fontconfig libX11 mesa mkfontscale xserver git update 11 jan 2013

fontconfig: 0831c1770e4bac7269a190936bbb0529d747e233
libX11: 0b148750027fd0557c5ed93afda861ddf4b92e0f
mkfontscale: 9cbe3256bc932b82f2435b23cda0931f4f5f5ba2
xserver: 6703a7c7cf1a349c137e247a0c8eb462ff7b07be
mesa: babab2876080af0fe65249dff559244aebd0b87e

1 files changed, 1051 insertions, 0 deletions

diff --git a/mesalib/src/glsl/link_varyings.cpp b/mesalib/src/glsl/link_varyings.cpp
new file mode 100644
index 000000000..5c27f231e
--- /dev/null
+++ b/mesalib/src/glsl/link_varyings.cpp
@@ -0,0 +1,1051 @@
+/*
+ * 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 "ir_optimization.h"
+#include "linker.h"
+#include "link_varyings.h"
+#include "main/macros.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;
+   /* 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.  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 there is a parse error, the error is
+ * reported using linker_error(), and false is returned.
+ */
+bool
+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;
+
+   if (ctx->Extensions.ARB_transform_feedback3) {
+      /* Parse gl_NextBuffer. */
+      if (strcmp(input, "gl_NextBuffer") == 0) {
+         this->next_buffer_separator = true;
+         return true;
+      }
+
+      /* 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 true;
+   }
+
+   /* Parse a declaration. */
+   const char *bracket = strrchr(input, '[');
+
+   if (bracket) {
+      this->var_name = ralloc_strndup(mem_ctx, input, bracket - input);
+      if (sscanf(bracket, "[%u]", &this->array_subscript) != 1) {
+         linker_error(prog, "Cannot parse transform feedback varying %s", input);
+         return false;
+      }
+      this->is_subscripted = true;
+   } else {
+      this->var_name = ralloc_strdup(mem_ctx, input);
+      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;
+   }
+
+   return 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 location
+ * assignment in output_var.
+ *
+ * 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,
+                                ir_variable *output_var)
+{
+   assert(this->is_varying());
+
+   if (output_var->type->is_array()) {
+      /* Array variable */
+      const unsigned matrix_cols =
+         output_var->type->fields.array->matrix_columns;
+      const unsigned vector_elements =
+         output_var->type->fields.array->vector_elements;
+      unsigned actual_array_size = this->is_clip_distance_mesa ?
+         prog->Vert.ClipDistanceArraySize : output_var->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;
+         }
+         if (this->is_clip_distance_mesa) {
+            this->location =
+               output_var->location + this->array_subscript / 4;
+            this->location_frac = this->array_subscript % 4;
+         } else {
+            unsigned fine_location
+               = output_var->location * 4 + output_var->location_frac;
+            unsigned array_elem_size = vector_elements * matrix_cols;
+            fine_location += array_elem_size * this->array_subscript;
+            this->location = fine_location / 4;
+            this->location_frac = fine_location % 4;
+         }
+         this->size = 1;
+      } else {
+         this->location = output_var->location;
+         this->location_frac = output_var->location_frac;
+         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 = output_var->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->location = output_var->location;
+      this->location_frac = output_var->location_frac;
+      this->size = 1;
+      this->vector_elements = output_var->type->vector_elements;
+      this->matrix_columns = output_var->type->matrix_columns;
+      this->type = output_var->type->gl_type;
+   }
+
+   /* From GL_EXT_transform_feedback:
+    *   A program will fail to link if:
+    *
+    *   * the total number of components to capture in any varying
+    *     variable in <varyings> 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;
+}
+
+
+ir_variable *
+tfeedback_decl::find_output_var(gl_shader_program *prog,
+                                gl_shader *producer) const
+{
+   const char *name = this->is_clip_distance_mesa
+      ? "gl_ClipDistanceMESA" : this->var_name;
+   ir_variable *var = producer->symbols->get_variable(name);
+   if (var && var->mode == ir_var_out)
+      return var;
+
+   /* From GL_EXT_transform_feedback:
+    *   A program will fail to link if:
+    *
+    *   * any variable name specified in the <varyings> 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 NULL;
+}
+
+
+/**
+ * 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) {
+      if (!decls[i].init(ctx, prog, mem_ctx, varying_names[i]))
+         return false;
+
+      if (!decls[i].is_varying())
+         continue;
+
+      /* From GL_EXT_transform_feedback:
+       *   A program will fail to link if:
+       *
+       *   * any two entries in the <varyings> array specify the same varying
+       *     variable;
+       *
+       * We interpret this to mean "any two entries in the <varyings> 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);
+   ~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 VERT_RESULT_VAR0 or FRAG_ATTRIB_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;
+};
+
+
+varying_matches::varying_matches(bool disable_varying_packing)
+   : disable_varying_packing(disable_varying_packing)
+{
+   /* 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.
+ */
+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 (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;
+
+   /* FINISHME: Support for "varying" records in GLSL 1.50. */
+   while (element_type->base_type == GLSL_TYPE_ARRAY) {
+      element_type = element_type->fields.array;
+   }
+
+   switch (element_type->vector_elements) {
+   case 1: return PACKING_ORDER_SCALAR;
+   case 2: return PACKING_ORDER_VEC2;
+   case 3: return PACKING_ORDER_VEC3;
+   case 4: 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_in) {
+      switch (var->location) {
+      case FRAG_ATTRIB_WPOS:
+      case FRAG_ATTRIB_FACE:
+      case FRAG_ATTRIB_PNTC:
+         return false;
+      default:
+         return true;
+      }
+   }
+   return false;
+}
+
+
+/**
+ * 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)
+{
+   /* FINISHME: Set dynamically when geometry shader support is added. */
+   const unsigned producer_base = VERT_RESULT_VAR0;
+   const unsigned consumer_base = FRAG_ATTRIB_VAR0;
+   varying_matches matches(ctx->Const.DisableVaryingPacking);
+
+   /* 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.
+    */
+
+   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))
+	 continue;
+
+      ir_variable *input_var =
+	 consumer ? consumer->symbols->get_variable(output_var->name) : NULL;
+
+      if (input_var && input_var->mode != ir_var_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;
+
+      ir_variable *output_var
+         = tfeedback_decls[i].find_output_var(prog, producer);
+
+      if (output_var == NULL)
+         return false;
+
+      if (output_var->is_unmatched_generic_inout) {
+         matches.record(output_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;
+
+      ir_variable *output_var
+         = tfeedback_decls[i].find_output_var(prog, producer);
+
+      if (!tfeedback_decls[i].assign_location(ctx, prog, output_var))
+         return false;
+   }
+
+   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_out,
+                            producer);
+      if (consumer) {
+         lower_packed_varyings(mem_ctx, consumer_base, slots_used, ir_var_in,
+                               consumer);
+      }
+   }
+
+   unsigned varying_vectors = 0;
+
+   if (consumer) {
+      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->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.
+                *
+                * 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(prog, "fragment shader varying %s not written "
+                            "by vertex shader\n.", var->name);
+            }
+
+            /* An 'in' variable is only really a shader input if its
+             * value is written by the previous stage.
+             */
+            var->mode = ir_var_auto;
+         } else if (is_varying_var(consumer->Type, var)) {
+            /* The packing rules are used for vertex shader inputs are also
+             * used for fragment shader inputs.
+             */
+            varying_vectors += count_attribute_slots(var->type);
+         }
+      }
+   }
+
+   if (ctx->API == API_OPENGLES2 || prog->IsES) {
+      if (varying_vectors > ctx->Const.MaxVarying) {
+         if (ctx->Const.GLSLSkipStrictMaxVaryingLimitCheck) {
+            linker_warning(prog, "shader uses too many varying vectors "
+                           "(%u > %u), but the driver will try to optimize "
+                           "them out; this is non-portable out-of-spec "
+                           "behavior\n",
+                           varying_vectors, ctx->Const.MaxVarying);
+         } else {
+            linker_error(prog, "shader uses too many varying vectors "
+                         "(%u > %u)\n",
+                         varying_vectors, ctx->Const.MaxVarying);
+            return false;
+         }
+      }
+   } else {
+      const unsigned float_components = varying_vectors * 4;
+      if (float_components > ctx->Const.MaxVarying * 4) {
+         if (ctx->Const.GLSLSkipStrictMaxVaryingLimitCheck) {
+            linker_warning(prog, "shader uses too many varying components "
+                           "(%u > %u), but the driver will try to optimize "
+                           "them out; this is non-portable out-of-spec "
+                           "behavior\n",
+                           float_components, ctx->Const.MaxVarying * 4);
+         } else {
+            linker_error(prog, "shader uses too many varying components "
+                         "(%u > %u)\n",
+                         float_components, ctx->Const.MaxVarying * 4);
+            return false;
+         }
+      }
+   }
+
+   return true;
+}