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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 "glsl_types.h"
45 * Visitor class for replacing expressions with ir_constant values.
48 class ir_vec_index_to_cond_assign_visitor
: public ir_hierarchical_visitor
{
50 ir_vec_index_to_cond_assign_visitor()
55 ir_rvalue
*convert_vec_index_to_cond_assign(ir_rvalue
*val
);
57 virtual ir_visitor_status
visit_enter(ir_expression
*);
58 virtual ir_visitor_status
visit_enter(ir_swizzle
*);
59 virtual ir_visitor_status
visit_leave(ir_assignment
*);
60 virtual ir_visitor_status
visit_enter(ir_return
*);
61 virtual ir_visitor_status
visit_enter(ir_call
*);
62 virtual ir_visitor_status
visit_enter(ir_if
*);
68 ir_vec_index_to_cond_assign_visitor::convert_vec_index_to_cond_assign(ir_rvalue
*ir
)
70 ir_dereference_array
*orig_deref
= ir
->as_dereference_array();
71 ir_assignment
*assign
, *value_assign
;
72 ir_variable
*index
, *var
, *value
;
73 ir_dereference
*deref
, *deref_value
;
79 if (orig_deref
->array
->type
->is_matrix() ||
80 orig_deref
->array
->type
->is_array())
83 void *mem_ctx
= ralloc_parent(ir
);
85 assert(orig_deref
->array_index
->type
->base_type
== GLSL_TYPE_INT
);
89 /* Store the index to a temporary to avoid reusing its tree. */
90 index
= new(base_ir
) ir_variable(glsl_type::int_type
,
93 list
.push_tail(index
);
94 deref
= new(base_ir
) ir_dereference_variable(index
);
95 assign
= new(base_ir
) ir_assignment(deref
, orig_deref
->array_index
, NULL
);
96 list
.push_tail(assign
);
98 /* Store the value inside a temp, thus avoiding matrixes duplication */
99 value
= new(base_ir
) ir_variable(orig_deref
->array
->type
, "vec_value_tmp",
101 list
.push_tail(value
);
102 deref_value
= new(base_ir
) ir_dereference_variable(value
);
103 value_assign
= new(base_ir
) ir_assignment(deref_value
, orig_deref
->array
);
104 list
.push_tail(value_assign
);
106 /* Temporary where we store whichever value we swizzle out. */
107 var
= new(base_ir
) ir_variable(ir
->type
, "vec_index_tmp_v",
111 /* Generate a single comparison condition "mask" for all of the components
114 ir_rvalue
*const cond_deref
=
115 compare_index_block(&list
, index
, 0,
116 orig_deref
->array
->type
->vector_elements
,
119 /* Generate a conditional move of each vector element to the temp. */
120 for (i
= 0; i
< orig_deref
->array
->type
->vector_elements
; i
++) {
121 ir_rvalue
*condition_swizzle
=
122 new(base_ir
) ir_swizzle(cond_deref
->clone(ir
, NULL
), i
, 0, 0, 0, 1);
124 /* Just clone the rest of the deref chain when trying to get at the
125 * underlying variable.
128 new(base_ir
) ir_swizzle(deref_value
->clone(mem_ctx
, NULL
),
131 deref
= new(base_ir
) ir_dereference_variable(var
);
132 assign
= new(base_ir
) ir_assignment(deref
, swizzle
, condition_swizzle
);
133 list
.push_tail(assign
);
136 /* Put all of the new instructions in the IR stream before the old
139 base_ir
->insert_before(&list
);
141 this->progress
= true;
142 return new(base_ir
) ir_dereference_variable(var
);
146 ir_vec_index_to_cond_assign_visitor::visit_enter(ir_expression
*ir
)
150 for (i
= 0; i
< ir
->get_num_operands(); i
++) {
151 ir
->operands
[i
] = convert_vec_index_to_cond_assign(ir
->operands
[i
]);
154 return visit_continue
;
158 ir_vec_index_to_cond_assign_visitor::visit_enter(ir_swizzle
*ir
)
160 /* Can't be hit from normal GLSL, since you can't swizzle a scalar (which
161 * the result of indexing a vector is. But maybe at some point we'll end up
162 * using swizzling of scalars for vector construction.
164 ir
->val
= convert_vec_index_to_cond_assign(ir
->val
);
166 return visit_continue
;
170 ir_vec_index_to_cond_assign_visitor::visit_leave(ir_assignment
*ir
)
172 ir_variable
*index
, *var
;
173 ir_dereference_variable
*deref
;
174 ir_assignment
*assign
;
177 ir
->rhs
= convert_vec_index_to_cond_assign(ir
->rhs
);
179 ir
->condition
= convert_vec_index_to_cond_assign(ir
->condition
);
181 /* Last, handle the LHS */
182 ir_dereference_array
*orig_deref
= ir
->lhs
->as_dereference_array();
185 orig_deref
->array
->type
->is_matrix() ||
186 orig_deref
->array
->type
->is_array())
187 return visit_continue
;
189 void *mem_ctx
= ralloc_parent(ir
);
191 assert(orig_deref
->array_index
->type
->base_type
== GLSL_TYPE_INT
);
195 /* Store the index to a temporary to avoid reusing its tree. */
196 index
= new(ir
) ir_variable(glsl_type::int_type
, "vec_index_tmp_i",
198 list
.push_tail(index
);
199 deref
= new(ir
) ir_dereference_variable(index
);
200 assign
= new(ir
) ir_assignment(deref
, orig_deref
->array_index
, NULL
);
201 list
.push_tail(assign
);
203 /* Store the RHS to a temporary to avoid reusing its tree. */
204 var
= new(ir
) ir_variable(ir
->rhs
->type
, "vec_index_tmp_v",
207 deref
= new(ir
) ir_dereference_variable(var
);
208 assign
= new(ir
) ir_assignment(deref
, ir
->rhs
, NULL
);
209 list
.push_tail(assign
);
211 /* Generate a single comparison condition "mask" for all of the components
214 ir_rvalue
*const cond_deref
=
215 compare_index_block(&list
, index
, 0,
216 orig_deref
->array
->type
->vector_elements
,
219 /* Generate a conditional move of each vector element to the temp. */
220 for (i
= 0; i
< orig_deref
->array
->type
->vector_elements
; i
++) {
221 ir_rvalue
*condition_swizzle
=
222 new(ir
) ir_swizzle(cond_deref
->clone(ir
, NULL
), i
, 0, 0, 0, 1);
225 /* Just clone the rest of the deref chain when trying to get at the
226 * underlying variable.
229 new(ir
) ir_swizzle(orig_deref
->array
->clone(mem_ctx
, NULL
),
232 deref
= new(ir
) ir_dereference_variable(var
);
233 assign
= new(ir
) ir_assignment(swizzle
, deref
, condition_swizzle
);
234 list
.push_tail(assign
);
237 /* If the original assignment has a condition, respect that original
238 * condition! This is acomplished by wrapping the new conditional
239 * assignments in an if-statement that uses the original condition.
241 if (ir
->condition
!= NULL
) {
242 /* No need to clone the condition because the IR that it hangs on is
243 * going to be removed from the instruction sequence.
245 ir_if
*if_stmt
= new(mem_ctx
) ir_if(ir
->condition
);
247 list
.move_nodes_to(&if_stmt
->then_instructions
);
248 ir
->insert_before(if_stmt
);
250 ir
->insert_before(&list
);
255 this->progress
= true;
257 return visit_continue
;
261 ir_vec_index_to_cond_assign_visitor::visit_enter(ir_call
*ir
)
263 foreach_iter(exec_list_iterator
, iter
, *ir
) {
264 ir_rvalue
*param
= (ir_rvalue
*)iter
.get();
265 ir_rvalue
*new_param
= convert_vec_index_to_cond_assign(param
);
267 if (new_param
!= param
) {
268 param
->replace_with(new_param
);
272 return visit_continue
;
276 ir_vec_index_to_cond_assign_visitor::visit_enter(ir_return
*ir
)
279 ir
->value
= convert_vec_index_to_cond_assign(ir
->value
);
282 return visit_continue
;
286 ir_vec_index_to_cond_assign_visitor::visit_enter(ir_if
*ir
)
288 ir
->condition
= convert_vec_index_to_cond_assign(ir
->condition
);
290 return visit_continue
;
294 do_vec_index_to_cond_assign(exec_list
*instructions
)
296 ir_vec_index_to_cond_assign_visitor v
;
298 visit_list_elements(&v
, instructions
);