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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
[3];
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 case ir_unop_bitfield_reverse
:
220 case ir_unop_bit_count
:
221 case ir_unop_find_msb
:
222 case ir_unop_find_lsb
:
223 for (i
= 0; i
< vector_elements
; i
++) {
224 ir_rvalue
*op0
= get_element(op_var
[0], i
);
226 assign(ir
, i
, new(mem_ctx
) ir_expression(expr
->operation
,
236 case ir_binop_imul_high
:
239 case ir_binop_borrow
:
244 case ir_binop_lshift
:
245 case ir_binop_rshift
:
246 case ir_binop_bit_and
:
247 case ir_binop_bit_xor
:
248 case ir_binop_bit_or
:
250 case ir_binop_greater
:
251 case ir_binop_lequal
:
252 case ir_binop_gequal
:
254 case ir_binop_nequal
:
255 for (i
= 0; i
< vector_elements
; i
++) {
256 ir_rvalue
*op0
= get_element(op_var
[0], i
);
257 ir_rvalue
*op1
= get_element(op_var
[1], i
);
259 assign(ir
, i
, new(mem_ctx
) ir_expression(expr
->operation
,
268 temp
= new(mem_ctx
) ir_expression(ir_binop_logic_or
,
270 get_element(op_var
[0], 0),
271 get_element(op_var
[0], 1));
273 for (i
= 2; i
< vector_elements
; i
++) {
274 temp
= new(mem_ctx
) ir_expression(ir_binop_logic_or
,
276 get_element(op_var
[0], i
),
284 ir_expression
*last
= NULL
;
285 for (i
= 0; i
< vector_elements
; i
++) {
286 ir_rvalue
*op0
= get_element(op_var
[0], i
);
287 ir_rvalue
*op1
= get_element(op_var
[1], i
);
290 temp
= new(mem_ctx
) ir_expression(ir_binop_mul
,
295 last
= new(mem_ctx
) ir_expression(ir_binop_add
,
307 case ir_binop_logic_and
:
308 case ir_binop_logic_xor
:
309 case ir_binop_logic_or
:
311 fprintf(stderr
, "\n");
312 assert(!"not reached: expression operates on scalars only");
314 case ir_binop_all_equal
:
315 case ir_binop_any_nequal
: {
316 ir_expression
*last
= NULL
;
317 for (i
= 0; i
< vector_elements
; i
++) {
318 ir_rvalue
*op0
= get_element(op_var
[0], i
);
319 ir_rvalue
*op1
= get_element(op_var
[1], i
);
321 ir_expression_operation join
;
323 if (expr
->operation
== ir_binop_all_equal
)
324 join
= ir_binop_logic_and
;
326 join
= ir_binop_logic_or
;
328 temp
= new(mem_ctx
) ir_expression(expr
->operation
,
333 last
= new(mem_ctx
) ir_expression(join
,
345 assert(!"noise should have been broken down to function call");
349 /* Does not need to be scalarized, since its result will be identical
352 ir_rvalue
*op0
= get_element(op_var
[0], 0);
353 ir_rvalue
*op1
= get_element(op_var
[1], 0);
355 assign(ir
, 0, new(mem_ctx
) ir_expression(expr
->operation
,
362 case ir_binop_ubo_load
:
363 assert(!"not yet supported");
369 case ir_triop_bitfield_extract
:
370 for (i
= 0; i
< vector_elements
; i
++) {
371 ir_rvalue
*op0
= get_element(op_var
[0], i
);
372 ir_rvalue
*op1
= get_element(op_var
[1], i
);
373 ir_rvalue
*op2
= get_element(op_var
[2], i
);
375 assign(ir
, i
, new(mem_ctx
) ir_expression(expr
->operation
,
384 /* Only a single BFM is needed for multiple BFIs. */
385 ir_rvalue
*op0
= get_element(op_var
[0], 0);
387 for (i
= 0; i
< vector_elements
; i
++) {
388 ir_rvalue
*op1
= get_element(op_var
[1], i
);
389 ir_rvalue
*op2
= get_element(op_var
[2], i
);
391 assign(ir
, i
, new(mem_ctx
) ir_expression(expr
->operation
,
393 op0
->clone(mem_ctx
, NULL
),
400 case ir_unop_pack_snorm_2x16
:
401 case ir_unop_pack_snorm_4x8
:
402 case ir_unop_pack_unorm_2x16
:
403 case ir_unop_pack_unorm_4x8
:
404 case ir_unop_pack_half_2x16
:
405 case ir_unop_unpack_snorm_2x16
:
406 case ir_unop_unpack_snorm_4x8
:
407 case ir_unop_unpack_unorm_2x16
:
408 case ir_unop_unpack_unorm_4x8
:
409 case ir_unop_unpack_half_2x16
:
411 case ir_binop_vector_extract
:
412 case ir_triop_vector_insert
:
413 case ir_quadop_bitfield_insert
:
414 case ir_quadop_vector
:
415 assert(!"should have been lowered");
418 case ir_unop_unpack_half_2x16_split_x
:
419 case ir_unop_unpack_half_2x16_split_y
:
420 case ir_binop_pack_half_2x16_split
:
421 assert(!"not reached: expression operates on scalars only");
426 this->progress
= true;
428 return visit_continue
;