diff options
Diffstat (limited to 'src/glsl/lower_variable_index_to_cond_assign.cpp')
| -rw-r--r-- | src/glsl/lower_variable_index_to_cond_assign.cpp | 313 |
1 files changed, 313 insertions, 0 deletions
diff --git a/src/glsl/lower_variable_index_to_cond_assign.cpp b/src/glsl/lower_variable_index_to_cond_assign.cpp new file mode 100644 index 0000000000..d9e6379c39 --- /dev/null +++ b/src/glsl/lower_variable_index_to_cond_assign.cpp @@ -0,0 +1,313 @@ +/* + * 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 = talloc_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 = talloc_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, 1, 2, 3, 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() + { + this->progress = false; + } + + bool progress; + + ir_variable *convert_dereference_array(ir_dereference_array *orig_deref, + ir_rvalue* value) + { + unsigned length; + if (orig_deref->array->type->is_array()) + length = orig_deref->array->type->length; + else if (orig_deref->array->type->is_matrix()) + length = orig_deref->array->type->matrix_columns; + else + assert(0); + + void *const mem_ctx = talloc_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 (orig_deref && !orig_deref->array_index->as_constant() + && (orig_deref->array->type->is_array() + || orig_deref->array->type->is_matrix())) { + ir_variable* var = convert_dereference_array(orig_deref, 0); + assert(var); + *pir = new(talloc_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 (orig_deref && !orig_deref->array_index->as_constant() + && (orig_deref->array->type->is_array() + || orig_deref->array->type->is_matrix())) { + 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) +{ + variable_index_to_cond_assign_visitor v; + + visit_list_elements(&v, instructions); + + return v.progress; +} |