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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_if_to_cond_assign.cpp |
| * |
| * This attempts to flatten if-statements to conditional assignments for |
| * GPUs with limited or no flow control support. |
| * |
| * 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. |
| * |
| * Drivers for GPUs with no control flow support should simply call |
| * |
| * lower_if_to_cond_assign(instructions) |
| * |
| * to attempt to flatten all if-statements. |
| * |
| * Some GPUs (such as i965 prior to gen6) do support control flow, but have a |
| * maximum nesting depth N. Drivers for such hardware can call |
| * |
| * lower_if_to_cond_assign(instructions, N) |
| * |
| * to attempt to flatten any if-statements appearing at depth > N. |
| */ |
| |
| #include "glsl_types.h" |
| #include "ir.h" |
| #include "program/hash_table.h" |
| |
| class ir_if_to_cond_assign_visitor : public ir_hierarchical_visitor { |
| public: |
| ir_if_to_cond_assign_visitor(unsigned max_depth) |
| { |
| this->progress = false; |
| this->max_depth = max_depth; |
| this->depth = 0; |
| |
| this->condition_variables = hash_table_ctor(0, hash_table_pointer_hash, |
| hash_table_pointer_compare); |
| } |
| |
| ~ir_if_to_cond_assign_visitor() |
| { |
| hash_table_dtor(this->condition_variables); |
| } |
| |
| ir_visitor_status visit_enter(ir_if *); |
| ir_visitor_status visit_leave(ir_if *); |
| |
| bool progress; |
| unsigned max_depth; |
| unsigned depth; |
| |
| struct hash_table *condition_variables; |
| }; |
| |
| bool |
| lower_if_to_cond_assign(exec_list *instructions, unsigned max_depth) |
| { |
| if (max_depth == UINT_MAX) |
| return false; |
| |
| ir_if_to_cond_assign_visitor v(max_depth); |
| |
| 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_rvalue *cond_expr, |
| exec_list *instructions, |
| struct hash_table *ht) |
| { |
| foreach_list_safe(node, instructions) { |
| ir_instruction *ir = (ir_instruction *) node; |
| |
| if (ir->ir_type == ir_type_assignment) { |
| ir_assignment *assign = (ir_assignment *)ir; |
| |
| if (hash_table_find(ht, assign) == NULL) { |
| hash_table_insert(ht, assign, assign); |
| |
| /* If the LHS of the assignment is a condition variable that was |
| * previously added, insert an additional assignment of false to |
| * the variable. |
| */ |
| const bool assign_to_cv = |
| hash_table_find(ht, assign->lhs->variable_referenced()) != NULL; |
| |
| if (!assign->condition) { |
| if (assign_to_cv) { |
| assign->rhs = |
| new(mem_ctx) ir_expression(ir_binop_logic_and, |
| glsl_type::bool_type, |
| cond_expr->clone(mem_ctx, NULL), |
| assign->rhs); |
| } else { |
| assign->condition = cond_expr->clone(mem_ctx, NULL); |
| } |
| } else { |
| assign->condition = |
| new(mem_ctx) ir_expression(ir_binop_logic_and, |
| glsl_type::bool_type, |
| cond_expr->clone(mem_ctx, NULL), |
| 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_enter(ir_if *ir) |
| { |
| (void) ir; |
| this->depth++; |
| |
| return visit_continue; |
| } |
| |
| ir_visitor_status |
| ir_if_to_cond_assign_visitor::visit_leave(ir_if *ir) |
| { |
| /* Only flatten when beyond the GPU's maximum supported nesting depth. */ |
| if (this->depth-- <= this->max_depth) |
| return visit_continue; |
| |
| bool found_control_flow = false; |
| ir_assignment *assign; |
| |
| /* 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 = ralloc_parent(ir); |
| |
| /* Store the condition to a variable. Move all of the instructions from |
| * the then-clause of the if-statement. Use the condition variable as a |
| * condition for all assignments. |
| */ |
| ir_variable *const then_var = |
| new(mem_ctx) ir_variable(glsl_type::bool_type, |
| "if_to_cond_assign_then", |
| ir_var_temporary); |
| ir->insert_before(then_var); |
| |
| ir_dereference_variable *then_cond = |
| new(mem_ctx) ir_dereference_variable(then_var); |
| |
| assign = new(mem_ctx) ir_assignment(then_cond, ir->condition); |
| ir->insert_before(assign); |
| |
| move_block_to_cond_assign(mem_ctx, ir, then_cond, |
| &ir->then_instructions, |
| this->condition_variables); |
| |
| /* Add the new condition variable to the hash table. This allows us to |
| * find this variable when lowering other (enclosing) if-statements. |
| */ |
| hash_table_insert(this->condition_variables, then_var, then_var); |
| |
| /* If there are instructions in the else-clause, store the inverse of the |
| * condition to a variable. Move all of the instructions from the |
| * else-clause if the if-statement. Use the (inverse) condition variable |
| * as a condition for all assignments. |
| */ |
| if (!ir->else_instructions.is_empty()) { |
| ir_variable *const else_var = |
| new(mem_ctx) ir_variable(glsl_type::bool_type, |
| "if_to_cond_assign_else", |
| ir_var_temporary); |
| ir->insert_before(else_var); |
| |
| ir_dereference_variable *else_cond = |
| new(mem_ctx) ir_dereference_variable(else_var); |
| |
| ir_rvalue *inverse = |
| new(mem_ctx) ir_expression(ir_unop_logic_not, |
| then_cond->clone(mem_ctx, NULL)); |
| |
| assign = new(mem_ctx) ir_assignment(else_cond, inverse); |
| ir->insert_before(assign); |
| |
| move_block_to_cond_assign(mem_ctx, ir, else_cond, |
| &ir->else_instructions, |
| this->condition_variables); |
| |
| /* Add the new condition variable to the hash table. This allows us to |
| * find this variable when lowering other (enclosing) if-statements. |
| */ |
| hash_table_insert(this->condition_variables, else_var, else_var); |
| } |
| |
| ir->remove(); |
| |
| this->progress = true; |
| |
| return visit_continue; |
| } |