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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_pointer_hash_table_create(NULL
);
45 free_entry(struct hash_entry
*entry
)
47 ir_variable_refcount_entry
*ivre
= (ir_variable_refcount_entry
*) entry
->data
;
49 /* Free assignment list */
51 while ((n
= ivre
->assign_list
.pop_head()) != NULL
) {
52 struct assignment_entry
*assignment_entry
=
53 exec_node_data(struct assignment_entry
, n
, link
);
54 free(assignment_entry
);
60 ir_variable_refcount_visitor::~ir_variable_refcount_visitor()
62 ralloc_free(this->mem_ctx
);
63 _mesa_hash_table_destroy(this->ht
, free_entry
);
67 ir_variable_refcount_entry::ir_variable_refcount_entry(ir_variable
*var
)
76 ir_variable_refcount_entry
*
77 ir_variable_refcount_visitor::get_variable_entry(ir_variable
*var
)
81 struct hash_entry
*e
= _mesa_hash_table_search(this->ht
, var
);
83 return (ir_variable_refcount_entry
*)e
->data
;
85 ir_variable_refcount_entry
*entry
= new ir_variable_refcount_entry(var
);
86 assert(entry
->referenced_count
== 0);
87 _mesa_hash_table_insert(this->ht
, var
, entry
);
94 ir_variable_refcount_visitor::visit(ir_variable
*ir
)
96 ir_variable_refcount_entry
*entry
= this->get_variable_entry(ir
);
98 entry
->declaration
= true;
100 return visit_continue
;
105 ir_variable_refcount_visitor::visit(ir_dereference_variable
*ir
)
107 ir_variable
*const var
= ir
->variable_referenced();
108 ir_variable_refcount_entry
*entry
= this->get_variable_entry(var
);
111 entry
->referenced_count
++;
113 return visit_continue
;
118 ir_variable_refcount_visitor::visit_enter(ir_function_signature
*ir
)
120 /* We don't want to descend into the function parameters and
121 * dead-code eliminate them, so just accept the body here.
123 visit_list_elements(this, &ir
->body
);
124 return visit_continue_with_parent
;
129 ir_variable_refcount_visitor::visit_leave(ir_assignment
*ir
)
131 ir_variable_refcount_entry
*entry
;
132 entry
= this->get_variable_entry(ir
->lhs
->variable_referenced());
134 entry
->assigned_count
++;
136 /* Build a list for dead code optimisation. Don't add assignment if it
137 * was declared out of scope (outside the instruction stream). Also don't
138 * bother adding any more to the list if there are more references than
139 * assignments as this means the variable is used and won't be optimised
142 assert(entry
->referenced_count
>= entry
->assigned_count
);
143 if (entry
->referenced_count
== entry
->assigned_count
) {
144 struct assignment_entry
*assignment_entry
=
145 (struct assignment_entry
*)calloc(1, sizeof(*assignment_entry
));
146 assignment_entry
->assign
= ir
;
147 entry
->assign_list
.push_head(&assignment_entry
->link
);
151 return visit_continue
;