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1 /* -*- mode: C; c-file-style: "k&r"; tab-width 4; indent-tabs-mode: t; -*- */
2 
3 /*
4  * Copyright (C) 2014 Rob Clark <robclark@freedesktop.org>
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a
7  * copy of this software and associated documentation files (the "Software"),
8  * to deal in the Software without restriction, including without limitation
9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10  * and/or sell copies of the Software, and to permit persons to whom the
11  * Software is furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice (including the next
14  * paragraph) shall be included in all copies or substantial portions of the
15  * Software.
16  *
17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23  * SOFTWARE.
24  *
25  * Authors:
26  *    Rob Clark <robclark@freedesktop.org>
27  */
28 
29 #include "util/u_math.h"
30 
31 #include "ir3.h"
32 
33 /*
34  * Instruction Depth:
35  *
36  * Calculates weighted instruction depth, ie. the sum of # of needed
37  * instructions plus delay slots back to original input (ie INPUT or
38  * CONST).  That is to say, an instructions depth is:
39  *
40  *   depth(instr) {
41  *     d = 0;
42  *     // for each src register:
43  *     foreach (src in instr->regs[1..n])
44  *       d = max(d, delayslots(src->instr, n) + depth(src->instr));
45  *     return d + 1;
46  *   }
47  *
48  * After an instruction's depth is calculated, it is inserted into the
49  * blocks depth sorted list, which is used by the scheduling pass.
50  */
51 
52 /* calculate required # of delay slots between the instruction that
53  * assigns a value and the one that consumes
54  */
ir3_delayslots(struct ir3_instruction * assigner,struct ir3_instruction * consumer,unsigned n)55 int ir3_delayslots(struct ir3_instruction *assigner,
56 		struct ir3_instruction *consumer, unsigned n)
57 {
58 	/* worst case is cat1-3 (alu) -> cat4/5 needing 6 cycles, normal
59 	 * alu -> alu needs 3 cycles, cat4 -> alu and texture fetch
60 	 * handled with sync bits
61 	 */
62 
63 	if (is_meta(assigner))
64 		return 0;
65 
66 	if (writes_addr(assigner))
67 		return 6;
68 
69 	/* handled via sync flags: */
70 	if (is_sfu(assigner) || is_tex(assigner) || is_mem(assigner))
71 		return 0;
72 
73 	/* assigner must be alu: */
74 	if (is_flow(consumer) || is_sfu(consumer) || is_tex(consumer) ||
75 			is_mem(consumer)) {
76 		return 6;
77 	} else if ((is_mad(consumer->opc) || is_madsh(consumer->opc)) &&
78 			(n == 3)) {
79 		/* special case, 3rd src to cat3 not required on first cycle */
80 		return 1;
81 	} else {
82 		return 3;
83 	}
84 }
85 
86 void
ir3_insert_by_depth(struct ir3_instruction * instr,struct list_head * list)87 ir3_insert_by_depth(struct ir3_instruction *instr, struct list_head *list)
88 {
89 	/* remove from existing spot in list: */
90 	list_delinit(&instr->node);
91 
92 	/* find where to re-insert instruction: */
93 	list_for_each_entry (struct ir3_instruction, pos, list, node) {
94 		if (pos->depth > instr->depth) {
95 			list_add(&instr->node, &pos->node);
96 			return;
97 		}
98 	}
99 	/* if we get here, we didn't find an insertion spot: */
100 	list_addtail(&instr->node, list);
101 }
102 
103 static void
ir3_instr_depth(struct ir3_instruction * instr)104 ir3_instr_depth(struct ir3_instruction *instr)
105 {
106 	struct ir3_instruction *src;
107 
108 	/* if we've already visited this instruction, bail now: */
109 	if (ir3_instr_check_mark(instr))
110 		return;
111 
112 	instr->depth = 0;
113 
114 	foreach_ssa_src_n(src, i, instr) {
115 		unsigned sd;
116 
117 		/* visit child to compute it's depth: */
118 		ir3_instr_depth(src);
119 
120 		/* for array writes, no need to delay on previous write: */
121 		if (i == 0)
122 			continue;
123 
124 		sd = ir3_delayslots(src, instr, i) + src->depth;
125 
126 		instr->depth = MAX2(instr->depth, sd);
127 	}
128 
129 	if (!is_meta(instr))
130 		instr->depth++;
131 
132 	ir3_insert_by_depth(instr, &instr->block->instr_list);
133 }
134 
135 static void
remove_unused_by_block(struct ir3_block * block)136 remove_unused_by_block(struct ir3_block *block)
137 {
138 	list_for_each_entry_safe (struct ir3_instruction, instr, &block->instr_list, node) {
139 		if (!ir3_instr_check_mark(instr)) {
140 			if (instr->opc == OPC_END)
141 				continue;
142 			/* mark it, in case it is input, so we can
143 			 * remove unused inputs:
144 			 */
145 			instr->flags |= IR3_INSTR_UNUSED;
146 			/* and remove from instruction list: */
147 			list_delinit(&instr->node);
148 		}
149 	}
150 }
151 
152 void
ir3_depth(struct ir3 * ir)153 ir3_depth(struct ir3 *ir)
154 {
155 	unsigned i;
156 
157 	ir3_clear_mark(ir);
158 	for (i = 0; i < ir->noutputs; i++)
159 		if (ir->outputs[i])
160 			ir3_instr_depth(ir->outputs[i]);
161 
162 	for (i = 0; i < ir->keeps_count; i++)
163 		ir3_instr_depth(ir->keeps[i]);
164 
165 	/* We also need to account for if-condition: */
166 	list_for_each_entry (struct ir3_block, block, &ir->block_list, node) {
167 		if (block->condition)
168 			ir3_instr_depth(block->condition);
169 	}
170 
171 	/* mark un-used instructions: */
172 	list_for_each_entry (struct ir3_block, block, &ir->block_list, node) {
173 		remove_unused_by_block(block);
174 	}
175 
176 	/* note that we can end up with unused indirects, but we should
177 	 * not end up with unused predicates.
178 	 */
179 	for (i = 0; i < ir->indirects_count; i++) {
180 		struct ir3_instruction *instr = ir->indirects[i];
181 		if (instr->flags & IR3_INSTR_UNUSED)
182 			ir->indirects[i] = NULL;
183 	}
184 
185 	/* cleanup unused inputs: */
186 	for (i = 0; i < ir->ninputs; i++) {
187 		struct ir3_instruction *in = ir->inputs[i];
188 		if (in && (in->flags & IR3_INSTR_UNUSED))
189 			ir->inputs[i] = NULL;
190 	}
191 }
192