glsl: Add a visitor to determine whether a uniform block is ever used

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

1 files changed, 162 insertions, 0 deletions

diff --git a/src/glsl/link_uniform_block_active_visitor.cpp b/src/glsl/link_uniform_block_active_visitor.cpp
new file mode 100644
index 00000000000..56a8384e996
--- /dev/null
+++ b/src/glsl/link_uniform_block_active_visitor.cpp
@@ -0,0 +1,162 @@
+/*
+ * Copyright © 2013 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.
+ */
+
+#include "link_uniform_block_active_visitor.h"
+#include "program.h"
+
+link_uniform_block_active *
+process_block(void *mem_ctx, struct hash_table *ht, ir_variable *var)
+{
+   const uint32_t h = _mesa_hash_string(var->interface_type->name);
+   const hash_entry *const existing_block =
+      _mesa_hash_table_search(ht, h, var->interface_type->name);
+
+   const glsl_type *const block_type = var->is_interface_instance()
+      ? var->type : var->interface_type;
+
+
+   /* If a block with this block-name has not previously been seen, add it.
+    * If a block with this block-name has been seen, it must be identical to
+    * the block currently being examined.
+    */
+   if (existing_block == NULL) {
+      link_uniform_block_active *const b =
+	 rzalloc(mem_ctx, struct link_uniform_block_active);
+
+      b->type = block_type;
+      b->has_instance_name = var->is_interface_instance();
+
+      _mesa_hash_table_insert(ht, h, var->interface_type->name,
+			      (void *) b);
+      return b;
+   } else {
+      link_uniform_block_active *const b =
+	 (link_uniform_block_active *) existing_block->data;
+
+      if (b->type != block_type
+	  || b->has_instance_name != var->is_interface_instance())
+	 return NULL;
+      else
+	 return b;
+   }
+
+   assert(!"Should not get here.");
+   return NULL;
+}
+
+ir_visitor_status
+link_uniform_block_active_visitor::visit_enter(ir_dereference_array *ir)
+{
+   ir_dereference_variable *const d = ir->array->as_dereference_variable();
+   ir_variable *const var = (d == NULL) ? NULL : d->var;
+
+   /* If the r-value being dereferenced is not a variable (e.g., a field of a
+    * structure) or is not a uniform block instance, continue.
+    *
+    * WARNING: It is not enough for the variable to be part of uniform block.
+    * It must represent the entire block.  Arrays (or matrices) inside blocks
+    * that lack an instance name are handled by the ir_dereference_variable
+    * function.
+    */
+   if (var == NULL
+       || !var->is_in_uniform_block()
+       || !var->is_interface_instance())
+      return visit_continue;
+
+   /* Process the block.  Bail if there was an error.
+    */
+   link_uniform_block_active *const b =
+      process_block(this->mem_ctx, this->ht, var);
+   if (b == NULL) {
+      linker_error(prog,
+		   "uniform block `%s' has mismatching definitions",
+		   var->interface_type->name);
+      this->success = false;
+      return visit_stop;
+   }
+
+   /* Block arrays must be declared with an instance name.
+    */
+   assert(b->has_instance_name);
+   assert((b->num_array_elements == 0) == (b->array_elements == NULL));
+   assert(b->type != NULL);
+
+   /* Determine whether or not this array index has already been added to the
+    * list of active array indices.  At this point all constant folding must
+    * have occured, and the array index must be a constant.
+    */
+   ir_constant *c = ir->array_index->as_constant();
+   assert(c != NULL);
+
+   const unsigned idx = c->get_uint_component(0);
+
+   unsigned i;
+   for (i = 0; i < b->num_array_elements; i++) {
+      if (b->array_elements[i] == idx)
+	 break;
+   }
+
+   assert(i <= b->num_array_elements);
+
+   if (i == b->num_array_elements) {
+      b->array_elements = reralloc(this->mem_ctx,
+				   b->array_elements,
+				   unsigned,
+				   b->num_array_elements + 1);
+
+      b->array_elements[b->num_array_elements] = idx;
+
+      b->num_array_elements++;
+   }
+
+   return visit_continue_with_parent;
+}
+
+ir_visitor_status
+link_uniform_block_active_visitor::visit(ir_dereference_variable *ir)
+{
+   ir_variable *var = ir->var;
+
+   if (!var->is_in_uniform_block())
+      return visit_continue;
+
+   assert(!var->is_interface_instance() || !var->type->is_array());
+
+   /* Process the block.  Bail if there was an error.
+    */
+   link_uniform_block_active *const b =
+      process_block(this->mem_ctx, this->ht, var);
+   if (b == NULL) {
+      linker_error(this->prog,
+		   "uniform block `%s' has mismatching definitions",
+		   var->interface_type->name);
+      this->success = false;
+      return visit_stop;
+   }
+
+   assert(b->num_array_elements == 0);
+   assert(b->array_elements == NULL);
+   assert(b->type != NULL);
+
+   return visit_continue;
+}