/* -*- c++ -*- */ /* * 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. */ #ifndef LOOP_ANALYSIS_H #define LOOP_ANALYSIS_H #include "ir.h" #include "util/hash_table.h" /** * Analyze and classify all variables used in all loops in the instruction list */ extern class loop_state * analyze_loop_variables(exec_list *instructions); /** * Fill in loop control fields * * Based on analysis of loop variables, this function tries to remove * redundant sequences in the loop of the form * * (if (expression bool ...) (break)) * * For example, if it is provable that one loop exit condition will * always be satisfied before another, the unnecessary exit condition will be * removed. */ extern bool set_loop_controls(exec_list *instructions, loop_state *ls); extern bool unroll_loops(exec_list *instructions, loop_state *ls, const struct gl_shader_compiler_options *options); ir_rvalue * find_initial_value(ir_loop *loop, ir_variable *var); int calculate_iterations(ir_rvalue *from, ir_rvalue *to, ir_rvalue *increment, enum ir_expression_operation op); /** * Tracking for all variables used in a loop */ class loop_variable_state : public exec_node { public: class loop_variable *get(const ir_variable *); class loop_variable *insert(ir_variable *); class loop_variable *get_or_insert(ir_variable *, bool in_assignee); class loop_terminator *insert(ir_if *); /** * Variables that have not yet been classified */ exec_list variables; /** * Variables whose values are constant within the body of the loop * * This list contains \c loop_variable objects. */ exec_list constants; /** * Induction variables for this loop * * This list contains \c loop_variable objects. */ exec_list induction_variables; /** * Simple if-statements that lead to the termination of the loop * * This list contains \c loop_terminator objects. * * \sa is_loop_terminator */ exec_list terminators; /** * If any of the terminators in \c terminators leads to termination of the * loop after a constant number of iterations, this is the terminator that * leads to termination after the smallest number of iterations. Otherwise * NULL. */ loop_terminator *limiting_terminator; /** * Hash table containing all variables accessed in this loop */ hash_table *var_hash; /** * Number of ir_loop_jump instructions that operate on this loop */ unsigned num_loop_jumps; /** * Whether this loop contains any function calls. */ bool contains_calls; loop_variable_state() { this->num_loop_jumps = 0; this->contains_calls = false; this->var_hash = _mesa_hash_table_create(NULL, _mesa_hash_pointer, _mesa_key_pointer_equal); this->limiting_terminator = NULL; } ~loop_variable_state() { _mesa_hash_table_destroy(this->var_hash, NULL); } DECLARE_RALLOC_CXX_OPERATORS(loop_variable_state) }; class loop_variable : public exec_node { public: /** The variable in question. */ ir_variable *var; /** Is the variable read in the loop before it is written? */ bool read_before_write; /** Are all variables in the RHS of the assignment loop constants? */ bool rhs_clean; /** * Is there an assignment to the variable that is conditional, or inside a * nested loop? */ bool conditional_or_nested_assignment; /** Reference to the first assignment to the variable in the loop body. */ ir_assignment *first_assignment; /** Number of assignments to the variable in the loop body. */ unsigned num_assignments; /** * Increment value for a loop induction variable * * If this is a loop induction variable, the amount by which the variable * is incremented on each iteration through the loop. * * If this is not a loop induction variable, NULL. */ ir_rvalue *increment; inline bool is_induction_var() const { /* Induction variables always have a non-null increment, and vice * versa. */ return this->increment != NULL; } inline bool is_loop_constant() const { const bool is_const = (this->num_assignments == 0) || (((this->num_assignments == 1) && !this->conditional_or_nested_assignment && !this->read_before_write && this->rhs_clean) || this->var->data.read_only); /* If the RHS of *the* assignment is clean, then there must be exactly * one assignment of the variable. */ assert((this->rhs_clean && (this->num_assignments == 1)) || !this->rhs_clean); return is_const; } void record_reference(bool in_assignee, bool in_conditional_code_or_nested_loop, ir_assignment *current_assignment); }; class loop_terminator : public exec_node { public: loop_terminator() : ir(NULL), iterations(-1) { } /** * Statement which terminates the loop. */ ir_if *ir; /** * The number of iterations after which the terminator is known to * terminate the loop (if that is a fixed value). Otherwise -1. */ int iterations; }; class loop_state { public: ~loop_state(); /** * Get the loop variable state data for a particular loop */ loop_variable_state *get(const ir_loop *); loop_variable_state *insert(ir_loop *ir); bool loop_found; private: loop_state(); /** * Hash table containing all loops that have been analyzed. */ hash_table *ht; void *mem_ctx; friend loop_state *analyze_loop_variables(exec_list *instructions); }; #endif /* LOOP_ANALYSIS_H */