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25 * \file brw_wm_channel_expressions.cpp
27 * Breaks vector operations down into operations on each component.
29 * The 965 fragment shader receives 8 or 16 pixels at a time, so each
30 * channel of a vector is laid out as 1 or 2 8-float registers. Each
31 * ALU operation operates on one of those channel registers. As a
32 * result, there is no value to the 965 fragment shader in tracking
33 * "vector" expressions in the sense of GLSL fragment shaders, when
34 * doing a channel at a time may help in constant folding, algebraic
35 * simplification, and reducing the liveness of channel registers.
37 * The exception to the desire to break everything down to floats is
38 * texturing. The texture sampler returns a writemasked masked
39 * 4/8-register sequence containing the texture values. We don't want
40 * to dispatch to the sampler separately for each channel we need, so
41 * we do retain the vector types in that case.
45 #include "main/core.h"
49 #include "glsl/ir_expression_flattening.h"
50 #include "glsl/glsl_types.h"
52 class ir_channel_expressions_visitor
: public ir_hierarchical_visitor
{
54 ir_channel_expressions_visitor()
56 this->progress
= false;
60 ir_visitor_status
visit_leave(ir_assignment
*);
62 ir_rvalue
*get_element(ir_variable
*var
, unsigned int element
);
63 void assign(ir_assignment
*ir
, int elem
, ir_rvalue
*val
);
70 channel_expressions_predicate(ir_instruction
*ir
)
72 ir_expression
*expr
= ir
->as_expression();
78 for (i
= 0; i
< expr
->get_num_operands(); i
++) {
79 if (expr
->operands
[i
]->type
->is_vector())
87 brw_do_channel_expressions(exec_list
*instructions
)
89 ir_channel_expressions_visitor v
;
91 /* Pull out any matrix expression to a separate assignment to a
92 * temp. This will make our handling of the breakdown to
93 * operations on the matrix's vector components much easier.
95 do_expression_flattening(instructions
, channel_expressions_predicate
);
97 visit_list_elements(&v
, instructions
);
103 ir_channel_expressions_visitor::get_element(ir_variable
*var
, unsigned int elem
)
105 ir_dereference
*deref
;
107 if (var
->type
->is_scalar())
108 return new(mem_ctx
) ir_dereference_variable(var
);
110 assert(elem
< var
->type
->components());
111 deref
= new(mem_ctx
) ir_dereference_variable(var
);
112 return new(mem_ctx
) ir_swizzle(deref
, elem
, 0, 0, 0, 1);
116 ir_channel_expressions_visitor::assign(ir_assignment
*ir
, int elem
, ir_rvalue
*val
)
118 ir_dereference
*lhs
= ir
->lhs
->clone(mem_ctx
, NULL
);
119 ir_assignment
*assign
;
121 /* This assign-of-expression should have been generated by the
122 * expression flattening visitor (since we never short circit to
123 * not flatten, even for plain assignments of variables), so the
124 * writemask is always full.
126 assert(ir
->write_mask
== (1 << ir
->lhs
->type
->components()) - 1);
128 assign
= new(mem_ctx
) ir_assignment(lhs
, val
, NULL
, (1 << elem
));
129 ir
->insert_before(assign
);
133 ir_channel_expressions_visitor::visit_leave(ir_assignment
*ir
)
135 ir_expression
*expr
= ir
->rhs
->as_expression();
136 bool found_vector
= false;
137 unsigned int i
, vector_elements
= 1;
138 ir_variable
*op_var
[2];
141 return visit_continue
;
144 this->mem_ctx
= ralloc_parent(ir
);
146 for (i
= 0; i
< expr
->get_num_operands(); i
++) {
147 if (expr
->operands
[i
]->type
->is_vector()) {
149 vector_elements
= expr
->operands
[i
]->type
->vector_elements
;
154 return visit_continue
;
156 /* Store the expression operands in temps so we can use them
159 for (i
= 0; i
< expr
->get_num_operands(); i
++) {
160 ir_assignment
*assign
;
161 ir_dereference
*deref
;
163 assert(!expr
->operands
[i
]->type
->is_matrix());
165 op_var
[i
] = new(mem_ctx
) ir_variable(expr
->operands
[i
]->type
,
166 "channel_expressions",
168 ir
->insert_before(op_var
[i
]);
170 deref
= new(mem_ctx
) ir_dereference_variable(op_var
[i
]);
171 assign
= new(mem_ctx
) ir_assignment(deref
,
174 ir
->insert_before(assign
);
177 const glsl_type
*element_type
= glsl_type::get_instance(ir
->lhs
->type
->base_type
,
180 /* OK, time to break down this vector operation. */
181 switch (expr
->operation
) {
182 case ir_unop_bit_not
:
183 case ir_unop_logic_not
:
194 case ir_unop_bitcast_i2f
:
195 case ir_unop_bitcast_f2i
:
196 case ir_unop_bitcast_f2u
:
197 case ir_unop_bitcast_u2f
:
212 case ir_unop_round_even
:
215 case ir_unop_sin_reduced
:
216 case ir_unop_cos_reduced
:
219 for (i
= 0; i
< vector_elements
; i
++) {
220 ir_rvalue
*op0
= get_element(op_var
[0], i
);
222 assign(ir
, i
, new(mem_ctx
) ir_expression(expr
->operation
,
237 case ir_binop_lshift
:
238 case ir_binop_rshift
:
239 case ir_binop_bit_and
:
240 case ir_binop_bit_xor
:
241 case ir_binop_bit_or
:
243 case ir_binop_greater
:
244 case ir_binop_lequal
:
245 case ir_binop_gequal
:
247 case ir_binop_nequal
:
248 for (i
= 0; i
< vector_elements
; i
++) {
249 ir_rvalue
*op0
= get_element(op_var
[0], i
);
250 ir_rvalue
*op1
= get_element(op_var
[1], i
);
252 assign(ir
, i
, new(mem_ctx
) ir_expression(expr
->operation
,
261 temp
= new(mem_ctx
) ir_expression(ir_binop_logic_or
,
263 get_element(op_var
[0], 0),
264 get_element(op_var
[0], 1));
266 for (i
= 2; i
< vector_elements
; i
++) {
267 temp
= new(mem_ctx
) ir_expression(ir_binop_logic_or
,
269 get_element(op_var
[0], i
),
277 ir_expression
*last
= NULL
;
278 for (i
= 0; i
< vector_elements
; i
++) {
279 ir_rvalue
*op0
= get_element(op_var
[0], i
);
280 ir_rvalue
*op1
= get_element(op_var
[1], i
);
283 temp
= new(mem_ctx
) ir_expression(ir_binop_mul
,
288 last
= new(mem_ctx
) ir_expression(ir_binop_add
,
300 case ir_binop_logic_and
:
301 case ir_binop_logic_xor
:
302 case ir_binop_logic_or
:
305 assert(!"not reached: expression operates on scalars only");
307 case ir_binop_all_equal
:
308 case ir_binop_any_nequal
: {
309 ir_expression
*last
= NULL
;
310 for (i
= 0; i
< vector_elements
; i
++) {
311 ir_rvalue
*op0
= get_element(op_var
[0], i
);
312 ir_rvalue
*op1
= get_element(op_var
[1], i
);
314 ir_expression_operation join
;
316 if (expr
->operation
== ir_binop_all_equal
)
317 join
= ir_binop_logic_and
;
319 join
= ir_binop_logic_or
;
321 temp
= new(mem_ctx
) ir_expression(expr
->operation
,
326 last
= new(mem_ctx
) ir_expression(join
,
338 assert(!"noise should have been broken down to function call");
340 case ir_quadop_vector
:
341 assert(!"should have been lowered");
346 this->progress
= true;
348 return visit_continue
;