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-rw-r--r--mesalib/src/glsl/opt_conditional_discard.cpp81
1 files changed, 81 insertions, 0 deletions
diff --git a/mesalib/src/glsl/opt_conditional_discard.cpp b/mesalib/src/glsl/opt_conditional_discard.cpp
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+++ b/mesalib/src/glsl/opt_conditional_discard.cpp
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+/*
+ * 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 opt_conditional_discard.cpp
+ *
+ * Replace
+ *
+ * if (cond) discard;
+ *
+ * with
+ *
+ * (discard <condition>)
+ */
+
+#include "glsl_types.h"
+#include "ir.h"
+
+namespace {
+
+class opt_conditional_discard_visitor : public ir_hierarchical_visitor {
+public:
+ opt_conditional_discard_visitor()
+ {
+ progress = false;
+ }
+
+ ir_visitor_status visit_leave(ir_if *);
+
+ bool progress;
+};
+
+} /* anonymous namespace */
+
+bool
+opt_conditional_discard(exec_list *instructions)
+{
+ opt_conditional_discard_visitor v;
+ v.run(instructions);
+ return v.progress;
+}
+
+ir_visitor_status
+opt_conditional_discard_visitor::visit_leave(ir_if *ir)
+{
+ /* Look for "if (...) discard" with no else clause or extra statements. */
+ if (ir->then_instructions.is_empty() ||
+ !ir->then_instructions.head->next->is_tail_sentinel() ||
+ !((ir_instruction *) ir->then_instructions.head)->as_discard() ||
+ !ir->else_instructions.is_empty())
+ return visit_continue;
+
+ /* Move the condition and replace the ir_if with the ir_discard. */
+ ir_discard *discard = (ir_discard *) ir->then_instructions.head;
+ discard->condition = ir->condition;
+ ir->replace_with(discard);
+
+ progress = true;
+
+ return visit_continue;
+}