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| /* -*- 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. |
| */ |
| |
| #pragma once |
| #ifndef LOOP_ANALYSIS_H |
| #define LOOP_ANALYSIS_H |
| |
| #include "ir.h" |
| #include "program/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 sequences |
| * in the loop of the form |
| * |
| * (if (expression bool ...) (break)) |
| * |
| * and fill in the \c ir_loop::from, \c ir_loop::to, and \c ir_loop::counter |
| * fields of the \c ir_loop. |
| * |
| * In this process, some conditional break-statements may be eliminated |
| * altogether. 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, unsigned max_iterations); |
| |
| |
| /** |
| * 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_terminator *insert(ir_if *); |
| |
| |
| /** |
| * Loop whose variable state is being tracked by this structure |
| */ |
| ir_loop *loop; |
| |
| /** |
| * 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; |
| |
| /** |
| * Hash table containing all variables accessed in this loop |
| */ |
| hash_table *var_hash; |
| |
| /** |
| * Maximum number of loop iterations. |
| * |
| * If this value is negative, then the loop may be infinite. This actually |
| * means that analysis was unable to determine an upper bound on the number |
| * of loop iterations. |
| */ |
| int max_iterations; |
| |
| /** |
| * Number of ir_loop_jump instructions that operate on this loop |
| */ |
| unsigned num_loop_jumps; |
| |
| loop_variable_state() |
| { |
| this->max_iterations = -1; |
| this->num_loop_jumps = 0; |
| this->var_hash = hash_table_ctor(0, hash_table_pointer_hash, |
| hash_table_pointer_compare); |
| } |
| |
| ~loop_variable_state() |
| { |
| hash_table_dtor(this->var_hash); |
| } |
| }; |
| |
| |
| 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? */ |
| bool conditional_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 values for loop induction variables |
| * |
| * Loop induction variables have a single increment of the form |
| * \c b * \c biv + \c c, where \c b and \c c are loop constants and \c i |
| * is a basic loop induction variable. |
| * |
| * If \c iv_scale is \c NULL, 1 is used. If \c biv is the same as \c var, |
| * then \c var is a basic loop induction variable. |
| */ |
| /*@{*/ |
| ir_rvalue *iv_scale; |
| ir_variable *biv; |
| ir_rvalue *increment; |
| /*@}*/ |
| |
| |
| inline bool is_loop_constant() const |
| { |
| const bool is_const = (this->num_assignments == 0) |
| || ((this->num_assignments == 1) |
| && !this->conditional_assignment |
| && !this->read_before_write |
| && this->rhs_clean); |
| |
| /* 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); |
| |
| /* Variables that are marked read-only *MUST* be loop constant. |
| */ |
| assert(!this->var->read_only || (this->var->read_only && is_const)); |
| |
| return is_const; |
| } |
| }; |
| |
| |
| class loop_terminator : public exec_node { |
| public: |
| ir_if *ir; |
| }; |
| |
| |
| 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); |
| |
| private: |
| loop_state(); |
| |
| /** |
| * Hash table containing all loops that have been analyzed. |
| */ |
| hash_table *ht; |
| |
| void *mem_ctx; |
| |
| friend class loop_analysis; |
| }; |
| |
| #endif /* LOOP_ANALYSIS_H */ |