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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 lower_vec_index_to_swizzle.cpp
*
* Turns constant indexing into vector types to swizzles. This will
* let other swizzle-aware optimization passes catch these constructs,
* and codegen backends not have to worry about this case.
*/
#include "ir.h"
#include "ir_rvalue_visitor.h"
#include "ir_optimization.h"
#include "compiler/glsl_types.h"
#include "main/macros.h"
namespace {
class ir_vec_index_to_swizzle_visitor : public ir_rvalue_visitor {
public:
ir_vec_index_to_swizzle_visitor()
{
progress = false;
}
ir_rvalue *convert_vector_extract_to_swizzle(ir_rvalue *val);
virtual void handle_rvalue(ir_rvalue **);
bool progress;
};
} /* anonymous namespace */
void
ir_vec_index_to_swizzle_visitor::handle_rvalue(ir_rvalue **rv)
{
if (*rv == NULL)
return;
ir_expression *const expr = (*rv)->as_expression();
if (expr == NULL || expr->operation != ir_binop_vector_extract)
return;
ir_constant *const idx = expr->operands[1]->constant_expression_value();
if (idx == NULL)
return;
void *ctx = ralloc_parent(expr);
this->progress = true;
/* Page 40 of the GLSL 1.20 spec says:
*
* "When indexing with non-constant expressions, behavior is undefined
* if the index is negative, or greater than or equal to the size of
* the vector."
*
* The quoted spec text mentions non-constant expressions, but this code
* operates on constants. These constants are the result of non-constant
* expressions that have been optimized to constants. The common case here
* is a loop counter from an unrolled loop that is used to index a vector.
*
* The ir_swizzle constructor gets angry if the index is negative or too
* large. For simplicity sake, just clamp the index to [0, size-1].
*/
const int i = CLAMP(idx->value.i[0], 0,
(int) expr->operands[0]->type->vector_elements - 1);
*rv = new(ctx) ir_swizzle(expr->operands[0], i, 0, 0, 0, 1);
}
bool
do_vec_index_to_swizzle(exec_list *instructions)
{
ir_vec_index_to_swizzle_visitor v;
v.run(instructions);
return v.progress;
}
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