103 lines
3.3 KiB
C++
103 lines
3.3 KiB
C++
/*
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* Copyright © 2010 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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/**
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* \file lower_vec_index_to_swizzle.cpp
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*
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* Turns constant indexing into vector types to swizzles. This will
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* let other swizzle-aware optimization passes catch these constructs,
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* and codegen backends not have to worry about this case.
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*/
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#include "ir.h"
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#include "ir_rvalue_visitor.h"
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#include "ir_optimization.h"
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#include "compiler/glsl_types.h"
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#include "main/macros.h"
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namespace {
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class ir_vec_index_to_swizzle_visitor : public ir_rvalue_visitor {
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public:
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ir_vec_index_to_swizzle_visitor()
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{
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progress = false;
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}
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ir_rvalue *convert_vector_extract_to_swizzle(ir_rvalue *val);
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virtual void handle_rvalue(ir_rvalue **);
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bool progress;
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};
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} /* anonymous namespace */
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void
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ir_vec_index_to_swizzle_visitor::handle_rvalue(ir_rvalue **rv)
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{
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if (*rv == NULL)
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return;
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ir_expression *const expr = (*rv)->as_expression();
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if (expr == NULL || expr->operation != ir_binop_vector_extract)
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return;
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void *mem_ctx = ralloc_parent(expr);
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ir_constant *const idx =
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expr->operands[1]->constant_expression_value(mem_ctx);
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if (idx == NULL)
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return;
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this->progress = true;
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/* Page 40 of the GLSL 1.20 spec says:
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*
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* "When indexing with non-constant expressions, behavior is undefined
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* if the index is negative, or greater than or equal to the size of
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* the vector."
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*
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* The quoted spec text mentions non-constant expressions, but this code
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* operates on constants. These constants are the result of non-constant
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* expressions that have been optimized to constants. The common case here
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* is a loop counter from an unrolled loop that is used to index a vector.
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*
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* The ir_swizzle constructor gets angry if the index is negative or too
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* large. For simplicity sake, just clamp the index to [0, size-1].
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*/
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const int i = CLAMP(idx->value.i[0], 0,
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(int) expr->operands[0]->type->vector_elements - 1);
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*rv = new(mem_ctx) ir_swizzle(expr->operands[0], i, 0, 0, 0, 1);
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}
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bool
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do_vec_index_to_swizzle(exec_list *instructions)
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{
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ir_vec_index_to_swizzle_visitor v;
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v.run(instructions);
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return v.progress;
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}
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