1 files changed, 111 insertions, 0 deletions
diff --git a/mesalib/src/glsl/lower_const_arrays_to_uniforms.cpp b/mesalib/src/glsl/lower_const_arrays_to_uniforms.cpp
new file mode 100644
index 000000000..2243f479a
--- /dev/null
+++ b/mesalib/src/glsl/lower_const_arrays_to_uniforms.cpp
@@ -0,0 +1,111 @@
+/*
+ * Copyright © 2014 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 lower_const_arrays_to_uniforms.cpp
+ *
+ * Lower constant arrays to uniform arrays.
+ *
+ * Some driver backends (such as i965 and nouveau) don't handle constant arrays
+ * gracefully, instead treating them as ordinary writable temporary arrays.
+ * Since arrays can be large, this often means spilling them to scratch memory,
+ * which usually involves a large number of instructions.
+ *
+ * This must be called prior to link_set_uniform_initializers(); we need the
+ * linker to process our new uniform's constant initializer.
+ *
+ * This should be called after optimizations, since those can result in
+ * splitting and removing arrays that are indexed by constant expressions.
+ */
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_rvalue_visitor.h"
+#include "glsl_types.h"
+
+namespace {
+class lower_const_array_visitor : public ir_rvalue_visitor {
+public:
+   lower_const_array_visitor(exec_list *insts)
+   {
+      instructions = insts;
+      progress = false;
+      index = 0;
+   }
+
+   bool run()
+   {
+      visit_list_elements(this, instructions);
+      return progress;
+   }
+
+   void handle_rvalue(ir_rvalue **rvalue);
+
+private:
+   exec_list *instructions;
+   bool progress;
+   unsigned index;
+};
+
+void
+lower_const_array_visitor::handle_rvalue(ir_rvalue **rvalue)
+{
+   if (!*rvalue)
+      return;
+
+   ir_dereference_array *dra = (*rvalue)->as_dereference_array();
+   if (!dra)
+      return;
+
+   ir_constant *con = dra->array->as_constant();
+   if (!con || !con->type->is_array())
+      return;
+
+   void *mem_ctx = ralloc_parent(con);
+
+   char *uniform_name = ralloc_asprintf(mem_ctx, "constarray__%d", index++);
+
+   ir_variable *uni =
+      new(mem_ctx) ir_variable(con->type, uniform_name, ir_var_uniform);
+   uni->constant_initializer = con;
+   uni->constant_value = con;
+   uni->data.has_initializer = true;
+   uni->data.how_declared = ir_var_hidden;
+   uni->data.read_only = true;
+   /* Assume the whole thing is accessed. */
+   uni->data.max_array_access = uni->type->length - 1;
+   instructions->push_head(uni);
+
+   ir_dereference_variable *varref = new(mem_ctx) ir_dereference_variable(uni);
+   *rvalue = new(mem_ctx) ir_dereference_array(varref, dra->array_index);
+
+   progress = true;
+}
+
+} /* anonymous namespace */
+
+bool
+lower_const_arrays_to_uniforms(exec_list *instructions)
+{
+   lower_const_array_visitor v(instructions);
+   return v.run();
+}