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25 * \file lower_vec_index_to_cond_assign.cpp
27 * Turns indexing into vector types to a series of conditional moves
28 * of each channel's swizzle into a temporary.
30 * Most GPUs don't have a native way to do this operation, and this
31 * works around that. For drivers using both this pass and
32 * ir_vec_index_to_swizzle, there's a risk that this pass will happen
33 * before sufficient constant folding to find that the array index is
34 * constant. However, we hope that other optimization passes,
35 * particularly constant folding of assignment conditions and copy
36 * propagation, will result in the same code in the end.
40 #include "ir_visitor.h"
41 #include "ir_optimization.h"
42 #include "compiler/glsl_types.h"
43 #include "ir_builder.h"
45 using namespace ir_builder
;
50 * Visitor class for replacing expressions with ir_constant values.
53 class ir_vec_index_to_cond_assign_visitor
: public ir_hierarchical_visitor
{
55 ir_vec_index_to_cond_assign_visitor()
61 ir_rvalue
*convert_vec_index_to_cond_assign(void *mem_ctx
,
62 ir_rvalue
*orig_vector
,
63 ir_rvalue
*orig_index
,
64 const glsl_type
*type
);
66 ir_rvalue
*convert_vector_extract_to_cond_assign(ir_rvalue
*ir
);
68 virtual ir_visitor_status
visit_enter(ir_expression
*);
69 virtual ir_visitor_status
visit_enter(ir_swizzle
*);
70 virtual ir_visitor_status
visit_leave(ir_assignment
*);
71 virtual ir_visitor_status
visit_enter(ir_return
*);
72 virtual ir_visitor_status
visit_enter(ir_call
*);
73 virtual ir_visitor_status
visit_enter(ir_if
*);
78 } /* anonymous namespace */
81 ir_vec_index_to_cond_assign_visitor::convert_vec_index_to_cond_assign(void *mem_ctx
,
82 ir_rvalue
*orig_vector
,
83 ir_rvalue
*orig_index
,
84 const glsl_type
*type
)
87 ir_factory
body(&list
, base_ir
);
89 /* Store the index to a temporary to avoid reusing its tree. */
90 assert(orig_index
->type
== glsl_type::int_type
||
91 orig_index
->type
== glsl_type::uint_type
);
92 ir_variable
*const index
=
93 body
.make_temp(orig_index
->type
, "vec_index_tmp_i");
95 body
.emit(assign(index
, orig_index
));
97 /* Store the value inside a temp, thus avoiding matrixes duplication */
98 ir_variable
*const value
=
99 body
.make_temp(orig_vector
->type
, "vec_value_tmp");
101 body
.emit(assign(value
, orig_vector
));
104 /* Temporary where we store whichever value we swizzle out. */
105 ir_variable
*const var
= body
.make_temp(type
, "vec_index_tmp_v");
107 /* Generate a single comparison condition "mask" for all of the components
110 ir_variable
*const cond
=
111 compare_index_block(&list
, index
, 0,
112 orig_vector
->type
->vector_elements
,
115 /* Generate a conditional move of each vector element to the temp. */
116 for (unsigned i
= 0; i
< orig_vector
->type
->vector_elements
; i
++)
117 body
.emit(assign(var
, swizzle(value
, i
, 1), swizzle(cond
, i
, 1)));
119 /* Put all of the new instructions in the IR stream before the old
122 base_ir
->insert_before(&list
);
124 this->progress
= true;
125 return deref(var
).val
;
129 ir_vec_index_to_cond_assign_visitor::convert_vector_extract_to_cond_assign(ir_rvalue
*ir
)
131 ir_expression
*const expr
= ir
->as_expression();
133 if (expr
== NULL
|| expr
->operation
!= ir_binop_vector_extract
)
136 return convert_vec_index_to_cond_assign(ralloc_parent(ir
),
143 ir_vec_index_to_cond_assign_visitor::visit_enter(ir_expression
*ir
)
145 for (unsigned i
= 0; i
< ir
->num_operands
; i
++)
146 ir
->operands
[i
] = convert_vector_extract_to_cond_assign(ir
->operands
[i
]);
148 return visit_continue
;
152 ir_vec_index_to_cond_assign_visitor::visit_enter(ir_swizzle
*ir
)
154 /* Can't be hit from normal GLSL, since you can't swizzle a scalar (which
155 * the result of indexing a vector is. But maybe at some point we'll end up
156 * using swizzling of scalars for vector construction.
158 ir
->val
= convert_vector_extract_to_cond_assign(ir
->val
);
160 return visit_continue
;
164 ir_vec_index_to_cond_assign_visitor::visit_leave(ir_assignment
*ir
)
166 ir
->rhs
= convert_vector_extract_to_cond_assign(ir
->rhs
);
169 ir
->condition
= convert_vector_extract_to_cond_assign(ir
->condition
);
171 return visit_continue
;
175 ir_vec_index_to_cond_assign_visitor::visit_enter(ir_call
*ir
)
177 foreach_in_list_safe(ir_rvalue
, param
, &ir
->actual_parameters
) {
178 ir_rvalue
*new_param
= convert_vector_extract_to_cond_assign(param
);
180 if (new_param
!= param
) {
181 param
->replace_with(new_param
);
185 return visit_continue
;
189 ir_vec_index_to_cond_assign_visitor::visit_enter(ir_return
*ir
)
192 ir
->value
= convert_vector_extract_to_cond_assign(ir
->value
);
194 return visit_continue
;
198 ir_vec_index_to_cond_assign_visitor::visit_enter(ir_if
*ir
)
200 ir
->condition
= convert_vector_extract_to_cond_assign(ir
->condition
);
202 return visit_continue
;
206 do_vec_index_to_cond_assign(exec_list
*instructions
)
208 ir_vec_index_to_cond_assign_visitor v
;
210 visit_list_elements(&v
, instructions
);