| 1 |
/* |
| 2 |
* match.S -- optimized version of longest_match() |
| 3 |
* based on the similar work by Gilles Vollant, and Brian Raiter, written 1998 |
| 4 |
* |
| 5 |
* This is free software; you can redistribute it and/or modify it |
| 6 |
* under the terms of the BSD License. Use by owners of Che Guevarra |
| 7 |
* parafernalia is prohibited, where possible, and highly discouraged |
| 8 |
* elsewhere. |
| 9 |
*/ |
| 10 |
|
| 11 |
#ifndef NO_UNDERLINE |
| 12 |
# define match_init _match_init |
| 13 |
# define longest_match _longest_match |
| 14 |
#endif |
| 15 |
|
| 16 |
#define scanend ebx |
| 17 |
#define scanendw bx |
| 18 |
#define chainlenwmask edx /* high word: current chain len low word: s->wmask */ |
| 19 |
#define curmatch rsi |
| 20 |
#define curmatchd esi |
| 21 |
#define windowbestlen r8 |
| 22 |
#define scanalign r9 |
| 23 |
#define scanalignd r9d |
| 24 |
#define window r10 |
| 25 |
#define bestlen r11 |
| 26 |
#define bestlend r11d |
| 27 |
#define scanstart r12d |
| 28 |
#define scanstartw r12w |
| 29 |
#define scan r13 |
| 30 |
#define nicematch r14d |
| 31 |
#define limit r15 |
| 32 |
#define limitd r15d |
| 33 |
#define prev rcx |
| 34 |
|
| 35 |
/* |
| 36 |
* The 258 is a "magic number, not a parameter -- changing it |
| 37 |
* breaks the hell loose |
| 38 |
*/ |
| 39 |
#define MAX_MATCH (258) |
| 40 |
#define MIN_MATCH (3) |
| 41 |
#define MIN_LOOKAHEAD (MAX_MATCH + MIN_MATCH + 1) |
| 42 |
#define MAX_MATCH_8 ((MAX_MATCH + 7) & ~7) |
| 43 |
|
| 44 |
/* stack frame offsets */ |
| 45 |
#define LocalVarsSize (112) |
| 46 |
#define _chainlenwmask ( 8-LocalVarsSize)(%rsp) |
| 47 |
#define _windowbestlen (16-LocalVarsSize)(%rsp) |
| 48 |
#define save_r14 (24-LocalVarsSize)(%rsp) |
| 49 |
#define save_rsi (32-LocalVarsSize)(%rsp) |
| 50 |
#define save_rbx (40-LocalVarsSize)(%rsp) |
| 51 |
#define save_r12 (56-LocalVarsSize)(%rsp) |
| 52 |
#define save_r13 (64-LocalVarsSize)(%rsp) |
| 53 |
#define save_r15 (80-LocalVarsSize)(%rsp) |
| 54 |
|
| 55 |
|
| 56 |
.globl match_init, longest_match |
| 57 |
|
| 58 |
/* |
| 59 |
* On AMD64 the first argument of a function (in our case -- the pointer to |
| 60 |
* deflate_state structure) is passed in %rdi, hence our offsets below are |
| 61 |
* all off of that. |
| 62 |
*/ |
| 63 |
|
| 64 |
/* you can check the structure offset by running |
| 65 |
|
| 66 |
#include <stdlib.h> |
| 67 |
#include <stdio.h> |
| 68 |
#include "deflate.h" |
| 69 |
|
| 70 |
void print_depl() |
| 71 |
{ |
| 72 |
deflate_state ds; |
| 73 |
deflate_state *s=&ds; |
| 74 |
printf("size pointer=%u\n",(int)sizeof(void*)); |
| 75 |
|
| 76 |
printf("#define dsWSize (%3u)(%%rdi)\n",(int)(((char*)&(s->w_size))-((char*)s))); |
| 77 |
printf("#define dsWMask (%3u)(%%rdi)\n",(int)(((char*)&(s->w_mask))-((char*)s))); |
| 78 |
printf("#define dsWindow (%3u)(%%rdi)\n",(int)(((char*)&(s->window))-((char*)s))); |
| 79 |
printf("#define dsPrev (%3u)(%%rdi)\n",(int)(((char*)&(s->prev))-((char*)s))); |
| 80 |
printf("#define dsMatchLen (%3u)(%%rdi)\n",(int)(((char*)&(s->match_length))-((char*)s))); |
| 81 |
printf("#define dsPrevMatch (%3u)(%%rdi)\n",(int)(((char*)&(s->prev_match))-((char*)s))); |
| 82 |
printf("#define dsStrStart (%3u)(%%rdi)\n",(int)(((char*)&(s->strstart))-((char*)s))); |
| 83 |
printf("#define dsMatchStart (%3u)(%%rdi)\n",(int)(((char*)&(s->match_start))-((char*)s))); |
| 84 |
printf("#define dsLookahead (%3u)(%%rdi)\n",(int)(((char*)&(s->lookahead))-((char*)s))); |
| 85 |
printf("#define dsPrevLen (%3u)(%%rdi)\n",(int)(((char*)&(s->prev_length))-((char*)s))); |
| 86 |
printf("#define dsMaxChainLen (%3u)(%%rdi)\n",(int)(((char*)&(s->max_chain_length))-((char*)s))); |
| 87 |
printf("#define dsGoodMatch (%3u)(%%rdi)\n",(int)(((char*)&(s->good_match))-((char*)s))); |
| 88 |
printf("#define dsNiceMatch (%3u)(%%rdi)\n",(int)(((char*)&(s->nice_match))-((char*)s))); |
| 89 |
} |
| 90 |
|
| 91 |
*/ |
| 92 |
|
| 93 |
|
| 94 |
/* |
| 95 |
to compile for XCode 3.2 on MacOSX x86_64 |
| 96 |
- run "gcc -g -c -DXCODE_MAC_X64_STRUCTURE amd64-match.S" |
| 97 |
*/ |
| 98 |
|
| 99 |
|
| 100 |
#ifndef CURRENT_LINX_XCODE_MAC_X64_STRUCTURE |
| 101 |
#define dsWSize ( 68)(%rdi) |
| 102 |
#define dsWMask ( 76)(%rdi) |
| 103 |
#define dsWindow ( 80)(%rdi) |
| 104 |
#define dsPrev ( 96)(%rdi) |
| 105 |
#define dsMatchLen (144)(%rdi) |
| 106 |
#define dsPrevMatch (148)(%rdi) |
| 107 |
#define dsStrStart (156)(%rdi) |
| 108 |
#define dsMatchStart (160)(%rdi) |
| 109 |
#define dsLookahead (164)(%rdi) |
| 110 |
#define dsPrevLen (168)(%rdi) |
| 111 |
#define dsMaxChainLen (172)(%rdi) |
| 112 |
#define dsGoodMatch (188)(%rdi) |
| 113 |
#define dsNiceMatch (192)(%rdi) |
| 114 |
|
| 115 |
#else |
| 116 |
|
| 117 |
#ifndef STRUCT_OFFSET |
| 118 |
# define STRUCT_OFFSET (0) |
| 119 |
#endif |
| 120 |
|
| 121 |
|
| 122 |
#define dsWSize ( 56 + STRUCT_OFFSET)(%rdi) |
| 123 |
#define dsWMask ( 64 + STRUCT_OFFSET)(%rdi) |
| 124 |
#define dsWindow ( 72 + STRUCT_OFFSET)(%rdi) |
| 125 |
#define dsPrev ( 88 + STRUCT_OFFSET)(%rdi) |
| 126 |
#define dsMatchLen (136 + STRUCT_OFFSET)(%rdi) |
| 127 |
#define dsPrevMatch (140 + STRUCT_OFFSET)(%rdi) |
| 128 |
#define dsStrStart (148 + STRUCT_OFFSET)(%rdi) |
| 129 |
#define dsMatchStart (152 + STRUCT_OFFSET)(%rdi) |
| 130 |
#define dsLookahead (156 + STRUCT_OFFSET)(%rdi) |
| 131 |
#define dsPrevLen (160 + STRUCT_OFFSET)(%rdi) |
| 132 |
#define dsMaxChainLen (164 + STRUCT_OFFSET)(%rdi) |
| 133 |
#define dsGoodMatch (180 + STRUCT_OFFSET)(%rdi) |
| 134 |
#define dsNiceMatch (184 + STRUCT_OFFSET)(%rdi) |
| 135 |
|
| 136 |
#endif |
| 137 |
|
| 138 |
|
| 139 |
|
| 140 |
|
| 141 |
.text |
| 142 |
|
| 143 |
/* uInt longest_match(deflate_state *deflatestate, IPos curmatch) */ |
| 144 |
|
| 145 |
longest_match: |
| 146 |
/* |
| 147 |
* Retrieve the function arguments. %curmatch will hold cur_match |
| 148 |
* throughout the entire function (passed via rsi on amd64). |
| 149 |
* rdi will hold the pointer to the deflate_state (first arg on amd64) |
| 150 |
*/ |
| 151 |
mov %rsi, save_rsi |
| 152 |
mov %rbx, save_rbx |
| 153 |
mov %r12, save_r12 |
| 154 |
mov %r13, save_r13 |
| 155 |
mov %r14, save_r14 |
| 156 |
mov %r15, save_r15 |
| 157 |
|
| 158 |
/* uInt wmask = s->w_mask; */ |
| 159 |
/* unsigned chain_length = s->max_chain_length; */ |
| 160 |
/* if (s->prev_length >= s->good_match) { */ |
| 161 |
/* chain_length >>= 2; */ |
| 162 |
/* } */ |
| 163 |
|
| 164 |
movl dsPrevLen, %eax |
| 165 |
movl dsGoodMatch, %ebx |
| 166 |
cmpl %ebx, %eax |
| 167 |
movl dsWMask, %eax |
| 168 |
movl dsMaxChainLen, %chainlenwmask |
| 169 |
jl LastMatchGood |
| 170 |
shrl $2, %chainlenwmask |
| 171 |
LastMatchGood: |
| 172 |
|
| 173 |
/* chainlen is decremented once beforehand so that the function can */ |
| 174 |
/* use the sign flag instead of the zero flag for the exit test. */ |
| 175 |
/* It is then shifted into the high word, to make room for the wmask */ |
| 176 |
/* value, which it will always accompany. */ |
| 177 |
|
| 178 |
decl %chainlenwmask |
| 179 |
shll $16, %chainlenwmask |
| 180 |
orl %eax, %chainlenwmask |
| 181 |
|
| 182 |
/* if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; */ |
| 183 |
|
| 184 |
movl dsNiceMatch, %eax |
| 185 |
movl dsLookahead, %ebx |
| 186 |
cmpl %eax, %ebx |
| 187 |
jl LookaheadLess |
| 188 |
movl %eax, %ebx |
| 189 |
LookaheadLess: movl %ebx, %nicematch |
| 190 |
|
| 191 |
/* register Bytef *scan = s->window + s->strstart; */ |
| 192 |
|
| 193 |
mov dsWindow, %window |
| 194 |
movl dsStrStart, %limitd |
| 195 |
lea (%limit, %window), %scan |
| 196 |
|
| 197 |
/* Determine how many bytes the scan ptr is off from being */ |
| 198 |
/* dword-aligned. */ |
| 199 |
|
| 200 |
mov %scan, %scanalign |
| 201 |
negl %scanalignd |
| 202 |
andl $3, %scanalignd |
| 203 |
|
| 204 |
/* IPos limit = s->strstart > (IPos)MAX_DIST(s) ? */ |
| 205 |
/* s->strstart - (IPos)MAX_DIST(s) : NIL; */ |
| 206 |
|
| 207 |
movl dsWSize, %eax |
| 208 |
subl $MIN_LOOKAHEAD, %eax |
| 209 |
xorl %ecx, %ecx |
| 210 |
subl %eax, %limitd |
| 211 |
cmovng %ecx, %limitd |
| 212 |
|
| 213 |
/* int best_len = s->prev_length; */ |
| 214 |
|
| 215 |
movl dsPrevLen, %bestlend |
| 216 |
|
| 217 |
/* Store the sum of s->window + best_len in %windowbestlen locally, and in memory. */ |
| 218 |
|
| 219 |
lea (%window, %bestlen), %windowbestlen |
| 220 |
mov %windowbestlen, _windowbestlen |
| 221 |
|
| 222 |
/* register ush scan_start = *(ushf*)scan; */ |
| 223 |
/* register ush scan_end = *(ushf*)(scan+best_len-1); */ |
| 224 |
/* Posf *prev = s->prev; */ |
| 225 |
|
| 226 |
movzwl (%scan), %scanstart |
| 227 |
movzwl -1(%scan, %bestlen), %scanend |
| 228 |
mov dsPrev, %prev |
| 229 |
|
| 230 |
/* Jump into the main loop. */ |
| 231 |
|
| 232 |
movl %chainlenwmask, _chainlenwmask |
| 233 |
jmp LoopEntry |
| 234 |
|
| 235 |
.balign 16 |
| 236 |
|
| 237 |
/* do { |
| 238 |
* match = s->window + cur_match; |
| 239 |
* if (*(ushf*)(match+best_len-1) != scan_end || |
| 240 |
* *(ushf*)match != scan_start) continue; |
| 241 |
* [...] |
| 242 |
* } while ((cur_match = prev[cur_match & wmask]) > limit |
| 243 |
* && --chain_length != 0); |
| 244 |
* |
| 245 |
* Here is the inner loop of the function. The function will spend the |
| 246 |
* majority of its time in this loop, and majority of that time will |
| 247 |
* be spent in the first ten instructions. |
| 248 |
*/ |
| 249 |
LookupLoop: |
| 250 |
andl %chainlenwmask, %curmatchd |
| 251 |
movzwl (%prev, %curmatch, 2), %curmatchd |
| 252 |
cmpl %limitd, %curmatchd |
| 253 |
jbe LeaveNow |
| 254 |
subl $0x00010000, %chainlenwmask |
| 255 |
js LeaveNow |
| 256 |
LoopEntry: cmpw -1(%windowbestlen, %curmatch), %scanendw |
| 257 |
jne LookupLoop |
| 258 |
cmpw %scanstartw, (%window, %curmatch) |
| 259 |
jne LookupLoop |
| 260 |
|
| 261 |
/* Store the current value of chainlen. */ |
| 262 |
movl %chainlenwmask, _chainlenwmask |
| 263 |
|
| 264 |
/* %scan is the string under scrutiny, and %prev to the string we */ |
| 265 |
/* are hoping to match it up with. In actuality, %esi and %edi are */ |
| 266 |
/* both pointed (MAX_MATCH_8 - scanalign) bytes ahead, and %edx is */ |
| 267 |
/* initialized to -(MAX_MATCH_8 - scanalign). */ |
| 268 |
|
| 269 |
mov $(-MAX_MATCH_8), %rdx |
| 270 |
lea (%curmatch, %window), %windowbestlen |
| 271 |
lea MAX_MATCH_8(%windowbestlen, %scanalign), %windowbestlen |
| 272 |
lea MAX_MATCH_8(%scan, %scanalign), %prev |
| 273 |
|
| 274 |
/* the prefetching below makes very little difference... */ |
| 275 |
prefetcht1 (%windowbestlen, %rdx) |
| 276 |
prefetcht1 (%prev, %rdx) |
| 277 |
|
| 278 |
/* |
| 279 |
* Test the strings for equality, 8 bytes at a time. At the end, |
| 280 |
* adjust %rdx so that it is offset to the exact byte that mismatched. |
| 281 |
* |
| 282 |
* It should be confessed that this loop usually does not represent |
| 283 |
* much of the total running time. Replacing it with a more |
| 284 |
* straightforward "rep cmpsb" would not drastically degrade |
| 285 |
* performance -- unrolling it, for example, makes no difference. |
| 286 |
*/ |
| 287 |
|
| 288 |
#undef USE_SSE /* works, but is 6-7% slower, than non-SSE... */ |
| 289 |
|
| 290 |
LoopCmps: |
| 291 |
#ifdef USE_SSE |
| 292 |
/* Preload the SSE registers */ |
| 293 |
movdqu (%windowbestlen, %rdx), %xmm1 |
| 294 |
movdqu (%prev, %rdx), %xmm2 |
| 295 |
pcmpeqb %xmm2, %xmm1 |
| 296 |
movdqu 16(%windowbestlen, %rdx), %xmm3 |
| 297 |
movdqu 16(%prev, %rdx), %xmm4 |
| 298 |
pcmpeqb %xmm4, %xmm3 |
| 299 |
movdqu 32(%windowbestlen, %rdx), %xmm5 |
| 300 |
movdqu 32(%prev, %rdx), %xmm6 |
| 301 |
pcmpeqb %xmm6, %xmm5 |
| 302 |
movdqu 48(%windowbestlen, %rdx), %xmm7 |
| 303 |
movdqu 48(%prev, %rdx), %xmm8 |
| 304 |
pcmpeqb %xmm8, %xmm7 |
| 305 |
|
| 306 |
/* Check the comparisions' results */ |
| 307 |
pmovmskb %xmm1, %rax |
| 308 |
notw %ax |
| 309 |
bsfw %ax, %ax |
| 310 |
jnz LeaveLoopCmps |
| 311 |
|
| 312 |
/* this is the only iteration of the loop with a possibility of having |
| 313 |
incremented rdx by 0x108 (each loop iteration add 16*4 = 0x40 |
| 314 |
and (0x40*4)+8=0x108 */ |
| 315 |
add $8, %rdx |
| 316 |
jz LenMaximum |
| 317 |
add $8, %rdx |
| 318 |
|
| 319 |
|
| 320 |
pmovmskb %xmm3, %rax |
| 321 |
notw %ax |
| 322 |
bsfw %ax, %ax |
| 323 |
jnz LeaveLoopCmps |
| 324 |
|
| 325 |
|
| 326 |
add $16, %rdx |
| 327 |
|
| 328 |
|
| 329 |
pmovmskb %xmm5, %rax |
| 330 |
notw %ax |
| 331 |
bsfw %ax, %ax |
| 332 |
jnz LeaveLoopCmps |
| 333 |
|
| 334 |
add $16, %rdx |
| 335 |
|
| 336 |
|
| 337 |
pmovmskb %xmm7, %rax |
| 338 |
notw %ax |
| 339 |
bsfw %ax, %ax |
| 340 |
jnz LeaveLoopCmps |
| 341 |
|
| 342 |
add $16, %rdx |
| 343 |
|
| 344 |
jmp LoopCmps |
| 345 |
LeaveLoopCmps: add %rax, %rdx |
| 346 |
#else |
| 347 |
mov (%windowbestlen, %rdx), %rax |
| 348 |
xor (%prev, %rdx), %rax |
| 349 |
jnz LeaveLoopCmps |
| 350 |
|
| 351 |
mov 8(%windowbestlen, %rdx), %rax |
| 352 |
xor 8(%prev, %rdx), %rax |
| 353 |
jnz LeaveLoopCmps8 |
| 354 |
|
| 355 |
mov 16(%windowbestlen, %rdx), %rax |
| 356 |
xor 16(%prev, %rdx), %rax |
| 357 |
jnz LeaveLoopCmps16 |
| 358 |
|
| 359 |
add $24, %rdx |
| 360 |
jnz LoopCmps |
| 361 |
jmp LenMaximum |
| 362 |
# if 0 |
| 363 |
/* |
| 364 |
* This three-liner is tantalizingly simple, but bsf is a slow instruction, |
| 365 |
* and the complicated alternative down below is quite a bit faster. Sad... |
| 366 |
*/ |
| 367 |
|
| 368 |
LeaveLoopCmps: bsf %rax, %rax /* find the first non-zero bit */ |
| 369 |
shrl $3, %eax /* divide by 8 to get the byte */ |
| 370 |
add %rax, %rdx |
| 371 |
# else |
| 372 |
LeaveLoopCmps16: |
| 373 |
add $8, %rdx |
| 374 |
LeaveLoopCmps8: |
| 375 |
add $8, %rdx |
| 376 |
LeaveLoopCmps: testl $0xFFFFFFFF, %eax /* Check the first 4 bytes */ |
| 377 |
jnz Check16 |
| 378 |
add $4, %rdx |
| 379 |
shr $32, %rax |
| 380 |
Check16: testw $0xFFFF, %ax |
| 381 |
jnz LenLower |
| 382 |
add $2, %rdx |
| 383 |
shrl $16, %eax |
| 384 |
LenLower: subb $1, %al |
| 385 |
adc $0, %rdx |
| 386 |
# endif |
| 387 |
#endif |
| 388 |
|
| 389 |
/* Calculate the length of the match. If it is longer than MAX_MATCH, */ |
| 390 |
/* then automatically accept it as the best possible match and leave. */ |
| 391 |
|
| 392 |
lea (%prev, %rdx), %rax |
| 393 |
sub %scan, %rax |
| 394 |
cmpl $MAX_MATCH, %eax |
| 395 |
jge LenMaximum |
| 396 |
|
| 397 |
/* If the length of the match is not longer than the best match we */ |
| 398 |
/* have so far, then forget it and return to the lookup loop. */ |
| 399 |
|
| 400 |
cmpl %bestlend, %eax |
| 401 |
jg LongerMatch |
| 402 |
mov _windowbestlen, %windowbestlen |
| 403 |
mov dsPrev, %prev |
| 404 |
movl _chainlenwmask, %edx |
| 405 |
jmp LookupLoop |
| 406 |
|
| 407 |
/* s->match_start = cur_match; */ |
| 408 |
/* best_len = len; */ |
| 409 |
/* if (len >= nice_match) break; */ |
| 410 |
/* scan_end = *(ushf*)(scan+best_len-1); */ |
| 411 |
|
| 412 |
LongerMatch: |
| 413 |
movl %eax, %bestlend |
| 414 |
movl %curmatchd, dsMatchStart |
| 415 |
cmpl %nicematch, %eax |
| 416 |
jge LeaveNow |
| 417 |
|
| 418 |
lea (%window, %bestlen), %windowbestlen |
| 419 |
mov %windowbestlen, _windowbestlen |
| 420 |
|
| 421 |
movzwl -1(%scan, %rax), %scanend |
| 422 |
mov dsPrev, %prev |
| 423 |
movl _chainlenwmask, %chainlenwmask |
| 424 |
jmp LookupLoop |
| 425 |
|
| 426 |
/* Accept the current string, with the maximum possible length. */ |
| 427 |
|
| 428 |
LenMaximum: |
| 429 |
movl $MAX_MATCH, %bestlend |
| 430 |
movl %curmatchd, dsMatchStart |
| 431 |
|
| 432 |
/* if ((uInt)best_len <= s->lookahead) return (uInt)best_len; */ |
| 433 |
/* return s->lookahead; */ |
| 434 |
|
| 435 |
LeaveNow: |
| 436 |
movl dsLookahead, %eax |
| 437 |
cmpl %eax, %bestlend |
| 438 |
cmovngl %bestlend, %eax |
| 439 |
LookaheadRet: |
| 440 |
|
| 441 |
/* Restore the registers and return from whence we came. */ |
| 442 |
|
| 443 |
mov save_rsi, %rsi |
| 444 |
mov save_rbx, %rbx |
| 445 |
mov save_r12, %r12 |
| 446 |
mov save_r13, %r13 |
| 447 |
mov save_r14, %r14 |
| 448 |
mov save_r15, %r15 |
| 449 |
|
| 450 |
ret |
| 451 |
|
| 452 |
match_init: ret |
