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Diffstat (limited to 'mesalib/src/glsl/loop_analysis.h')
| -rw-r--r-- | mesalib/src/glsl/loop_analysis.h | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/mesalib/src/glsl/loop_analysis.h b/mesalib/src/glsl/loop_analysis.h new file mode 100644 index 000000000..7b0511fbb --- /dev/null +++ b/mesalib/src/glsl/loop_analysis.h @@ -0,0 +1,230 @@ +/* -*- 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 */ |