From aae338104fa6022b8b1d6b22c7ad1115b252b9b6 Mon Sep 17 00:00:00 2001
From: Eric Anholt <eric@anholt.net>
Date: Thu, 30 Sep 2010 20:07:27 -0700
Subject: [PATCH] glsl: Add a lowering pass for texture projection.

---
 src/glsl/Makefile                     |   1 +
 src/glsl/ir_optimization.h            |   1 +
 src/glsl/lower_texture_projection.cpp | 100 ++++++++++++++++++++++++++
 3 files changed, 102 insertions(+)
 create mode 100644 src/glsl/lower_texture_projection.cpp

diff --git a/src/glsl/Makefile b/src/glsl/Makefile
index 47ac42667c7..83869b1d846 100644
--- a/src/glsl/Makefile
+++ b/src/glsl/Makefile
@@ -76,6 +76,7 @@ CXX_SOURCES = \
 	loop_controls.cpp \
 	loop_unroll.cpp \
 	lower_noise.cpp \
+	lower_texture_projection.cpp \
 	lower_variable_index_to_cond_assign.cpp \
 	opt_redundant_jumps.cpp \
 	s_expression.cpp
diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h
index 6a37e167fe5..ffdc66b9f75 100644
--- a/src/glsl/ir_optimization.h
+++ b/src/glsl/ir_optimization.h
@@ -44,6 +44,7 @@ bool do_div_to_mul_rcp(exec_list *instructions);
 bool do_explog_to_explog2(exec_list *instructions);
 bool do_function_inlining(exec_list *instructions);
 bool do_lower_jumps(exec_list *instructions, bool pull_out_jumps = true, bool lower_sub_return = true, bool lower_main_return = false, bool lower_continue = false, bool lower_break = false);
+bool do_lower_texture_projection(exec_list *instructions);
 bool do_if_simplification(exec_list *instructions);
 bool do_if_to_cond_assign(exec_list *instructions);
 bool do_mat_op_to_vec(exec_list *instructions);
diff --git a/src/glsl/lower_texture_projection.cpp b/src/glsl/lower_texture_projection.cpp
new file mode 100644
index 00000000000..f82ca0a9fd9
--- /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;
+}
-- 
2.30.2