diff options
Diffstat (limited to 'src/glsl/lower_if_to_cond_assign.cpp')
| -rw-r--r-- | src/glsl/lower_if_to_cond_assign.cpp | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/src/glsl/lower_if_to_cond_assign.cpp b/src/glsl/lower_if_to_cond_assign.cpp new file mode 100644 index 0000000000..cf48cfb8d6 --- /dev/null +++ b/src/glsl/lower_if_to_cond_assign.cpp @@ -0,0 +1,168 @@ +/* + * 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_if_to_cond_assign.cpp + * + * This attempts to flatten all if statements to conditional + * assignments for GPUs that don't do control flow. + * + * It can't handle other control flow being inside of its block, such + * as calls or loops. Hopefully loop unrolling and inlining will take + * care of those. + */ + +#include "glsl_types.h" +#include "ir.h" + +class ir_if_to_cond_assign_visitor : public ir_hierarchical_visitor { +public: + ir_if_to_cond_assign_visitor() + { + this->progress = false; + } + + ir_visitor_status visit_leave(ir_if *); + + bool progress; +}; + +bool +do_if_to_cond_assign(exec_list *instructions) +{ + ir_if_to_cond_assign_visitor v; + + visit_list_elements(&v, instructions); + + return v.progress; +} + +void +check_control_flow(ir_instruction *ir, void *data) +{ + bool *found_control_flow = (bool *)data; + switch (ir->ir_type) { + case ir_type_call: + case ir_type_discard: + case ir_type_loop: + case ir_type_loop_jump: + case ir_type_return: + *found_control_flow = true; + break; + default: + break; + } +} + +void +move_block_to_cond_assign(void *mem_ctx, + ir_if *if_ir, ir_variable *cond_var, bool then) +{ + exec_list *instructions; + + if (then) { + instructions = &if_ir->then_instructions; + } else { + instructions = &if_ir->else_instructions; + } + + foreach_iter(exec_list_iterator, iter, *instructions) { + ir_instruction *ir = (ir_instruction *)iter.get(); + + if (ir->ir_type == ir_type_assignment) { + ir_assignment *assign = (ir_assignment *)ir; + ir_rvalue *cond_expr; + ir_dereference *deref = new(mem_ctx) ir_dereference_variable(cond_var); + + if (then) { + cond_expr = deref; + } else { + cond_expr = new(mem_ctx) ir_expression(ir_unop_logic_not, + glsl_type::bool_type, + deref, + NULL); + } + + if (!assign->condition) { + assign->condition = cond_expr; + } else { + assign->condition = new(mem_ctx) ir_expression(ir_binop_logic_and, + glsl_type::bool_type, + cond_expr, + assign->condition); + } + } + + /* Now, move from the if block to the block surrounding it. */ + ir->remove(); + if_ir->insert_before(ir); + } +} + +ir_visitor_status +ir_if_to_cond_assign_visitor::visit_leave(ir_if *ir) +{ + bool found_control_flow = false; + ir_variable *cond_var; + ir_assignment *assign; + ir_dereference_variable *deref; + + /* Check that both blocks don't contain anything we can't support. */ + foreach_iter(exec_list_iterator, then_iter, ir->then_instructions) { + ir_instruction *then_ir = (ir_instruction *)then_iter.get(); + visit_tree(then_ir, check_control_flow, &found_control_flow); + } + foreach_iter(exec_list_iterator, else_iter, ir->else_instructions) { + ir_instruction *else_ir = (ir_instruction *)else_iter.get(); + visit_tree(else_ir, check_control_flow, &found_control_flow); + } + if (found_control_flow) + return visit_continue; + + void *mem_ctx = talloc_parent(ir); + + /* Store the condition to a variable so the assignment conditions are + * simpler. + */ + cond_var = new(mem_ctx) ir_variable(glsl_type::bool_type, + "if_to_cond_assign_condition", + ir_var_temporary); + ir->insert_before(cond_var); + + deref = new(mem_ctx) ir_dereference_variable(cond_var); + assign = new(mem_ctx) ir_assignment(deref, + ir->condition, NULL); + ir->insert_before(assign); + + /* Now, move all of the instructions out of the if blocks, putting + * conditions on assignments. + */ + move_block_to_cond_assign(mem_ctx, ir, cond_var, true); + move_block_to_cond_assign(mem_ctx, ir, cond_var, false); + + ir->remove(); + + this->progress = true; + + return visit_continue; +} |