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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. |
| */ |
| |
| #include <limits.h> |
| #include "main/compiler.h" |
| #include "glsl_types.h" |
| #include "loop_analysis.h" |
| #include "ir_hierarchical_visitor.h" |
| |
| /** |
| * Find an initializer of a variable outside a loop |
| * |
| * Works backwards from the loop to find the pre-loop value of the variable. |
| * This is used, for example, to find the initial value of loop induction |
| * variables. |
| * |
| * \param loop Loop where \c var is an induction variable |
| * \param var Variable whose initializer is to be found |
| * |
| * \return |
| * The \c ir_rvalue assigned to the variable outside the loop. May return |
| * \c NULL if no initializer can be found. |
| */ |
| ir_rvalue * |
| find_initial_value(ir_loop *loop, ir_variable *var) |
| { |
| for (exec_node *node = loop->prev; |
| !node->is_head_sentinel(); |
| node = node->prev) { |
| ir_instruction *ir = (ir_instruction *) node; |
| |
| switch (ir->ir_type) { |
| case ir_type_call: |
| case ir_type_loop: |
| case ir_type_loop_jump: |
| case ir_type_return: |
| case ir_type_if: |
| return NULL; |
| |
| case ir_type_function: |
| case ir_type_function_signature: |
| assert(!"Should not get here."); |
| return NULL; |
| |
| case ir_type_assignment: { |
| ir_assignment *assign = ir->as_assignment(); |
| ir_variable *assignee = assign->lhs->whole_variable_referenced(); |
| |
| if (assignee == var) |
| return (assign->condition != NULL) ? NULL : assign->rhs; |
| |
| break; |
| } |
| |
| default: |
| break; |
| } |
| } |
| |
| return NULL; |
| } |
| |
| |
| int |
| calculate_iterations(ir_rvalue *from, ir_rvalue *to, ir_rvalue *increment, |
| enum ir_expression_operation op) |
| { |
| if (from == NULL || to == NULL || increment == NULL) |
| return -1; |
| |
| void *mem_ctx = ralloc_context(NULL); |
| |
| ir_expression *const sub = |
| new(mem_ctx) ir_expression(ir_binop_sub, from->type, to, from); |
| |
| ir_expression *const div = |
| new(mem_ctx) ir_expression(ir_binop_div, sub->type, sub, increment); |
| |
| ir_constant *iter = div->constant_expression_value(); |
| |
| if (iter == NULL) |
| return -1; |
| |
| if (!iter->type->is_integer()) { |
| const ir_expression_operation op = iter->type->is_double() |
| ? ir_unop_d2i : ir_unop_f2i; |
| ir_rvalue *cast = |
| new(mem_ctx) ir_expression(op, glsl_type::int_type, iter, NULL); |
| |
| iter = cast->constant_expression_value(); |
| } |
| |
| int iter_value = iter->get_int_component(0); |
| |
| /* Make sure that the calculated number of iterations satisfies the exit |
| * condition. This is needed to catch off-by-one errors and some types of |
| * ill-formed loops. For example, we need to detect that the following |
| * loop does not have a maximum iteration count. |
| * |
| * for (float x = 0.0; x != 0.9; x += 0.2) |
| * ; |
| */ |
| const int bias[] = { -1, 0, 1 }; |
| bool valid_loop = false; |
| |
| for (unsigned i = 0; i < ARRAY_SIZE(bias); i++) { |
| /* Increment may be of type int, uint or float. */ |
| switch (increment->type->base_type) { |
| case GLSL_TYPE_INT: |
| iter = new(mem_ctx) ir_constant(iter_value + bias[i]); |
| break; |
| case GLSL_TYPE_UINT: |
| iter = new(mem_ctx) ir_constant(unsigned(iter_value + bias[i])); |
| break; |
| case GLSL_TYPE_FLOAT: |
| iter = new(mem_ctx) ir_constant(float(iter_value + bias[i])); |
| break; |
| case GLSL_TYPE_DOUBLE: |
| iter = new(mem_ctx) ir_constant(double(iter_value + bias[i])); |
| break; |
| default: |
| unreachable("Unsupported type for loop iterator."); |
| } |
| |
| ir_expression *const mul = |
| new(mem_ctx) ir_expression(ir_binop_mul, increment->type, iter, |
| increment); |
| |
| ir_expression *const add = |
| new(mem_ctx) ir_expression(ir_binop_add, mul->type, mul, from); |
| |
| ir_expression *const cmp = |
| new(mem_ctx) ir_expression(op, glsl_type::bool_type, add, to); |
| |
| ir_constant *const cmp_result = cmp->constant_expression_value(); |
| |
| assert(cmp_result != NULL); |
| if (cmp_result->get_bool_component(0)) { |
| iter_value += bias[i]; |
| valid_loop = true; |
| break; |
| } |
| } |
| |
| ralloc_free(mem_ctx); |
| return (valid_loop) ? iter_value : -1; |
| } |
| |
| namespace { |
| |
| class loop_control_visitor : public ir_hierarchical_visitor { |
| public: |
| loop_control_visitor(loop_state *state) |
| { |
| this->state = state; |
| this->progress = false; |
| } |
| |
| virtual ir_visitor_status visit_leave(ir_loop *ir); |
| |
| loop_state *state; |
| |
| bool progress; |
| }; |
| |
| } /* anonymous namespace */ |
| |
| ir_visitor_status |
| loop_control_visitor::visit_leave(ir_loop *ir) |
| { |
| loop_variable_state *const ls = this->state->get(ir); |
| |
| /* If we've entered a loop that hasn't been analyzed, something really, |
| * really bad has happened. |
| */ |
| if (ls == NULL) { |
| assert(ls != NULL); |
| return visit_continue; |
| } |
| |
| if (ls->limiting_terminator != NULL) { |
| /* If the limiting terminator has an iteration count of zero, then we've |
| * proven that the loop cannot run, so delete it. |
| */ |
| int iterations = ls->limiting_terminator->iterations; |
| if (iterations == 0) { |
| ir->remove(); |
| this->progress = true; |
| return visit_continue; |
| } |
| } |
| |
| /* Remove the conditional break statements associated with all terminators |
| * that are associated with a fixed iteration count, except for the one |
| * associated with the limiting terminator--that one needs to stay, since |
| * it terminates the loop. Exception: if the loop still has a normative |
| * bound, then that terminates the loop, so we don't even need the limiting |
| * terminator. |
| */ |
| foreach_in_list(loop_terminator, t, &ls->terminators) { |
| if (t->iterations < 0) |
| continue; |
| |
| if (t != ls->limiting_terminator) { |
| t->ir->remove(); |
| |
| assert(ls->num_loop_jumps > 0); |
| ls->num_loop_jumps--; |
| |
| this->progress = true; |
| } |
| } |
| |
| return visit_continue; |
| } |
| |
| |
| bool |
| set_loop_controls(exec_list *instructions, loop_state *ls) |
| { |
| loop_control_visitor v(ls); |
| |
| v.run(instructions); |
| |
| return v.progress; |
| } |