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-rw-r--r--mesalib/src/glsl/opt_flatten_nested_if_blocks.cpp103
1 files changed, 103 insertions, 0 deletions
diff --git a/mesalib/src/glsl/opt_flatten_nested_if_blocks.cpp b/mesalib/src/glsl/opt_flatten_nested_if_blocks.cpp
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index 000000000..c70210204
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+++ b/mesalib/src/glsl/opt_flatten_nested_if_blocks.cpp
@@ -0,0 +1,103 @@
+/*
+ * 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.
+ */
+
+/**
+ * \file opt_flatten_nested_if_blocks.cpp
+ *
+ * Flattens nested if blocks such as:
+ *
+ * if (x) {
+ * if (y) {
+ * ...
+ * }
+ * }
+ *
+ * into a single if block with a combined condition:
+ *
+ * if (x && y) {
+ * ...
+ * }
+ */
+
+#include "ir.h"
+#include "ir_builder.h"
+
+using namespace ir_builder;
+
+namespace {
+
+class nested_if_flattener : public ir_hierarchical_visitor {
+public:
+ nested_if_flattener()
+ {
+ progress = false;
+ }
+
+ ir_visitor_status visit_leave(ir_if *);
+ ir_visitor_status visit_enter(ir_assignment *);
+
+ bool progress;
+};
+
+} /* unnamed namespace */
+
+/* We only care about the top level "if" instructions, so don't
+ * descend into expressions.
+ */
+ir_visitor_status
+nested_if_flattener::visit_enter(ir_assignment *ir)
+{
+ (void) ir;
+ return visit_continue_with_parent;
+}
+
+bool
+opt_flatten_nested_if_blocks(exec_list *instructions)
+{
+ nested_if_flattener v;
+
+ v.run(instructions);
+ return v.progress;
+}
+
+
+ir_visitor_status
+nested_if_flattener::visit_leave(ir_if *ir)
+{
+ /* Only handle a single ir_if within the then clause of an ir_if. No extra
+ * instructions, no else clauses, nothing.
+ */
+ if (ir->then_instructions.is_empty() || !ir->else_instructions.is_empty())
+ return visit_continue;
+
+ ir_if *inner = ((ir_instruction *) ir->then_instructions.head)->as_if();
+ if (!inner || !inner->next->is_tail_sentinel() ||
+ !inner->else_instructions.is_empty())
+ return visit_continue;
+
+ ir->condition = logic_and(ir->condition, inner->condition);
+ inner->then_instructions.move_nodes_to(&ir->then_instructions);
+
+ progress = true;
+ return visit_continue;
+}