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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_cond_assign.cpp
*
* Turns indexing into vector types to a series of conditional moves
* of each channel's swizzle into a temporary.
*
* Most GPUs don't have a native way to do this operation, and this
* works around that. For drivers using both this pass and
* ir_vec_index_to_swizzle, there's a risk that this pass will happen
* before sufficient constant folding to find that the array index is
* constant. However, we hope that other optimization passes,
* particularly constant folding of assignment conditions and copy
* propagation, will result in the same code in the end.
*/
#include "ir.h"
#include "ir_visitor.h"
#include "ir_optimization.h"
#include "compiler/glsl_types.h"
#include "ir_builder.h"
using namespace ir_builder;
namespace {
/**
* Visitor class for replacing expressions with ir_constant values.
*/
class ir_vec_index_to_cond_assign_visitor : public ir_hierarchical_visitor {
public:
ir_vec_index_to_cond_assign_visitor()
: progress(false)
{
/* empty */
}
ir_rvalue *convert_vec_index_to_cond_assign(void *mem_ctx,
ir_rvalue *orig_vector,
ir_rvalue *orig_index,
const glsl_type *type);
ir_rvalue *convert_vector_extract_to_cond_assign(ir_rvalue *ir);
virtual ir_visitor_status visit_enter(ir_expression *);
virtual ir_visitor_status visit_enter(ir_swizzle *);
virtual ir_visitor_status visit_leave(ir_assignment *);
virtual ir_visitor_status visit_enter(ir_return *);
virtual ir_visitor_status visit_enter(ir_call *);
virtual ir_visitor_status visit_enter(ir_if *);
bool progress;
};
} /* anonymous namespace */
ir_rvalue *
ir_vec_index_to_cond_assign_visitor::convert_vec_index_to_cond_assign(void *mem_ctx,
ir_rvalue *orig_vector,
ir_rvalue *orig_index,
const glsl_type *type)
{
exec_list list;
ir_factory body(&list, base_ir);
/* Store the index to a temporary to avoid reusing its tree. */
assert(orig_index->type == glsl_type::int_type ||
orig_index->type == glsl_type::uint_type);
ir_variable *const index =
body.make_temp(orig_index->type, "vec_index_tmp_i");
body.emit(assign(index, orig_index));
/* Store the value inside a temp, thus avoiding matrixes duplication */
ir_variable *const value =
body.make_temp(orig_vector->type, "vec_value_tmp");
body.emit(assign(value, orig_vector));
/* Temporary where we store whichever value we swizzle out. */
ir_variable *const var = body.make_temp(type, "vec_index_tmp_v");
/* Generate a single comparison condition "mask" for all of the components
* in the vector.
*/
ir_variable *const cond =
compare_index_block(body, index, 0, orig_vector->type->vector_elements);
/* Generate a conditional move of each vector element to the temp. */
for (unsigned i = 0; i < orig_vector->type->vector_elements; i++)
body.emit(assign(var, swizzle(value, i, 1), swizzle(cond, i, 1)));
/* Put all of the new instructions in the IR stream before the old
* instruction.
*/
base_ir->insert_before(&list);
this->progress = true;
return deref(var).val;
}
ir_rvalue *
ir_vec_index_to_cond_assign_visitor::convert_vector_extract_to_cond_assign(ir_rvalue *ir)
{
ir_expression *const expr = ir->as_expression();
if (expr == NULL)
return ir;
if (expr->operation == ir_unop_interpolate_at_centroid ||
expr->operation == ir_binop_interpolate_at_offset ||
expr->operation == ir_binop_interpolate_at_sample) {
/* Lower interpolateAtXxx(some_vec[idx], ...) to
* interpolateAtXxx(some_vec, ...)[idx] before lowering to conditional
* assignments, to maintain the rule that the interpolant is an l-value
* referring to a (part of a) shader input.
*
* This is required when idx is dynamic (otherwise it gets lowered to
* a swizzle).
*/
ir_expression *const interpolant = expr->operands[0]->as_expression();
if (!interpolant || interpolant->operation != ir_binop_vector_extract)
return ir;
ir_rvalue *vec_input = interpolant->operands[0];
ir_expression *const vec_interpolate =
new(base_ir) ir_expression(expr->operation, vec_input->type,
vec_input, expr->operands[1]);
return convert_vec_index_to_cond_assign(ralloc_parent(ir),
vec_interpolate,
interpolant->operands[1],
ir->type);
}
if (expr->operation != ir_binop_vector_extract)
return ir;
return convert_vec_index_to_cond_assign(ralloc_parent(ir),
expr->operands[0],
expr->operands[1],
ir->type);
}
ir_visitor_status
ir_vec_index_to_cond_assign_visitor::visit_enter(ir_expression *ir)
{
for (unsigned i = 0; i < ir->num_operands; i++)
ir->operands[i] = convert_vector_extract_to_cond_assign(ir->operands[i]);
return visit_continue;
}
ir_visitor_status
ir_vec_index_to_cond_assign_visitor::visit_enter(ir_swizzle *ir)
{
/* Can't be hit from normal GLSL, since you can't swizzle a scalar (which
* the result of indexing a vector is. But maybe at some point we'll end up
* using swizzling of scalars for vector construction.
*/
ir->val = convert_vector_extract_to_cond_assign(ir->val);
return visit_continue;
}
ir_visitor_status
ir_vec_index_to_cond_assign_visitor::visit_leave(ir_assignment *ir)
{
ir->rhs = convert_vector_extract_to_cond_assign(ir->rhs);
if (ir->condition)
ir->condition = convert_vector_extract_to_cond_assign(ir->condition);
return visit_continue;
}
ir_visitor_status
ir_vec_index_to_cond_assign_visitor::visit_enter(ir_call *ir)
{
foreach_in_list_safe(ir_rvalue, param, &ir->actual_parameters) {
ir_rvalue *new_param = convert_vector_extract_to_cond_assign(param);
if (new_param != param) {
param->replace_with(new_param);
}
}
return visit_continue;
}
ir_visitor_status
ir_vec_index_to_cond_assign_visitor::visit_enter(ir_return *ir)
{
if (ir->value)
ir->value = convert_vector_extract_to_cond_assign(ir->value);
return visit_continue;
}
ir_visitor_status
ir_vec_index_to_cond_assign_visitor::visit_enter(ir_if *ir)
{
ir->condition = convert_vector_extract_to_cond_assign(ir->condition);
return visit_continue;
}
bool
do_vec_index_to_cond_assign(exec_list *instructions)
{
ir_vec_index_to_cond_assign_visitor v;
visit_list_elements(&v, instructions);
return v.progress;
}