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diff --git a/src/glsl/ir_explog_to_explog2.cpp b/src/glsl/ir_explog_to_explog2.cpp
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+/*
+ * 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 ir_explog_to_explog2.cpp
+ *
+ * Many GPUs don't have a base e log or exponent instruction, but they
+ * do have base 2 versions, so this pass converts exp and log to exp2
+ * and log2 operations.
+ */
+
+#include <math.h>
+#include "ir.h"
+#include "glsl_types.h"
+
+class ir_explog_to_explog2_visitor : public ir_hierarchical_visitor {
+public:
+ ir_explog_to_explog2_visitor()
+ {
+ this->progress = false;
+ }
+
+ ir_visitor_status visit_leave(ir_expression *);
+
+ bool progress;
+};
+
+bool
+do_explog_to_explog2(exec_list *instructions)
+{
+ ir_explog_to_explog2_visitor v;
+
+ visit_list_elements(&v, instructions);
+ return v.progress;
+}
+
+ir_visitor_status
+ir_explog_to_explog2_visitor::visit_leave(ir_expression *ir)
+{
+ if (ir->operation == ir_unop_exp) {
+ void *mem_ctx = talloc_parent(ir);
+ ir_constant *log2_e = new(mem_ctx) ir_constant(log2f(M_E));
+
+ ir->operation = ir_unop_exp2;
+ ir->operands[0] = new(mem_ctx) ir_expression(ir_binop_mul,
+ ir->operands[0]->type,
+ ir->operands[0],
+ log2_e);
+ this->progress = true;
+ }
+
+ if (ir->operation == ir_unop_log) {
+ void *mem_ctx = talloc_parent(ir);
+
+ ir->operation = ir_binop_mul;
+ ir->operands[0] = new(mem_ctx) ir_expression(ir_unop_log2,
+ ir->operands[0]->type,
+ ir->operands[0],
+ NULL);
+ ir->operands[1] = new(mem_ctx) ir_constant(1.0f / log2f(M_E));
+ this->progress = true;
+ }
+
+ return visit_continue;
+}