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25 * \file opt_redundant_jumps.cpp
26 * Remove certain types of redundant jumps
31 class redundant_jumps_visitor
: public ir_hierarchical_visitor
{
33 redundant_jumps_visitor()
35 this->progress
= false;
38 virtual ir_visitor_status
visit_leave(ir_if
*);
39 virtual ir_visitor_status
visit_leave(ir_loop
*);
46 redundant_jumps_visitor::visit_leave(ir_if
*ir
)
48 /* If the last instruction in both branches is a 'break' or a 'continue',
49 * pull it out of the branches and insert it after the if-statment. Note
50 * that both must be the same type (either 'break' or 'continue').
52 ir_instruction
*const last_then
=
53 (ir_instruction
*) ir
->then_instructions
.get_tail();
54 ir_instruction
*const last_else
=
55 (ir_instruction
*) ir
->else_instructions
.get_tail();
57 if ((last_then
== NULL
) || (last_else
== NULL
))
58 return visit_continue
;
60 if ((last_then
->ir_type
!= ir_type_loop_jump
)
61 || (last_else
->ir_type
!= ir_type_loop_jump
))
62 return visit_continue
;
64 ir_loop_jump
*const then_jump
= (ir_loop_jump
*) last_then
;
65 ir_loop_jump
*const else_jump
= (ir_loop_jump
*) last_else
;
67 if (then_jump
->mode
!= else_jump
->mode
)
68 return visit_continue
;
72 this->progress
= true;
74 ir
->insert_after(then_jump
);
76 /* If both branchs of the if-statement are now empty, remove the
79 if (ir
->then_instructions
.is_empty() && ir
->else_instructions
.is_empty())
82 return visit_continue
;
87 redundant_jumps_visitor::visit_leave(ir_loop
*ir
)
89 /* If the last instruction of a loop body is a 'continue', remove it.
91 ir_instruction
*const last
=
92 (ir_instruction
*) ir
->body_instructions
.get_tail();
94 if (last
&& (last
->ir_type
== ir_type_loop_jump
)
95 && (((ir_loop_jump
*) last
)->mode
== ir_loop_jump::jump_continue
)) {
97 this->progress
= true;
100 return visit_continue
;
105 optimize_redundant_jumps(exec_list
*instructions
)
107 redundant_jumps_visitor v
;