1 //===- SimplifyLibCalls.cpp - Optimize specific well-known library calls --===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements a simple pass that applies a variety of small 11 // optimizations for calls to specific well-known function calls (e.g. runtime 12 // library functions). Any optimization that takes the very simple form 13 // "replace call to library function with simpler code that provides the same 14 // result" belongs in this file. 15 // 16 //===----------------------------------------------------------------------===// 17 18 #define DEBUG_TYPE "simplify-libcalls" 19 #include "llvm/Transforms/Scalar.h" 20 #include "llvm/ADT/STLExtras.h" 21 #include "llvm/ADT/SmallPtrSet.h" 22 #include "llvm/ADT/Statistic.h" 23 #include "llvm/ADT/StringMap.h" 24 #include "llvm/Analysis/ValueTracking.h" 25 #include "llvm/Config/config.h" // FIXME: Shouldn't depend on host! 26 #include "llvm/IR/DataLayout.h" 27 #include "llvm/IR/IRBuilder.h" 28 #include "llvm/IR/LLVMContext.h" 29 #include "llvm/IR/Module.h" 30 #include "llvm/Pass.h" 31 #include "llvm/Support/CommandLine.h" 32 #include "llvm/Support/Debug.h" 33 #include "llvm/Support/raw_ostream.h" 34 #include "llvm/Target/TargetLibraryInfo.h" 35 #include "llvm/Transforms/Utils/BuildLibCalls.h" 36 using namespace llvm; 37 38 STATISTIC(NumAnnotated, "Number of attributes added to library functions"); 39 40 //===----------------------------------------------------------------------===// 41 // Optimizer Base Class 42 //===----------------------------------------------------------------------===// 43 44 /// This class is the abstract base class for the set of optimizations that 45 /// corresponds to one library call. 46 namespace { 47 class LibCallOptimization { 48 protected: 49 Function *Caller; 50 const DataLayout *TD; 51 const TargetLibraryInfo *TLI; 52 LLVMContext* Context; 53 public: 54 LibCallOptimization() { } 55 virtual ~LibCallOptimization() {} 56 57 /// CallOptimizer - This pure virtual method is implemented by base classes to 58 /// do various optimizations. If this returns null then no transformation was 59 /// performed. If it returns CI, then it transformed the call and CI is to be 60 /// deleted. If it returns something else, replace CI with the new value and 61 /// delete CI. 62 virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) 63 =0; 64 65 Value *OptimizeCall(CallInst *CI, const DataLayout *TD, 66 const TargetLibraryInfo *TLI, IRBuilder<> &B) { 67 Caller = CI->getParent()->getParent(); 68 this->TD = TD; 69 this->TLI = TLI; 70 if (CI->getCalledFunction()) 71 Context = &CI->getCalledFunction()->getContext(); 72 73 // We never change the calling convention. 74 if (CI->getCallingConv() != llvm::CallingConv::C) 75 return NULL; 76 77 return CallOptimizer(CI->getCalledFunction(), CI, B); 78 } 79 }; 80 } // End anonymous namespace. 81 82 83 //===----------------------------------------------------------------------===// 84 // SimplifyLibCalls Pass Implementation 85 //===----------------------------------------------------------------------===// 86 87 namespace { 88 /// This pass optimizes well known library functions from libc and libm. 89 /// 90 class SimplifyLibCalls : public FunctionPass { 91 TargetLibraryInfo *TLI; 92 93 StringMap<LibCallOptimization*> Optimizations; 94 95 bool Modified; // This is only used by doInitialization. 96 public: 97 static char ID; // Pass identification 98 SimplifyLibCalls() : FunctionPass(ID) { 99 initializeSimplifyLibCallsPass(*PassRegistry::getPassRegistry()); 100 } 101 void AddOpt(LibFunc::Func F, LibCallOptimization* Opt); 102 void AddOpt(LibFunc::Func F1, LibFunc::Func F2, LibCallOptimization* Opt); 103 104 void InitOptimizations(); 105 bool runOnFunction(Function &F); 106 107 void setDoesNotAccessMemory(Function &F); 108 void setOnlyReadsMemory(Function &F); 109 void setDoesNotThrow(Function &F); 110 void setDoesNotCapture(Function &F, unsigned n); 111 void setDoesNotAlias(Function &F, unsigned n); 112 bool doInitialization(Module &M); 113 114 void inferPrototypeAttributes(Function &F); 115 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 116 AU.addRequired<TargetLibraryInfo>(); 117 } 118 }; 119 } // end anonymous namespace. 120 121 char SimplifyLibCalls::ID = 0; 122 123 INITIALIZE_PASS_BEGIN(SimplifyLibCalls, "simplify-libcalls", 124 "Simplify well-known library calls", false, false) 125 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo) 126 INITIALIZE_PASS_END(SimplifyLibCalls, "simplify-libcalls", 127 "Simplify well-known library calls", false, false) 128 129 // Public interface to the Simplify LibCalls pass. 130 FunctionPass *llvm::createSimplifyLibCallsPass() { 131 return new SimplifyLibCalls(); 132 } 133 134 void SimplifyLibCalls::AddOpt(LibFunc::Func F, LibCallOptimization* Opt) { 135 if (TLI->has(F)) 136 Optimizations[TLI->getName(F)] = Opt; 137 } 138 139 void SimplifyLibCalls::AddOpt(LibFunc::Func F1, LibFunc::Func F2, 140 LibCallOptimization* Opt) { 141 if (TLI->has(F1) && TLI->has(F2)) 142 Optimizations[TLI->getName(F1)] = Opt; 143 } 144 145 /// Optimizations - Populate the Optimizations map with all the optimizations 146 /// we know. 147 void SimplifyLibCalls::InitOptimizations() { 148 } 149 150 151 /// runOnFunction - Top level algorithm. 152 /// 153 bool SimplifyLibCalls::runOnFunction(Function &F) { 154 TLI = &getAnalysis<TargetLibraryInfo>(); 155 156 if (Optimizations.empty()) 157 InitOptimizations(); 158 159 const DataLayout *TD = getAnalysisIfAvailable<DataLayout>(); 160 161 IRBuilder<> Builder(F.getContext()); 162 163 bool Changed = false; 164 for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { 165 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) { 166 // Ignore non-calls. 167 CallInst *CI = dyn_cast<CallInst>(I++); 168 if (!CI || CI->hasFnAttr(Attribute::NoBuiltin)) continue; 169 170 // Ignore indirect calls and calls to non-external functions. 171 Function *Callee = CI->getCalledFunction(); 172 if (Callee == 0 || !Callee->isDeclaration() || 173 !(Callee->hasExternalLinkage() || Callee->hasDLLImportLinkage())) 174 continue; 175 176 // Ignore unknown calls. 177 LibCallOptimization *LCO = Optimizations.lookup(Callee->getName()); 178 if (!LCO) continue; 179 180 // Set the builder to the instruction after the call. 181 Builder.SetInsertPoint(BB, I); 182 183 // Use debug location of CI for all new instructions. 184 Builder.SetCurrentDebugLocation(CI->getDebugLoc()); 185 186 // Try to optimize this call. 187 Value *Result = LCO->OptimizeCall(CI, TD, TLI, Builder); 188 if (Result == 0) continue; 189 190 DEBUG(dbgs() << "SimplifyLibCalls simplified: " << *CI; 191 dbgs() << " into: " << *Result << "\n"); 192 193 // Something changed! 194 Changed = true; 195 196 // Inspect the instruction after the call (which was potentially just 197 // added) next. 198 I = CI; ++I; 199 200 if (CI != Result && !CI->use_empty()) { 201 CI->replaceAllUsesWith(Result); 202 if (!Result->hasName()) 203 Result->takeName(CI); 204 } 205 CI->eraseFromParent(); 206 } 207 } 208 return Changed; 209 } 210 211 // Utility methods for doInitialization. 212 213 void SimplifyLibCalls::setDoesNotAccessMemory(Function &F) { 214 if (!F.doesNotAccessMemory()) { 215 F.setDoesNotAccessMemory(); 216 ++NumAnnotated; 217 Modified = true; 218 } 219 } 220 void SimplifyLibCalls::setOnlyReadsMemory(Function &F) { 221 if (!F.onlyReadsMemory()) { 222 F.setOnlyReadsMemory(); 223 ++NumAnnotated; 224 Modified = true; 225 } 226 } 227 void SimplifyLibCalls::setDoesNotThrow(Function &F) { 228 if (!F.doesNotThrow()) { 229 F.setDoesNotThrow(); 230 ++NumAnnotated; 231 Modified = true; 232 } 233 } 234 void SimplifyLibCalls::setDoesNotCapture(Function &F, unsigned n) { 235 if (!F.doesNotCapture(n)) { 236 F.setDoesNotCapture(n); 237 ++NumAnnotated; 238 Modified = true; 239 } 240 } 241 void SimplifyLibCalls::setDoesNotAlias(Function &F, unsigned n) { 242 if (!F.doesNotAlias(n)) { 243 F.setDoesNotAlias(n); 244 ++NumAnnotated; 245 Modified = true; 246 } 247 } 248 249 250 void SimplifyLibCalls::inferPrototypeAttributes(Function &F) { 251 FunctionType *FTy = F.getFunctionType(); 252 253 StringRef Name = F.getName(); 254 switch (Name[0]) { 255 case 's': 256 if (Name == "strlen") { 257 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) 258 return; 259 setOnlyReadsMemory(F); 260 setDoesNotThrow(F); 261 setDoesNotCapture(F, 1); 262 } else if (Name == "strchr" || 263 Name == "strrchr") { 264 if (FTy->getNumParams() != 2 || 265 !FTy->getParamType(0)->isPointerTy() || 266 !FTy->getParamType(1)->isIntegerTy()) 267 return; 268 setOnlyReadsMemory(F); 269 setDoesNotThrow(F); 270 } else if (Name == "strcpy" || 271 Name == "stpcpy" || 272 Name == "strcat" || 273 Name == "strtol" || 274 Name == "strtod" || 275 Name == "strtof" || 276 Name == "strtoul" || 277 Name == "strtoll" || 278 Name == "strtold" || 279 Name == "strncat" || 280 Name == "strncpy" || 281 Name == "stpncpy" || 282 Name == "strtoull") { 283 if (FTy->getNumParams() < 2 || 284 !FTy->getParamType(1)->isPointerTy()) 285 return; 286 setDoesNotThrow(F); 287 setDoesNotCapture(F, 2); 288 } else if (Name == "strxfrm") { 289 if (FTy->getNumParams() != 3 || 290 !FTy->getParamType(0)->isPointerTy() || 291 !FTy->getParamType(1)->isPointerTy()) 292 return; 293 setDoesNotThrow(F); 294 setDoesNotCapture(F, 1); 295 setDoesNotCapture(F, 2); 296 } else if (Name == "strcmp" || 297 Name == "strspn" || 298 Name == "strncmp" || 299 Name == "strcspn" || 300 Name == "strcoll" || 301 Name == "strcasecmp" || 302 Name == "strncasecmp") { 303 if (FTy->getNumParams() < 2 || 304 !FTy->getParamType(0)->isPointerTy() || 305 !FTy->getParamType(1)->isPointerTy()) 306 return; 307 setOnlyReadsMemory(F); 308 setDoesNotThrow(F); 309 setDoesNotCapture(F, 1); 310 setDoesNotCapture(F, 2); 311 } else if (Name == "strstr" || 312 Name == "strpbrk") { 313 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) 314 return; 315 setOnlyReadsMemory(F); 316 setDoesNotThrow(F); 317 setDoesNotCapture(F, 2); 318 } else if (Name == "strtok" || 319 Name == "strtok_r") { 320 if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy()) 321 return; 322 setDoesNotThrow(F); 323 setDoesNotCapture(F, 2); 324 } else if (Name == "scanf" || 325 Name == "setbuf" || 326 Name == "setvbuf") { 327 if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy()) 328 return; 329 setDoesNotThrow(F); 330 setDoesNotCapture(F, 1); 331 } else if (Name == "strdup" || 332 Name == "strndup") { 333 if (FTy->getNumParams() < 1 || !FTy->getReturnType()->isPointerTy() || 334 !FTy->getParamType(0)->isPointerTy()) 335 return; 336 setDoesNotThrow(F); 337 setDoesNotAlias(F, 0); 338 setDoesNotCapture(F, 1); 339 } else if (Name == "stat" || 340 Name == "sscanf" || 341 Name == "sprintf" || 342 Name == "statvfs") { 343 if (FTy->getNumParams() < 2 || 344 !FTy->getParamType(0)->isPointerTy() || 345 !FTy->getParamType(1)->isPointerTy()) 346 return; 347 setDoesNotThrow(F); 348 setDoesNotCapture(F, 1); 349 setDoesNotCapture(F, 2); 350 } else if (Name == "snprintf") { 351 if (FTy->getNumParams() != 3 || 352 !FTy->getParamType(0)->isPointerTy() || 353 !FTy->getParamType(2)->isPointerTy()) 354 return; 355 setDoesNotThrow(F); 356 setDoesNotCapture(F, 1); 357 setDoesNotCapture(F, 3); 358 } else if (Name == "setitimer") { 359 if (FTy->getNumParams() != 3 || 360 !FTy->getParamType(1)->isPointerTy() || 361 !FTy->getParamType(2)->isPointerTy()) 362 return; 363 setDoesNotThrow(F); 364 setDoesNotCapture(F, 2); 365 setDoesNotCapture(F, 3); 366 } else if (Name == "system") { 367 if (FTy->getNumParams() != 1 || 368 !FTy->getParamType(0)->isPointerTy()) 369 return; 370 // May throw; "system" is a valid pthread cancellation point. 371 setDoesNotCapture(F, 1); 372 } 373 break; 374 case 'm': 375 if (Name == "malloc") { 376 if (FTy->getNumParams() != 1 || 377 !FTy->getReturnType()->isPointerTy()) 378 return; 379 setDoesNotThrow(F); 380 setDoesNotAlias(F, 0); 381 } else if (Name == "memcmp") { 382 if (FTy->getNumParams() != 3 || 383 !FTy->getParamType(0)->isPointerTy() || 384 !FTy->getParamType(1)->isPointerTy()) 385 return; 386 setOnlyReadsMemory(F); 387 setDoesNotThrow(F); 388 setDoesNotCapture(F, 1); 389 setDoesNotCapture(F, 2); 390 } else if (Name == "memchr" || 391 Name == "memrchr") { 392 if (FTy->getNumParams() != 3) 393 return; 394 setOnlyReadsMemory(F); 395 setDoesNotThrow(F); 396 } else if (Name == "modf" || 397 Name == "modff" || 398 Name == "modfl" || 399 Name == "memcpy" || 400 Name == "memccpy" || 401 Name == "memmove") { 402 if (FTy->getNumParams() < 2 || 403 !FTy->getParamType(1)->isPointerTy()) 404 return; 405 setDoesNotThrow(F); 406 setDoesNotCapture(F, 2); 407 } else if (Name == "memalign") { 408 if (!FTy->getReturnType()->isPointerTy()) 409 return; 410 setDoesNotAlias(F, 0); 411 } else if (Name == "mkdir" || 412 Name == "mktime") { 413 if (FTy->getNumParams() == 0 || 414 !FTy->getParamType(0)->isPointerTy()) 415 return; 416 setDoesNotThrow(F); 417 setDoesNotCapture(F, 1); 418 } 419 break; 420 case 'r': 421 if (Name == "realloc") { 422 if (FTy->getNumParams() != 2 || 423 !FTy->getParamType(0)->isPointerTy() || 424 !FTy->getReturnType()->isPointerTy()) 425 return; 426 setDoesNotThrow(F); 427 setDoesNotAlias(F, 0); 428 setDoesNotCapture(F, 1); 429 } else if (Name == "read") { 430 if (FTy->getNumParams() != 3 || 431 !FTy->getParamType(1)->isPointerTy()) 432 return; 433 // May throw; "read" is a valid pthread cancellation point. 434 setDoesNotCapture(F, 2); 435 } else if (Name == "rmdir" || 436 Name == "rewind" || 437 Name == "remove" || 438 Name == "realpath") { 439 if (FTy->getNumParams() < 1 || 440 !FTy->getParamType(0)->isPointerTy()) 441 return; 442 setDoesNotThrow(F); 443 setDoesNotCapture(F, 1); 444 } else if (Name == "rename" || 445 Name == "readlink") { 446 if (FTy->getNumParams() < 2 || 447 !FTy->getParamType(0)->isPointerTy() || 448 !FTy->getParamType(1)->isPointerTy()) 449 return; 450 setDoesNotThrow(F); 451 setDoesNotCapture(F, 1); 452 setDoesNotCapture(F, 2); 453 } 454 break; 455 case 'w': 456 if (Name == "write") { 457 if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy()) 458 return; 459 // May throw; "write" is a valid pthread cancellation point. 460 setDoesNotCapture(F, 2); 461 } 462 break; 463 case 'b': 464 if (Name == "bcopy") { 465 if (FTy->getNumParams() != 3 || 466 !FTy->getParamType(0)->isPointerTy() || 467 !FTy->getParamType(1)->isPointerTy()) 468 return; 469 setDoesNotThrow(F); 470 setDoesNotCapture(F, 1); 471 setDoesNotCapture(F, 2); 472 } else if (Name == "bcmp") { 473 if (FTy->getNumParams() != 3 || 474 !FTy->getParamType(0)->isPointerTy() || 475 !FTy->getParamType(1)->isPointerTy()) 476 return; 477 setDoesNotThrow(F); 478 setOnlyReadsMemory(F); 479 setDoesNotCapture(F, 1); 480 setDoesNotCapture(F, 2); 481 } else if (Name == "bzero") { 482 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy()) 483 return; 484 setDoesNotThrow(F); 485 setDoesNotCapture(F, 1); 486 } 487 break; 488 case 'c': 489 if (Name == "calloc") { 490 if (FTy->getNumParams() != 2 || 491 !FTy->getReturnType()->isPointerTy()) 492 return; 493 setDoesNotThrow(F); 494 setDoesNotAlias(F, 0); 495 } else if (Name == "chmod" || 496 Name == "chown" || 497 Name == "ctermid" || 498 Name == "clearerr" || 499 Name == "closedir") { 500 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy()) 501 return; 502 setDoesNotThrow(F); 503 setDoesNotCapture(F, 1); 504 } 505 break; 506 case 'a': 507 if (Name == "atoi" || 508 Name == "atol" || 509 Name == "atof" || 510 Name == "atoll") { 511 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) 512 return; 513 setDoesNotThrow(F); 514 setOnlyReadsMemory(F); 515 setDoesNotCapture(F, 1); 516 } else if (Name == "access") { 517 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy()) 518 return; 519 setDoesNotThrow(F); 520 setDoesNotCapture(F, 1); 521 } 522 break; 523 case 'f': 524 if (Name == "fopen") { 525 if (FTy->getNumParams() != 2 || 526 !FTy->getReturnType()->isPointerTy() || 527 !FTy->getParamType(0)->isPointerTy() || 528 !FTy->getParamType(1)->isPointerTy()) 529 return; 530 setDoesNotThrow(F); 531 setDoesNotAlias(F, 0); 532 setDoesNotCapture(F, 1); 533 setDoesNotCapture(F, 2); 534 } else if (Name == "fdopen") { 535 if (FTy->getNumParams() != 2 || 536 !FTy->getReturnType()->isPointerTy() || 537 !FTy->getParamType(1)->isPointerTy()) 538 return; 539 setDoesNotThrow(F); 540 setDoesNotAlias(F, 0); 541 setDoesNotCapture(F, 2); 542 } else if (Name == "feof" || 543 Name == "free" || 544 Name == "fseek" || 545 Name == "ftell" || 546 Name == "fgetc" || 547 Name == "fseeko" || 548 Name == "ftello" || 549 Name == "fileno" || 550 Name == "fflush" || 551 Name == "fclose" || 552 Name == "fsetpos" || 553 Name == "flockfile" || 554 Name == "funlockfile" || 555 Name == "ftrylockfile") { 556 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy()) 557 return; 558 setDoesNotThrow(F); 559 setDoesNotCapture(F, 1); 560 } else if (Name == "ferror") { 561 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) 562 return; 563 setDoesNotThrow(F); 564 setDoesNotCapture(F, 1); 565 setOnlyReadsMemory(F); 566 } else if (Name == "fputc" || 567 Name == "fstat" || 568 Name == "frexp" || 569 Name == "frexpf" || 570 Name == "frexpl" || 571 Name == "fstatvfs") { 572 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) 573 return; 574 setDoesNotThrow(F); 575 setDoesNotCapture(F, 2); 576 } else if (Name == "fgets") { 577 if (FTy->getNumParams() != 3 || 578 !FTy->getParamType(0)->isPointerTy() || 579 !FTy->getParamType(2)->isPointerTy()) 580 return; 581 setDoesNotThrow(F); 582 setDoesNotCapture(F, 3); 583 } else if (Name == "fread" || 584 Name == "fwrite") { 585 if (FTy->getNumParams() != 4 || 586 !FTy->getParamType(0)->isPointerTy() || 587 !FTy->getParamType(3)->isPointerTy()) 588 return; 589 setDoesNotThrow(F); 590 setDoesNotCapture(F, 1); 591 setDoesNotCapture(F, 4); 592 } else if (Name == "fputs" || 593 Name == "fscanf" || 594 Name == "fprintf" || 595 Name == "fgetpos") { 596 if (FTy->getNumParams() < 2 || 597 !FTy->getParamType(0)->isPointerTy() || 598 !FTy->getParamType(1)->isPointerTy()) 599 return; 600 setDoesNotThrow(F); 601 setDoesNotCapture(F, 1); 602 setDoesNotCapture(F, 2); 603 } 604 break; 605 case 'g': 606 if (Name == "getc" || 607 Name == "getlogin_r" || 608 Name == "getc_unlocked") { 609 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy()) 610 return; 611 setDoesNotThrow(F); 612 setDoesNotCapture(F, 1); 613 } else if (Name == "getenv") { 614 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) 615 return; 616 setDoesNotThrow(F); 617 setOnlyReadsMemory(F); 618 setDoesNotCapture(F, 1); 619 } else if (Name == "gets" || 620 Name == "getchar") { 621 setDoesNotThrow(F); 622 } else if (Name == "getitimer") { 623 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) 624 return; 625 setDoesNotThrow(F); 626 setDoesNotCapture(F, 2); 627 } else if (Name == "getpwnam") { 628 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) 629 return; 630 setDoesNotThrow(F); 631 setDoesNotCapture(F, 1); 632 } 633 break; 634 case 'u': 635 if (Name == "ungetc") { 636 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) 637 return; 638 setDoesNotThrow(F); 639 setDoesNotCapture(F, 2); 640 } else if (Name == "uname" || 641 Name == "unlink" || 642 Name == "unsetenv") { 643 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) 644 return; 645 setDoesNotThrow(F); 646 setDoesNotCapture(F, 1); 647 } else if (Name == "utime" || 648 Name == "utimes") { 649 if (FTy->getNumParams() != 2 || 650 !FTy->getParamType(0)->isPointerTy() || 651 !FTy->getParamType(1)->isPointerTy()) 652 return; 653 setDoesNotThrow(F); 654 setDoesNotCapture(F, 1); 655 setDoesNotCapture(F, 2); 656 } 657 break; 658 case 'p': 659 if (Name == "putc") { 660 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) 661 return; 662 setDoesNotThrow(F); 663 setDoesNotCapture(F, 2); 664 } else if (Name == "puts" || 665 Name == "printf" || 666 Name == "perror") { 667 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) 668 return; 669 setDoesNotThrow(F); 670 setDoesNotCapture(F, 1); 671 } else if (Name == "pread" || 672 Name == "pwrite") { 673 if (FTy->getNumParams() != 4 || !FTy->getParamType(1)->isPointerTy()) 674 return; 675 // May throw; these are valid pthread cancellation points. 676 setDoesNotCapture(F, 2); 677 } else if (Name == "putchar") { 678 setDoesNotThrow(F); 679 } else if (Name == "popen") { 680 if (FTy->getNumParams() != 2 || 681 !FTy->getReturnType()->isPointerTy() || 682 !FTy->getParamType(0)->isPointerTy() || 683 !FTy->getParamType(1)->isPointerTy()) 684 return; 685 setDoesNotThrow(F); 686 setDoesNotAlias(F, 0); 687 setDoesNotCapture(F, 1); 688 setDoesNotCapture(F, 2); 689 } else if (Name == "pclose") { 690 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) 691 return; 692 setDoesNotThrow(F); 693 setDoesNotCapture(F, 1); 694 } 695 break; 696 case 'v': 697 if (Name == "vscanf") { 698 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) 699 return; 700 setDoesNotThrow(F); 701 setDoesNotCapture(F, 1); 702 } else if (Name == "vsscanf" || 703 Name == "vfscanf") { 704 if (FTy->getNumParams() != 3 || 705 !FTy->getParamType(1)->isPointerTy() || 706 !FTy->getParamType(2)->isPointerTy()) 707 return; 708 setDoesNotThrow(F); 709 setDoesNotCapture(F, 1); 710 setDoesNotCapture(F, 2); 711 } else if (Name == "valloc") { 712 if (!FTy->getReturnType()->isPointerTy()) 713 return; 714 setDoesNotThrow(F); 715 setDoesNotAlias(F, 0); 716 } else if (Name == "vprintf") { 717 if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy()) 718 return; 719 setDoesNotThrow(F); 720 setDoesNotCapture(F, 1); 721 } else if (Name == "vfprintf" || 722 Name == "vsprintf") { 723 if (FTy->getNumParams() != 3 || 724 !FTy->getParamType(0)->isPointerTy() || 725 !FTy->getParamType(1)->isPointerTy()) 726 return; 727 setDoesNotThrow(F); 728 setDoesNotCapture(F, 1); 729 setDoesNotCapture(F, 2); 730 } else if (Name == "vsnprintf") { 731 if (FTy->getNumParams() != 4 || 732 !FTy->getParamType(0)->isPointerTy() || 733 !FTy->getParamType(2)->isPointerTy()) 734 return; 735 setDoesNotThrow(F); 736 setDoesNotCapture(F, 1); 737 setDoesNotCapture(F, 3); 738 } 739 break; 740 case 'o': 741 if (Name == "open") { 742 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy()) 743 return; 744 // May throw; "open" is a valid pthread cancellation point. 745 setDoesNotCapture(F, 1); 746 } else if (Name == "opendir") { 747 if (FTy->getNumParams() != 1 || 748 !FTy->getReturnType()->isPointerTy() || 749 !FTy->getParamType(0)->isPointerTy()) 750 return; 751 setDoesNotThrow(F); 752 setDoesNotAlias(F, 0); 753 setDoesNotCapture(F, 1); 754 } 755 break; 756 case 't': 757 if (Name == "tmpfile") { 758 if (!FTy->getReturnType()->isPointerTy()) 759 return; 760 setDoesNotThrow(F); 761 setDoesNotAlias(F, 0); 762 } else if (Name == "times") { 763 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) 764 return; 765 setDoesNotThrow(F); 766 setDoesNotCapture(F, 1); 767 } 768 break; 769 case 'h': 770 if (Name == "htonl" || 771 Name == "htons") { 772 setDoesNotThrow(F); 773 setDoesNotAccessMemory(F); 774 } 775 break; 776 case 'n': 777 if (Name == "ntohl" || 778 Name == "ntohs") { 779 setDoesNotThrow(F); 780 setDoesNotAccessMemory(F); 781 } 782 break; 783 case 'l': 784 if (Name == "lstat") { 785 if (FTy->getNumParams() != 2 || 786 !FTy->getParamType(0)->isPointerTy() || 787 !FTy->getParamType(1)->isPointerTy()) 788 return; 789 setDoesNotThrow(F); 790 setDoesNotCapture(F, 1); 791 setDoesNotCapture(F, 2); 792 } else if (Name == "lchown") { 793 if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy()) 794 return; 795 setDoesNotThrow(F); 796 setDoesNotCapture(F, 1); 797 } 798 break; 799 case 'q': 800 if (Name == "qsort") { 801 if (FTy->getNumParams() != 4 || !FTy->getParamType(3)->isPointerTy()) 802 return; 803 // May throw; places call through function pointer. 804 setDoesNotCapture(F, 4); 805 } 806 break; 807 case '_': 808 if (Name == "__strdup" || 809 Name == "__strndup") { 810 if (FTy->getNumParams() < 1 || 811 !FTy->getReturnType()->isPointerTy() || 812 !FTy->getParamType(0)->isPointerTy()) 813 return; 814 setDoesNotThrow(F); 815 setDoesNotAlias(F, 0); 816 setDoesNotCapture(F, 1); 817 } else if (Name == "__strtok_r") { 818 if (FTy->getNumParams() != 3 || 819 !FTy->getParamType(1)->isPointerTy()) 820 return; 821 setDoesNotThrow(F); 822 setDoesNotCapture(F, 2); 823 } else if (Name == "_IO_getc") { 824 if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy()) 825 return; 826 setDoesNotThrow(F); 827 setDoesNotCapture(F, 1); 828 } else if (Name == "_IO_putc") { 829 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) 830 return; 831 setDoesNotThrow(F); 832 setDoesNotCapture(F, 2); 833 } 834 break; 835 case 1: 836 if (Name == "\1__isoc99_scanf") { 837 if (FTy->getNumParams() < 1 || 838 !FTy->getParamType(0)->isPointerTy()) 839 return; 840 setDoesNotThrow(F); 841 setDoesNotCapture(F, 1); 842 } else if (Name == "\1stat64" || 843 Name == "\1lstat64" || 844 Name == "\1statvfs64" || 845 Name == "\1__isoc99_sscanf") { 846 if (FTy->getNumParams() < 1 || 847 !FTy->getParamType(0)->isPointerTy() || 848 !FTy->getParamType(1)->isPointerTy()) 849 return; 850 setDoesNotThrow(F); 851 setDoesNotCapture(F, 1); 852 setDoesNotCapture(F, 2); 853 } else if (Name == "\1fopen64") { 854 if (FTy->getNumParams() != 2 || 855 !FTy->getReturnType()->isPointerTy() || 856 !FTy->getParamType(0)->isPointerTy() || 857 !FTy->getParamType(1)->isPointerTy()) 858 return; 859 setDoesNotThrow(F); 860 setDoesNotAlias(F, 0); 861 setDoesNotCapture(F, 1); 862 setDoesNotCapture(F, 2); 863 } else if (Name == "\1fseeko64" || 864 Name == "\1ftello64") { 865 if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy()) 866 return; 867 setDoesNotThrow(F); 868 setDoesNotCapture(F, 1); 869 } else if (Name == "\1tmpfile64") { 870 if (!FTy->getReturnType()->isPointerTy()) 871 return; 872 setDoesNotThrow(F); 873 setDoesNotAlias(F, 0); 874 } else if (Name == "\1fstat64" || 875 Name == "\1fstatvfs64") { 876 if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy()) 877 return; 878 setDoesNotThrow(F); 879 setDoesNotCapture(F, 2); 880 } else if (Name == "\1open64") { 881 if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy()) 882 return; 883 // May throw; "open" is a valid pthread cancellation point. 884 setDoesNotCapture(F, 1); 885 } 886 break; 887 } 888 } 889 890 /// doInitialization - Add attributes to well-known functions. 891 /// 892 bool SimplifyLibCalls::doInitialization(Module &M) { 893 Modified = false; 894 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) { 895 Function &F = *I; 896 if (F.isDeclaration() && F.hasName()) 897 inferPrototypeAttributes(F); 898 } 899 return Modified; 900 } 901 902 // TODO: 903 // Additional cases that we need to add to this file: 904 // 905 // cbrt: 906 // * cbrt(expN(X)) -> expN(x/3) 907 // * cbrt(sqrt(x)) -> pow(x,1/6) 908 // * cbrt(sqrt(x)) -> pow(x,1/9) 909 // 910 // exp, expf, expl: 911 // * exp(log(x)) -> x 912 // 913 // log, logf, logl: 914 // * log(exp(x)) -> x 915 // * log(x**y) -> y*log(x) 916 // * log(exp(y)) -> y*log(e) 917 // * log(exp2(y)) -> y*log(2) 918 // * log(exp10(y)) -> y*log(10) 919 // * log(sqrt(x)) -> 0.5*log(x) 920 // * log(pow(x,y)) -> y*log(x) 921 // 922 // lround, lroundf, lroundl: 923 // * lround(cnst) -> cnst' 924 // 925 // pow, powf, powl: 926 // * pow(exp(x),y) -> exp(x*y) 927 // * pow(sqrt(x),y) -> pow(x,y*0.5) 928 // * pow(pow(x,y),z)-> pow(x,y*z) 929 // 930 // round, roundf, roundl: 931 // * round(cnst) -> cnst' 932 // 933 // signbit: 934 // * signbit(cnst) -> cnst' 935 // * signbit(nncst) -> 0 (if pstv is a non-negative constant) 936 // 937 // sqrt, sqrtf, sqrtl: 938 // * sqrt(expN(x)) -> expN(x*0.5) 939 // * sqrt(Nroot(x)) -> pow(x,1/(2*N)) 940 // * sqrt(pow(x,y)) -> pow(|x|,y*0.5) 941 // 942 // strchr: 943 // * strchr(p, 0) -> strlen(p) 944 // tan, tanf, tanl: 945 // * tan(atan(x)) -> x 946 // 947 // trunc, truncf, truncl: 948 // * trunc(cnst) -> cnst' 949 // 950 // 951
