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/*

 * Copyright © 2012 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 link_varyings.cpp

 *

 * Linker functions related specifically to linking varyings between shader

 * stages.

 */

#include "main/mtypes.h"

#include "glsl_symbol_table.h"

#include "glsl_parser_extras.h"

#include "ir_optimization.h"

#include "linker.h"

#include "link_varyings.h"

#include "main/macros.h"

#include "program/hash_table.h"

#include "program.h"

/**

 * 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;

   const char *const producer_stage =

      _mesa_glsl_shader_target_name(producer->Type);

   const char *const consumer_stage =

      _mesa_glsl_shader_target_name(consumer->Type);

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

    */

   foreach_list(node, producer->ir) {

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

      if ((var == NULL) || (var->mode != ir_var_shader_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();

      if ((input == NULL) || (input->mode != ir_var_shader_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.  Applications 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(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(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(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(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;

}

/**

 * Initialize this object based on a string that was passed to

 * glTransformFeedbackVaryings.

 *

 * If the input is mal-formed, this call still succeeds, but it sets

 * this->var_name to a mal-formed input, so tfeedback_decl::find_output_var()

 * will fail to find any matching variable.

 */

void

tfeedback_decl::init(struct gl_context *ctx, struct gl_shader_program *prog,

                     const void *mem_ctx, const char *input)

{

   /* We don't have to be pedantic about what is a valid GLSL variable name,

    * because any variable with an invalid name can't exist in the IR anyway.

    */

   this->location = -1;

   this->orig_name = input;

   this->is_clip_distance_mesa = false;

   this->skip_components = 0;

   this->next_buffer_separator = false;

   this->matched_candidate = NULL;

   if (ctx->Extensions.ARB_transform_feedback3) {

      /* Parse gl_NextBuffer. */

      if (strcmp(input, "gl_NextBuffer") == 0) {

         this->next_buffer_separator = true;

         return;

      }

      /* Parse gl_SkipComponents. */

      if (strcmp(input, "gl_SkipComponents1") == 0)

         this->skip_components = 1;

      else if (strcmp(input, "gl_SkipComponents2") == 0)

         this->skip_components = 2;

      else if (strcmp(input, "gl_SkipComponents3") == 0)

         this->skip_components = 3;

      else if (strcmp(input, "gl_SkipComponents4") == 0)

         this->skip_components = 4;

      if (this->skip_components)

         return;

   }

   /* Parse a declaration. */

   const char *base_name_end;

   long subscript = parse_program_resource_name(input, &base_name_end);

   this->var_name = ralloc_strndup(mem_ctx, input, base_name_end - input);

   if (subscript >= 0) {

      this->array_subscript = subscript;

      this->is_subscripted = true;

   } else {

      this->is_subscripted = false;

   }

   /* For drivers that lower gl_ClipDistance to gl_ClipDistanceMESA, this

    * class must behave specially to account for the fact that gl_ClipDistance

    * is converted from a float[8] to a vec4[2].

    */

   if (ctx->ShaderCompilerOptions[MESA_SHADER_VERTEX].LowerClipDistance &&

       strcmp(this->var_name, "gl_ClipDistance") == 0) {

      this->is_clip_distance_mesa = true;

   }

}

/**

 * Determine whether two tfeedback_decl objects refer to the same variable and

 * array index (if applicable).

 */

bool

tfeedback_decl::is_same(const tfeedback_decl &x, const tfeedback_decl &y)

{

   assert(x.is_varying() && y.is_varying());

   if (strcmp(x.var_name, y.var_name) != 0)

      return false;

   if (x.is_subscripted != y.is_subscripted)

      return false;

   if (x.is_subscripted && x.array_subscript != y.array_subscript)

      return false;

   return true;

}

/**

 * Assign a location for this tfeedback_decl object based on the transform

 * feedback candidate found by find_candidate.

 *

 * If an error occurs, the error is reported through linker_error() and false

 * is returned.

 */

bool

tfeedback_decl::assign_location(struct gl_context *ctx,

                                struct gl_shader_program *prog)

{

   assert(this->is_varying());

   unsigned fine_location

      = this->matched_candidate->toplevel_var->location * 4

      + this->matched_candidate->toplevel_var->location_frac

      + this->matched_candidate->offset;

   if (this->matched_candidate->type->is_array()) {

      /* Array variable */

      const unsigned matrix_cols =

         this->matched_candidate->type->fields.array->matrix_columns;

      const unsigned vector_elements =

         this->matched_candidate->type->fields.array->vector_elements;

      unsigned actual_array_size = this->is_clip_distance_mesa ?

         prog->Vert.ClipDistanceArraySize :

         this->matched_candidate->type->array_size();

      if (this->is_subscripted) {

         /* Check array bounds. */

         if (this->array_subscript >= actual_array_size) {

            linker_error(prog, "Transform feedback varying %s has index "

                         "%i, but the array size is %u.",

                         this->orig_name, this->array_subscript,

                         actual_array_size);

            return false;

         }

         unsigned array_elem_size = this->is_clip_distance_mesa ?

            1 : vector_elements * matrix_cols;

         fine_location += array_elem_size * this->array_subscript;

         this->size = 1;

      } else {

         this->size = actual_array_size;

      }

      this->vector_elements = vector_elements;

      this->matrix_columns = matrix_cols;

      if (this->is_clip_distance_mesa)

         this->type = GL_FLOAT;

      else

         this->type = this->matched_candidate->type->fields.array->gl_type;

   } else {

      /* Regular variable (scalar, vector, or matrix) */

      if (this->is_subscripted) {

         linker_error(prog, "Transform feedback varying %s requested, "

                      "but %s is not an array.",

                      this->orig_name, this->var_name);

         return false;

      }

      this->size = 1;

      this->vector_elements = this->matched_candidate->type->vector_elements;

      this->matrix_columns = this->matched_candidate->type->matrix_columns;

      this->type = this->matched_candidate->type->gl_type;

   }

   this->location = fine_location / 4;

   this->location_frac = fine_location % 4;

   /* From GL_EXT_transform_feedback:

    *   A program will fail to link if:

    *

    *   * the total number of components to capture in any varying

    *     variable in  is greater than the constant

    *     MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS_EXT and the

    *     buffer mode is SEPARATE_ATTRIBS_EXT;

    */

   if (prog->TransformFeedback.BufferMode == GL_SEPARATE_ATTRIBS &&

       this->num_components() >

       ctx->Const.MaxTransformFeedbackSeparateComponents) {

      linker_error(prog, "Transform feedback varying %s exceeds "

                   "MAX_TRANSFORM_FEEDBACK_SEPARATE_COMPONENTS.",

                   this->orig_name);

      return false;

   }

   return true;

}

unsigned

tfeedback_decl::get_num_outputs() const

{

   if (!this->is_varying()) {

      return 0;

   }

   return (this->num_components() + this->location_frac + 3)/4;

}

/**

 * Update gl_transform_feedback_info to reflect this tfeedback_decl.

 *

 * If an error occurs, the error is reported through linker_error() and false

 * is returned.

 */

bool

tfeedback_decl::store(struct gl_context *ctx, struct gl_shader_program *prog,

                      struct gl_transform_feedback_info *info,

                      unsigned buffer, const unsigned max_outputs) const

{

   assert(!this->next_buffer_separator);

   /* Handle gl_SkipComponents. */

   if (this->skip_components) {

      info->BufferStride[buffer] += this->skip_components;

      return true;

   }

   /* From GL_EXT_transform_feedback:

    *   A program will fail to link if:

    *

    *     * the total number of components to capture is greater than

    *       the constant MAX_TRANSFORM_FEEDBACK_INTERLEAVED_COMPONENTS_EXT

    *       and the buffer mode is INTERLEAVED_ATTRIBS_EXT.

    */

   if (prog->TransformFeedback.BufferMode == GL_INTERLEAVED_ATTRIBS &&

       info->BufferStride[buffer] + this->num_components() >

       ctx->Const.MaxTransformFeedbackInterleavedComponents) {

      linker_error(prog, "The MAX_TRANSFORM_FEEDBACK_INTERLEAVED_COMPONENTS "

                   "limit has been exceeded.");

      return false;

   }

   unsigned location = this->location;

   unsigned location_frac = this->location_frac;

   unsigned num_components = this->num_components();

   while (num_components > 0) {

      unsigned output_size = MIN2(num_components, 4 - location_frac);

      assert(info->NumOutputs < max_outputs);

      info->Outputs[info->NumOutputs].ComponentOffset = location_frac;

      info->Outputs[info->NumOutputs].OutputRegister = location;

      info->Outputs[info->NumOutputs].NumComponents = output_size;

      info->Outputs[info->NumOutputs].OutputBuffer = buffer;

      info->Outputs[info->NumOutputs].DstOffset = info->BufferStride[buffer];

      ++info->NumOutputs;

      info->BufferStride[buffer] += output_size;

      num_components -= output_size;

      location++;

      location_frac = 0;

   }

   info->Varyings[info->NumVarying].Name = ralloc_strdup(prog, this->orig_name);

   info->Varyings[info->NumVarying].Type = this->type;

   info->Varyings[info->NumVarying].Size = this->size;

   info->NumVarying++;

   return true;

}

const tfeedback_candidate *

tfeedback_decl::find_candidate(gl_shader_program *prog,

                               hash_table *tfeedback_candidates)

{

   const char *name = this->is_clip_distance_mesa

      ? "gl_ClipDistanceMESA" : this->var_name;

   this->matched_candidate = (const tfeedback_candidate *)

      hash_table_find(tfeedback_candidates, name);

   if (!this->matched_candidate) {

      /* From GL_EXT_transform_feedback:

       *   A program will fail to link if:

       *

       *   * any variable name specified in the  array is not

       *     declared as an output in the geometry shader (if present) or

       *     the vertex shader (if no geometry shader is present);

       */

      linker_error(prog, "Transform feedback varying %s undeclared.",

                   this->orig_name);

   }

   return this->matched_candidate;

}

/**

 * Parse all the transform feedback declarations that were passed to

 * glTransformFeedbackVaryings() and store them in tfeedback_decl objects.

 *

 * If an error occurs, the error is reported through linker_error() and false

 * is returned.

 */

bool

parse_tfeedback_decls(struct gl_context *ctx, struct gl_shader_program *prog,

                      const void *mem_ctx, unsigned num_names,

                      char **varying_names, tfeedback_decl *decls)

{

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

      decls[i].init(ctx, prog, mem_ctx, varying_names[i]);

      if (!decls[i].is_varying())

         continue;

      /* From GL_EXT_transform_feedback:

       *   A program will fail to link if:

       *

       *   * any two entries in the  array specify the same varying

       *     variable;

       *

       * We interpret this to mean "any two entries in the  array

       * specify the same varying variable and array index", since transform

       * feedback of arrays would be useless otherwise.

       */

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

         if (!decls[j].is_varying())

            continue;

         if (tfeedback_decl::is_same(decls[i], decls[j])) {

            linker_error(prog, "Transform feedback varying %s specified "

                         "more than once.", varying_names[i]);

            return false;

         }

      }

   }

   return true;

}

/**

 * Store transform feedback location assignments into

 * prog->LinkedTransformFeedback based on the data stored in tfeedback_decls.

 *

 * If an error occurs, the error is reported through linker_error() and false

 * is returned.

 */

bool

store_tfeedback_info(struct gl_context *ctx, struct gl_shader_program *prog,

                     unsigned num_tfeedback_decls,

                     tfeedback_decl *tfeedback_decls)

{

   bool separate_attribs_mode =

      prog->TransformFeedback.BufferMode == GL_SEPARATE_ATTRIBS;

   ralloc_free(prog->LinkedTransformFeedback.Varyings);

   ralloc_free(prog->LinkedTransformFeedback.Outputs);

   memset(&prog->LinkedTransformFeedback, 0,

          sizeof(prog->LinkedTransformFeedback));

   prog->LinkedTransformFeedback.Varyings =

      rzalloc_array(prog,

		    struct gl_transform_feedback_varying_info,

		    num_tfeedback_decls);

   unsigned num_outputs = 0;

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

      num_outputs += tfeedback_decls[i].get_num_outputs();

   prog->LinkedTransformFeedback.Outputs =

      rzalloc_array(prog,

                    struct gl_transform_feedback_output,

                    num_outputs);

   unsigned num_buffers = 0;

   if (separate_attribs_mode) {

      /* GL_SEPARATE_ATTRIBS */

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

         if (!tfeedback_decls[i].store(ctx, prog, &prog->LinkedTransformFeedback,

                                       num_buffers, num_outputs))

            return false;

         num_buffers++;

      }

   }

   else {

      /* GL_INVERLEAVED_ATTRIBS */

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

         if (tfeedback_decls[i].is_next_buffer_separator()) {

            num_buffers++;

            continue;

         }

         if (!tfeedback_decls[i].store(ctx, prog,

                                       &prog->LinkedTransformFeedback,

                                       num_buffers, num_outputs))

            return false;

      }

      num_buffers++;

   }

   assert(prog->LinkedTransformFeedback.NumOutputs == num_outputs);

   prog->LinkedTransformFeedback.NumBuffers = num_buffers;

   return true;

}

/**

 * Data structure recording the relationship between outputs of one shader

 * stage (the "producer") and inputs of another (the "consumer").

 */

class varying_matches

{

public:

   varying_matches(bool disable_varying_packing, bool consumer_is_fs);

   ~varying_matches();

   void record(ir_variable *producer_var, ir_variable *consumer_var);

   unsigned assign_locations();

   void store_locations(unsigned producer_base, unsigned consumer_base) const;

private:

   /**

    * If true, this driver disables varying packing, so all varyings need to

    * be aligned on slot boundaries, and take up a number of slots equal to

    * their number of matrix columns times their array size.

    */

   const bool disable_varying_packing;

   /**

    * Enum representing the order in which varyings are packed within a

    * packing class.

    *

    * Currently we pack vec4's first, then vec2's, then scalar values, then

    * vec3's.  This order ensures that the only vectors that are at risk of

    * having to be "double parked" (split between two adjacent varying slots)

    * are the vec3's.

    */

   enum packing_order_enum {

      PACKING_ORDER_VEC4,

      PACKING_ORDER_VEC2,

      PACKING_ORDER_SCALAR,

      PACKING_ORDER_VEC3,

   };

   static unsigned compute_packing_class(ir_variable *var);

   static packing_order_enum compute_packing_order(ir_variable *var);

   static int match_comparator(const void *x_generic, const void *y_generic);

   /**

    * Structure recording the relationship between a single producer output

    * and a single consumer input.

    */

   struct match {

      /**

       * Packing class for this varying, computed by compute_packing_class().

       */

      unsigned packing_class;

      /**

       * Packing order for this varying, computed by compute_packing_order().

       */

      packing_order_enum packing_order;

      unsigned num_components;

      /**

       * The output variable in the producer stage.

       */

      ir_variable *producer_var;

      /**

       * The input variable in the consumer stage.

       */

      ir_variable *consumer_var;

      /**

       * The location which has been assigned for this varying.  This is

       * expressed in multiples of a float, with the first generic varying

       * (i.e. the one referred to by VARYING_SLOT_VAR0) represented by the

       * value 0.

       */

      unsigned generic_location;

   } *matches;

   /**

    * The number of elements in the \c matches array that are currently in

    * use.

    */

   unsigned num_matches;

   /**

    * The number of elements that were set aside for the \c matches array when

    * it was allocated.

    */

   unsigned matches_capacity;

   const bool consumer_is_fs;

};

varying_matches::varying_matches(bool disable_varying_packing,

                                 bool consumer_is_fs)

   : disable_varying_packing(disable_varying_packing),

     consumer_is_fs(consumer_is_fs)

{

   /* Note: this initial capacity is rather arbitrarily chosen to be large

    * enough for many cases without wasting an unreasonable amount of space.

    * varying_matches::record() will resize the array if there are more than

    * this number of varyings.

    */

   this->matches_capacity = 8;

   this->matches = (match *)

      malloc(sizeof(*this->matches) * this->matches_capacity);

   this->num_matches = 0;

}

varying_matches::~varying_matches()

{

   free(this->matches);

}

/**

 * Record the given producer/consumer variable pair in the list of variables

 * that should later be assigned locations.

 *

 * It is permissible for \c consumer_var to be NULL (this happens if a

 * variable is output by the producer and consumed by transform feedback, but

 * not consumed by the consumer).

 *

 * If \c producer_var has already been paired up with a consumer_var, or

 * producer_var is part of fixed pipeline functionality (and hence already has

 * a location assigned), this function has no effect.

 *

 * Note: as a side effect this function may change the interpolation type of

 * \c producer_var, but only when the change couldn't possibly affect

 * rendering.

 */

void

varying_matches::record(ir_variable *producer_var, ir_variable *consumer_var)

{

   if (!producer_var->is_unmatched_generic_inout) {

      /* Either a location already exists for this variable (since it is part

       * of fixed functionality), or it has already been recorded as part of a

       * previous match.

       */

      return;

   }

   if ((consumer_var == NULL && producer_var->type->contains_integer()) ||

       !consumer_is_fs) {

      /* Since this varying is not being consumed by the fragment shader, its

       * interpolation type varying cannot possibly affect rendering.  Also,

       * this variable is non-flat and is (or contains) an integer.

       *

       * lower_packed_varyings requires all integer varyings to flat,

       * regardless of where they appear.  We can trivially satisfy that

       * requirement by changing the interpolation type to flat here.

       */

      producer_var->centroid = false;

      producer_var->interpolation = INTERP_QUALIFIER_FLAT;

      if (consumer_var) {

         consumer_var->centroid = false;

         consumer_var->interpolation = INTERP_QUALIFIER_FLAT;

      }

   }

   if (this->num_matches == this->matches_capacity) {

      this->matches_capacity *= 2;

      this->matches = (match *)

         realloc(this->matches,

                 sizeof(*this->matches) * this->matches_capacity);

   }

   this->matches[this->num_matches].packing_class

      = this->compute_packing_class(producer_var);

   this->matches[this->num_matches].packing_order

      = this->compute_packing_order(producer_var);

   if (this->disable_varying_packing) {

      unsigned slots = producer_var->type->is_array()

         ? (producer_var->type->length

            * producer_var->type->fields.array->matrix_columns)

         : producer_var->type->matrix_columns;

      this->matches[this->num_matches].num_components = 4 * slots;

   } else {

      this->matches[this->num_matches].num_components

         = producer_var->type->component_slots();

   }

   this->matches[this->num_matches].producer_var = producer_var;

   this->matches[this->num_matches].consumer_var = consumer_var;

   this->num_matches++;

   producer_var->is_unmatched_generic_inout = 0;

   if (consumer_var)

      consumer_var->is_unmatched_generic_inout = 0;

}

/**

 * Choose locations for all of the variable matches that were previously

 * passed to varying_matches::record().

 */

unsigned

varying_matches::assign_locations()

{

   /* Sort varying matches into an order that makes them easy to pack. */

   qsort(this->matches, this->num_matches, sizeof(*this->matches),

         &varying_matches::match_comparator);

   unsigned generic_location = 0;

   for (unsigned i = 0; i < this->num_matches; i++) {

      /* Advance to the next slot if this varying has a different packing

       * class than the previous one, and we're not already on a slot

       * boundary.

       */

      if (i > 0 &&

          this->matches[i - 1].packing_class

          != this->matches[i].packing_class) {

         generic_location = ALIGN(generic_location, 4);

      }

      this->matches[i].generic_location = generic_location;

      generic_location += this->matches[i].num_components;

   }

   return (generic_location + 3) / 4;

}

/**

 * Update the producer and consumer shaders to reflect the locations

 * assignments that were made by varying_matches::assign_locations().

 */

void

varying_matches::store_locations(unsigned producer_base,

                                 unsigned consumer_base) const

{

   for (unsigned i = 0; i < this->num_matches; i++) {

      ir_variable *producer_var = this->matches[i].producer_var;

      ir_variable *consumer_var = this->matches[i].consumer_var;

      unsigned generic_location = this->matches[i].generic_location;

      unsigned slot = generic_location / 4;

      unsigned offset = generic_location % 4;

      producer_var->location = producer_base + slot;

      producer_var->location_frac = offset;

      if (consumer_var) {

         assert(consumer_var->location == -1);

         consumer_var->location = consumer_base + slot;

         consumer_var->location_frac = offset;

      }

   }

}

/**

 * Compute the "packing class" of the given varying.  This is an unsigned

 * integer with the property that two variables in the same packing class can

 * be safely backed into the same vec4.

 */

unsigned

varying_matches::compute_packing_class(ir_variable *var)

{

   /* Without help from the back-end, there is no way to pack together

    * variables with different interpolation types, because

    * lower_packed_varyings must choose exactly one interpolation type for

    * each packed varying it creates.

    *

    * However, we can safely pack together floats, ints, and uints, because:

    *

    * - varyings of base type "int" and "uint" must use the "flat"

    *   interpolation type, which can only occur in GLSL 1.30 and above.

    *

    * - On platforms that support GLSL 1.30 and above, lower_packed_varyings

    *   can store flat floats as ints without losing any information (using

    *   the ir_unop_bitcast_* opcodes).

    *

    * Therefore, the packing class depends only on the interpolation type.

    */

   unsigned packing_class = var->centroid ? 1 : 0;

   packing_class *= 4;

   packing_class += var->interpolation;

   return packing_class;

}

/**

 * Compute the "packing order" of the given varying.  This is a sort key we

 * use to determine when to attempt to pack the given varying relative to

 * other varyings in the same packing class.

 */

varying_matches::packing_order_enum

varying_matches::compute_packing_order(ir_variable *var)

{

   const glsl_type *element_type = var->type;

   while (element_type->base_type == GLSL_TYPE_ARRAY) {

      element_type = element_type->fields.array;

   }

   switch (element_type->component_slots() % 4) {

   case 1: return PACKING_ORDER_SCALAR;

   case 2: return PACKING_ORDER_VEC2;

   case 3: return PACKING_ORDER_VEC3;

   case 0: return PACKING_ORDER_VEC4;

   default:

      assert(!"Unexpected value of vector_elements");

      return PACKING_ORDER_VEC4;

   }

}

/**

 * Comparison function passed to qsort() to sort varyings by packing_class and

 * then by packing_order.

 */

int

varying_matches::match_comparator(const void *x_generic, const void *y_generic)

{

   const match *x = (const match *) x_generic;

   const match *y = (const match *) y_generic;

   if (x->packing_class != y->packing_class)

      return x->packing_class - y->packing_class;

   return x->packing_order - y->packing_order;

}

/**

 * Is the given variable a varying variable to be counted against the

 * limit in ctx->Const.MaxVarying?

 * This includes variables such as texcoords, colors and generic

 * varyings, but excludes variables such as gl_FrontFacing and gl_FragCoord.

 */

static bool

is_varying_var(GLenum shaderType, const ir_variable *var)

{

   /* Only fragment shaders will take a varying variable as an input */

   if (shaderType == GL_FRAGMENT_SHADER &&

       var->mode == ir_var_shader_in) {

      switch (var->location) {

      case VARYING_SLOT_POS:

      case VARYING_SLOT_FACE:

      case VARYING_SLOT_PNTC:

         return false;

      default:

         return true;

      }

   }

   return false;

}

/**

 * Visitor class that generates tfeedback_candidate structs describing all

 * possible targets of transform feedback.

 *

 * tfeedback_candidate structs are stored in the hash table

 * tfeedback_candidates, which is passed to the constructor.  This hash table

 * maps varying names to instances of the tfeedback_candidate struct.

 */

class tfeedback_candidate_generator : public program_resource_visitor

{

public:

   tfeedback_candidate_generator(void *mem_ctx,

                                 hash_table *tfeedback_candidates)

      : mem_ctx(mem_ctx),

        tfeedback_candidates(tfeedback_candidates),

        toplevel_var(NULL),

        varying_floats(0)

   {

   }

   void process(ir_variable *var)

   {

      this->toplevel_var = var;

      this->varying_floats = 0;

      if (var->is_interface_instance())

         program_resource_visitor::process(var->interface_type,

                                           var->interface_type->name);

      else

         program_resource_visitor::process(var);

   }

private:

   virtual void visit_field(const glsl_type *type, const char *name,

                            bool row_major)

   {

      assert(!type->is_record());

      assert(!(type->is_array() && type->fields.array->is_record()));

      assert(!type->is_interface());

      assert(!(type->is_array() && type->fields.array->is_interface()));

      (void) row_major;

      tfeedback_candidate *candidate

         = rzalloc(this->mem_ctx, tfeedback_candidate);

      candidate->toplevel_var = this->toplevel_var;

      candidate->type = type;

      candidate->offset = this->varying_floats;

      hash_table_insert(this->tfeedback_candidates, candidate,

                        ralloc_strdup(this->mem_ctx, name));

      this->varying_floats += type->component_slots();

   }

   /**

    * Memory context used to allocate hash table keys and values.

    */

   void * const mem_ctx;

   /**

    * Hash table in which tfeedback_candidate objects should be stored.

    */

   hash_table * const tfeedback_candidates;

   /**

    * Pointer to the toplevel variable that is being traversed.

    */

   ir_variable *toplevel_var;

   /**

    * Total number of varying floats that have been visited so far.  This is

    * used to determine the offset to each varying within the toplevel

    * variable.

    */

   unsigned varying_floats;

};

/**

 * Assign locations for all variables that are produced in one pipeline stage

 * (the "producer") and consumed in the next stage (the "consumer").

 *

 * Variables produced by the producer may also be consumed by transform

 * feedback.

 *

 * \param num_tfeedback_decls is the number of declarations indicating

 *        variables that may be consumed by transform feedback.

 *

 * \param tfeedback_decls is a pointer to an array of tfeedback_decl objects

 *        representing the result of parsing the strings passed to

 *        glTransformFeedbackVaryings().  assign_location() will be called for

 *        each of these objects that matches one of the outputs of the

 *        producer.

 *

 * When num_tfeedback_decls is nonzero, it is permissible for the consumer to

 * be NULL.  In this case, varying locations are assigned solely based on the

 * requirements of transform feedback.

 */

bool

assign_varying_locations(struct gl_context *ctx,

			 void *mem_ctx,

			 struct gl_shader_program *prog,

			 gl_shader *producer, gl_shader *consumer,

                         unsigned num_tfeedback_decls,

                         tfeedback_decl *tfeedback_decls)

{

   const unsigned producer_base = VARYING_SLOT_VAR0;

   const unsigned consumer_base = VARYING_SLOT_VAR0;

   varying_matches matches(ctx->Const.DisableVaryingPacking,

                           consumer && consumer->Type == GL_FRAGMENT_SHADER);

   hash_table *tfeedback_candidates

      = hash_table_ctor(0, hash_table_string_hash, hash_table_string_compare);

   hash_table *consumer_inputs

      = hash_table_ctor(0, hash_table_string_hash, hash_table_string_compare);

   hash_table *consumer_interface_inputs

      = hash_table_ctor(0, hash_table_string_hash, hash_table_string_compare);

   /* 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.

    */

   if (consumer) {

      foreach_list(node, consumer->ir) {

         ir_variable *const input_var =

            ((ir_instruction *) node)->as_variable();

         if ((input_var != NULL) && (input_var->mode == ir_var_shader_in)) {

            if (input_var->interface_type != NULL) {

               char *const iface_field_name =

                  ralloc_asprintf(mem_ctx, "%s.%s",

                                  input_var->interface_type->name,

                                  input_var->name);

               hash_table_insert(consumer_interface_inputs, input_var,

                                 iface_field_name);

            } else {

               hash_table_insert(consumer_inputs, input_var,

                                 ralloc_strdup(mem_ctx, input_var->name));

            }

         }

      }

   }

   foreach_list(node, producer->ir) {

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

      if ((output_var == NULL) || (output_var->mode != ir_var_shader_out))

	 continue;

      tfeedback_candidate_generator g(mem_ctx, tfeedback_candidates);

      g.process(output_var);

      ir_variable *input_var;

      if (output_var->interface_type != NULL) {

         char *const iface_field_name =

            ralloc_asprintf(mem_ctx, "%s.%s",

                            output_var->interface_type->name,

                            output_var->name);

         input_var =

            (ir_variable *) hash_table_find(consumer_interface_inputs,

                                            iface_field_name);

      } else {

         input_var =

            (ir_variable *) hash_table_find(consumer_inputs, output_var->name);

      }

      if (input_var && input_var->mode != ir_var_shader_in)

         input_var = NULL;

      if (input_var) {

         matches.record(output_var, input_var);

      }

   }

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

      if (!tfeedback_decls[i].is_varying())

         continue;

      const tfeedback_candidate *matched_candidate

         = tfeedback_decls[i].find_candidate(prog, tfeedback_candidates);

      if (matched_candidate == NULL) {

         hash_table_dtor(tfeedback_candidates);

         hash_table_dtor(consumer_inputs);

         hash_table_dtor(consumer_interface_inputs);

         return false;

      }

      if (matched_candidate->toplevel_var->is_unmatched_generic_inout)

         matches.record(matched_candidate->toplevel_var, NULL);

   }

   const unsigned slots_used = matches.assign_locations();

   matches.store_locations(producer_base, consumer_base);

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

      if (!tfeedback_decls[i].is_varying())

         continue;

      if (!tfeedback_decls[i].assign_location(ctx, prog)) {

         hash_table_dtor(tfeedback_candidates);

         hash_table_dtor(consumer_inputs);

         hash_table_dtor(consumer_interface_inputs);

         return false;

      }

   }

   hash_table_dtor(tfeedback_candidates);

   hash_table_dtor(consumer_inputs);

   hash_table_dtor(consumer_interface_inputs);

   if (ctx->Const.DisableVaryingPacking) {

      /* Transform feedback code assumes varyings are packed, so if the driver

       * has disabled varying packing, make sure it does not support transform

       * feedback.

       */

      assert(!ctx->Extensions.EXT_transform_feedback);

   } else {

      lower_packed_varyings(mem_ctx, producer_base, slots_used,

                            ir_var_shader_out, producer);

      if (consumer) {

         lower_packed_varyings(mem_ctx, consumer_base, slots_used,

                               ir_var_shader_in, consumer);

      }

   }

   if (consumer) {

      foreach_list(node, consumer->ir) {

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

         if (var && var->mode == ir_var_shader_in &&

             var->is_unmatched_generic_inout) {

            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.