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24 #include "glsl_types.h"
25 #include "loop_analysis.h"
26 #include "ir_hierarchical_visitor.h"
28 class loop_unroll_visitor
: public ir_hierarchical_visitor
{
30 loop_unroll_visitor(loop_state
*state
, unsigned max_iterations
)
33 this->progress
= false;
34 this->max_iterations
= max_iterations
;
37 virtual ir_visitor_status
visit_leave(ir_loop
*ir
);
42 unsigned max_iterations
;
47 is_break(ir_instruction
*ir
)
49 return ir
!= NULL
&& ir
->ir_type
== ir_type_loop_jump
50 && ((ir_loop_jump
*) ir
)->is_break();
53 class loop_unroll_count
: public ir_hierarchical_visitor
{
58 loop_unroll_count(exec_list
*list
)
66 virtual ir_visitor_status
visit_enter(ir_assignment
*ir
)
69 return visit_continue
;
72 virtual ir_visitor_status
visit_enter(ir_expression
*ir
)
75 return visit_continue
;
78 virtual ir_visitor_status
visit_enter(ir_loop
*ir
)
81 return visit_continue
;
87 loop_unroll_visitor::visit_leave(ir_loop
*ir
)
89 loop_variable_state
*const ls
= this->state
->get(ir
);
92 /* If we've entered a loop that hasn't been analyzed, something really,
93 * really bad has happened.
97 return visit_continue
;
100 iterations
= ls
->max_iterations
;
102 /* Don't try to unroll loops where the number of iterations is not known
106 return visit_continue
;
108 /* Don't try to unroll loops that have zillions of iterations either.
110 if (iterations
> (int) max_iterations
)
111 return visit_continue
;
113 /* Don't try to unroll nested loops and loops with a huge body.
115 loop_unroll_count
count(&ir
->body_instructions
);
117 if (count
.fail
|| count
.nodes
* iterations
> (int)max_iterations
* 5)
118 return visit_continue
;
120 if (ls
->num_loop_jumps
> 1)
121 return visit_continue
;
122 else if (ls
->num_loop_jumps
) {
123 ir_instruction
*last_ir
= (ir_instruction
*) ir
->body_instructions
.get_tail();
124 assert(last_ir
!= NULL
);
126 if (is_break(last_ir
)) {
127 /* If the only loop-jump is a break at the end of the loop, the loop
128 * will execute exactly once. Remove the break, set the iteration
129 * count, and fall through to the normal unroller.
134 this->progress
= true;
137 ir_instruction
*break_ir
= NULL
;
138 bool continue_from_then_branch
= false;
140 foreach_list(node
, &ir
->body_instructions
) {
141 /* recognize loops in the form produced by ir_lower_jumps */
142 ir_instruction
*cur_ir
= (ir_instruction
*) node
;
144 ir_if
= cur_ir
->as_if();
146 /* Determine which if-statement branch, if any, ends with a
147 * break. The branch that did *not* have the break will get a
148 * temporary continue inserted in each iteration of the loop
151 * Note that since ls->num_loop_jumps is <= 1, it is impossible
152 * for both branches to end with a break.
154 ir_instruction
*ir_if_last
=
155 (ir_instruction
*) ir_if
->then_instructions
.get_tail();
157 if (is_break(ir_if_last
)) {
158 continue_from_then_branch
= false;
159 break_ir
= ir_if_last
;
163 (ir_instruction
*) ir_if
->else_instructions
.get_tail();
165 if (is_break(ir_if_last
)) {
166 break_ir
= ir_if_last
;
167 continue_from_then_branch
= true;
174 if (break_ir
== NULL
)
175 return visit_continue
;
177 /* move instructions after then if in the continue branch */
178 while (!ir_if
->get_next()->is_tail_sentinel()) {
179 ir_instruction
*move_ir
= (ir_instruction
*) ir_if
->get_next();
182 if (continue_from_then_branch
)
183 ir_if
->then_instructions
.push_tail(move_ir
);
185 ir_if
->else_instructions
.push_tail(move_ir
);
188 /* Remove the break from the if-statement.
192 void *const mem_ctx
= ralloc_parent(ir
);
193 ir_instruction
*ir_to_replace
= ir
;
195 for (int i
= 0; i
< iterations
; i
++) {
198 copy_list
.make_empty();
199 clone_ir_list(mem_ctx
, ©_list
, &ir
->body_instructions
);
201 ir_if
= ((ir_instruction
*) copy_list
.get_tail())->as_if();
202 assert(ir_if
!= NULL
);
204 ir_to_replace
->insert_before(©_list
);
205 ir_to_replace
->remove();
207 /* placeholder that will be removed in the next iteration */
209 new(mem_ctx
) ir_loop_jump(ir_loop_jump::jump_continue
);
211 exec_list
*const list
= (continue_from_then_branch
)
212 ? &ir_if
->then_instructions
: &ir_if
->else_instructions
;
214 list
->push_tail(ir_to_replace
);
217 ir_to_replace
->remove();
219 this->progress
= true;
220 return visit_continue
;
224 void *const mem_ctx
= ralloc_parent(ir
);
226 for (int i
= 0; i
< iterations
; i
++) {
229 copy_list
.make_empty();
230 clone_ir_list(mem_ctx
, ©_list
, &ir
->body_instructions
);
232 ir
->insert_before(©_list
);
235 /* The loop has been replaced by the unrolled copies. Remove the original
236 * loop from the IR sequence.
240 this->progress
= true;
241 return visit_continue
;
246 unroll_loops(exec_list
*instructions
, loop_state
*ls
, unsigned max_iterations
)
248 loop_unroll_visitor
v(ls
, max_iterations
);