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1/* Copyright (C) 2000-2019 Free Software Foundation, Inc.
2 Contributed by Richard Henderson (rth@tamu.edu)
3 EV6 optimized by Rick Gorton <rick.gorton@alpha-processor.com>.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library. If not, see
18 <http://www.gnu.org/licenses/>. */
19
20#include <sysdep.h>
21
22 .arch ev6
23 .set noat
24 .set noreorder
25
26ENTRY(memset)
27#ifdef PROF
28 ldgp gp, 0(pv)
29 lda AT, _mcount
30 jsr AT, (AT), _mcount
31 .prologue 1
32#else
33 .prologue 0
34#endif
35
36 /*
37 * Serious stalling happens. The only way to mitigate this is to
38 * undertake a major re-write to interleave the constant materialization
39 * with other parts of the fall-through code. This is important, even
40 * though it makes maintenance tougher.
41 * Do this later.
42 */
43 and $17, 255, $1 # E : 00000000000000ch
44 insbl $17, 1, $2 # U : 000000000000ch00
45 mov $16, $0 # E : return value
46 ble $18, $end # U : zero length requested?
47
48 addq $18, $16, $6 # E : max address to write to
49 or $1, $2, $17 # E : 000000000000chch
50 insbl $1, 2, $3 # U : 0000000000ch0000
51 insbl $1, 3, $4 # U : 00000000ch000000
52
53 or $3, $4, $3 # E : 00000000chch0000
54 inswl $17, 4, $5 # U : 0000chch00000000
55 xor $16, $6, $1 # E : will complete write be within one quadword?
56 inswl $17, 6, $2 # U : chch000000000000
57
58 or $17, $3, $17 # E : 00000000chchchch
59 or $2, $5, $2 # E : chchchch00000000
60 bic $1, 7, $1 # E : fit within a single quadword?
61 and $16, 7, $3 # E : Target addr misalignment
62
63 or $17, $2, $17 # E : chchchchchchchch
64 beq $1, $within_quad # U :
65 nop # E :
66 beq $3, $aligned # U : target is 0mod8
67
68 /*
69 * Target address is misaligned, and won't fit within a quadword.
70 */
71 ldq_u $4, 0($16) # L : Fetch first partial
72 mov $16, $5 # E : Save the address
73 insql $17, $16, $2 # U : Insert new bytes
74 subq $3, 8, $3 # E : Invert (for addressing uses)
75
76 addq $18, $3, $18 # E : $18 is new count ($3 is negative)
77 mskql $4, $16, $4 # U : clear relevant parts of the quad
78 subq $16, $3, $16 # E : $16 is new aligned destination
79 or $2, $4, $1 # E : Final bytes
80
81 nop
82 stq_u $1,0($5) # L : Store result
83 nop
84 nop
85
86 .align 4
87$aligned:
88 /*
89 * We are now guaranteed to be quad aligned, with at least
90 * one partial quad to write.
91 */
92
93 sra $18, 3, $3 # U : Number of remaining quads to write
94 and $18, 7, $18 # E : Number of trailing bytes to write
95 mov $16, $5 # E : Save dest address
96 beq $3, $no_quad # U : tail stuff only
97
98 /*
99 * It's worth the effort to unroll this and use wh64 if possible.
100 * At this point, entry values are:
101 * $16 Current destination address
102 * $5 A copy of $16
103 * $6 The max quadword address to write to
104 * $18 Number trailer bytes
105 * $3 Number quads to write
106 */
107
108 and $16, 0x3f, $2 # E : Forward work (only useful for unrolled loop)
109 subq $3, 16, $4 # E : Only try to unroll if > 128 bytes
110 subq $2, 0x40, $1 # E : bias counter (aligning stuff 0mod64)
111 blt $4, $loop # U :
112
113 /*
114 * We know we've got at least 16 quads, minimum of one trip
115 * through unrolled loop. Do a quad at a time to get us 0mod64
116 * aligned.
117 */
118
119 nop # E :
120 nop # E :
121 nop # E :
122 beq $1, $bigalign # U :
123
124$alignmod64:
125 stq $17, 0($5) # L :
126 subq $3, 1, $3 # E : For consistency later
127 addq $1, 8, $1 # E : Increment towards zero for alignment
128 addq $5, 8, $4 # E : Initial wh64 address (filler instruction)
129
130 nop
131 nop
132 addq $5, 8, $5 # E : Inc address
133 blt $1, $alignmod64 # U :
134
135$bigalign:
136 /*
137 * $3 - number quads left to go
138 * $5 - target address (aligned 0mod64)
139 * $17 - mask of stuff to store
140 * Scratch registers available: $7, $2, $4, $1
141 * We know that we'll be taking a minimum of one trip through.
142 * CWG Section 3.7.6: do not expect a sustained store rate of > 1/cycle
143 * Assumes the wh64 needs to be for 2 trips through the loop in the future.
144 * The wh64 is issued on for the starting destination address for trip +2
145 * through the loop, and if there are less than two trips left, the target
146 * address will be for the current trip.
147 */
148
149$do_wh64:
150 wh64 ($4) # L1 : memory subsystem write hint
151 subq $3, 24, $2 # E : For determining future wh64 addresses
152 stq $17, 0($5) # L :
153 nop # E :
154
155 addq $5, 128, $4 # E : speculative target of next wh64
156 stq $17, 8($5) # L :
157 stq $17, 16($5) # L :
158 addq $5, 64, $7 # E : Fallback address for wh64 (== next trip addr)
159
160 stq $17, 24($5) # L :
161 stq $17, 32($5) # L :
162 cmovlt $2, $7, $4 # E : Latency 2, extra mapping cycle
163 nop
164
165 stq $17, 40($5) # L :
166 stq $17, 48($5) # L :
167 subq $3, 16, $2 # E : Repeat the loop at least once more?
168 nop
169
170 stq $17, 56($5) # L :
171 addq $5, 64, $5 # E :
172 subq $3, 8, $3 # E :
173 bge $2, $do_wh64 # U :
174
175 nop
176 nop
177 nop
178 beq $3, $no_quad # U : Might have finished already
179
180 .align 4
181 /*
182 * Simple loop for trailing quadwords, or for small amounts
183 * of data (where we can't use an unrolled loop and wh64)
184 */
185$loop:
186 stq $17, 0($5) # L :
187 subq $3, 1, $3 # E : Decrement number quads left
188 addq $5, 8, $5 # E : Inc address
189 bne $3, $loop # U : more?
190
191$no_quad:
192 /*
193 * Write 0..7 trailing bytes.
194 */
195 nop # E :
196 beq $18, $end # U : All done?
197 ldq $7, 0($5) # L :
198 mskqh $7, $6, $2 # U : Mask final quad
199
200 insqh $17, $6, $4 # U : New bits
201 or $2, $4, $1 # E : Put it all together
202 stq $1, 0($5) # L : And back to memory
203 ret $31,($26),1 # L0 :
204
205$within_quad:
206 ldq_u $1, 0($16) # L :
207 insql $17, $16, $2 # U : New bits
208 mskql $1, $16, $4 # U : Clear old
209 or $2, $4, $2 # E : New result
210
211 mskql $2, $6, $4 # U :
212 mskqh $1, $6, $2 # U :
213 or $2, $4, $1 # E :
214 stq_u $1, 0($16) # L :
215
216$end:
217 nop
218 nop
219 nop
220 ret $31,($26),1 # L0 :
221
222 END(memset)
223libc_hidden_builtin_def (memset)
224

Warning: That file was not part of the compilation database. It may have many parsing errors.