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9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the next
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
25 #include "nir_builder.h"
27 /** @file nir_opt_undef.c
29 * Handles optimization of operations involving ssa_undef.
33 * Turn conditional selects between an undef and some other value into a move
34 * of that other value (on the assumption that the condition's going to be
35 * choosing the defined value). This reduces work after if flattening when
36 * each side of the if is defining a variable.
39 opt_undef_csel(nir_alu_instr
*instr
)
41 if (instr
->op
!= nir_op_bcsel
&& instr
->op
!= nir_op_fcsel
)
44 assert(instr
->dest
.dest
.is_ssa
);
46 for (int i
= 1; i
<= 2; i
++) {
47 if (!instr
->src
[i
].src
.is_ssa
)
50 nir_instr
*parent
= instr
->src
[i
].src
.ssa
->parent_instr
;
51 if (parent
->type
!= nir_instr_type_ssa_undef
)
54 /* We can't just use nir_alu_src_copy, because we need the def/use
57 nir_instr_rewrite_src(&instr
->instr
, &instr
->src
[0].src
,
58 instr
->src
[i
== 1 ? 2 : 1].src
);
59 nir_alu_src_copy(&instr
->src
[0], &instr
->src
[i
== 1 ? 2 : 1],
60 ralloc_parent(instr
));
63 memset(&empty_src
, 0, sizeof(empty_src
));
64 nir_instr_rewrite_src(&instr
->instr
, &instr
->src
[1].src
, empty_src
);
65 nir_instr_rewrite_src(&instr
->instr
, &instr
->src
[2].src
, empty_src
);
66 instr
->op
= nir_op_imov
;
75 * Replace vecN(undef, undef, ...) with a single undef.
78 opt_undef_vecN(nir_builder
*b
, nir_alu_instr
*alu
)
80 if (alu
->op
!= nir_op_vec2
&&
81 alu
->op
!= nir_op_vec3
&&
82 alu
->op
!= nir_op_vec4
&&
83 alu
->op
!= nir_op_fmov
&&
84 alu
->op
!= nir_op_imov
)
87 assert(alu
->dest
.dest
.is_ssa
);
89 for (unsigned i
= 0; i
< nir_op_infos
[alu
->op
].num_inputs
; i
++) {
90 if (!alu
->src
[i
].src
.is_ssa
||
91 alu
->src
[i
].src
.ssa
->parent_instr
->type
!= nir_instr_type_ssa_undef
)
95 b
->cursor
= nir_before_instr(&alu
->instr
);
96 nir_ssa_def
*undef
= nir_ssa_undef(b
, alu
->dest
.dest
.ssa
.num_components
,
97 nir_dest_bit_size(alu
->dest
.dest
));
98 nir_ssa_def_rewrite_uses(&alu
->dest
.dest
.ssa
, nir_src_for_ssa(undef
));
104 * Remove any store intrinsics whose value is undefined (the existing
105 * value is a fine representation of "undefined").
108 opt_undef_store(nir_intrinsic_instr
*intrin
)
111 switch (intrin
->intrinsic
) {
112 case nir_intrinsic_store_deref
:
115 case nir_intrinsic_store_output
:
116 case nir_intrinsic_store_per_vertex_output
:
117 case nir_intrinsic_store_ssbo
:
118 case nir_intrinsic_store_shared
:
125 if (!intrin
->src
[arg_index
].is_ssa
||
126 intrin
->src
[arg_index
].ssa
->parent_instr
->type
!= nir_instr_type_ssa_undef
)
129 nir_instr_remove(&intrin
->instr
);
135 nir_opt_undef(nir_shader
*shader
)
138 bool progress
= false;
140 nir_foreach_function(function
, shader
) {
141 if (function
->impl
) {
142 nir_builder_init(&b
, function
->impl
);
143 nir_foreach_block(block
, function
->impl
) {
144 nir_foreach_instr_safe(instr
, block
) {
145 if (instr
->type
== nir_instr_type_alu
) {
146 nir_alu_instr
*alu
= nir_instr_as_alu(instr
);
148 progress
= opt_undef_csel(alu
) || progress
;
149 progress
= opt_undef_vecN(&b
, alu
) || progress
;
150 } else if (instr
->type
== nir_instr_type_intrinsic
) {
151 nir_intrinsic_instr
*intrin
= nir_instr_as_intrinsic(instr
);
152 progress
= opt_undef_store(intrin
) || progress
;
158 nir_metadata_preserve(function
->impl
,
159 nir_metadata_block_index
|
160 nir_metadata_dominance
);
163 function
->impl
->valid_metadata
&= ~nir_metadata_not_properly_reset
;