glsl: Add a lowering pass for texture projection.

1 files changed, 100 insertions, 0 deletions

diff --git a/src/glsl/lower_texture_projection.cpp b/src/glsl/lower_texture_projection.cpp
new file mode 100644
index 0000000000..f82ca0a9fd
--- /dev/null
+++ b/src/glsl/lower_texture_projection.cpp
@@ -0,0 +1,100 @@
+/*
+ * Copyright © 2010 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_texture_projection.cpp
+ *
+ * IR lower pass to perform the division of texture coordinates by the texture
+ * projector if present.
+ *
+ * Many GPUs have a texture sampling opcode that takes the projector
+ * and does the divide internally, thus the presence of the projector
+ * in the IR.  For GPUs that don't, this saves the driver needing the
+ * logic for handling the divide.
+ *
+ * \author Eric Anholt <eric@anholt.net>
+ */
+
+#include "ir.h"
+#include "ir_rvalue_visitor.h"
+
+class lower_texture_projection_visitor : public ir_hierarchical_visitor {
+public:
+   lower_texture_projection_visitor()
+   {
+      progress = false;
+   }
+
+   ir_visitor_status visit_leave(ir_texture *ir);
+
+   bool progress;
+};
+
+ir_visitor_status
+lower_texture_projection_visitor::visit_leave(ir_texture *ir)
+{
+   if (!ir->projector)
+      return visit_continue;
+
+   void *mem_ctx = talloc_parent(ir);
+
+   ir_variable *var = new(mem_ctx) ir_variable(ir->projector->type,
+					       "projector", ir_var_auto);
+   base_ir->insert_before(var);
+   ir_dereference *deref = new(mem_ctx) ir_dereference_variable(var);
+   ir_expression *expr = new(mem_ctx) ir_expression(ir_unop_rcp,
+						    ir->projector->type,
+						    ir->projector,
+						    NULL);
+   ir_assignment *assign = new(mem_ctx) ir_assignment(deref, expr, NULL);
+   base_ir->insert_before(assign);
+
+   deref = new(mem_ctx) ir_dereference_variable(var);
+   ir->coordinate = new(mem_ctx) ir_expression(ir_binop_mul,
+					       ir->coordinate->type,
+					       ir->coordinate,
+					       deref);
+
+   if (ir->shadow_comparitor) {
+      deref = new(mem_ctx) ir_dereference_variable(var);
+      ir->shadow_comparitor = new(mem_ctx) ir_expression(ir_binop_mul,
+						  ir->shadow_comparitor->type,
+						  ir->shadow_comparitor,
+						  deref);
+   }
+
+   ir->projector = NULL;
+
+   progress = true;
+   return visit_continue;
+}
+
+bool
+do_lower_texture_projection(exec_list *instructions)
+{
+   lower_texture_projection_visitor v;
+
+   visit_list_elements(&v, instructions);
+
+   return v.progress;
+}