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25 #ifndef LOOP_ANALYSIS_H
26 #define LOOP_ANALYSIS_H
29 #include "util/hash_table.h"
32 * Analyze and classify all variables used in all loops in the instruction list
34 extern class loop_state
*
35 analyze_loop_variables(exec_list
*instructions
);
39 * Fill in loop control fields
41 * Based on analysis of loop variables, this function tries to remove
42 * redundant sequences in the loop of the form
44 * (if (expression bool ...) (break))
46 * For example, if it is provable that one loop exit condition will
47 * always be satisfied before another, the unnecessary exit condition will be
51 set_loop_controls(exec_list
*instructions
, loop_state
*ls
);
55 unroll_loops(exec_list
*instructions
, loop_state
*ls
,
56 const struct gl_shader_compiler_options
*options
);
60 * Tracking for all variables used in a loop
62 class loop_variable_state
: public exec_node
{
64 class loop_variable
*get(const ir_variable
*);
65 class loop_variable
*insert(ir_variable
*);
66 class loop_variable
*get_or_insert(ir_variable
*, bool in_assignee
);
67 class loop_terminator
*insert(ir_if
*);
71 * Variables that have not yet been classified
76 * Variables whose values are constant within the body of the loop
78 * This list contains \c loop_variable objects.
83 * Induction variables for this loop
85 * This list contains \c loop_variable objects.
87 exec_list induction_variables
;
90 * Simple if-statements that lead to the termination of the loop
92 * This list contains \c loop_terminator objects.
94 * \sa is_loop_terminator
96 exec_list terminators
;
99 * If any of the terminators in \c terminators leads to termination of the
100 * loop after a constant number of iterations, this is the terminator that
101 * leads to termination after the smallest number of iterations. Otherwise
104 loop_terminator
*limiting_terminator
;
107 * Hash table containing all variables accessed in this loop
109 hash_table
*var_hash
;
112 * Number of ir_loop_jump instructions that operate on this loop
114 unsigned num_loop_jumps
;
117 * Whether this loop contains any function calls.
121 loop_variable_state()
123 this->num_loop_jumps
= 0;
124 this->contains_calls
= false;
125 this->var_hash
= _mesa_hash_table_create(NULL
, _mesa_hash_pointer
,
126 _mesa_key_pointer_equal
);
127 this->limiting_terminator
= NULL
;
130 ~loop_variable_state()
132 _mesa_hash_table_destroy(this->var_hash
, NULL
);
135 DECLARE_RALLOC_CXX_OPERATORS(loop_variable_state
)
139 class loop_variable
: public exec_node
{
141 /** The variable in question. */
144 /** Is the variable read in the loop before it is written? */
145 bool read_before_write
;
147 /** Are all variables in the RHS of the assignment loop constants? */
151 * Is there an assignment to the variable that is conditional, or inside a
154 bool conditional_or_nested_assignment
;
156 /** Reference to the first assignment to the variable in the loop body. */
157 ir_assignment
*first_assignment
;
159 /** Number of assignments to the variable in the loop body. */
160 unsigned num_assignments
;
163 * Increment value for a loop induction variable
165 * If this is a loop induction variable, the amount by which the variable
166 * is incremented on each iteration through the loop.
168 * If this is not a loop induction variable, NULL.
170 ir_rvalue
*increment
;
173 inline bool is_induction_var() const
175 /* Induction variables always have a non-null increment, and vice
178 return this->increment
!= NULL
;
182 inline bool is_loop_constant() const
184 const bool is_const
= (this->num_assignments
== 0)
185 || (((this->num_assignments
== 1)
186 && !this->conditional_or_nested_assignment
187 && !this->read_before_write
188 && this->rhs_clean
) || this->var
->data
.read_only
);
190 /* If the RHS of *the* assignment is clean, then there must be exactly
191 * one assignment of the variable.
193 assert((this->rhs_clean
&& (this->num_assignments
== 1))
194 || !this->rhs_clean
);
199 void record_reference(bool in_assignee
,
200 bool in_conditional_code_or_nested_loop
,
201 ir_assignment
*current_assignment
);
205 class loop_terminator
: public exec_node
{
208 : ir(NULL
), iterations(-1)
213 * Statement which terminates the loop.
218 * The number of iterations after which the terminator is known to
219 * terminate the loop (if that is a fixed value). Otherwise -1.
230 * Get the loop variable state data for a particular loop
232 loop_variable_state
*get(const ir_loop
*);
234 loop_variable_state
*insert(ir_loop
*ir
);
242 * Hash table containing all loops that have been analyzed.
248 friend loop_state
*analyze_loop_variables(exec_list
*instructions
);
251 #endif /* LOOP_ANALYSIS_H */