+/**
+ * Data structure tracking information about a transform feedback declaration
+ * during linking.
+ */
+class tfeedback_decl
+{
+public:
+ bool init(struct gl_context *ctx, struct gl_shader_program *prog,
+ const void *mem_ctx, const char *input);
+ static bool is_same(const tfeedback_decl &x, const tfeedback_decl &y);
+ bool assign_location(struct gl_context *ctx, struct gl_shader_program *prog,
+ ir_variable *output_var);
+ bool accumulate_num_outputs(struct gl_shader_program *prog, unsigned *count);
+ bool store(struct gl_context *ctx, struct gl_shader_program *prog,
+ struct gl_transform_feedback_info *info, unsigned buffer,
+ unsigned varying, const unsigned max_outputs) const;
+
+
+ /**
+ * True if assign_location() has been called for this object.
+ */
+ bool is_assigned() const
+ {
+ return this->location != -1;
+ }
+
+ /**
+ * Determine whether this object refers to the variable var.
+ */
+ bool matches_var(ir_variable *var) const
+ {
+ if (this->is_clip_distance_mesa)
+ return strcmp(var->name, "gl_ClipDistanceMESA") == 0;
+ else
+ return strcmp(var->name, this->var_name) == 0;
+ }
+
+ /**
+ * The total number of varying components taken up by this variable. Only
+ * valid if is_assigned() is true.
+ */
+ unsigned num_components() const
+ {
+ if (this->is_clip_distance_mesa)
+ return this->size;
+ else
+ return this->vector_elements * this->matrix_columns * this->size;
+ }
+
+private:
+ /**
+ * The name that was supplied to glTransformFeedbackVaryings. Used for
+ * error reporting and glGetTransformFeedbackVarying().
+ */
+ const char *orig_name;
+
+ /**
+ * The name of the variable, parsed from orig_name.
+ */
+ const char *var_name;
+
+ /**
+ * True if the declaration in orig_name represents an array.
+ */
+ bool is_subscripted;
+
+ /**
+ * If is_subscripted is true, the subscript that was specified in orig_name.
+ */
+ unsigned array_subscript;
+
+ /**
+ * True if the variable is gl_ClipDistance and the driver lowers
+ * gl_ClipDistance to gl_ClipDistanceMESA.
+ */
+ bool is_clip_distance_mesa;
+
+ /**
+ * The vertex shader output location that the linker assigned for this
+ * variable. -1 if a location hasn't been assigned yet.
+ */
+ int location;
+
+ /**
+ * If location != -1, the number of vector elements in this variable, or 1
+ * if this variable is a scalar.
+ */
+ unsigned vector_elements;
+
+ /**
+ * If location != -1, the number of matrix columns in this variable, or 1
+ * if this variable is not a matrix.
+ */
+ unsigned matrix_columns;
+
+ /** Type of the varying returned by glGetTransformFeedbackVarying() */
+ GLenum type;
+
+ /**
+ * If location != -1, the size that should be returned by
+ * glGetTransformFeedbackVarying().
+ */
+ unsigned size;
+};
+
+
+/**
+ * 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;
+
+ 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)
+{
+ 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)
+{
+ if (output_var->type->is_array()) {
+ /* Array variable */
+ const unsigned matrix_cols =
+ output_var->type->fields.array->matrix_columns;
+ 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;
+ } else {
+ this->location =
+ output_var->location + this->array_subscript * matrix_cols;
+ }
+ this->size = 1;
+ } else {
+ this->location = output_var->location;
+ this->size = actual_array_size;
+ }
+ this->vector_elements = output_var->type->fields.array->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->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;
+}
+
+
+bool
+tfeedback_decl::accumulate_num_outputs(struct gl_shader_program *prog,
+ unsigned *count)
+{
+ if (!this->is_assigned()) {
+ /* 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 false;
+ }
+
+ unsigned translated_size = this->size;
+ if (this->is_clip_distance_mesa)
+ translated_size = (translated_size + 3) / 4;
+
+ *count += translated_size * this->matrix_columns;
+
+ return true;
+}
+
+
+/**
+ * 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,
+ unsigned varying, const unsigned max_outputs) const
+{
+ /* 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 translated_size = this->size;
+ if (this->is_clip_distance_mesa)
+ translated_size = (translated_size + 3) / 4;
+ unsigned components_so_far = 0;
+ for (unsigned index = 0; index < translated_size; ++index) {
+ for (unsigned v = 0; v < this->matrix_columns; ++v) {
+ unsigned num_components = this->vector_elements;
+ assert(info->NumOutputs < max_outputs);
+ info->Outputs[info->NumOutputs].ComponentOffset = 0;
+ if (this->is_clip_distance_mesa) {
+ if (this->is_subscripted) {
+ num_components = 1;
+ info->Outputs[info->NumOutputs].ComponentOffset =
+ this->array_subscript % 4;
+ } else {
+ num_components = MIN2(4, this->size - components_so_far);
+ }
+ }
+ info->Outputs[info->NumOutputs].OutputRegister =
+ this->location + v + index * this->matrix_columns;
+ info->Outputs[info->NumOutputs].NumComponents = num_components;
+ info->Outputs[info->NumOutputs].OutputBuffer = buffer;
+ info->Outputs[info->NumOutputs].DstOffset = info->BufferStride[buffer];
+ ++info->NumOutputs;
+ info->BufferStride[buffer] += num_components;
+ components_so_far += num_components;
+ }
+ }
+ assert(components_so_far == this->num_components());
+
+ info->Varyings[varying].Name = ralloc_strdup(prog, this->orig_name);
+ info->Varyings[varying].Type = this->type;
+ info->Varyings[varying].Size = this->size;
+ info->NumVarying++;
+
+ return true;
+}
+
+
+/**
+ * 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.
+ */
+static 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;
+ /* 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 (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;
+}
+
+
+/**
+ * Assign a location for a variable that is produced in one pipeline stage
+ * (the "producer") and consumed in the next stage (the "consumer").
+ *
+ * \param input_var is the input variable declaration in the consumer.
+ *
+ * \param output_var is the output variable declaration in the producer.
+ *
+ * \param input_index is the counter that keeps track of assigned input
+ * locations in the consumer.
+ *
+ * \param output_index is the counter that keeps track of assigned output
+ * locations in the producer.
+ *
+ * It is permissible for \c input_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 the variable has already been assigned a location, this function has no
+ * effect.
+ */