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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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24 /** @file brw_fs_register_coalesce.cpp
26 * Implements register coalescing: Checks if the two registers involved in a
27 * raw move don't interfere, in which case they can both be stored in the same
28 * place and the MOV removed.
30 * To do this, all uses of the source of the MOV in the shader are replaced
31 * with the destination of the MOV. For example:
33 * add vgrf3:F, vgrf1:F, vgrf2:F
34 * mov vgrf4:F, vgrf3:F
35 * mul vgrf5:F, vgrf5:F, vgrf4:F
39 * add vgrf4:F, vgrf1:F, vgrf2:F
40 * mul vgrf5:F, vgrf5:F, vgrf4:F
44 #include "brw_fs_live_variables.h"
47 is_nop_mov(const fs_inst
*inst
)
49 if (inst
->opcode
== BRW_OPCODE_MOV
) {
50 return inst
->dst
.equals(inst
->src
[0]);
57 is_coalesce_candidate(const fs_inst
*inst
, const int *virtual_grf_sizes
)
59 if (inst
->opcode
!= BRW_OPCODE_MOV
||
60 inst
->is_partial_write() ||
62 inst
->src
[0].file
!= GRF
||
63 inst
->src
[0].negate
||
65 !inst
->src
[0].is_contiguous() ||
66 inst
->dst
.file
!= GRF
||
67 inst
->dst
.type
!= inst
->src
[0].type
) {
71 if (virtual_grf_sizes
[inst
->src
[0].reg
] >
72 virtual_grf_sizes
[inst
->dst
.reg
])
79 can_coalesce_vars(brw::fs_live_variables
*live_intervals
,
80 const exec_list
*instructions
, const fs_inst
*inst
, int ip
,
81 int var_to
, int var_from
)
83 if (!live_intervals
->vars_interfere(var_from
, var_to
))
86 assert(ip
>= live_intervals
->start
[var_to
]);
89 for (scan_inst
= (fs_inst
*)inst
->next
;
90 !scan_inst
->is_tail_sentinel() && ip
<= live_intervals
->end
[var_to
];
91 scan_inst
= (fs_inst
*)scan_inst
->next
, ip
++) {
92 if (scan_inst
->opcode
== BRW_OPCODE_WHILE
)
95 if (scan_inst
->dst
.equals(inst
->dst
) ||
96 scan_inst
->dst
.equals(inst
->src
[0]))
104 fs_visitor::register_coalesce()
106 bool progress
= false;
108 calculate_live_intervals();
111 int channels_remaining
= 0;
112 int reg_from
= -1, reg_to
= -1;
113 int reg_to_offset
[MAX_SAMPLER_MESSAGE_SIZE
];
114 fs_inst
*mov
[MAX_SAMPLER_MESSAGE_SIZE
];
115 int var_to
[MAX_SAMPLER_MESSAGE_SIZE
];
116 int var_from
[MAX_SAMPLER_MESSAGE_SIZE
];
119 foreach_list(node
, &this->instructions
) {
120 fs_inst
*inst
= (fs_inst
*)node
;
123 if (!is_coalesce_candidate(inst
, virtual_grf_sizes
))
126 if (is_nop_mov(inst
)) {
127 inst
->opcode
= BRW_OPCODE_NOP
;
132 if (reg_from
!= inst
->src
[0].reg
) {
133 reg_from
= inst
->src
[0].reg
;
135 src_size
= virtual_grf_sizes
[inst
->src
[0].reg
];
136 assert(src_size
<= MAX_SAMPLER_MESSAGE_SIZE
);
138 channels_remaining
= src_size
;
139 memset(mov
, 0, sizeof(mov
));
141 reg_to
= inst
->dst
.reg
;
144 if (reg_to
!= inst
->dst
.reg
)
147 const int offset
= inst
->src
[0].reg_offset
;
148 reg_to_offset
[offset
] = inst
->dst
.reg_offset
;
150 channels_remaining
--;
152 if (channels_remaining
)
155 bool can_coalesce
= true;
156 for (int i
= 0; i
< src_size
; i
++) {
157 var_to
[i
] = live_intervals
->var_from_vgrf
[reg_to
] + reg_to_offset
[i
];
158 var_from
[i
] = live_intervals
->var_from_vgrf
[reg_from
] + i
;
160 if (!can_coalesce_vars(live_intervals
, &instructions
, inst
, ip
,
161 var_to
[i
], var_from
[i
])) {
162 can_coalesce
= false;
173 for (int i
= 0; i
< src_size
; i
++) {
175 mov
[i
]->opcode
= BRW_OPCODE_NOP
;
176 mov
[i
]->conditional_mod
= BRW_CONDITIONAL_NONE
;
177 mov
[i
]->dst
= reg_undef
;
178 mov
[i
]->src
[0] = reg_undef
;
179 mov
[i
]->src
[1] = reg_undef
;
180 mov
[i
]->src
[2] = reg_undef
;
184 foreach_list(node
, &this->instructions
) {
185 fs_inst
*scan_inst
= (fs_inst
*)node
;
187 for (int i
= 0; i
< src_size
; i
++) {
189 if (scan_inst
->dst
.file
== GRF
&&
190 scan_inst
->dst
.reg
== reg_from
&&
191 scan_inst
->dst
.reg_offset
== i
) {
192 scan_inst
->dst
.reg
= reg_to
;
193 scan_inst
->dst
.reg_offset
= reg_to_offset
[i
];
195 for (int j
= 0; j
< 3; j
++) {
196 if (scan_inst
->src
[j
].file
== GRF
&&
197 scan_inst
->src
[j
].reg
== reg_from
&&
198 scan_inst
->src
[j
].reg_offset
== i
) {
199 scan_inst
->src
[j
].reg
= reg_to
;
200 scan_inst
->src
[j
].reg_offset
= reg_to_offset
[i
];
207 for (int i
= 0; i
< src_size
; i
++) {
208 live_intervals
->start
[var_to
[i
]] =
209 MIN2(live_intervals
->start
[var_to
[i
]],
210 live_intervals
->start
[var_from
[i
]]);
211 live_intervals
->end
[var_to
[i
]] =
212 MAX2(live_intervals
->end
[var_to
[i
]],
213 live_intervals
->end
[var_from
[i
]]);
219 foreach_list_safe(node
, &this->instructions
) {
220 fs_inst
*inst
= (fs_inst
*)node
;
222 if (inst
->opcode
== BRW_OPCODE_NOP
) {
227 invalidate_live_intervals();