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25 * \file ir_variable_refcount.cpp
27 * Provides a visitor which produces a list of variables referenced,
28 * how many times they were referenced and assigned, and whether they
29 * were defined in the scope.
33 #include "ir_visitor.h"
34 #include "ir_variable_refcount.h"
35 #include "compiler/glsl_types.h"
36 #include "util/hash_table.h"
38 ir_variable_refcount_visitor::ir_variable_refcount_visitor()
40 this->mem_ctx
= ralloc_context(NULL
);
41 this->ht
= _mesa_hash_table_create(NULL
, _mesa_hash_pointer
,
42 _mesa_key_pointer_equal
);
46 free_entry(struct hash_entry
*entry
)
48 ir_variable_refcount_entry
*ivre
= (ir_variable_refcount_entry
*) entry
->data
;
50 /* Free assignment list */
52 while ((n
= ivre
->assign_list
.pop_head()) != NULL
) {
53 struct assignment_entry
*assignment_entry
=
54 exec_node_data(struct assignment_entry
, n
, link
);
55 free(assignment_entry
);
61 ir_variable_refcount_visitor::~ir_variable_refcount_visitor()
63 ralloc_free(this->mem_ctx
);
64 _mesa_hash_table_destroy(this->ht
, free_entry
);
68 ir_variable_refcount_entry::ir_variable_refcount_entry(ir_variable
*var
)
77 ir_variable_refcount_entry
*
78 ir_variable_refcount_visitor::get_variable_entry(ir_variable
*var
)
82 struct hash_entry
*e
= _mesa_hash_table_search(this->ht
, var
);
84 return (ir_variable_refcount_entry
*)e
->data
;
86 ir_variable_refcount_entry
*entry
= new ir_variable_refcount_entry(var
);
87 assert(entry
->referenced_count
== 0);
88 _mesa_hash_table_insert(this->ht
, var
, entry
);
95 ir_variable_refcount_visitor::visit(ir_variable
*ir
)
97 ir_variable_refcount_entry
*entry
= this->get_variable_entry(ir
);
99 entry
->declaration
= true;
101 return visit_continue
;
106 ir_variable_refcount_visitor::visit(ir_dereference_variable
*ir
)
108 ir_variable
*const var
= ir
->variable_referenced();
109 ir_variable_refcount_entry
*entry
= this->get_variable_entry(var
);
112 entry
->referenced_count
++;
114 return visit_continue
;
119 ir_variable_refcount_visitor::visit_enter(ir_function_signature
*ir
)
121 /* We don't want to descend into the function parameters and
122 * dead-code eliminate them, so just accept the body here.
124 visit_list_elements(this, &ir
->body
);
125 return visit_continue_with_parent
;
130 ir_variable_refcount_visitor::visit_leave(ir_assignment
*ir
)
132 ir_variable_refcount_entry
*entry
;
133 entry
= this->get_variable_entry(ir
->lhs
->variable_referenced());
135 entry
->assigned_count
++;
137 /* Build a list for dead code optimisation. Don't add assignment if it
138 * was declared out of scope (outside the instruction stream). Also don't
139 * bother adding any more to the list if there are more references than
140 * assignments as this means the variable is used and won't be optimised
143 assert(entry
->referenced_count
>= entry
->assigned_count
);
144 if (entry
->referenced_count
== entry
->assigned_count
) {
145 struct assignment_entry
*assignment_entry
=
146 (struct assignment_entry
*)calloc(1, sizeof(*assignment_entry
));
147 assignment_entry
->assign
= ir
;
148 entry
->assign_list
.push_head(&assignment_entry
->link
);
152 return visit_continue
;