guest_generic_x87.c revision b32f58018498ea2225959b0ba11c18f0c433deef
1 2/*---------------------------------------------------------------*/ 3/*--- begin guest_generic_x87.c ---*/ 4/*---------------------------------------------------------------*/ 5 6/* 7 This file is part of Valgrind, a dynamic binary instrumentation 8 framework. 9 10 Copyright (C) 2004-2011 OpenWorks LLP 11 info@open-works.net 12 13 This program is free software; you can redistribute it and/or 14 modify it under the terms of the GNU General Public License as 15 published by the Free Software Foundation; either version 2 of the 16 License, or (at your option) any later version. 17 18 This program is distributed in the hope that it will be useful, but 19 WITHOUT ANY WARRANTY; without even the implied warranty of 20 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 21 General Public License for more details. 22 23 You should have received a copy of the GNU General Public License 24 along with this program; if not, write to the Free Software 25 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 26 02110-1301, USA. 27 28 The GNU General Public License is contained in the file COPYING. 29 30 Neither the names of the U.S. Department of Energy nor the 31 University of California nor the names of its contributors may be 32 used to endorse or promote products derived from this software 33 without prior written permission. 34*/ 35 36/* This file contains functions for doing some x87-specific 37 operations. Both the amd64 and x86 front ends (guests) indirectly 38 call these functions via guest helper calls. By putting them here, 39 code duplication is avoided. Some of these functions are tricky 40 and hard to verify, so there is much to be said for only having one 41 copy thereof. 42*/ 43 44#include "libvex_basictypes.h" 45 46#include "main_util.h" 47#include "guest_generic_x87.h" 48 49 50/* 80 and 64-bit floating point formats: 51 52 80-bit: 53 54 S 0 0-------0 zero 55 S 0 0X------X denormals 56 S 1-7FFE 1X------X normals (all normals have leading 1) 57 S 7FFF 10------0 infinity 58 S 7FFF 10X-----X snan 59 S 7FFF 11X-----X qnan 60 61 S is the sign bit. For runs X----X, at least one of the Xs must be 62 nonzero. Exponent is 15 bits, fractional part is 63 bits, and 63 there is an explicitly represented leading 1, and a sign bit, 64 giving 80 in total. 65 66 64-bit avoids the confusion of an explicitly represented leading 1 67 and so is simpler: 68 69 S 0 0------0 zero 70 S 0 X------X denormals 71 S 1-7FE any normals 72 S 7FF 0------0 infinity 73 S 7FF 0X-----X snan 74 S 7FF 1X-----X qnan 75 76 Exponent is 11 bits, fractional part is 52 bits, and there is a 77 sign bit, giving 64 in total. 78*/ 79 80 81static inline UInt read_bit_array ( UChar* arr, UInt n ) 82{ 83 UChar c = arr[n >> 3]; 84 c >>= (n&7); 85 return c & 1; 86} 87 88static inline void write_bit_array ( UChar* arr, UInt n, UInt b ) 89{ 90 UChar c = arr[n >> 3]; 91 c = toUChar( c & ~(1 << (n&7)) ); 92 c = toUChar( c | ((b&1) << (n&7)) ); 93 arr[n >> 3] = c; 94} 95 96/* Convert an IEEE754 double (64-bit) into an x87 extended double 97 (80-bit), mimicing the hardware fairly closely. Both numbers are 98 stored little-endian. Limitations, all of which could be fixed, 99 given some level of hassle: 100 101 * Identity of NaNs is not preserved. 102 103 See comments in the code for more details. 104*/ 105void convert_f64le_to_f80le ( /*IN*/UChar* f64, /*OUT*/UChar* f80 ) 106{ 107 Bool mantissaIsZero; 108 Int bexp, i, j, shift; 109 UChar sign; 110 111 sign = toUChar( (f64[7] >> 7) & 1 ); 112 bexp = (f64[7] << 4) | ((f64[6] >> 4) & 0x0F); 113 bexp &= 0x7FF; 114 115 mantissaIsZero = False; 116 if (bexp == 0 || bexp == 0x7FF) { 117 /* We'll need to know whether or not the mantissa (bits 51:0) is 118 all zeroes in order to handle these cases. So figure it 119 out. */ 120 mantissaIsZero 121 = toBool( 122 (f64[6] & 0x0F) == 0 123 && f64[5] == 0 && f64[4] == 0 && f64[3] == 0 124 && f64[2] == 0 && f64[1] == 0 && f64[0] == 0 125 ); 126 } 127 128 /* If the exponent is zero, either we have a zero or a denormal. 129 Produce a zero. This is a hack in that it forces denormals to 130 zero. Could do better. */ 131 if (bexp == 0) { 132 f80[9] = toUChar( sign << 7 ); 133 f80[8] = f80[7] = f80[6] = f80[5] = f80[4] 134 = f80[3] = f80[2] = f80[1] = f80[0] = 0; 135 136 if (mantissaIsZero) 137 /* It really is zero, so that's all we can do. */ 138 return; 139 140 /* There is at least one 1-bit in the mantissa. So it's a 141 potentially denormalised double -- but we can produce a 142 normalised long double. Count the leading zeroes in the 143 mantissa so as to decide how much to bump the exponent down 144 by. Note, this is SLOW. */ 145 shift = 0; 146 for (i = 51; i >= 0; i--) { 147 if (read_bit_array(f64, i)) 148 break; 149 shift++; 150 } 151 152 /* and copy into place as many bits as we can get our hands on. */ 153 j = 63; 154 for (i = 51 - shift; i >= 0; i--) { 155 write_bit_array( f80, j, 156 read_bit_array( f64, i ) ); 157 j--; 158 } 159 160 /* Set the exponent appropriately, and we're done. */ 161 bexp -= shift; 162 bexp += (16383 - 1023); 163 f80[9] = toUChar( (sign << 7) | ((bexp >> 8) & 0xFF) ); 164 f80[8] = toUChar( bexp & 0xFF ); 165 return; 166 } 167 168 /* If the exponent is 7FF, this is either an Infinity, a SNaN or 169 QNaN, as determined by examining bits 51:0, thus: 170 0 ... 0 Inf 171 0X ... X SNaN 172 1X ... X QNaN 173 where at least one of the Xs is not zero. 174 */ 175 if (bexp == 0x7FF) { 176 if (mantissaIsZero) { 177 /* Produce an appropriately signed infinity: 178 S 1--1 (15) 1 0--0 (63) 179 */ 180 f80[9] = toUChar( (sign << 7) | 0x7F ); 181 f80[8] = 0xFF; 182 f80[7] = 0x80; 183 f80[6] = f80[5] = f80[4] = f80[3] 184 = f80[2] = f80[1] = f80[0] = 0; 185 return; 186 } 187 /* So it's either a QNaN or SNaN. Distinguish by considering 188 bit 51. Note, this destroys all the trailing bits 189 (identity?) of the NaN. IEEE754 doesn't require preserving 190 these (it only requires that there be one QNaN value and one 191 SNaN value), but x87 does seem to have some ability to 192 preserve them. Anyway, here, the NaN's identity is 193 destroyed. Could be improved. */ 194 if (f64[6] & 8) { 195 /* QNaN. Make a QNaN: 196 S 1--1 (15) 1 1--1 (63) 197 */ 198 f80[9] = toUChar( (sign << 7) | 0x7F ); 199 f80[8] = 0xFF; 200 f80[7] = 0xFF; 201 f80[6] = f80[5] = f80[4] = f80[3] 202 = f80[2] = f80[1] = f80[0] = 0xFF; 203 } else { 204 /* SNaN. Make a SNaN: 205 S 1--1 (15) 0 1--1 (63) 206 */ 207 f80[9] = toUChar( (sign << 7) | 0x7F ); 208 f80[8] = 0xFF; 209 f80[7] = 0x7F; 210 f80[6] = f80[5] = f80[4] = f80[3] 211 = f80[2] = f80[1] = f80[0] = 0xFF; 212 } 213 return; 214 } 215 216 /* It's not a zero, denormal, infinity or nan. So it must be a 217 normalised number. Rebias the exponent and build the new 218 number. */ 219 bexp += (16383 - 1023); 220 221 f80[9] = toUChar( (sign << 7) | ((bexp >> 8) & 0xFF) ); 222 f80[8] = toUChar( bexp & 0xFF ); 223 f80[7] = toUChar( (1 << 7) | ((f64[6] << 3) & 0x78) 224 | ((f64[5] >> 5) & 7) ); 225 f80[6] = toUChar( ((f64[5] << 3) & 0xF8) | ((f64[4] >> 5) & 7) ); 226 f80[5] = toUChar( ((f64[4] << 3) & 0xF8) | ((f64[3] >> 5) & 7) ); 227 f80[4] = toUChar( ((f64[3] << 3) & 0xF8) | ((f64[2] >> 5) & 7) ); 228 f80[3] = toUChar( ((f64[2] << 3) & 0xF8) | ((f64[1] >> 5) & 7) ); 229 f80[2] = toUChar( ((f64[1] << 3) & 0xF8) | ((f64[0] >> 5) & 7) ); 230 f80[1] = toUChar( ((f64[0] << 3) & 0xF8) ); 231 f80[0] = toUChar( 0 ); 232} 233 234 235/* Convert an x87 extended double (80-bit) into an IEEE 754 double 236 (64-bit), mimicking the hardware fairly closely. Both numbers are 237 stored little-endian. Limitations, both of which could be fixed, 238 given some level of hassle: 239 240 * Rounding following truncation could be a bit better. 241 242 * Identity of NaNs is not preserved. 243 244 See comments in the code for more details. 245*/ 246void convert_f80le_to_f64le ( /*IN*/UChar* f80, /*OUT*/UChar* f64 ) 247{ 248 Bool isInf; 249 Int bexp, i, j; 250 UChar sign; 251 252 sign = toUChar((f80[9] >> 7) & 1); 253 bexp = (((UInt)f80[9]) << 8) | (UInt)f80[8]; 254 bexp &= 0x7FFF; 255 256 /* If the exponent is zero, either we have a zero or a denormal. 257 But an extended precision denormal becomes a double precision 258 zero, so in either case, just produce the appropriately signed 259 zero. */ 260 if (bexp == 0) { 261 f64[7] = toUChar(sign << 7); 262 f64[6] = f64[5] = f64[4] = f64[3] = f64[2] = f64[1] = f64[0] = 0; 263 return; 264 } 265 266 /* If the exponent is 7FFF, this is either an Infinity, a SNaN or 267 QNaN, as determined by examining bits 62:0, thus: 268 0 ... 0 Inf 269 0X ... X SNaN 270 1X ... X QNaN 271 where at least one of the Xs is not zero. 272 */ 273 if (bexp == 0x7FFF) { 274 isInf = toBool( 275 (f80[7] & 0x7F) == 0 276 && f80[6] == 0 && f80[5] == 0 && f80[4] == 0 277 && f80[3] == 0 && f80[2] == 0 && f80[1] == 0 278 && f80[0] == 0 279 ); 280 if (isInf) { 281 if (0 == (f80[7] & 0x80)) 282 goto wierd_NaN; 283 /* Produce an appropriately signed infinity: 284 S 1--1 (11) 0--0 (52) 285 */ 286 f64[7] = toUChar((sign << 7) | 0x7F); 287 f64[6] = 0xF0; 288 f64[5] = f64[4] = f64[3] = f64[2] = f64[1] = f64[0] = 0; 289 return; 290 } 291 /* So it's either a QNaN or SNaN. Distinguish by considering 292 bit 62. Note, this destroys all the trailing bits 293 (identity?) of the NaN. IEEE754 doesn't require preserving 294 these (it only requires that there be one QNaN value and one 295 SNaN value), but x87 does seem to have some ability to 296 preserve them. Anyway, here, the NaN's identity is 297 destroyed. Could be improved. */ 298 if (f80[8] & 0x40) { 299 /* QNaN. Make a QNaN: 300 S 1--1 (11) 1 1--1 (51) 301 */ 302 f64[7] = toUChar((sign << 7) | 0x7F); 303 f64[6] = 0xFF; 304 f64[5] = f64[4] = f64[3] = f64[2] = f64[1] = f64[0] = 0xFF; 305 } else { 306 /* SNaN. Make a SNaN: 307 S 1--1 (11) 0 1--1 (51) 308 */ 309 f64[7] = toUChar((sign << 7) | 0x7F); 310 f64[6] = 0xF7; 311 f64[5] = f64[4] = f64[3] = f64[2] = f64[1] = f64[0] = 0xFF; 312 } 313 return; 314 } 315 316 /* If it's not a Zero, NaN or Inf, and the integer part (bit 62) is 317 zero, the x87 FPU appears to consider the number denormalised 318 and converts it to a QNaN. */ 319 if (0 == (f80[7] & 0x80)) { 320 wierd_NaN: 321 /* Strange hardware QNaN: 322 S 1--1 (11) 1 0--0 (51) 323 */ 324 /* On a PIII, these QNaNs always appear with sign==1. I have 325 no idea why. */ 326 f64[7] = (1 /*sign*/ << 7) | 0x7F; 327 f64[6] = 0xF8; 328 f64[5] = f64[4] = f64[3] = f64[2] = f64[1] = f64[0] = 0; 329 return; 330 } 331 332 /* It's not a zero, denormal, infinity or nan. So it must be a 333 normalised number. Rebias the exponent and consider. */ 334 bexp -= (16383 - 1023); 335 if (bexp >= 0x7FF) { 336 /* It's too big for a double. Construct an infinity. */ 337 f64[7] = toUChar((sign << 7) | 0x7F); 338 f64[6] = 0xF0; 339 f64[5] = f64[4] = f64[3] = f64[2] = f64[1] = f64[0] = 0; 340 return; 341 } 342 343 if (bexp <= 0) { 344 /* It's too small for a normalised double. First construct a 345 zero and then see if it can be improved into a denormal. */ 346 f64[7] = toUChar(sign << 7); 347 f64[6] = f64[5] = f64[4] = f64[3] = f64[2] = f64[1] = f64[0] = 0; 348 349 if (bexp < -52) 350 /* Too small even for a denormal. */ 351 return; 352 353 /* Ok, let's make a denormal. Note, this is SLOW. */ 354 /* Copy bits 63, 62, 61, etc of the src mantissa into the dst, 355 indexes 52+bexp, 51+bexp, etc, until k+bexp < 0. */ 356 /* bexp is in range -52 .. 0 inclusive */ 357 for (i = 63; i >= 0; i--) { 358 j = i - 12 + bexp; 359 if (j < 0) break; 360 /* We shouldn't really call vassert from generated code. */ 361 vassert(j >= 0 && j < 52); 362 write_bit_array ( f64, 363 j, 364 read_bit_array ( f80, i ) ); 365 } 366 /* and now we might have to round ... */ 367 if (read_bit_array(f80, 10+1 - bexp) == 1) 368 goto do_rounding; 369 370 return; 371 } 372 373 /* Ok, it's a normalised number which is representable as a double. 374 Copy the exponent and mantissa into place. */ 375 /* 376 for (i = 0; i < 52; i++) 377 write_bit_array ( f64, 378 i, 379 read_bit_array ( f80, i+11 ) ); 380 */ 381 f64[0] = toUChar( (f80[1] >> 3) | (f80[2] << 5) ); 382 f64[1] = toUChar( (f80[2] >> 3) | (f80[3] << 5) ); 383 f64[2] = toUChar( (f80[3] >> 3) | (f80[4] << 5) ); 384 f64[3] = toUChar( (f80[4] >> 3) | (f80[5] << 5) ); 385 f64[4] = toUChar( (f80[5] >> 3) | (f80[6] << 5) ); 386 f64[5] = toUChar( (f80[6] >> 3) | (f80[7] << 5) ); 387 388 f64[6] = toUChar( ((bexp << 4) & 0xF0) | ((f80[7] >> 3) & 0x0F) ); 389 390 f64[7] = toUChar( (sign << 7) | ((bexp >> 4) & 0x7F) ); 391 392 /* Now consider any rounding that needs to happen as a result of 393 truncating the mantissa. */ 394 if (f80[1] & 4) /* read_bit_array(f80, 10) == 1) */ { 395 396 /* If the bottom bits of f80 are "100 0000 0000", then the 397 infinitely precise value is deemed to be mid-way between the 398 two closest representable values. Since we're doing 399 round-to-nearest (the default mode), in that case it is the 400 bit immediately above which indicates whether we should round 401 upwards or not -- if 0, we don't. All that is encapsulated 402 in the following simple test. */ 403 if ((f80[1] & 0xF) == 4/*0100b*/ && f80[0] == 0) 404 return; 405 406 do_rounding: 407 /* Round upwards. This is a kludge. Once in every 2^24 408 roundings (statistically) the bottom three bytes are all 0xFF 409 and so we don't round at all. Could be improved. */ 410 if (f64[0] != 0xFF) { 411 f64[0]++; 412 } 413 else 414 if (f64[0] == 0xFF && f64[1] != 0xFF) { 415 f64[0] = 0; 416 f64[1]++; 417 } 418 else 419 if (f64[0] == 0xFF && f64[1] == 0xFF && f64[2] != 0xFF) { 420 f64[0] = 0; 421 f64[1] = 0; 422 f64[2]++; 423 } 424 /* else we don't round, but we should. */ 425 } 426} 427 428 429/* CALLED FROM GENERATED CODE: CLEAN HELPER */ 430/* Extract the signed significand or exponent component as per 431 fxtract. Arg and result are doubles travelling under the guise of 432 ULongs. Returns significand when getExp is zero and exponent 433 otherwise. */ 434ULong x86amd64g_calculate_FXTRACT ( ULong arg, HWord getExp ) 435{ 436 ULong uSig, uExp; 437 /* Long sSig; */ 438 Int sExp, i; 439 UInt sign, expExp; 440 441 /* 442 S 7FF 0------0 infinity 443 S 7FF 0X-----X snan 444 S 7FF 1X-----X qnan 445 */ 446 const ULong posInf = 0x7FF0000000000000ULL; 447 const ULong negInf = 0xFFF0000000000000ULL; 448 const ULong nanMask = 0x7FF0000000000000ULL; 449 const ULong qNan = 0x7FF8000000000000ULL; 450 const ULong posZero = 0x0000000000000000ULL; 451 const ULong negZero = 0x8000000000000000ULL; 452 const ULong bit51 = 1ULL << 51; 453 const ULong bit52 = 1ULL << 52; 454 const ULong sigMask = bit52 - 1; 455 456 /* Mimic Core i5 behaviour for special cases. */ 457 if (arg == posInf) 458 return getExp ? posInf : posInf; 459 if (arg == negInf) 460 return getExp ? posInf : negInf; 461 if ((arg & nanMask) == nanMask) 462 return qNan | (arg & (1ULL << 63)); 463 if (arg == posZero) 464 return getExp ? negInf : posZero; 465 if (arg == negZero) 466 return getExp ? negInf : negZero; 467 468 /* Split into sign, exponent and significand. */ 469 sign = ((UInt)(arg >> 63)) & 1; 470 471 /* Mask off exponent & sign. uSig is in range 0 .. 2^52-1. */ 472 uSig = arg & sigMask; 473 474 /* Get the exponent. */ 475 sExp = ((Int)(arg >> 52)) & 0x7FF; 476 477 /* Deal with denormals: if the exponent is zero, then the 478 significand cannot possibly be zero (negZero/posZero are handled 479 above). Shift the significand left until bit 51 of it becomes 480 1, and decrease the exponent accordingly. 481 */ 482 if (sExp == 0) { 483 for (i = 0; i < 52; i++) { 484 if (uSig & bit51) 485 break; 486 uSig <<= 1; 487 sExp--; 488 } 489 uSig <<= 1; 490 } else { 491 /* Add the implied leading-1 in the significand. */ 492 uSig |= bit52; 493 } 494 495 /* Roll in the sign. */ 496 /* sSig = uSig; */ 497 /* if (sign) sSig =- sSig; */ 498 499 /* Convert sig into a double. This should be an exact conversion. 500 Then divide by 2^52, which should give a value in the range 1.0 501 to 2.0-epsilon, at least for normalised args. */ 502 /* dSig = (Double)sSig; */ 503 /* dSig /= 67108864.0; */ /* 2^26 */ 504 /* dSig /= 67108864.0; */ /* 2^26 */ 505 uSig &= sigMask; 506 uSig |= 0x3FF0000000000000ULL; 507 if (sign) 508 uSig ^= negZero; 509 510 /* Convert exp into a double. Also an exact conversion. */ 511 /* dExp = (Double)(sExp - 1023); */ 512 sExp -= 1023; 513 if (sExp == 0) { 514 uExp = 0; 515 } else { 516 uExp = sExp < 0 ? -sExp : sExp; 517 expExp = 0x3FF +52; 518 /* 1 <= uExp <= 1074 */ 519 /* Skip first 42 iterations of normalisation loop as we know they 520 will always happen */ 521 uExp <<= 42; 522 expExp -= 42; 523 for (i = 0; i < 52-42; i++) { 524 if (uExp & bit52) 525 break; 526 uExp <<= 1; 527 expExp--; 528 } 529 uExp &= sigMask; 530 uExp |= ((ULong)expExp) << 52; 531 if (sExp < 0) uExp ^= negZero; 532 } 533 534 return getExp ? uExp : uSig; 535} 536 537 538 539/*---------------------------------------------------------*/ 540/*--- SSE4.2 PCMP{E,I}STR{I,M} helpers ---*/ 541/*---------------------------------------------------------*/ 542 543/* We need the definitions for OSZACP eflags/rflags offsets. 544 #including guest_{amd64,x86}_defs.h causes chaos, so just copy the 545 required values directly. They are not going to change in the 546 foreseeable future :-) 547*/ 548 549#define SHIFT_O 11 550#define SHIFT_S 7 551#define SHIFT_Z 6 552#define SHIFT_A 4 553#define SHIFT_C 0 554#define SHIFT_P 2 555 556#define MASK_O (1 << SHIFT_O) 557#define MASK_S (1 << SHIFT_S) 558#define MASK_Z (1 << SHIFT_Z) 559#define MASK_A (1 << SHIFT_A) 560#define MASK_C (1 << SHIFT_C) 561#define MASK_P (1 << SHIFT_P) 562 563 564/* Count leading zeroes, w/ 0-produces-32 semantics, a la Hacker's 565 Delight. */ 566static UInt clz32 ( UInt x ) 567{ 568 Int y, m, n; 569 y = -(x >> 16); 570 m = (y >> 16) & 16; 571 n = 16 - m; 572 x = x >> m; 573 y = x - 0x100; 574 m = (y >> 16) & 8; 575 n = n + m; 576 x = x << m; 577 y = x - 0x1000; 578 m = (y >> 16) & 4; 579 n = n + m; 580 x = x << m; 581 y = x - 0x4000; 582 m = (y >> 16) & 2; 583 n = n + m; 584 x = x << m; 585 y = x >> 14; 586 m = y & ~(y >> 1); 587 return n + 2 - m; 588} 589 590static UInt ctz32 ( UInt x ) 591{ 592 return 32 - clz32((~x) & (x-1)); 593} 594 595/* Convert a 4-bit value to a 32-bit value by cloning each bit 8 596 times. There's surely a better way to do this, but I don't know 597 what it is. */ 598static UInt bits4_to_bytes4 ( UInt bits4 ) 599{ 600 UInt r = 0; 601 r |= (bits4 & 1) ? 0x000000FF : 0; 602 r |= (bits4 & 2) ? 0x0000FF00 : 0; 603 r |= (bits4 & 4) ? 0x00FF0000 : 0; 604 r |= (bits4 & 8) ? 0xFF000000 : 0; 605 return r; 606} 607 608 609/* Given partial results from a pcmpXstrX operation (intRes1, 610 basically), generate an I- or M-format output value, also the new 611 OSZACP flags. */ 612static 613void compute_PCMPxSTRx_gen_output (/*OUT*/V128* resV, 614 /*OUT*/UInt* resOSZACP, 615 UInt intRes1, 616 UInt zmaskL, UInt zmaskR, 617 UInt validL, 618 UInt pol, UInt idx, 619 Bool isxSTRM ) 620{ 621 vassert((pol >> 2) == 0); 622 vassert((idx >> 1) == 0); 623 624 UInt intRes2 = 0; 625 switch (pol) { 626 case 0: intRes2 = intRes1; break; // pol + 627 case 1: intRes2 = ~intRes1; break; // pol - 628 case 2: intRes2 = intRes1; break; // pol m+ 629 case 3: intRes2 = intRes1 ^ validL; break; // pol m- 630 } 631 intRes2 &= 0xFFFF; 632 633 if (isxSTRM) { 634 635 // generate M-format output (a bit or byte mask in XMM0) 636 if (idx) { 637 resV->w32[0] = bits4_to_bytes4( (intRes2 >> 0) & 0xF ); 638 resV->w32[1] = bits4_to_bytes4( (intRes2 >> 4) & 0xF ); 639 resV->w32[2] = bits4_to_bytes4( (intRes2 >> 8) & 0xF ); 640 resV->w32[3] = bits4_to_bytes4( (intRes2 >> 12) & 0xF ); 641 } else { 642 resV->w32[0] = intRes2 & 0xFFFF; 643 resV->w32[1] = 0; 644 resV->w32[2] = 0; 645 resV->w32[3] = 0; 646 } 647 648 } else { 649 650 // generate I-format output (an index in ECX) 651 // generate ecx value 652 UInt newECX = 0; 653 if (idx) { 654 // index of ms-1-bit 655 newECX = intRes2 == 0 ? 16 : (31 - clz32(intRes2)); 656 } else { 657 // index of ls-1-bit 658 newECX = intRes2 == 0 ? 16 : ctz32(intRes2); 659 } 660 661 resV->w32[0] = newECX; 662 resV->w32[1] = 0; 663 resV->w32[2] = 0; 664 resV->w32[3] = 0; 665 666 } 667 668 // generate new flags, common to all ISTRI and ISTRM cases 669 *resOSZACP // A, P are zero 670 = ((intRes2 == 0) ? 0 : MASK_C) // C == 0 iff intRes2 == 0 671 | ((zmaskL == 0) ? 0 : MASK_Z) // Z == 1 iff any in argL is 0 672 | ((zmaskR == 0) ? 0 : MASK_S) // S == 1 iff any in argR is 0 673 | ((intRes2 & 1) << SHIFT_O); // O == IntRes2[0] 674} 675 676 677/* Compute result and new OSZACP flags for all PCMP{E,I}STR{I,M} 678 variants. 679 680 For xSTRI variants, the new ECX value is placed in the 32 bits 681 pointed to by *resV, and the top 96 bits are zeroed. For xSTRM 682 variants, the result is a 128 bit value and is placed at *resV in 683 the obvious way. 684 685 For all variants, the new OSZACP value is placed at *resOSZACP. 686 687 argLV and argRV are the vector args. The caller must prepare a 688 16-bit mask for each, zmaskL and zmaskR. For ISTRx variants this 689 must be 1 for each zero byte of of the respective arg. For ESTRx 690 variants this is derived from the explicit length indication, and 691 must be 0 in all places except at the bit index corresponding to 692 the valid length (0 .. 16). If the valid length is 16 then the 693 mask must be all zeroes. In all cases, bits 31:16 must be zero. 694 695 imm8 is the original immediate from the instruction. isSTRM 696 indicates whether this is a xSTRM or xSTRI variant, which controls 697 how much of *res is written. 698 699 If the given imm8 case can be handled, the return value is True. 700 If not, False is returned, and neither *res not *resOSZACP are 701 altered. 702*/ 703 704Bool compute_PCMPxSTRx ( /*OUT*/V128* resV, 705 /*OUT*/UInt* resOSZACP, 706 V128* argLV, V128* argRV, 707 UInt zmaskL, UInt zmaskR, 708 UInt imm8, Bool isxSTRM ) 709{ 710 vassert(imm8 < 0x80); 711 vassert((zmaskL >> 16) == 0); 712 vassert((zmaskR >> 16) == 0); 713 714 /* Explicitly reject any imm8 values that haven't been validated, 715 even if they would probably work. Life is too short to have 716 unvalidated cases in the code base. */ 717 switch (imm8) { 718 case 0x00: 719 case 0x02: case 0x08: case 0x0A: case 0x0C: case 0x12: 720 case 0x1A: case 0x38: case 0x3A: case 0x44: case 0x4A: 721 break; 722 default: 723 return False; 724 } 725 726 UInt fmt = (imm8 >> 0) & 3; // imm8[1:0] data format 727 UInt agg = (imm8 >> 2) & 3; // imm8[3:2] aggregation fn 728 UInt pol = (imm8 >> 4) & 3; // imm8[5:4] polarity 729 UInt idx = (imm8 >> 6) & 1; // imm8[6] 1==msb/bytemask 730 731 /*----------------------------------------*/ 732 /*-- strcmp on byte data --*/ 733 /*----------------------------------------*/ 734 735 if (agg == 2/*equal each, aka strcmp*/ 736 && (fmt == 0/*ub*/ || fmt == 2/*sb*/)) { 737 Int i; 738 UChar* argL = (UChar*)argLV; 739 UChar* argR = (UChar*)argRV; 740 UInt boolResII = 0; 741 for (i = 15; i >= 0; i--) { 742 UChar cL = argL[i]; 743 UChar cR = argR[i]; 744 boolResII = (boolResII << 1) | (cL == cR ? 1 : 0); 745 } 746 UInt validL = ~(zmaskL | -zmaskL); // not(left(zmaskL)) 747 UInt validR = ~(zmaskR | -zmaskR); // not(left(zmaskR)) 748 749 // do invalidation, common to all equal-each cases 750 UInt intRes1 751 = (boolResII & validL & validR) // if both valid, use cmpres 752 | (~ (validL | validR)); // if both invalid, force 1 753 // else force 0 754 intRes1 &= 0xFFFF; 755 756 // generate I-format output 757 compute_PCMPxSTRx_gen_output( 758 resV, resOSZACP, 759 intRes1, zmaskL, zmaskR, validL, pol, idx, isxSTRM 760 ); 761 762 return True; 763 } 764 765 /*----------------------------------------*/ 766 /*-- set membership on byte data --*/ 767 /*----------------------------------------*/ 768 769 if (agg == 0/*equal any, aka find chars in a set*/ 770 && (fmt == 0/*ub*/ || fmt == 2/*sb*/)) { 771 /* argL: the string, argR: charset */ 772 UInt si, ci; 773 UChar* argL = (UChar*)argLV; 774 UChar* argR = (UChar*)argRV; 775 UInt boolRes = 0; 776 UInt validL = ~(zmaskL | -zmaskL); // not(left(zmaskL)) 777 UInt validR = ~(zmaskR | -zmaskR); // not(left(zmaskR)) 778 779 for (si = 0; si < 16; si++) { 780 if ((validL & (1 << si)) == 0) 781 // run off the end of the string. 782 break; 783 UInt m = 0; 784 for (ci = 0; ci < 16; ci++) { 785 if ((validR & (1 << ci)) == 0) break; 786 if (argR[ci] == argL[si]) { m = 1; break; } 787 } 788 boolRes |= (m << si); 789 } 790 791 // boolRes is "pre-invalidated" 792 UInt intRes1 = boolRes & 0xFFFF; 793 794 // generate I-format output 795 compute_PCMPxSTRx_gen_output( 796 resV, resOSZACP, 797 intRes1, zmaskL, zmaskR, validL, pol, idx, isxSTRM 798 ); 799 800 return True; 801 } 802 803 /*----------------------------------------*/ 804 /*-- substring search on byte data --*/ 805 /*----------------------------------------*/ 806 807 if (agg == 3/*equal ordered, aka substring search*/ 808 && (fmt == 0/*ub*/ || fmt == 2/*sb*/)) { 809 810 /* argL: haystack, argR: needle */ 811 UInt ni, hi; 812 UChar* argL = (UChar*)argLV; 813 UChar* argR = (UChar*)argRV; 814 UInt boolRes = 0; 815 UInt validL = ~(zmaskL | -zmaskL); // not(left(zmaskL)) 816 UInt validR = ~(zmaskR | -zmaskR); // not(left(zmaskR)) 817 for (hi = 0; hi < 16; hi++) { 818 if ((validL & (1 << hi)) == 0) 819 // run off the end of the haystack 820 break; 821 UInt m = 1; 822 for (ni = 0; ni < 16; ni++) { 823 if ((validR & (1 << ni)) == 0) break; 824 UInt i = ni + hi; 825 if (i >= 16) break; 826 if (argL[i] != argR[ni]) { m = 0; break; } 827 } 828 boolRes |= (m << hi); 829 } 830 831 // boolRes is "pre-invalidated" 832 UInt intRes1 = boolRes & 0xFFFF; 833 834 // generate I-format output 835 compute_PCMPxSTRx_gen_output( 836 resV, resOSZACP, 837 intRes1, zmaskL, zmaskR, validL, pol, idx, isxSTRM 838 ); 839 840 return True; 841 } 842 843 /*----------------------------------------*/ 844 /*-- ranges, unsigned byte data --*/ 845 /*----------------------------------------*/ 846 847 if (agg == 1/*ranges*/ 848 && fmt == 0/*ub*/) { 849 850 /* argL: string, argR: range-pairs */ 851 UInt ri, si; 852 UChar* argL = (UChar*)argLV; 853 UChar* argR = (UChar*)argRV; 854 UInt boolRes = 0; 855 UInt validL = ~(zmaskL | -zmaskL); // not(left(zmaskL)) 856 UInt validR = ~(zmaskR | -zmaskR); // not(left(zmaskR)) 857 for (si = 0; si < 16; si++) { 858 if ((validL & (1 << si)) == 0) 859 // run off the end of the string 860 break; 861 UInt m = 0; 862 for (ri = 0; ri < 16; ri += 2) { 863 if ((validR & (3 << ri)) != (3 << ri)) break; 864 if (argR[ri] <= argL[si] && argL[si] <= argR[ri+1]) { 865 m = 1; break; 866 } 867 } 868 boolRes |= (m << si); 869 } 870 871 // boolRes is "pre-invalidated" 872 UInt intRes1 = boolRes & 0xFFFF; 873 874 // generate I-format output 875 compute_PCMPxSTRx_gen_output( 876 resV, resOSZACP, 877 intRes1, zmaskL, zmaskR, validL, pol, idx, isxSTRM 878 ); 879 880 return True; 881 } 882 883 return False; 884} 885 886 887/*---------------------------------------------------------------*/ 888/*--- end guest_generic_x87.c ---*/ 889/*---------------------------------------------------------------*/ 890