1 | /* Optimized version of the standard memset() function. |
2 | This file is part of the GNU C Library. |
3 | Copyright (C) 2000-2022 Free Software Foundation, Inc. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <https://www.gnu.org/licenses/>. */ |
18 | |
19 | /* Return: dest |
20 | |
21 | Inputs: |
22 | in0: dest |
23 | in1: value |
24 | in2: count |
25 | |
26 | The algorithm is fairly straightforward: set byte by byte until we |
27 | we get to a 16B-aligned address, then loop on 128 B chunks using an |
28 | early store as prefetching, then loop on 32B chucks, then clear remaining |
29 | words, finally clear remaining bytes. |
30 | Since a stf.spill f0 can store 16B in one go, we use this instruction |
31 | to get peak speed when value = 0. */ |
32 | |
33 | #include <sysdep.h> |
34 | #undef ret |
35 | |
36 | #define dest in0 |
37 | #define value in1 |
38 | #define cnt in2 |
39 | |
40 | #define tmp r31 |
41 | #define save_lc r30 |
42 | #define ptr0 r29 |
43 | #define ptr1 r28 |
44 | #define ptr2 r27 |
45 | #define ptr3 r26 |
46 | #define ptr9 r24 |
47 | #define loopcnt r23 |
48 | #define linecnt r22 |
49 | #define bytecnt r21 |
50 | |
51 | #define fvalue f6 |
52 | |
53 | // This routine uses only scratch predicate registers (p6 - p15) |
54 | #define p_scr p6 // default register for same-cycle branches |
55 | #define p_nz p7 |
56 | #define p_zr p8 |
57 | #define p_unalgn p9 |
58 | #define p_y p11 |
59 | #define p_n p12 |
60 | #define p_yy p13 |
61 | #define p_nn p14 |
62 | |
63 | #define movi0 mov |
64 | |
65 | #define MIN1 15 |
66 | #define MIN1P1HALF 8 |
67 | #define LINE_SIZE 128 |
68 | #define LSIZE_SH 7 // shift amount |
69 | #define PREF_AHEAD 8 |
70 | |
71 | #define USE_FLP |
72 | #if defined(USE_INT) |
73 | #define store st8 |
74 | #define myval value |
75 | #elif defined(USE_FLP) |
76 | #define store stf8 |
77 | #define myval fvalue |
78 | #endif |
79 | |
80 | .align 64 |
81 | ENTRY(memset) |
82 | { .mmi |
83 | .prologue |
84 | alloc tmp = ar.pfs, 3, 0, 0, 0 |
85 | lfetch.nt1 [dest] |
86 | .save ar.lc, save_lc |
87 | movi0 save_lc = ar.lc |
88 | } { .mmi |
89 | .body |
90 | mov ret0 = dest // return value |
91 | cmp.ne p_nz, p_zr = value, r0 // use stf.spill if value is zero |
92 | cmp.eq p_scr, p0 = cnt, r0 |
93 | ;; } |
94 | { .mmi |
95 | and ptr2 = -(MIN1+1), dest // aligned address |
96 | and tmp = MIN1, dest // prepare to check for alignment |
97 | tbit.nz p_y, p_n = dest, 0 // Do we have an odd address? (M_B_U) |
98 | } { .mib |
99 | mov ptr1 = dest |
100 | mux1 value = value, @brcst // create 8 identical bytes in word |
101 | (p_scr) br.ret.dpnt.many rp // return immediately if count = 0 |
102 | ;; } |
103 | { .mib |
104 | cmp.ne p_unalgn, p0 = tmp, r0 |
105 | } { .mib // NB: # of bytes to move is 1 higher |
106 | sub bytecnt = (MIN1+1), tmp // than loopcnt |
107 | cmp.gt p_scr, p0 = 16, cnt // is it a minimalistic task? |
108 | (p_scr) br.cond.dptk.many .move_bytes_unaligned // go move just a few (M_B_U) |
109 | ;; } |
110 | { .mmi |
111 | (p_unalgn) add ptr1 = (MIN1+1), ptr2 // after alignment |
112 | (p_unalgn) add ptr2 = MIN1P1HALF, ptr2 // after alignment |
113 | (p_unalgn) tbit.nz.unc p_y, p_n = bytecnt, 3 // should we do a st8 ? |
114 | ;; } |
115 | { .mib |
116 | (p_y) add cnt = -8, cnt |
117 | (p_unalgn) tbit.nz.unc p_yy, p_nn = bytecnt, 2 // should we do a st4 ? |
118 | } { .mib |
119 | (p_y) st8 [ptr2] = value, -4 |
120 | (p_n) add ptr2 = 4, ptr2 |
121 | ;; } |
122 | { .mib |
123 | (p_yy) add cnt = -4, cnt |
124 | (p_unalgn) tbit.nz.unc p_y, p_n = bytecnt, 1 // should we do a st2 ? |
125 | } { .mib |
126 | (p_yy) st4 [ptr2] = value, -2 |
127 | (p_nn) add ptr2 = 2, ptr2 |
128 | ;; } |
129 | { .mmi |
130 | mov tmp = LINE_SIZE+1 // for compare |
131 | (p_y) add cnt = -2, cnt |
132 | (p_unalgn) tbit.nz.unc p_yy, p_nn = bytecnt, 0 // should we do a st1 ? |
133 | } { .mmi |
134 | setf.sig fvalue=value // transfer value to FLP side |
135 | (p_y) st2 [ptr2] = value, -1 |
136 | (p_n) add ptr2 = 1, ptr2 |
137 | ;; } |
138 | |
139 | { .mmi |
140 | (p_yy) st1 [ptr2] = value |
141 | cmp.gt p_scr, p0 = tmp, cnt // is it a minimalistic task? |
142 | } { .mbb |
143 | (p_yy) add cnt = -1, cnt |
144 | (p_scr) br.cond.dpnt.many .fraction_of_line // go move just a few |
145 | ;; } |
146 | |
147 | { .mib |
148 | nop.m 0 |
149 | shr.u linecnt = cnt, LSIZE_SH |
150 | (p_zr) br.cond.dptk.many .l1b // Jump to use stf.spill |
151 | ;; } |
152 | |
153 | #ifndef GAS_ALIGN_BREAKS_UNWIND_INFO |
154 | .align 32 // -------- // L1A: store ahead into cache lines; fill later |
155 | #endif |
156 | { .mmi |
157 | and tmp = -(LINE_SIZE), cnt // compute end of range |
158 | mov ptr9 = ptr1 // used for prefetching |
159 | and cnt = (LINE_SIZE-1), cnt // remainder |
160 | } { .mmi |
161 | mov loopcnt = PREF_AHEAD-1 // default prefetch loop |
162 | cmp.gt p_scr, p0 = PREF_AHEAD, linecnt // check against actual value |
163 | ;; } |
164 | { .mmi |
165 | (p_scr) add loopcnt = -1, linecnt // start of stores |
166 | add ptr2 = 8, ptr1 // (beyond prefetch stores) |
167 | add ptr1 = tmp, ptr1 // first address beyond total |
168 | ;; } // range |
169 | { .mmi |
170 | add tmp = -1, linecnt // next loop count |
171 | movi0 ar.lc = loopcnt |
172 | ;; } |
173 | .pref_l1a: |
174 | { .mib |
175 | store [ptr9] = myval, 128 // Do stores one cache line apart |
176 | nop.i 0 |
177 | br.cloop.dptk.few .pref_l1a |
178 | ;; } |
179 | { .mmi |
180 | add ptr0 = 16, ptr2 // Two stores in parallel |
181 | movi0 ar.lc = tmp |
182 | ;; } |
183 | .l1ax: |
184 | { .mmi |
185 | store [ptr2] = myval, 8 |
186 | store [ptr0] = myval, 8 |
187 | ;; } |
188 | { .mmi |
189 | store [ptr2] = myval, 24 |
190 | store [ptr0] = myval, 24 |
191 | ;; } |
192 | { .mmi |
193 | store [ptr2] = myval, 8 |
194 | store [ptr0] = myval, 8 |
195 | ;; } |
196 | { .mmi |
197 | store [ptr2] = myval, 24 |
198 | store [ptr0] = myval, 24 |
199 | ;; } |
200 | { .mmi |
201 | store [ptr2] = myval, 8 |
202 | store [ptr0] = myval, 8 |
203 | ;; } |
204 | { .mmi |
205 | store [ptr2] = myval, 24 |
206 | store [ptr0] = myval, 24 |
207 | ;; } |
208 | { .mmi |
209 | store [ptr2] = myval, 8 |
210 | store [ptr0] = myval, 32 |
211 | cmp.lt p_scr, p0 = ptr9, ptr1 // do we need more prefetching? |
212 | ;; } |
213 | { .mmb |
214 | store [ptr2] = myval, 24 |
215 | (p_scr) store [ptr9] = myval, 128 |
216 | br.cloop.dptk.few .l1ax |
217 | ;; } |
218 | { .mbb |
219 | cmp.le p_scr, p0 = 8, cnt // just a few bytes left ? |
220 | (p_scr) br.cond.dpnt.many .fraction_of_line // Branch no. 2 |
221 | br.cond.dpnt.many .move_bytes_from_alignment // Branch no. 3 |
222 | ;; } |
223 | |
224 | #ifdef GAS_ALIGN_BREAKS_UNWIND_INFO |
225 | { nop 0 } |
226 | #else |
227 | .align 32 |
228 | #endif |
229 | .l1b: // ------------------ // L1B: store ahead into cache lines; fill later |
230 | { .mmi |
231 | and tmp = -(LINE_SIZE), cnt // compute end of range |
232 | mov ptr9 = ptr1 // used for prefetching |
233 | and cnt = (LINE_SIZE-1), cnt // remainder |
234 | } { .mmi |
235 | mov loopcnt = PREF_AHEAD-1 // default prefetch loop |
236 | cmp.gt p_scr, p0 = PREF_AHEAD, linecnt // check against actual value |
237 | ;; } |
238 | { .mmi |
239 | (p_scr) add loopcnt = -1, linecnt |
240 | add ptr2 = 16, ptr1 // start of stores (beyond prefetch stores) |
241 | add ptr1 = tmp, ptr1 // first address beyond total range |
242 | ;; } |
243 | { .mmi |
244 | add tmp = -1, linecnt // next loop count |
245 | movi0 ar.lc = loopcnt |
246 | ;; } |
247 | .pref_l1b: |
248 | { .mib |
249 | stf.spill [ptr9] = f0, 128 // Do stores one cache line apart |
250 | nop.i 0 |
251 | br.cloop.dptk.few .pref_l1b |
252 | ;; } |
253 | { .mmi |
254 | add ptr0 = 16, ptr2 // Two stores in parallel |
255 | movi0 ar.lc = tmp |
256 | ;; } |
257 | .l1bx: |
258 | { .mmi |
259 | stf.spill [ptr2] = f0, 32 |
260 | stf.spill [ptr0] = f0, 32 |
261 | ;; } |
262 | { .mmi |
263 | stf.spill [ptr2] = f0, 32 |
264 | stf.spill [ptr0] = f0, 32 |
265 | ;; } |
266 | { .mmi |
267 | stf.spill [ptr2] = f0, 32 |
268 | stf.spill [ptr0] = f0, 64 |
269 | cmp.lt p_scr, p0 = ptr9, ptr1 // do we need more prefetching? |
270 | ;; } |
271 | { .mmb |
272 | stf.spill [ptr2] = f0, 32 |
273 | (p_scr) stf.spill [ptr9] = f0, 128 |
274 | br.cloop.dptk.few .l1bx |
275 | ;; } |
276 | { .mib |
277 | cmp.gt p_scr, p0 = 8, cnt // just a few bytes left ? |
278 | (p_scr) br.cond.dpnt.many .move_bytes_from_alignment |
279 | ;; } |
280 | |
281 | .fraction_of_line: |
282 | { .mib |
283 | add ptr2 = 16, ptr1 |
284 | shr.u loopcnt = cnt, 5 // loopcnt = cnt / 32 |
285 | ;; } |
286 | { .mib |
287 | cmp.eq p_scr, p0 = loopcnt, r0 |
288 | add loopcnt = -1, loopcnt |
289 | (p_scr) br.cond.dpnt.many store_words |
290 | ;; } |
291 | { .mib |
292 | and cnt = 0x1f, cnt // compute the remaining cnt |
293 | movi0 ar.lc = loopcnt |
294 | ;; } |
295 | #ifndef GAS_ALIGN_BREAKS_UNWIND_INFO |
296 | .align 32 |
297 | #endif |
298 | .l2: // ---------------------------- // L2A: store 32B in 2 cycles |
299 | { .mmb |
300 | store [ptr1] = myval, 8 |
301 | store [ptr2] = myval, 8 |
302 | ;; } { .mmb |
303 | store [ptr1] = myval, 24 |
304 | store [ptr2] = myval, 24 |
305 | br.cloop.dptk.many .l2 |
306 | ;; } |
307 | store_words: |
308 | { .mib |
309 | cmp.gt p_scr, p0 = 8, cnt // just a few bytes left ? |
310 | (p_scr) br.cond.dpnt.many .move_bytes_from_alignment // Branch |
311 | ;; } |
312 | |
313 | { .mmi |
314 | store [ptr1] = myval, 8 // store |
315 | cmp.le p_y, p_n = 16, cnt // |
316 | add cnt = -8, cnt // subtract |
317 | ;; } |
318 | { .mmi |
319 | (p_y) store [ptr1] = myval, 8 // store |
320 | (p_y) cmp.le.unc p_yy, p_nn = 16, cnt // |
321 | (p_y) add cnt = -8, cnt // subtract |
322 | ;; } |
323 | { .mmi // store |
324 | (p_yy) store [ptr1] = myval, 8 // |
325 | (p_yy) add cnt = -8, cnt // subtract |
326 | ;; } |
327 | |
328 | .move_bytes_from_alignment: |
329 | { .mib |
330 | cmp.eq p_scr, p0 = cnt, r0 |
331 | tbit.nz.unc p_y, p0 = cnt, 2 // should we terminate with a st4 ? |
332 | (p_scr) br.cond.dpnt.few .restore_and_exit |
333 | ;; } |
334 | { .mib |
335 | (p_y) st4 [ptr1] = value, 4 |
336 | tbit.nz.unc p_yy, p0 = cnt, 1 // should we terminate with a st2 ? |
337 | ;; } |
338 | { .mib |
339 | (p_yy) st2 [ptr1] = value, 2 |
340 | tbit.nz.unc p_y, p0 = cnt, 0 |
341 | ;; } |
342 | |
343 | { .mib |
344 | (p_y) st1 [ptr1] = value |
345 | ;; } |
346 | .restore_and_exit: |
347 | { .mib |
348 | nop.m 0 |
349 | movi0 ar.lc = save_lc |
350 | br.ret.sptk.many rp |
351 | ;; } |
352 | |
353 | .move_bytes_unaligned: |
354 | { .mmi |
355 | .pred.rel "mutex" ,p_y, p_n |
356 | .pred.rel "mutex" ,p_yy, p_nn |
357 | (p_n) cmp.le p_yy, p_nn = 4, cnt |
358 | (p_y) cmp.le p_yy, p_nn = 5, cnt |
359 | (p_n) add ptr2 = 2, ptr1 |
360 | } { .mmi |
361 | (p_y) add ptr2 = 3, ptr1 |
362 | (p_y) st1 [ptr1] = value, 1 // fill 1 (odd-aligned) byte |
363 | (p_y) add cnt = -1, cnt // [15, 14 (or less) left] |
364 | ;; } |
365 | { .mmi |
366 | (p_yy) cmp.le.unc p_y, p0 = 8, cnt |
367 | add ptr3 = ptr1, cnt // prepare last store |
368 | movi0 ar.lc = save_lc |
369 | } { .mmi |
370 | (p_yy) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes |
371 | (p_yy) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes |
372 | (p_yy) add cnt = -4, cnt // [11, 10 (o less) left] |
373 | ;; } |
374 | { .mmi |
375 | (p_y) cmp.le.unc p_yy, p0 = 8, cnt |
376 | add ptr3 = -1, ptr3 // last store |
377 | tbit.nz p_scr, p0 = cnt, 1 // will there be a st2 at the end ? |
378 | } { .mmi |
379 | (p_y) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes |
380 | (p_y) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes |
381 | (p_y) add cnt = -4, cnt // [7, 6 (or less) left] |
382 | ;; } |
383 | { .mmi |
384 | (p_yy) st2 [ptr1] = value, 4 // fill 2 (aligned) bytes |
385 | (p_yy) st2 [ptr2] = value, 4 // fill 2 (aligned) bytes |
386 | // [3, 2 (or less) left] |
387 | tbit.nz p_y, p0 = cnt, 0 // will there be a st1 at the end ? |
388 | } { .mmi |
389 | (p_yy) add cnt = -4, cnt |
390 | ;; } |
391 | { .mmb |
392 | (p_scr) st2 [ptr1] = value // fill 2 (aligned) bytes |
393 | (p_y) st1 [ptr3] = value // fill last byte (using ptr3) |
394 | br.ret.sptk.many rp |
395 | ;; } |
396 | END(memset) |
397 | libc_hidden_builtin_def (memset) |
398 | |