IntelÂ® 64 and IA-32 Architectures Optimization Reference Manual

More documents

Recommendations

Info

GENERAL OPTIMIZATION GUIDELINESstate that the rounding mode should be truncation. With the Pentium 4 processor,one can use the CVTTSD2SI and CVTTSS2SI instructions to convert operands withtruncation without ever needing to change rounding modes. The cost savings ofusing these instructions over the methods below is enough to justify using SSE andSSE2 wherever possible when truncation is involved.For x87 floating point, the FIST instruction uses the rounding mode represented inthe floating-point control word (FCW). The rounding mode is generally “round tonearest”, so many compiler writers implement a change in the rounding mode in theprocessor in order to conform to the C and FORTRAN standards. This implementationrequires changing the control word on the processor using the FLDCW instruction.For a change in the rounding, precision, and infinity bits, use the FSTCW instructionto store the floating-point control word. Then use the FLDCW instruction to changethe rounding mode to truncation.In a typical code sequence that changes the rounding mode in the FCW, a FSTCWinstruction is usually followed by a load operation. The load operation from memoryshould be a 16-bit operand to prevent store-forwarding problem. If the load operationon the previously-stored FCW word involves either an 8-bit or a 32-bit operand,this will cause a store-forwarding problem due to mismatch of the size of the databetween the store operation and the load operation.To avoid store-forwarding problems, make sure that the write and read to the FCWare both 16-bit operations.If there is more than one change to the rounding, precision, and infinity bits, and therounding mode is not important to the result, use the algorithm in Example 3-45 toavoid synchronization issues, the overhead of the FLDCW instruction, and having tochange the rounding mode. Note that the example suffers from a store-forwardingproblem which will lead to a performance penalty. However, its performance is stillbetter than changing the rounding, precision, and infinity bits among more than twovalues.Example 3-45. Algorithm to Avoid Changing Rounding Mode_fto132proclea ecx, [esp-8]sub esp, 16 ; Allocate frameand ecx, -8 ; Align pointer on boundary of 8fld st(0) ; Duplicate FPU stack topfistp qword ptr[ecx]fild qword ptr[ecx]mov edx, [ecx+4] ; High DWORD of integermov eax, [ecx] ; Low DWIRD of integertest eax, eaxje integer_QnaN_or_zero3-82
GENERAL OPTIMIZATION GUIDELINESExample 3-45. Algorithm to Avoid Changing Rounding Mode (Contd.)arg_is_not_integer_QnaN:fsubp st(1), st ; TOS=d-round(d), { st(1) = st(1)-st & pop ST}test edx, edx ; What’s sign of integerjns positive ; Number is negativefstp dword ptr[ecx] ; Result of subtractionmov ecx, [ecx] ; DWORD of diff(single-precision)add esp, 16xor ecx, 80000000hadd ecx,7fffffffh ; If diff
Page 1 and 2:
NIntel® 64 and IA-32 Architectures
Page 4 and 5:
CONTENTS2.3.1 Front End. . . . . .
Page 6 and 7:
CONTENTS3.7 PREFETCHING . . . . . .
Page 8 and 9:
CONTENTS5.7.2.1 Increasing Memory B
Page 10 and 11:
CONTENTS9.5.3 Streaming Store Instr
Page 13 and 14:
CONTENTSB.7.4.3B.7.4.4B.7.4.5B.7.4.
Page 15 and 16:
CONTENTSExample 4-1. Identification
Page 17 and 18:
CONTENTSExample 9-8. Using HW Prefe
Page 19 and 20:
CONTENTSFigure 9-7. Cache Blocking
Page 21 and 22:
CHAPTER 1INTRODUCTIONThe Intel® 64
Page 23 and 24:
INTRODUCTION• Chapter 10: Power O
Page 25 and 26:
CHAPTER 2INTEL ® 64 AND IA-32 PROC
Page 27 and 28:
INTEL® 64 AND IA-32 PROCESSOR ARCH
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
CHAPTER 3GENERAL OPTIMIZATION GUIDE
Page 77 and 78:
GENERAL OPTIMIZATION GUIDELINESThe
Page 79 and 80:
GENERAL OPTIMIZATION GUIDELINEScomp
Page 81 and 82:
GENERAL OPTIMIZATION GUIDELINES•
Page 83 and 84:
GENERAL OPTIMIZATION GUIDELINESExam
Page 85 and 86:
GENERAL OPTIMIZATION GUIDELINESthro
Page 87 and 88:
GENERAL OPTIMIZATION GUIDELINESAsse
Page 90 and 91:
GENERAL OPTIMIZATION GUIDELINESpred
Page 92 and 93:
GENERAL OPTIMIZATION GUIDELINESIn t
Page 94 and 95:
GENERAL OPTIMIZATION GUIDELINESExam
Page 96 and 97:
GENERAL OPTIMIZATION GUIDELINESThe
Page 98 and 99:
GENERAL OPTIMIZATION GUIDELINESBeca
Page 100 and 101:
GENERAL OPTIMIZATION GUIDELINESInst
Page 102 and 103:
GENERAL OPTIMIZATION GUIDELINESXOR
Page 104 and 105:
GENERAL OPTIMIZATION GUIDELINESUse
Page 106 and 107: GENERAL OPTIMIZATION GUIDELINESvalu
Page 108 and 109: GENERAL OPTIMIZATION GUIDELINES•
Page 110 and 111: GENERAL OPTIMIZATION GUIDELINESMOVS
Page 112 and 113: GENERAL OPTIMIZATION GUIDELINESAsse
Page 114 and 115: GENERAL OPTIMIZATION GUIDELINESPack
Page 116 and 117: GENERAL OPTIMIZATION GUIDELINES3.5.
Page 120 and 121: GENERAL OPTIMIZATION GUIDELINESFor
Page 126 and 127: GENERAL OPTIMIZATION GUIDELINESThe
Page 128 and 129: GENERAL OPTIMIZATION GUIDELINESAs a
Page 130 and 131: GENERAL OPTIMIZATION GUIDELINESTher
Page 132 and 133: GENERAL OPTIMIZATION GUIDELINESExam
Page 134 and 135: GENERAL OPTIMIZATION GUIDELINESExam
Page 136 and 137: GENERAL OPTIMIZATION GUIDELINES—
Page 138 and 139: GENERAL OPTIMIZATION GUIDELINESAsse
Page 140 and 141: GENERAL OPTIMIZATION GUIDELINESmore
Page 142 and 143: GENERAL OPTIMIZATION GUIDELINESrequ
Page 144 and 145: GENERAL OPTIMIZATION GUIDELINESmiss
Page 146 and 147: GENERAL OPTIMIZATION GUIDELINESpref
Page 148 and 149: GENERAL OPTIMIZATION GUIDELINESpref
Page 150 and 151: GENERAL OPTIMIZATION GUIDELINES—
Page 152 and 153: GENERAL OPTIMIZATION GUIDELINES•
Page 154 and 155: GENERAL OPTIMIZATION GUIDELINESTher
Page 158 and 159: GENERAL OPTIMIZATION GUIDELINESexte
Page 160 and 161: GENERAL OPTIMIZATION GUIDELINESFor
Page 162 and 163: CODING FOR SIMD ARCHITECTURES4.1.1
Page 164 and 165: CODING FOR SIMD ARCHITECTURESSoftwa
Page 166 and 167: CODING FOR SIMD ARCHITECTURESTo use
Page 170 and 171: CODING FOR SIMD ARCHITECTURESExampl
Page 172 and 173: CODING FOR SIMD ARCHITECTURESmance
Page 174 and 175: CODING FOR SIMD ARCHITECTURESpurpos
Page 178 and 179: CODING FOR SIMD ARCHITECTURESIf the
Page 180 and 181: CODING FOR SIMD ARCHITECTURESExampl
Page 182 and 183: CODING FOR SIMD ARCHITECTURES• Us
Page 184 and 185: CODING FOR SIMD ARCHITECTURESpatter
Page 186 and 187: CODING FOR SIMD ARCHITECTURESmoves
Page 188 and 189: CODING FOR SIMD ARCHITECTURES4-28
Page 190 and 191: OPTIMIZING FOR SIMD INTEGER APPLICA
Page 206 and 207:
OPTIMIZING FOR SIMD INTEGER APPLICA
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
OPTIMIZING FOR SIMD FLOATING-POINT
Page 230 and 231:
Page 232 and 233:
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
Page 246 and 247:
Page 248 and 249:
Page 250 and 251:
MULTICORE AND HYPER-THREADING TECHN
Page 252 and 253:
Page 254 and 255:
Page 256 and 257:
Page 258 and 259:
Page 260 and 261:
Page 262 and 263:
Page 264 and 265:
Page 266 and 267:
Page 268 and 269:
Page 270 and 271:
Page 272 and 273:
Page 274 and 275:
Page 276 and 277:
Page 278 and 279:
Page 280 and 281:
Page 282 and 283:
Page 284 and 285:
Page 286 and 287:
Page 288 and 289:
Page 290 and 291:
Page 292 and 293:
Page 294 and 295:
OPTIMIZING CACHE USAGE• Take adva
Page 296 and 297:
OPTIMIZING CACHE USAGEHardware pref
Page 298 and 299:
OPTIMIZING CACHE USAGEThe non-tempo
Page 300 and 301:
OPTIMIZING CACHE USAGE9.5.1.3 Memor
Page 302 and 303:
OPTIMIZING CACHE USAGENOTEFailure t
Page 304 and 305:
OPTIMIZING CACHE USAGE9.5.5 CLFLUSH
Page 306 and 307:
OPTIMIZING CACHE USAGE• The hardw
Page 308 and 309:
OPTIMIZING CACHE USAGETimeExecution
Page 310 and 311:
OPTIMIZING CACHE USAGEschedule pref
Page 312 and 313:
OPTIMIZING CACHE USAGEtime is large
Page 314 and 315:
OPTIMIZING CACHE USAGEresource stal
Page 316 and 317:
OPTIMIZING CACHE USAGEPrefetchntaDa
Page 318 and 319:
OPTIMIZING CACHE USAGEExample 9-7.
Page 320 and 321:
OPTIMIZING CACHE USAGEA characteris
Page 322 and 323:
OPTIMIZING CACHE USAGE9.7 MEMORY OP
Page 324 and 325:
OPTIMIZING CACHE USAGE9.7.2.3 Concl
Page 326 and 327:
OPTIMIZING CACHE USAGEis not reside
Page 328 and 329:
OPTIMIZING CACHE USAGEExample 9-11.
Page 330 and 331:
OPTIMIZING CACHE USAGETable 9-3. De
Page 332 and 333:
OPTIMIZING CACHE USAGE• If a proc
Page 334 and 335:
64-BIT MODE CODING GUIDELINESAssemb
Page 336 and 337:
64-BIT MODE CODING GUIDELINESinstru
Page 338 and 339:
64-BIT MODE CODING GUIDELINES9-6
Page 340 and 341:
POWER OPTIMIZATION FOR MOBILE USAGE
Page 342 and 343:
Page 344 and 345:
Page 346 and 347:
Page 348 and 349:
Page 350 and 351:
Page 352 and 353:
Page 354 and 355:
APPLICATION PERFORMANCE TOOLSThe /f
Page 356 and 357:
APPLICATION PERFORMANCE TOOLSTable
Page 358 and 359:
APPLICATION PERFORMANCE TOOLSA.1.6.
Page 360 and 361:
APPLICATION PERFORMANCE TOOLSExampl
Page 362 and 363:
APPLICATION PERFORMANCE TOOLSExampl
Page 364 and 365:
APPLICATION PERFORMANCE TOOLSprogra
Page 366 and 367:
APPLICATION PERFORMANCE TOOLSThe Li
Page 368 and 369:
APPLICATION PERFORMANCE TOOLSA.5 IN
Page 370 and 371:
USING PERFORMANCE MONITORING EVENTS
Page 372 and 373:
Page 374 and 375:
Page 376 and 377:
Page 378 and 379:
Page 380 and 381:
Page 382 and 383:
Page 384 and 385:
Page 386 and 387:
Page 388 and 389:
Page 390 and 391:
Page 392 and 393:
Page 394 and 395:
Page 396 and 397:
Page 398 and 399:
Page 400 and 401:
Page 402 and 403:
Page 404 and 405:
Page 406 and 407:
Page 408 and 409:
Page 410 and 411:
Page 412 and 413:
Page 414 and 415:
Page 416 and 417:
Page 418 and 419:
Page 420 and 421:
Page 422 and 423:
Page 424 and 425:
Page 426 and 427:
Page 428 and 429:
Page 430 and 431:
Page 432 and 433:
INSTRUCTION LATENCY AND THROUGHPUTW
Page 434 and 435:
INSTRUCTION LATENCY AND THROUGHPUTo
Page 436 and 437:
INSTRUCTION LATENCY AND THROUGHPUTT
Page 438 and 439:
Page 440 and 441:
Page 442 and 443:
Page 444 and 445:
Page 446 and 447:
Page 448 and 449:
Page 450 and 451:
Page 452 and 453:
Page 454 and 455:
Page 456 and 457:
INSTRUCTION LATENCY AND THROUGHPUT
Page 458 and 459:
INSTRUCTION LATENCY AND THROUGHPUTC
Page 460 and 461:
STACK ALIGNMENTThe solution to this
Page 462 and 463:
STACK ALIGNMENTExample D-1. Aligned
Page 464 and 465:
STACK ALIGNMENTExample D-2. Aligned
Page 466 and 467:
STACK ALIGNMENTD-8
Page 468 and 469:
SUMMARY OF RULES AND SUGGESTIONSret
Page 470 and 471:
SUMMARY OF RULES AND SUGGESTIONSfou
Page 472 and 473:
SUMMARY OF RULES AND SUGGESTIONSvar
Page 474 and 475:
SUMMARY OF RULES AND SUGGESTIONSto
Page 476 and 477:
SUMMARY OF RULES AND SUGGESTIONSCor
Page 478 and 479:
SUMMARY OF RULES AND SUGGESTIONSE-1
Page 480 and 481:
INDEXsummary of rules, E-1tuning hi
Page 482 and 483:
INDEXevent ratios, B-50execution co
Page 484 and 485:
INDEXprefetching, 8-5SFENCE instruc
Page 486 and 487:
INDEXPMAXSW, 5-28PMAXUB, 5-28PMINSW
Page 488 and 489:
INDEXIndex-10
Page 490:
Intel Corp.999 CANADA PLACE,Suite 4
show all

IntelÂ® 64 and IA-32 Architectures Optimization Reference Manual

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?