable(prog->Attributes->Parameters[i].Name);

+

+	 /* Note: attributes that occupy multiple slots, such as arrays or

+	  * matrices, may appear in the attrib array multiple times.

+	  */

+	 if ((var == NULL) || (var->location != -1))

+	    continue;

+

+	 /* From page 61 of the OpenGL 4.0 spec:

+	  *

+	  *     "LinkProgram will fail if the attribute bindings assigned by

+	  *     BindAttribLocation do not leave not enough space to assign a

+	  *     location for an active matrix attribute or an active attribute

+	  *     array, both of which require multiple contiguous generic

+	  *     attributes."

+	  *

+	  * Previous versions of the spec contain similar language but omit the

+	  * bit about attribute arrays.

+	  *

+	  * Page 61 of the OpenGL 4.0 spec also says:

+	  *

+	  *     "It is possible for an application to bind more than one

+	  *     attribute name to the same location. This is referred to as

+	  *     aliasing. This will only work if only one of the aliased

+	  *     attributes is active in the executable program, or if no path

+	  *     through the shader consumes more than one attribute of a set

+	  *     of attributes aliased to the same location. A link error can

+	  *     occur if the linker determines that every path through the

+	  *     shader consumes multiple aliased attributes, but

+	  *     implementations are not required to generate an error in this

+	  *     case."

+	  *

+	  * These two paragraphs are either somewhat contradictory, or I don't

+	  * fully understand one or both of them.

+	  */

+	 /* FINISHME: The code as currently written does not support attribute

+	  * FINISHME: location aliasing (see comment above).

+	  */

+	 const int attr = prog->Attributes->Parameters[i].StateIndexes[0];

+	 const unsigned slots = count_attribute_slots(var->type);

+

+	 /* Mask representing the contiguous slots that will be used by this

+	  * attribute.

+	  */

+	 const unsigned use_mask = (1 << slots) - 1;

+

+	 /* Generate a link error if the set of bits requested for this

+	  * attribute overlaps any previously allocated bits.

+	  */

+	 if ((~(use_mask << attr) & used_locations) != used_locations) {

+	    linker_error_printf(prog,

+				"insufficient contiguous attribute locations "

+				"available for vertex shader input `%s'",

+				var->name);

+	    return false;

+	 }

+

+	 var->location = VERT_ATTRIB_GENERIC0 + attr;

+	 used_locations |= (use_mask << attr);

+      }

+   }

+

+   /* Temporary storage for the set of attributes that need locations assigned.

+    */

+   struct temp_attr {

+      unsigned slots;

+      ir_variable *var;

+

+      /* Used below in the call to qsort. */

+      static int compare(const void *a, const void *b)

+      {

+	 const temp_attr *const l = (const temp_attr *) a;

+	 const temp_attr *const r = (const temp_attr *) b;

+

+	 /* Reversed because we want a descending order sort below. */

+	 return r->slots - l->slots;

+      }

+   } to_assign[16];

+

+   unsigned num_attr = 0;

+

+   foreach_list(node, sh->ir) {

+      ir_variable *const var = ((ir_instruction *) node)->as_variable();

+

+      if ((var == NULL) || (var->mode != ir_var_in))

+	 continue;

+

+      if (var->explicit_location) {

+	 const unsigned slots = count_attribute_slots(var->type);

+	 const unsigned use_mask = (1 << slots) - 1;

+	 const int attr = var->location - VERT_ATTRIB_GENERIC0;

+

+	 if ((var->location >= (int)(max_attribute_index + VERT_ATTRIB_GENERIC0))

+	     || (var->location < 0)) {

+	    linker_error_printf(prog,

+				"invalid explicit location %d specified for "

+				"`%s'\n",

+				(var->location < 0) ? var->location : attr,

+				var->name);

+	    return false;

+	 } else if (var->location >= VERT_ATTRIB_GENERIC0) {

+	    used_locations |= (use_mask << attr);

+	 }

+      }

+

+      /* The location was explicitly assigned, nothing to do here.

+       */

+      if (var->location != -1)

+	 continue;

+

+      to_assign[num_attr].slots = count_attribute_slots(var->type);

+      to_assign[num_attr].var = var;

+      num_attr++;

+   }

+

+   /* If all of the attributes were assigned locations by the application (or

+    * are built-in attributes with fixed locations), return early.  This should

+    * be the common case.

+    */

+   if (num_attr == 0)

+      return true;

+

+   qsort(to_assign, num_attr, sizeof(to_assign[0]), temp_attr::compare);

+

+   /* VERT_ATTRIB_GENERIC0 is a psdueo-alias for VERT_ATTRIB_POS.  It can only

+    * be explicitly assigned by via glBindAttribLocation.  Mark it as reserved

+    * to prevent it from being automatically allocated below.

+    */

+   find_deref_visitor find("gl_Vertex");

+   find.run(sh->ir);

+   if (find.variable_found())

+      used_locations |= (1 << 0);

+

+   for (unsigned i = 0; i < num_attr; i++) {

+      /* Mask representing the contiguous slots that will be used by this

+       * attribute.

+       */

+      const unsigned use_mask = (1 << to_assign[i].slots) - 1;

+

+      int location = find_available_slots(used_locations, to_assign[i].slots);

+

+      if (location < 0) {

+	 linker_error_printf(prog,

+			     "insufficient contiguous attribute locations "

+			     "available for vertex shader input `%s'",

+			     to_assign[i].var->name);

+	 return false;

+      }

+

+      to_assign[i].var->location = VERT_ATTRIB_GENERIC0 + location;

+      used_locations |= (use_mask << location);

+   }

+

+   return true;

+}

+

+

+/**

+ * Demote shader inputs and outputs that are not used in other stages

+ */

+void

+demote_shader_inputs_and_outputs(gl_shader *sh, enum ir_variable_mode mode)

+{

+   foreach_list(node, sh->ir) {

+      ir_variable *const var = ((ir_instruction *) node)->as_variable();

+

+      if ((var == NULL) || (var->mode != int(mode)))

+	 continue;

+

+      /* A shader 'in' or 'out' variable is only really an input or output if

+       * its value is used by other shader stages.  This will cause the variable

+       * to have a location assigned.

+       */

+      if (var->location == -1) {

+	 var->mode = ir_var_auto;

+      }

+   }

+}

+

+

+void

+assign_varying_locations(struct gl_shader_program *prog,

+			 gl_shader *producer, gl_shader *consumer)

+{

+   /* FINISHME: Set dynamically when geometry shader support is added. */

+   unsigned output_index = VERT_RESULT_VAR0;

+   unsigned input_index = FRAG_ATTRIB_VAR0;

+

+   /* Operate in a total of three passes.

+    *

+    * 1. Assign locations for any matching inputs and outputs.

+    *

+    * 2. Mark output variables in the producer that do not have locations as

+    *    not being outputs.  This lets the optimizer eliminate them.

+    *

+    * 3. Mark input variables in the consumer that do not have locations as

+    *    not being inputs.  This lets the optimizer eliminate them.

+    */

+

+   invalidate_variable_locations(producer, ir_var_out, VERT_RESULT_VAR0);

+   invalidate_variable_locations(consumer, ir_var_in, FRAG_ATTRIB_VAR0);

+

+   foreach_list(node, producer->ir) {

+      ir_variable *const output_var = ((ir_instruction *) node)->as_variable();

+

+      if ((output_var == NULL) || (output_var->mode != ir_var_out)

+	  || (output_var->location != -1))

+	 continue;

+

+      ir_variable *const input_var =

+	 consumer->symbols->get_variable(output_var->name);

+

+      if ((input_var == NULL) || (input_var->mode != ir_var_in))

+	 continue;

+

+      assert(input_var->location == -1);

+

+      output_var->location = output_index;

+      input_var->location = input_index;

+

+      /* FINISHME: Support for "varying" records in GLSL 1.50. */

+      assert(!output_var->type->is_record());

+

+      if (output_var->type->is_array()) {

+	 const unsigned slots = output_var->type->length

+	    * output_var->type->fields.array->matrix_columns;

+

+	 output_index += slots;

+	 input_index += slots;

+      } else {

+	 const unsigned slots = output_var->type->matrix_columns;

+

+	 output_index += slots;

+	 input_index += slots;

+      }

+   }

+

+   foreach_list(node, consumer->ir) {

+      ir_variable *const var = ((ir_instruction *) node)->as_variable();

+

+      if ((var == NULL) || (var->mode != ir_var_in))

+	 continue;

+

+      if (var->location == -1) {

+	 if (prog->Version <= 120) {

+	    /* On page 25 (page 31 of the PDF) of the GLSL 1.20 spec:

+	     *

+	     *     Only those varying variables used (i.e. read) in

+	     *     the fragment shader executable must be written to

+	     *     by the vertex shader executable; declaring

+	     *     superfluous varying variables in a vertex shader is

+	     *     permissible.

+	     *

+	     * We interpret this text as meaning that the VS must

+	     * write the variable for the FS to read it.  See

+	     * "glsl1-varying read but not written" in piglit.

+	     */

+

+	    linker_error_printf(prog, "fragment shader varying %s not written "

+				"by vertex shader\n.", var->name);

+	    prog->LinkStatus = false;

+	 }

+

+	 /* An 'in' variable is only really a shader input if its

+	  * value is written by the previous stage.

+	  */

+	 var->mode = ir_var_auto;

+      }

+   }

+}

+

+

+void

+link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)

+{

+   void *mem_ctx = ralloc_context(NULL); // temporary linker context

+

+   prog->LinkStatus = false;

+   prog->Validated = false;

+   prog->_Used = false;

+

+   if (prog->InfoLog != NULL)

+      ralloc_free(prog->InfoLog);

+

+   prog->InfoLog = ralloc_strdup(NULL, "");

+

+   /* Separate the shaders into groups based on their type.

+    */

+   struct gl_shader **vert_shader_list;

+   unsigned num_vert_shaders = 0;

+   struct gl_shader **frag_shader_list;

+   unsigned num_frag_shaders = 0;

+

+   vert_shader_list = (struct gl_shader **)

+      calloc(2 * prog->NumShaders, sizeof(struct gl_shader *));

+   frag_shader_list =  &vert_shader_list[prog->NumShaders];

+

+   unsigned min_version = UINT_MAX;

+   unsigned max_version = 0;

+   for (unsigned i = 0; i < prog->NumShaders; i++) {

+      min_version = MIN2(min_version, prog->Shaders[i]->Version);

+      max_version = MAX2(max_version, prog->Shaders[i]->Version);

+

+      switch (prog->Shaders[i]->Type) {

+      case GL_VERTEX_SHADER:

+	 vert_shader_list[num_vert_shaders] = prog->Shaders[i];

+	 num_vert_shaders++;

+	 break;

+      case GL_FRAGMENT_SHADER:

+	 frag_shader_list[num_frag_shaders] = prog->Shaders[i];

+	 num_frag_shaders++;

+	 break;

+      case GL_GEOMETRY_SHADER:

+	 /* FINISHME: Support geometry shaders. */

+	 assert(prog->Shaders[i]->Type != GL_GEOMETRY_SHADER);

+	 break;

+      }

+   }

+

+   /* Previous to GLSL version 1.30, different compilation units could mix and

+    * match shading language versions.  With GLSL 1.30 and later, the versions

+    * of all shaders must match.

+    */

+   assert(min_version >= 100);

+   assert(max_version <= 130);

+   if ((max_version >= 130 || min_version == 100)

+       && min_version != max_version) {

+      linker_error_printf(prog, "all shaders must use same shading "

+			  "language version\n");

+      goto done;

+   }

+

+   prog->Version = max_version;

+

+   for (unsigned int i = 0; i < MESA_SHADER_TYPES; i++) {

+      if (prog->_LinkedShaders[i] != NULL)

+	 ctx->Driver.DeleteShader(ctx, prog->_LinkedShaders[i]);

+

+      prog->_LinkedShaders[i] = NULL;

+   }

+

+   /* Link all shaders for a particular stage and validate the result.

+    */

+   if (num_vert_shaders > 0) {

+      gl_shader *const sh =

+	 link_intrastage_shaders(mem_ctx, ctx, prog, vert_shader_list,

+				 num_vert_shaders);

+

+      if (sh == NULL)

+	 goto done;

+

+      if (!validate_vertex_shader_executable(prog, sh))

+	 goto done;

+

+      _mesa_reference_shader(ctx, &prog->_LinkedShaders[MESA_SHADER_VERTEX],

+			     sh);

+   }

+

+   if (num_frag_shaders > 0) {

+      gl_shader *const sh =

+	 link_intrastage_shaders(mem_ctx, ctx, prog, frag_shader_list,

+				 num_frag_shaders);

+

+      if (sh == NULL)

+	 goto done;

+

+      if (!validate_fragment_shader_executable(prog, sh))

+	 goto done;

+

+      _mesa_reference_shader(ctx, &prog->_LinkedShaders[MESA_SHADER_FRAGMENT],

+			     sh);

+   }

+

+   /* Here begins the inter-stage linking phase.  Some initial validation is

+    * performed, then locations are assigned for uniforms, attributes, and

+    * varyings.

+    */

+   if (cross_validate_uniforms(prog)) {

+      unsigned prev;

+

+      for (prev = 0; prev < MESA_SHADER_TYPES; prev++) {

+	 if (prog->_LinkedShaders[prev] != NULL)

+	    break;

+      }

+

+      /* Validate the inputs of each stage with the output of the preceeding

+       * stage.

+       */

+      for (unsigned i = prev + 1; i < MESA_SHADER_TYPES; i++) {

+	 if (prog->_LinkedShaders[i] == NULL)

+	    continue;

+

+	 if (!cross_validate_outputs_to_inputs(prog,

+					       prog->_LinkedShaders[prev],

+					       prog->_LinkedShaders[i]))

+	    goto done;

+

+	 prev = i;

+      }

+

+      prog->LinkStatus = true;

+   }

+

+   /* Do common optimization before assigning storage for attributes,

+    * uniforms, and varyings.  Later optimization could possibly make

+    * some of that unused.

+    */

+   for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {

+      if (prog->_LinkedShaders[i] == NULL)

+	 continue;

+

+      while (do_common_optimization(prog->_LinkedShaders[i]->ir, true, 32))

+	 ;

+   }

+

+   update_array_sizes(prog);

+

+   assign_uniform_locations(prog);

+

+   if (prog->_LinkedShaders[MESA_SHADER_VERTEX] != NULL) {

+      /* FINISHME: The value of the max_attribute_index parameter is

+       * FINISHME: implementation dependent based on the value of

+       * FINISHME: GL_MAX_VERTEX_ATTRIBS.  GL_MAX_VERTEX_ATTRIBS must be

+       * FINISHME: at least 16, so hardcode 16 for now.

+       */

+      if (!assign_attribute_locations(prog, 16)) {

+	 prog->LinkStatus = false;

+	 goto done;

+      }

+   }

+

+   unsigned prev;

+   for (prev = 0; prev < MESA_SHADER_TYPES; prev++) {

+      if (prog->_LinkedShaders[prev] != NULL)

+	 break;

+   }

+

+   for (unsigned i = prev + 1; i < MESA_SHADER_TYPES; i++) {

+      if (prog->_LinkedShaders[i] == NULL)

+	 continue;

+

+      assign_varying_locations(prog,

+			       prog->_LinkedShaders[prev],

+			       prog->_LinkedShaders[i]);

+      prev = i;

+   }

+

+   if (prog->_LinkedShaders[MESA_SHADER_VERTEX] != NULL) {

+      demote_shader_inputs_and_outputs(prog->_LinkedShaders[MESA_SHADER_VERTEX],

+				       ir_var_out);

+   }

+

+   if (prog->_LinkedShaders[MESA_SHADER_GEOMETRY] != NULL) {

+      gl_shader *const sh = prog->_LinkedShaders[MESA_SHADER_GEOMETRY];

+

+      demote_shader_inputs_and_outputs(sh, ir_var_in);

+      demote_shader_inputs_and_outputs(sh, ir_var_inout);

+      demote_shader_inputs_and_outputs(sh, ir_var_out);

+   }

+

+   if (prog->_LinkedShaders[MESA_SHADER_FRAGMENT] != NULL) {

+      gl_shader *const sh = prog->_LinkedShaders[MESA_SHADER_FRAGMENT];

+

+      demote_shader_inputs_and_outputs(sh, ir_var_in);

+   }

+

+   /* OpenGL ES requires that a vertex shader and a fragment shader both be

+    * present in a linked program.  By checking for use of shading language

+    * version 1.00, we also catch the GL_ARB_ES2_compatibility case.

+    */

+   if (ctx->API == API_OPENGLES2 || prog->Version == 100) {

+      if (prog->_LinkedShaders[MESA_SHADER_VERTEX] == NULL) {

+	 linker_error_printf(prog, "program lacks a vertex shader\n");

+	 prog->LinkStatus = false;

+      } else if (prog->_LinkedShaders[MESA_SHADER_FRAGMENT] == NULL) {

+	 linker_error_printf(prog, "program lacks a fragment shader\n");

+	 prog->LinkStatus = false;

+      }

+   }

+

+   /* FINISHME: Assign fragment shader output locations. */

+

+done:

+   free(vert_shader_list);

+

+   for (unsigned i = 0; i < MESA_SHADER_TYPES; i++) {

+      if (prog->_LinkedShaders[i] == NULL)

+	 continue;

+

+      /* Retain any live IR, but trash the rest. */

+      reparent_ir(prog->_LinkedShaders[i]->ir, prog->_LinkedShaders[i]->ir);

+   }

+

+   ralloc_free(mem_ctx);

+}