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diff --git a/mesalib/src/glsl/link_varyings.cpp b/mesalib/src/glsl/link_varyings.cpp
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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 "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;
+}