/*
* Copyright © 2010 Luca Barbieri
*
* 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_variable_index_to_cond_assign.cpp
*
* Turns non-constant indexing into array types to a series of
* conditional moves of each element into a temporary.
*
* Pre-DX10 GPUs often don't have a native way to do this operation,
* and this works around that.
*/
#include "ir.h"
#include "ir_rvalue_visitor.h"
#include "ir_optimization.h"
#include "glsl_types.h"
#include "main/macros.h"
struct assignment_generator
{
ir_instruction* base_ir;
ir_rvalue* array;
bool is_write;
ir_variable* var;
assignment_generator()
{
}
void generate(unsigned i, ir_rvalue* condition, exec_list *list) const
{
/* Just clone the rest of the deref chain when trying to get at the
* underlying variable.
*/
void *mem_ctx = hieralloc_parent(base_ir);
ir_rvalue *element =
new(mem_ctx) ir_dereference_array(this->array->clone(mem_ctx, NULL),
new(mem_ctx) ir_constant(i));
ir_rvalue *variable = new(mem_ctx) ir_dereference_variable(this->var);
ir_assignment *assignment = (is_write)
? new(mem_ctx) ir_assignment(element, variable, condition)
: new(mem_ctx) ir_assignment(variable, element, condition);
list->push_tail(assignment);
}
};
struct switch_generator
{
/* make TFunction a template parameter if you need to use other generators */
typedef assignment_generator TFunction;
const TFunction& generator;
ir_variable* index;
unsigned linear_sequence_max_length;
unsigned condition_components;
void *mem_ctx;
switch_generator(const TFunction& generator, ir_variable *index,
unsigned linear_sequence_max_length,
unsigned condition_components)
: generator(generator), index(index),
linear_sequence_max_length(linear_sequence_max_length),
condition_components(condition_components)
{
this->mem_ctx = hieralloc_parent(index);
}
void linear_sequence(unsigned begin, unsigned end, exec_list *list)
{
if (begin == end)
return;
/* If the array access is a read, read the first element of this subregion
* unconditionally. The remaining tests will possibly overwrite this
* value with one of the other array elements.
*
* This optimization cannot be done for writes because it will cause the
* first element of the subregion to be written possibly *in addition* to
* one of the other elements.
*/
unsigned first;
if (!this->generator.is_write) {
this->generator.generate(begin, 0, list);
first = begin + 1;
} else {
first = begin;
}
for (unsigned i = first; i < end; i += 4) {
const unsigned comps = MIN2(condition_components, end - i);
ir_rvalue *broadcast_index =
new(this->mem_ctx) ir_dereference_variable(index);
if (comps) {
const ir_swizzle_mask m = { 0, 0, 0, 0, comps, false };
broadcast_index = new(this->mem_ctx) ir_swizzle(broadcast_index, m);
}
/* Compare the desired index value with the next block of four indices.
*/
ir_constant_data test_indices_data;
memset(&test_indices_data, 0, sizeof(test_indices_data));
test_indices_data.i[0] = i;
test_indices_data.i[1] = i + 1;
test_indices_data.i[2] = i + 2;
test_indices_data.i[3] = i + 3;
ir_constant *const test_indices =
new(this->mem_ctx) ir_constant(broadcast_index->type,
&test_indices_data);
ir_rvalue *const condition_val =
new(this->mem_ctx) ir_expression(ir_binop_equal,
&glsl_type::bool_type[comps - 1],
broadcast_index,
test_indices);
ir_variable *const condition =
new(this->mem_ctx) ir_variable(condition_val->type,
"dereference_array_condition",
ir_var_temporary);
list->push_tail(condition);
ir_rvalue *const cond_deref =
new(this->mem_ctx) ir_dereference_variable(condition);
list->push_tail(new(this->mem_ctx) ir_assignment(cond_deref,
condition_val, 0));
if (comps == 1) {
ir_rvalue *const cond_deref =
new(this->mem_ctx) ir_dereference_variable(condition);
this->generator.generate(i, cond_deref, list);
} else {
for (unsigned j = 0; j < comps; j++) {
ir_rvalue *const cond_deref =
new(this->mem_ctx) ir_dereference_variable(condition);
ir_rvalue *const cond_swiz =
new(this->mem_ctx) ir_swizzle(cond_deref, j, 0, 0, 0, 1);
this->generator.generate(i + j, cond_swiz, list);
}
}
}
}
void bisect(unsigned begin, unsigned end, exec_list *list)
{
unsigned middle = (begin + end) >> 1;
assert(index->type->is_integer());
ir_constant *const middle_c = (index->type->base_type == GLSL_TYPE_UINT)
? new(this->mem_ctx) ir_constant((unsigned)middle)
: new(this->mem_ctx) ir_constant((int)middle);
ir_dereference_variable *deref =
new(this->mem_ctx) ir_dereference_variable(this->index);
ir_expression *less =
new(this->mem_ctx) ir_expression(ir_binop_less, glsl_type::bool_type,
deref, middle_c);
ir_if *if_less = new(this->mem_ctx) ir_if(less);
generate(begin, middle, &if_less->then_instructions);
generate(middle, end, &if_less->else_instructions);
list->push_tail(if_less);
}
void generate(unsigned begin, unsigned end, exec_list *list)
{
unsigned length = end - begin;
if (length <= this->linear_sequence_max_length)
return linear_sequence(begin, end, list);
else
return bisect(begin, end, list);
}
};
/**
* Visitor class for replacing expressions with ir_constant values.
*/
class variable_index_to_cond_assign_visitor : public ir_rvalue_visitor {
public:
variable_index_to_cond_assign_visitor(bool lower_input,
bool lower_output,
bool lower_temp,
bool lower_uniform)
{
this->progress = false;
this->lower_inputs = lower_input;
this->lower_outputs = lower_output;
this->lower_temps = lower_temp;
this->lower_uniforms = lower_uniform;
}
bool progress;
bool lower_inputs;
bool lower_outputs;
bool lower_temps;
bool lower_uniforms;
bool is_array_or_matrix(const ir_instruction *ir) const
{
return (ir->type->is_array() || ir->type->is_matrix());
}
bool needs_lowering(ir_dereference_array *deref) const
{
if (deref == NULL || deref->array_index->as_constant()
|| !is_array_or_matrix(deref->array))
return false;
if (deref->array->ir_type == ir_type_constant)
return this->lower_temps;
const ir_variable *const var = deref->array->variable_referenced();
switch (var->mode) {
case ir_var_auto:
case ir_var_temporary:
return this->lower_temps;
case ir_var_uniform:
return this->lower_uniforms;
case ir_var_in:
return (var->location == -1) ? this->lower_temps : this->lower_inputs;
case ir_var_out:
return (var->location == -1) ? this->lower_temps : this->lower_outputs;
case ir_var_inout:
return this->lower_temps;
}
assert(!"Should not get here.");
return false;
}
ir_variable *convert_dereference_array(ir_dereference_array *orig_deref,
ir_rvalue* value)
{
assert(is_array_or_matrix(orig_deref->array));
const unsigned length = (orig_deref->array->type->is_array())
? orig_deref->array->type->length
: orig_deref->array->type->matrix_columns;
void *const mem_ctx = hieralloc_parent(base_ir);
ir_variable *var =
new(mem_ctx) ir_variable(orig_deref->type, "dereference_array_value",
ir_var_temporary);
base_ir->insert_before(var);
if (value) {
ir_dereference *lhs = new(mem_ctx) ir_dereference_variable(var);
ir_assignment *assign = new(mem_ctx) ir_assignment(lhs, value, NULL);
base_ir->insert_before(assign);
}
/* Store the index to a temporary to avoid reusing its tree. */
ir_variable *index =
new(mem_ctx) ir_variable(orig_deref->array_index->type,
"dereference_array_index", ir_var_temporary);
base_ir->insert_before(index);
ir_dereference *lhs = new(mem_ctx) ir_dereference_variable(index);
ir_assignment *assign =
new(mem_ctx) ir_assignment(lhs, orig_deref->array_index, NULL);
base_ir->insert_before(assign);
assignment_generator ag;
ag.array = orig_deref->array;
ag.base_ir = base_ir;
ag.var = var;
ag.is_write = !!value;
switch_generator sg(ag, index, 4, 4);
exec_list list;
sg.generate(0, length, &list);
base_ir->insert_before(&list);
return var;
}
virtual void handle_rvalue(ir_rvalue **pir)
{
if (!*pir)
return;
ir_dereference_array* orig_deref = (*pir)->as_dereference_array();
if (needs_lowering(orig_deref)) {
ir_variable* var = convert_dereference_array(orig_deref, 0);
assert(var);
*pir = new(hieralloc_parent(base_ir)) ir_dereference_variable(var);
this->progress = true;
}
}
ir_visitor_status
visit_leave(ir_assignment *ir)
{
ir_rvalue_visitor::visit_leave(ir);
ir_dereference_array *orig_deref = ir->lhs->as_dereference_array();
if (needs_lowering(orig_deref)) {
convert_dereference_array(orig_deref, ir->rhs);
ir->remove();
this->progress = true;
}
return visit_continue;
}
};
bool
lower_variable_index_to_cond_assign(exec_list *instructions,
bool lower_input,
bool lower_output,
bool lower_temp,
bool lower_uniform)
{
variable_index_to_cond_assign_visitor v(lower_input,
lower_output,
lower_temp,
lower_uniform);
visit_list_elements(&v, instructions);
return v.progress;
}