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25 * \file ir_sub_to_add_neg.cpp
27 * Breaks an ir_binop_sub expression down to add(op0, neg(op1))
29 * This simplifies expression reassociation, and for many backends
30 * there is no subtract operation separate from adding the negation.
31 * For backends with native subtract operations, they will probably
32 * want to recognize add(op0, neg(op1)) or the other way around to
33 * produce a subtract anyway.
38 class ir_sub_to_add_neg_visitor
: public ir_hierarchical_visitor
{
40 ir_sub_to_add_neg_visitor()
42 this->progress
= false;
45 ir_visitor_status
visit_leave(ir_expression
*);
51 do_sub_to_add_neg(exec_list
*instructions
)
53 ir_sub_to_add_neg_visitor v
;
55 visit_list_elements(&v
, instructions
);
60 ir_sub_to_add_neg_visitor::visit_leave(ir_expression
*ir
)
62 if (ir
->operation
!= ir_binop_sub
)
63 return visit_continue
;
65 void *mem_ctx
= talloc_parent(ir
);
67 ir
->operation
= ir_binop_add
;
68 ir
->operands
[1] = new(mem_ctx
) ir_expression(ir_unop_neg
,
69 ir
->operands
[1]->type
,
73 this->progress
= true;
75 return visit_continue
;