lib/Transforms/Scalar/SimplifyLibCalls.cpp

   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/Transforms/Utils/BuildLibCalls.h"
  21 #include "llvm/Intrinsics.h"
  22 #include "llvm/LLVMContext.h"
  23 #include "llvm/Module.h"
  24 #include "llvm/Pass.h"
  25 #include "llvm/Support/IRBuilder.h"
  26 #include "llvm/Analysis/ValueTracking.h"
  27 #include "llvm/Target/TargetData.h"
  28 #include "llvm/Target/TargetLibraryInfo.h"
  29 #include "llvm/ADT/SmallPtrSet.h"
  30 #include "llvm/ADT/StringMap.h"
  31 #include "llvm/ADT/Statistic.h"
  32 #include "llvm/ADT/STLExtras.h"
  33 #include "llvm/Support/Debug.h"
  34 #include "llvm/Support/raw_ostream.h"
  35 #include "llvm/Config/config.h"            // FIXME: Shouldn't depend on host!
  36 using namespace llvm;
  37
  38 STATISTIC(NumSimplified, "Number of library calls simplified");
  39 STATISTIC(NumAnnotated, "Number of attributes added to library functions");
  40
  41 //===----------------------------------------------------------------------===//
  42 // Optimizer Base Class
  43 //===----------------------------------------------------------------------===//
  44
  45 /// This class is the abstract base class for the set of optimizations that
  46 /// corresponds to one library call.
  47 namespace {
  48 class LibCallOptimization {
  49 protected:
  50   Function *Caller;
  51   const TargetData *TD;
  52   const TargetLibraryInfo *TLI;
  53   LLVMContext* Context;
  54 public:
  55   LibCallOptimization() { }
  56   virtual ~LibCallOptimization() {}
  57
  58   /// CallOptimizer - This pure virtual method is implemented by base classes to
  59   /// do various optimizations.  If this returns null then no transformation was
  60   /// performed.  If it returns CI, then it transformed the call and CI is to be
  61   /// deleted.  If it returns something else, replace CI with the new value and
  62   /// delete CI.
  63   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B)
  64     =0;
  65
  66   Value *OptimizeCall(CallInst *CI, const TargetData *TD,
  67                       const TargetLibraryInfo *TLI, IRBuilder<> &B) {
  68     Caller = CI->getParent()->getParent();
  69     this->TD = TD;
  70     this->TLI = TLI;
  71     if (CI->getCalledFunction())
  72       Context = &CI->getCalledFunction()->getContext();
  73
  74     // We never change the calling convention.
  75     if (CI->getCallingConv() != llvm::CallingConv::C)
  76       return NULL;
  77
  78     return CallOptimizer(CI->getCalledFunction(), CI, B);
  79   }
  80 };
  81 } // End anonymous namespace.
  82
  83
  84 //===----------------------------------------------------------------------===//
  85 // Helper Functions
  86 //===----------------------------------------------------------------------===//
  87
  88 /// IsOnlyUsedInZeroEqualityComparison - Return true if it only matters that the
  89 /// value is equal or not-equal to zero.
  90 static bool IsOnlyUsedInZeroEqualityComparison(Value *V) {
  91   for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
  92        UI != E; ++UI) {
  93     if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
  94       if (IC->isEquality())
  95         if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
  96           if (C->isNullValue())
  97             continue;
  98     // Unknown instruction.
  99     return false;
 100   }
 101   return true;
 102 }
 103
 104 static bool CallHasFloatingPointArgument(const CallInst *CI) {
 105   for (CallInst::const_op_iterator it = CI->op_begin(), e = CI->op_end();
 106        it != e; ++it) {
 107     if ((*it)->getType()->isFloatingPointTy())
 108       return true;
 109   }
 110   return false;
 111 }
 112
 113 /// IsOnlyUsedInEqualityComparison - Return true if it is only used in equality
 114 /// comparisons with With.
 115 static bool IsOnlyUsedInEqualityComparison(Value *V, Value *With) {
 116   for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
 117        UI != E; ++UI) {
 118     if (ICmpInst *IC = dyn_cast<ICmpInst>(*UI))
 119       if (IC->isEquality() && IC->getOperand(1) == With)
 120         continue;
 121     // Unknown instruction.
 122     return false;
 123   }
 124   return true;
 125 }
 126
 127 //===----------------------------------------------------------------------===//
 128 // String and Memory LibCall Optimizations
 129 //===----------------------------------------------------------------------===//
 130
 131 //===---------------------------------------===//
 132 // 'strcat' Optimizations
 133 namespace {
 134 struct StrCatOpt : public LibCallOptimization {
 135   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 136     // Verify the "strcat" function prototype.
 137     const FunctionType *FT = Callee->getFunctionType();
 138     if (FT->getNumParams() != 2 ||
 139         FT->getReturnType() != B.getInt8PtrTy() ||
 140         FT->getParamType(0) != FT->getReturnType() ||
 141         FT->getParamType(1) != FT->getReturnType())
 142       return 0;
 143
 144     // Extract some information from the instruction
 145     Value *Dst = CI->getArgOperand(0);
 146     Value *Src = CI->getArgOperand(1);
 147
 148     // See if we can get the length of the input string.
 149     uint64_t Len = GetStringLength(Src);
 150     if (Len == 0) return 0;
 151     --Len;  // Unbias length.
 152
 153     // Handle the simple, do-nothing case: strcat(x, "") -> x
 154     if (Len == 0)
 155       return Dst;
 156
 157     // These optimizations require TargetData.
 158     if (!TD) return 0;
 159
 160     EmitStrLenMemCpy(Src, Dst, Len, B);
 161     return Dst;
 162   }
 163
 164   void EmitStrLenMemCpy(Value *Src, Value *Dst, uint64_t Len, IRBuilder<> &B) {
 165     // We need to find the end of the destination string.  That's where the
 166     // memory is to be moved to. We just generate a call to strlen.
 167     Value *DstLen = EmitStrLen(Dst, B, TD);
 168
 169     // Now that we have the destination's length, we must index into the
 170     // destination's pointer to get the actual memcpy destination (end of
 171     // the string .. we're concatenating).
 172     Value *CpyDst = B.CreateGEP(Dst, DstLen, "endptr");
 173
 174     // We have enough information to now generate the memcpy call to do the
 175     // concatenation for us.  Make a memcpy to copy the nul byte with align = 1.
 176     B.CreateMemCpy(CpyDst, Src,
 177                    ConstantInt::get(TD->getIntPtrType(*Context), Len + 1), 1);
 178   }
 179 };
 180
 181 //===---------------------------------------===//
 182 // 'strncat' Optimizations
 183
 184 struct StrNCatOpt : public StrCatOpt {
 185   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 186     // Verify the "strncat" function prototype.
 187     const FunctionType *FT = Callee->getFunctionType();
 188     if (FT->getNumParams() != 3 ||
 189         FT->getReturnType() != B.getInt8PtrTy() ||
 190         FT->getParamType(0) != FT->getReturnType() ||
 191         FT->getParamType(1) != FT->getReturnType() ||
 192         !FT->getParamType(2)->isIntegerTy())
 193       return 0;
 194
 195     // Extract some information from the instruction
 196     Value *Dst = CI->getArgOperand(0);
 197     Value *Src = CI->getArgOperand(1);
 198     uint64_t Len;
 199
 200     // We don't do anything if length is not constant
 201     if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getArgOperand(2)))
 202       Len = LengthArg->getZExtValue();
 203     else
 204       return 0;
 205
 206     // See if we can get the length of the input string.
 207     uint64_t SrcLen = GetStringLength(Src);
 208     if (SrcLen == 0) return 0;
 209     --SrcLen;  // Unbias length.
 210
 211     // Handle the simple, do-nothing cases:
 212     // strncat(x, "", c) -> x
 213     // strncat(x,  c, 0) -> x
 214     if (SrcLen == 0 || Len == 0) return Dst;
 215
 216     // These optimizations require TargetData.
 217     if (!TD) return 0;
 218
 219     // We don't optimize this case
 220     if (Len < SrcLen) return 0;
 221
 222     // strncat(x, s, c) -> strcat(x, s)
 223     // s is constant so the strcat can be optimized further
 224     EmitStrLenMemCpy(Src, Dst, SrcLen, B);
 225     return Dst;
 226   }
 227 };
 228
 229 //===---------------------------------------===//
 230 // 'strchr' Optimizations
 231
 232 struct StrChrOpt : public LibCallOptimization {
 233   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 234     // Verify the "strchr" function prototype.
 235     const FunctionType *FT = Callee->getFunctionType();
 236     if (FT->getNumParams() != 2 ||
 237         FT->getReturnType() != B.getInt8PtrTy() ||
 238         FT->getParamType(0) != FT->getReturnType() ||
 239         !FT->getParamType(1)->isIntegerTy(32))
 240       return 0;
 241
 242     Value *SrcStr = CI->getArgOperand(0);
 243
 244     // If the second operand is non-constant, see if we can compute the length
 245     // of the input string and turn this into memchr.
 246     ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getArgOperand(1));
 247     if (CharC == 0) {
 248       // These optimizations require TargetData.
 249       if (!TD) return 0;
 250
 251       uint64_t Len = GetStringLength(SrcStr);
 252       if (Len == 0 || !FT->getParamType(1)->isIntegerTy(32))// memchr needs i32.
 253         return 0;
 254
 255       return EmitMemChr(SrcStr, CI->getArgOperand(1), // include nul.
 256                         ConstantInt::get(TD->getIntPtrType(*Context), Len),
 257                         B, TD);
 258     }
 259
 260     // Otherwise, the character is a constant, see if the first argument is
 261     // a string literal.  If so, we can constant fold.
 262     std::string Str;
 263     if (!GetConstantStringInfo(SrcStr, Str))
 264       return 0;
 265
 266     // strchr can find the nul character.
 267     Str += '\0';
 268
 269     // Compute the offset.
 270     size_t I = Str.find(CharC->getSExtValue());
 271     if (I == std::string::npos) // Didn't find the char.  strchr returns null.
 272       return Constant::getNullValue(CI->getType());
 273
 274     // strchr(s+n,c)  -> gep(s+n+i,c)
 275     return B.CreateGEP(SrcStr, B.getInt64(I), "strchr");
 276   }
 277 };
 278
 279 //===---------------------------------------===//
 280 // 'strrchr' Optimizations
 281
 282 struct StrRChrOpt : public LibCallOptimization {
 283   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 284     // Verify the "strrchr" function prototype.
 285     const FunctionType *FT = Callee->getFunctionType();
 286     if (FT->getNumParams() != 2 ||
 287         FT->getReturnType() != B.getInt8PtrTy() ||
 288         FT->getParamType(0) != FT->getReturnType() ||
 289         !FT->getParamType(1)->isIntegerTy(32))
 290       return 0;
 291
 292     Value *SrcStr = CI->getArgOperand(0);
 293     ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getArgOperand(1));
 294
 295     // Cannot fold anything if we're not looking for a constant.
 296     if (!CharC)
 297       return 0;
 298
 299     std::string Str;
 300     if (!GetConstantStringInfo(SrcStr, Str)) {
 301       // strrchr(s, 0) -> strchr(s, 0)
 302       if (TD && CharC->isZero())
 303         return EmitStrChr(SrcStr, '\0', B, TD);
 304       return 0;
 305     }
 306
 307     // strrchr can find the nul character.
 308     Str += '\0';
 309
 310     // Compute the offset.
 311     size_t I = Str.rfind(CharC->getSExtValue());
 312     if (I == std::string::npos) // Didn't find the char. Return null.
 313       return Constant::getNullValue(CI->getType());
 314
 315     // strrchr(s+n,c) -> gep(s+n+i,c)
 316     return B.CreateGEP(SrcStr, B.getInt64(I), "strrchr");
 317   }
 318 };
 319
 320 //===---------------------------------------===//
 321 // 'strcmp' Optimizations
 322
 323 struct StrCmpOpt : public LibCallOptimization {
 324   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 325     // Verify the "strcmp" function prototype.
 326     const FunctionType *FT = Callee->getFunctionType();
 327     if (FT->getNumParams() != 2 ||
 328         !FT->getReturnType()->isIntegerTy(32) ||
 329         FT->getParamType(0) != FT->getParamType(1) ||
 330         FT->getParamType(0) != B.getInt8PtrTy())
 331       return 0;
 332
 333     Value *Str1P = CI->getArgOperand(0), *Str2P = CI->getArgOperand(1);
 334     if (Str1P == Str2P)      // strcmp(x,x)  -> 0
 335       return ConstantInt::get(CI->getType(), 0);
 336
 337     std::string Str1, Str2;
 338     bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
 339     bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
 340
 341     if (HasStr1 && Str1.empty()) // strcmp("", x) -> *x
 342       return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
 343
 344     if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x
 345       return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
 346
 347     // strcmp(x, y)  -> cnst  (if both x and y are constant strings)
 348     if (HasStr1 && HasStr2)
 349       return ConstantInt::get(CI->getType(),
 350                                      strcmp(Str1.c_str(),Str2.c_str()));
 351
 352     // strcmp(P, "x") -> memcmp(P, "x", 2)
 353     uint64_t Len1 = GetStringLength(Str1P);
 354     uint64_t Len2 = GetStringLength(Str2P);
 355     if (Len1 && Len2) {
 356       // These optimizations require TargetData.
 357       if (!TD) return 0;
 358
 359       return EmitMemCmp(Str1P, Str2P,
 360                         ConstantInt::get(TD->getIntPtrType(*Context),
 361                         std::min(Len1, Len2)), B, TD);
 362     }
 363
 364     return 0;
 365   }
 366 };
 367
 368 //===---------------------------------------===//
 369 // 'strncmp' Optimizations
 370
 371 struct StrNCmpOpt : public LibCallOptimization {
 372   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 373     // Verify the "strncmp" function prototype.
 374     const FunctionType *FT = Callee->getFunctionType();
 375     if (FT->getNumParams() != 3 ||
 376         !FT->getReturnType()->isIntegerTy(32) ||
 377         FT->getParamType(0) != FT->getParamType(1) ||
 378         FT->getParamType(0) != B.getInt8PtrTy() ||
 379         !FT->getParamType(2)->isIntegerTy())
 380       return 0;
 381
 382     Value *Str1P = CI->getArgOperand(0), *Str2P = CI->getArgOperand(1);
 383     if (Str1P == Str2P)      // strncmp(x,x,n)  -> 0
 384       return ConstantInt::get(CI->getType(), 0);
 385
 386     // Get the length argument if it is constant.
 387     uint64_t Length;
 388     if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getArgOperand(2)))
 389       Length = LengthArg->getZExtValue();
 390     else
 391       return 0;
 392
 393     if (Length == 0) // strncmp(x,y,0)   -> 0
 394       return ConstantInt::get(CI->getType(), 0);
 395
 396     if (TD && Length == 1) // strncmp(x,y,1) -> memcmp(x,y,1)
 397       return EmitMemCmp(Str1P, Str2P, CI->getArgOperand(2), B, TD);
 398
 399     std::string Str1, Str2;
 400     bool HasStr1 = GetConstantStringInfo(Str1P, Str1);
 401     bool HasStr2 = GetConstantStringInfo(Str2P, Str2);
 402
 403     if (HasStr1 && Str1.empty())  // strncmp("", x, n) -> *x
 404       return B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType());
 405
 406     if (HasStr2 && Str2.empty())  // strncmp(x, "", n) -> *x
 407       return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType());
 408
 409     // strncmp(x, y)  -> cnst  (if both x and y are constant strings)
 410     if (HasStr1 && HasStr2)
 411       return ConstantInt::get(CI->getType(),
 412                               strncmp(Str1.c_str(), Str2.c_str(), Length));
 413     return 0;
 414   }
 415 };
 416
 417
 418 //===---------------------------------------===//
 419 // 'strcpy' Optimizations
 420
 421 struct StrCpyOpt : public LibCallOptimization {
 422   bool OptChkCall;  // True if it's optimizing a __strcpy_chk libcall.
 423
 424   StrCpyOpt(bool c) : OptChkCall(c) {}
 425
 426   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 427     // Verify the "strcpy" function prototype.
 428     unsigned NumParams = OptChkCall ? 3 : 2;
 429     const FunctionType *FT = Callee->getFunctionType();
 430     if (FT->getNumParams() != NumParams ||
 431         FT->getReturnType() != FT->getParamType(0) ||
 432         FT->getParamType(0) != FT->getParamType(1) ||
 433         FT->getParamType(0) != B.getInt8PtrTy())
 434       return 0;
 435
 436     Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1);
 437     if (Dst == Src)      // strcpy(x,x)  -> x
 438       return Src;
 439
 440     // These optimizations require TargetData.
 441     if (!TD) return 0;
 442
 443     // See if we can get the length of the input string.
 444     uint64_t Len = GetStringLength(Src);
 445     if (Len == 0) return 0;
 446
 447     // We have enough information to now generate the memcpy call to do the
 448     // concatenation for us.  Make a memcpy to copy the nul byte with align = 1.
 449     if (OptChkCall)
 450       EmitMemCpyChk(Dst, Src,
 451                     ConstantInt::get(TD->getIntPtrType(*Context), Len),
 452                     CI->getArgOperand(2), B, TD);
 453     else
 454       B.CreateMemCpy(Dst, Src,
 455                      ConstantInt::get(TD->getIntPtrType(*Context), Len), 1);
 456     return Dst;
 457   }
 458 };
 459
 460 //===---------------------------------------===//
 461 // 'strncpy' Optimizations
 462
 463 struct StrNCpyOpt : public LibCallOptimization {
 464   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 465     const FunctionType *FT = Callee->getFunctionType();
 466     if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
 467         FT->getParamType(0) != FT->getParamType(1) ||
 468         FT->getParamType(0) != B.getInt8PtrTy() ||
 469         !FT->getParamType(2)->isIntegerTy())
 470       return 0;
 471
 472     Value *Dst = CI->getArgOperand(0);
 473     Value *Src = CI->getArgOperand(1);
 474     Value *LenOp = CI->getArgOperand(2);
 475
 476     // See if we can get the length of the input string.
 477     uint64_t SrcLen = GetStringLength(Src);
 478     if (SrcLen == 0) return 0;
 479     --SrcLen;
 480
 481     if (SrcLen == 0) {
 482       // strncpy(x, "", y) -> memset(x, '\0', y, 1)
 483       B.CreateMemSet(Dst, B.getInt8('\0'), LenOp, 1);
 484       return Dst;
 485     }
 486
 487     uint64_t Len;
 488     if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(LenOp))
 489       Len = LengthArg->getZExtValue();
 490     else
 491       return 0;
 492
 493     if (Len == 0) return Dst; // strncpy(x, y, 0) -> x
 494
 495     // These optimizations require TargetData.
 496     if (!TD) return 0;
 497
 498     // Let strncpy handle the zero padding
 499     if (Len > SrcLen+1) return 0;
 500
 501     // strncpy(x, s, c) -> memcpy(x, s, c, 1) [s and c are constant]
 502     B.CreateMemCpy(Dst, Src,
 503                    ConstantInt::get(TD->getIntPtrType(*Context), Len), 1);
 504
 505     return Dst;
 506   }
 507 };
 508
 509 //===---------------------------------------===//
 510 // 'strlen' Optimizations
 511
 512 struct StrLenOpt : public LibCallOptimization {
 513   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 514     const FunctionType *FT = Callee->getFunctionType();
 515     if (FT->getNumParams() != 1 ||
 516         FT->getParamType(0) != B.getInt8PtrTy() ||
 517         !FT->getReturnType()->isIntegerTy())
 518       return 0;
 519
 520     Value *Src = CI->getArgOperand(0);
 521
 522     // Constant folding: strlen("xyz") -> 3
 523     if (uint64_t Len = GetStringLength(Src))
 524       return ConstantInt::get(CI->getType(), Len-1);
 525
 526     // strlen(x) != 0 --> *x != 0
 527     // strlen(x) == 0 --> *x == 0
 528     if (IsOnlyUsedInZeroEqualityComparison(CI))
 529       return B.CreateZExt(B.CreateLoad(Src, "strlenfirst"), CI->getType());
 530     return 0;
 531   }
 532 };
 533
 534
 535 //===---------------------------------------===//
 536 // 'strpbrk' Optimizations
 537
 538 struct StrPBrkOpt : public LibCallOptimization {
 539   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 540     const FunctionType *FT = Callee->getFunctionType();
 541     if (FT->getNumParams() != 2 ||
 542         FT->getParamType(0) != B.getInt8PtrTy() ||
 543         FT->getParamType(1) != FT->getParamType(0) ||
 544         FT->getReturnType() != FT->getParamType(0))
 545       return 0;
 546
 547     std::string S1, S2;
 548     bool HasS1 = GetConstantStringInfo(CI->getArgOperand(0), S1);
 549     bool HasS2 = GetConstantStringInfo(CI->getArgOperand(1), S2);
 550
 551     // strpbrk(s, "") -> NULL
 552     // strpbrk("", s) -> NULL
 553     if ((HasS1 && S1.empty()) || (HasS2 && S2.empty()))
 554       return Constant::getNullValue(CI->getType());
 555
 556     // Constant folding.
 557     if (HasS1 && HasS2) {
 558       size_t I = S1.find_first_of(S2);
 559       if (I == std::string::npos) // No match.
 560         return Constant::getNullValue(CI->getType());
 561
 562       return B.CreateGEP(CI->getArgOperand(0), B.getInt64(I), "strpbrk");
 563     }
 564
 565     // strpbrk(s, "a") -> strchr(s, 'a')
 566     if (TD && HasS2 && S2.size() == 1)
 567       return EmitStrChr(CI->getArgOperand(0), S2[0], B, TD);
 568
 569     return 0;
 570   }
 571 };
 572
 573 //===---------------------------------------===//
 574 // 'strto*' Optimizations.  This handles strtol, strtod, strtof, strtoul, etc.
 575
 576 struct StrToOpt : public LibCallOptimization {
 577   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 578     const FunctionType *FT = Callee->getFunctionType();
 579     if ((FT->getNumParams() != 2 && FT->getNumParams() != 3) ||
 580         !FT->getParamType(0)->isPointerTy() ||
 581         !FT->getParamType(1)->isPointerTy())
 582       return 0;
 583
 584     Value *EndPtr = CI->getArgOperand(1);
 585     if (isa<ConstantPointerNull>(EndPtr)) {
 586       // With a null EndPtr, this function won't capture the main argument.
 587       // It would be readonly too, except that it still may write to errno.
 588       CI->addAttribute(1, Attribute::NoCapture);
 589     }
 590
 591     return 0;
 592   }
 593 };
 594
 595 //===---------------------------------------===//
 596 // 'strspn' Optimizations
 597
 598 struct StrSpnOpt : public LibCallOptimization {
 599   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 600     const FunctionType *FT = Callee->getFunctionType();
 601     if (FT->getNumParams() != 2 ||
 602         FT->getParamType(0) != B.getInt8PtrTy() ||
 603         FT->getParamType(1) != FT->getParamType(0) ||
 604         !FT->getReturnType()->isIntegerTy())
 605       return 0;
 606
 607     std::string S1, S2;
 608     bool HasS1 = GetConstantStringInfo(CI->getArgOperand(0), S1);
 609     bool HasS2 = GetConstantStringInfo(CI->getArgOperand(1), S2);
 610
 611     // strspn(s, "") -> 0
 612     // strspn("", s) -> 0
 613     if ((HasS1 && S1.empty()) || (HasS2 && S2.empty()))
 614       return Constant::getNullValue(CI->getType());
 615
 616     // Constant folding.
 617     if (HasS1 && HasS2)
 618       return ConstantInt::get(CI->getType(), strspn(S1.c_str(), S2.c_str()));
 619
 620     return 0;
 621   }
 622 };
 623
 624 //===---------------------------------------===//
 625 // 'strcspn' Optimizations
 626
 627 struct StrCSpnOpt : public LibCallOptimization {
 628   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 629     const FunctionType *FT = Callee->getFunctionType();
 630     if (FT->getNumParams() != 2 ||
 631         FT->getParamType(0) != B.getInt8PtrTy() ||
 632         FT->getParamType(1) != FT->getParamType(0) ||
 633         !FT->getReturnType()->isIntegerTy())
 634       return 0;
 635
 636     std::string S1, S2;
 637     bool HasS1 = GetConstantStringInfo(CI->getArgOperand(0), S1);
 638     bool HasS2 = GetConstantStringInfo(CI->getArgOperand(1), S2);
 639
 640     // strcspn("", s) -> 0
 641     if (HasS1 && S1.empty())
 642       return Constant::getNullValue(CI->getType());
 643
 644     // Constant folding.
 645     if (HasS1 && HasS2)
 646       return ConstantInt::get(CI->getType(), strcspn(S1.c_str(), S2.c_str()));
 647
 648     // strcspn(s, "") -> strlen(s)
 649     if (TD && HasS2 && S2.empty())
 650       return EmitStrLen(CI->getArgOperand(0), B, TD);
 651
 652     return 0;
 653   }
 654 };
 655
 656 //===---------------------------------------===//
 657 // 'strstr' Optimizations
 658
 659 struct StrStrOpt : public LibCallOptimization {
 660   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 661     const FunctionType *FT = Callee->getFunctionType();
 662     if (FT->getNumParams() != 2 ||
 663         !FT->getParamType(0)->isPointerTy() ||
 664         !FT->getParamType(1)->isPointerTy() ||
 665         !FT->getReturnType()->isPointerTy())
 666       return 0;
 667
 668     // fold strstr(x, x) -> x.
 669     if (CI->getArgOperand(0) == CI->getArgOperand(1))
 670       return B.CreateBitCast(CI->getArgOperand(0), CI->getType());
 671
 672     // fold strstr(a, b) == a -> strncmp(a, b, strlen(b)) == 0
 673     if (TD && IsOnlyUsedInEqualityComparison(CI, CI->getArgOperand(0))) {
 674       Value *StrLen = EmitStrLen(CI->getArgOperand(1), B, TD);
 675       Value *StrNCmp = EmitStrNCmp(CI->getArgOperand(0), CI->getArgOperand(1),
 676                                    StrLen, B, TD);
 677       for (Value::use_iterator UI = CI->use_begin(), UE = CI->use_end();
 678            UI != UE; ) {
 679         ICmpInst *Old = cast<ICmpInst>(*UI++);
 680         Value *Cmp = B.CreateICmp(Old->getPredicate(), StrNCmp,
 681                                   ConstantInt::getNullValue(StrNCmp->getType()),
 682                                   "cmp");
 683         Old->replaceAllUsesWith(Cmp);
 684         Old->eraseFromParent();
 685       }
 686       return CI;
 687     }
 688
 689     // See if either input string is a constant string.
 690     std::string SearchStr, ToFindStr;
 691     bool HasStr1 = GetConstantStringInfo(CI->getArgOperand(0), SearchStr);
 692     bool HasStr2 = GetConstantStringInfo(CI->getArgOperand(1), ToFindStr);
 693
 694     // fold strstr(x, "") -> x.
 695     if (HasStr2 && ToFindStr.empty())
 696       return B.CreateBitCast(CI->getArgOperand(0), CI->getType());
 697
 698     // If both strings are known, constant fold it.
 699     if (HasStr1 && HasStr2) {
 700       std::string::size_type Offset = SearchStr.find(ToFindStr);
 701
 702       if (Offset == std::string::npos) // strstr("foo", "bar") -> null
 703         return Constant::getNullValue(CI->getType());
 704
 705       // strstr("abcd", "bc") -> gep((char*)"abcd", 1)
 706       Value *Result = CastToCStr(CI->getArgOperand(0), B);
 707       Result = B.CreateConstInBoundsGEP1_64(Result, Offset, "strstr");
 708       return B.CreateBitCast(Result, CI->getType());
 709     }
 710
 711     // fold strstr(x, "y") -> strchr(x, 'y').
 712     if (HasStr2 && ToFindStr.size() == 1)
 713       return B.CreateBitCast(EmitStrChr(CI->getArgOperand(0),
 714                              ToFindStr[0], B, TD), CI->getType());
 715     return 0;
 716   }
 717 };
 718
 719
 720 //===---------------------------------------===//
 721 // 'memcmp' Optimizations
 722
 723 struct MemCmpOpt : public LibCallOptimization {
 724   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 725     const FunctionType *FT = Callee->getFunctionType();
 726     if (FT->getNumParams() != 3 || !FT->getParamType(0)->isPointerTy() ||
 727         !FT->getParamType(1)->isPointerTy() ||
 728         !FT->getReturnType()->isIntegerTy(32))
 729       return 0;
 730
 731     Value *LHS = CI->getArgOperand(0), *RHS = CI->getArgOperand(1);
 732
 733     if (LHS == RHS)  // memcmp(s,s,x) -> 0
 734       return Constant::getNullValue(CI->getType());
 735
 736     // Make sure we have a constant length.
 737     ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getArgOperand(2));
 738     if (!LenC) return 0;
 739     uint64_t Len = LenC->getZExtValue();
 740
 741     if (Len == 0) // memcmp(s1,s2,0) -> 0
 742       return Constant::getNullValue(CI->getType());
 743
 744     // memcmp(S1,S2,1) -> *(unsigned char*)LHS - *(unsigned char*)RHS
 745     if (Len == 1) {
 746       Value *LHSV = B.CreateZExt(B.CreateLoad(CastToCStr(LHS, B), "lhsc"),
 747                                  CI->getType(), "lhsv");
 748       Value *RHSV = B.CreateZExt(B.CreateLoad(CastToCStr(RHS, B), "rhsc"),
 749                                  CI->getType(), "rhsv");
 750       return B.CreateSub(LHSV, RHSV, "chardiff");
 751     }
 752
 753     // Constant folding: memcmp(x, y, l) -> cnst (all arguments are constant)
 754     std::string LHSStr, RHSStr;
 755     if (GetConstantStringInfo(LHS, LHSStr) &&
 756         GetConstantStringInfo(RHS, RHSStr)) {
 757       // Make sure we're not reading out-of-bounds memory.
 758       if (Len > LHSStr.length() || Len > RHSStr.length())
 759         return 0;
 760       uint64_t Ret = memcmp(LHSStr.data(), RHSStr.data(), Len);
 761       return ConstantInt::get(CI->getType(), Ret);
 762     }
 763
 764     return 0;
 765   }
 766 };
 767
 768 //===---------------------------------------===//
 769 // 'memcpy' Optimizations
 770
 771 struct MemCpyOpt : public LibCallOptimization {
 772   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 773     // These optimizations require TargetData.
 774     if (!TD) return 0;
 775
 776     const FunctionType *FT = Callee->getFunctionType();
 777     if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
 778         !FT->getParamType(0)->isPointerTy() ||
 779         !FT->getParamType(1)->isPointerTy() ||
 780         FT->getParamType(2) != TD->getIntPtrType(*Context))
 781       return 0;
 782
 783     // memcpy(x, y, n) -> llvm.memcpy(x, y, n, 1)
 784     B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
 785                    CI->getArgOperand(2), 1);
 786     return CI->getArgOperand(0);
 787   }
 788 };
 789
 790 //===---------------------------------------===//
 791 // 'memmove' Optimizations
 792
 793 struct MemMoveOpt : public LibCallOptimization {
 794   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 795     // These optimizations require TargetData.
 796     if (!TD) return 0;
 797
 798     const FunctionType *FT = Callee->getFunctionType();
 799     if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
 800         !FT->getParamType(0)->isPointerTy() ||
 801         !FT->getParamType(1)->isPointerTy() ||
 802         FT->getParamType(2) != TD->getIntPtrType(*Context))
 803       return 0;
 804
 805     // memmove(x, y, n) -> llvm.memmove(x, y, n, 1)
 806     B.CreateMemMove(CI->getArgOperand(0), CI->getArgOperand(1),
 807                     CI->getArgOperand(2), 1);
 808     return CI->getArgOperand(0);
 809   }
 810 };
 811
 812 //===---------------------------------------===//
 813 // 'memset' Optimizations
 814
 815 struct MemSetOpt : public LibCallOptimization {
 816   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 817     // These optimizations require TargetData.
 818     if (!TD) return 0;
 819
 820     const FunctionType *FT = Callee->getFunctionType();
 821     if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
 822         !FT->getParamType(0)->isPointerTy() ||
 823         !FT->getParamType(1)->isIntegerTy() ||
 824         FT->getParamType(2) != TD->getIntPtrType(*Context))
 825       return 0;
 826
 827     // memset(p, v, n) -> llvm.memset(p, v, n, 1)
 828     Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(), false);
 829     B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1);
 830     return CI->getArgOperand(0);
 831   }
 832 };
 833
 834 //===----------------------------------------------------------------------===//
 835 // Math Library Optimizations
 836 //===----------------------------------------------------------------------===//
 837
 838 //===---------------------------------------===//
 839 // 'pow*' Optimizations
 840
 841 struct PowOpt : public LibCallOptimization {
 842   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 843     const FunctionType *FT = Callee->getFunctionType();
 844     // Just make sure this has 2 arguments of the same FP type, which match the
 845     // result type.
 846     if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) ||
 847         FT->getParamType(0) != FT->getParamType(1) ||
 848         !FT->getParamType(0)->isFloatingPointTy())
 849       return 0;
 850
 851     Value *Op1 = CI->getArgOperand(0), *Op2 = CI->getArgOperand(1);
 852     if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) {
 853       if (Op1C->isExactlyValue(1.0))  // pow(1.0, x) -> 1.0
 854         return Op1C;
 855       if (Op1C->isExactlyValue(2.0))  // pow(2.0, x) -> exp2(x)
 856         return EmitUnaryFloatFnCall(Op2, "exp2", B, Callee->getAttributes());
 857     }
 858
 859     ConstantFP *Op2C = dyn_cast<ConstantFP>(Op2);
 860     if (Op2C == 0) return 0;
 861
 862     if (Op2C->getValueAPF().isZero())  // pow(x, 0.0) -> 1.0
 863       return ConstantFP::get(CI->getType(), 1.0);
 864
 865     if (Op2C->isExactlyValue(0.5)) {
 866       // Expand pow(x, 0.5) to (x == -infinity ? +infinity : fabs(sqrt(x))).
 867       // This is faster than calling pow, and still handles negative zero
 868       // and negative infinite correctly.
 869       // TODO: In fast-math mode, this could be just sqrt(x).
 870       // TODO: In finite-only mode, this could be just fabs(sqrt(x)).
 871       Value *Inf = ConstantFP::getInfinity(CI->getType());
 872       Value *NegInf = ConstantFP::getInfinity(CI->getType(), true);
 873       Value *Sqrt = EmitUnaryFloatFnCall(Op1, "sqrt", B,
 874                                          Callee->getAttributes());
 875       Value *FAbs = EmitUnaryFloatFnCall(Sqrt, "fabs", B,
 876                                          Callee->getAttributes());
 877       Value *FCmp = B.CreateFCmpOEQ(Op1, NegInf, "tmp");
 878       Value *Sel = B.CreateSelect(FCmp, Inf, FAbs, "tmp");
 879       return Sel;
 880     }
 881
 882     if (Op2C->isExactlyValue(1.0))  // pow(x, 1.0) -> x
 883       return Op1;
 884     if (Op2C->isExactlyValue(2.0))  // pow(x, 2.0) -> x*x
 885       return B.CreateFMul(Op1, Op1, "pow2");
 886     if (Op2C->isExactlyValue(-1.0)) // pow(x, -1.0) -> 1.0/x
 887       return B.CreateFDiv(ConstantFP::get(CI->getType(), 1.0),
 888                           Op1, "powrecip");
 889     return 0;
 890   }
 891 };
 892
 893 //===---------------------------------------===//
 894 // 'exp2' Optimizations
 895
 896 struct Exp2Opt : public LibCallOptimization {
 897   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 898     const FunctionType *FT = Callee->getFunctionType();
 899     // Just make sure this has 1 argument of FP type, which matches the
 900     // result type.
 901     if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
 902         !FT->getParamType(0)->isFloatingPointTy())
 903       return 0;
 904
 905     Value *Op = CI->getArgOperand(0);
 906     // Turn exp2(sitofp(x)) -> ldexp(1.0, sext(x))  if sizeof(x) <= 32
 907     // Turn exp2(uitofp(x)) -> ldexp(1.0, zext(x))  if sizeof(x) < 32
 908     Value *LdExpArg = 0;
 909     if (SIToFPInst *OpC = dyn_cast<SIToFPInst>(Op)) {
 910       if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() <= 32)
 911         LdExpArg = B.CreateSExt(OpC->getOperand(0), B.getInt32Ty(), "tmp");
 912     } else if (UIToFPInst *OpC = dyn_cast<UIToFPInst>(Op)) {
 913       if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() < 32)
 914         LdExpArg = B.CreateZExt(OpC->getOperand(0), B.getInt32Ty(), "tmp");
 915     }
 916
 917     if (LdExpArg) {
 918       const char *Name;
 919       if (Op->getType()->isFloatTy())
 920         Name = "ldexpf";
 921       else if (Op->getType()->isDoubleTy())
 922         Name = "ldexp";
 923       else
 924         Name = "ldexpl";
 925
 926       Constant *One = ConstantFP::get(*Context, APFloat(1.0f));
 927       if (!Op->getType()->isFloatTy())
 928         One = ConstantExpr::getFPExtend(One, Op->getType());
 929
 930       Module *M = Caller->getParent();
 931       Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
 932                                              Op->getType(),
 933                                              B.getInt32Ty(), NULL);
 934       CallInst *CI = B.CreateCall2(Callee, One, LdExpArg);
 935       if (const Function *F = dyn_cast<Function>(Callee->stripPointerCasts()))
 936         CI->setCallingConv(F->getCallingConv());
 937
 938       return CI;
 939     }
 940     return 0;
 941   }
 942 };
 943
 944 //===---------------------------------------===//
 945 // Double -> Float Shrinking Optimizations for Unary Functions like 'floor'
 946
 947 struct UnaryDoubleFPOpt : public LibCallOptimization {
 948   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 949     const FunctionType *FT = Callee->getFunctionType();
 950     if (FT->getNumParams() != 1 || !FT->getReturnType()->isDoubleTy() ||
 951         !FT->getParamType(0)->isDoubleTy())
 952       return 0;
 953
 954     // If this is something like 'floor((double)floatval)', convert to floorf.
 955     FPExtInst *Cast = dyn_cast<FPExtInst>(CI->getArgOperand(0));
 956     if (Cast == 0 || !Cast->getOperand(0)->getType()->isFloatTy())
 957       return 0;
 958
 959     // floor((double)floatval) -> (double)floorf(floatval)
 960     Value *V = Cast->getOperand(0);
 961     V = EmitUnaryFloatFnCall(V, Callee->getName().data(), B,
 962                              Callee->getAttributes());
 963     return B.CreateFPExt(V, B.getDoubleTy());
 964   }
 965 };
 966
 967 //===----------------------------------------------------------------------===//
 968 // Integer Optimizations
 969 //===----------------------------------------------------------------------===//
 970
 971 //===---------------------------------------===//
 972 // 'ffs*' Optimizations
 973
 974 struct FFSOpt : public LibCallOptimization {
 975   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
 976     const FunctionType *FT = Callee->getFunctionType();
 977     // Just make sure this has 2 arguments of the same FP type, which match the
 978     // result type.
 979     if (FT->getNumParams() != 1 ||
 980         !FT->getReturnType()->isIntegerTy(32) ||
 981         !FT->getParamType(0)->isIntegerTy())
 982       return 0;
 983
 984     Value *Op = CI->getArgOperand(0);
 985
 986     // Constant fold.
 987     if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) {
 988       if (CI->getValue() == 0)  // ffs(0) -> 0.
 989         return Constant::getNullValue(CI->getType());
 990       // ffs(c) -> cttz(c)+1
 991       return B.getInt32(CI->getValue().countTrailingZeros() + 1);
 992     }
 993
 994     // ffs(x) -> x != 0 ? (i32)llvm.cttz(x)+1 : 0
 995     const Type *ArgType = Op->getType();
 996     Value *F = Intrinsic::getDeclaration(Callee->getParent(),
 997                                          Intrinsic::cttz, &ArgType, 1);
 998     Value *V = B.CreateCall(F, Op, "cttz");
 999     V = B.CreateAdd(V, ConstantInt::get(V->getType(), 1), "tmp");
1000     V = B.CreateIntCast(V, B.getInt32Ty(), false, "tmp");
1001
1002     Value *Cond = B.CreateICmpNE(Op, Constant::getNullValue(ArgType), "tmp");
1003     return B.CreateSelect(Cond, V, B.getInt32(0));
1004   }
1005 };
1006
1007 //===---------------------------------------===//
1008 // 'isdigit' Optimizations
1009
1010 struct IsDigitOpt : public LibCallOptimization {
1011   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
1012     const FunctionType *FT = Callee->getFunctionType();
1013     // We require integer(i32)
1014     if (FT->getNumParams() != 1 || !FT->getReturnType()->isIntegerTy() ||
1015         !FT->getParamType(0)->isIntegerTy(32))
1016       return 0;
1017
1018     // isdigit(c) -> (c-'0') <u 10
1019     Value *Op = CI->getArgOperand(0);
1020     Op = B.CreateSub(Op, B.getInt32('0'), "isdigittmp");
1021     Op = B.CreateICmpULT(Op, B.getInt32(10), "isdigit");
1022     return B.CreateZExt(Op, CI->getType());
1023   }
1024 };
1025
1026 //===---------------------------------------===//
1027 // 'isascii' Optimizations
1028
1029 struct IsAsciiOpt : public LibCallOptimization {
1030   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
1031     const FunctionType *FT = Callee->getFunctionType();
1032     // We require integer(i32)
1033     if (FT->getNumParams() != 1 || !FT->getReturnType()->isIntegerTy() ||
1034         !FT->getParamType(0)->isIntegerTy(32))
1035       return 0;
1036
1037     // isascii(c) -> c <u 128
1038     Value *Op = CI->getArgOperand(0);
1039     Op = B.CreateICmpULT(Op, B.getInt32(128), "isascii");
1040     return B.CreateZExt(Op, CI->getType());
1041   }
1042 };
1043
1044 //===---------------------------------------===//
1045 // 'abs', 'labs', 'llabs' Optimizations
1046
1047 struct AbsOpt : public LibCallOptimization {
1048   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
1049     const FunctionType *FT = Callee->getFunctionType();
1050     // We require integer(integer) where the types agree.
1051     if (FT->getNumParams() != 1 || !FT->getReturnType()->isIntegerTy() ||
1052         FT->getParamType(0) != FT->getReturnType())
1053       return 0;
1054
1055     // abs(x) -> x >s -1 ? x : -x
1056     Value *Op = CI->getArgOperand(0);
1057     Value *Pos = B.CreateICmpSGT(Op, Constant::getAllOnesValue(Op->getType()),
1058                                  "ispos");
1059     Value *Neg = B.CreateNeg(Op, "neg");
1060     return B.CreateSelect(Pos, Op, Neg);
1061   }
1062 };
1063
1064
1065 //===---------------------------------------===//
1066 // 'toascii' Optimizations
1067
1068 struct ToAsciiOpt : public LibCallOptimization {
1069   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
1070     const FunctionType *FT = Callee->getFunctionType();
1071     // We require i32(i32)
1072     if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
1073         !FT->getParamType(0)->isIntegerTy(32))
1074       return 0;
1075
1076     // isascii(c) -> c & 0x7f
1077     return B.CreateAnd(CI->getArgOperand(0),
1078                        ConstantInt::get(CI->getType(),0x7F));
1079   }
1080 };
1081
1082 //===----------------------------------------------------------------------===//
1083 // Formatting and IO Optimizations
1084 //===----------------------------------------------------------------------===//
1085
1086 //===---------------------------------------===//
1087 // 'printf' Optimizations
1088
1089 struct PrintFOpt : public LibCallOptimization {
1090   Value *OptimizeFixedFormatString(Function *Callee, CallInst *CI,
1091                                    IRBuilder<> &B) {
1092     // Check for a fixed format string.
1093     std::string FormatStr;
1094     if (!GetConstantStringInfo(CI->getArgOperand(0), FormatStr))
1095       return 0;
1096
1097     // Empty format string -> noop.
1098     if (FormatStr.empty())  // Tolerate printf's declared void.
1099       return CI->use_empty() ? (Value*)CI :
1100                                ConstantInt::get(CI->getType(), 0);
1101
1102     // Do not do any of the following transformations if the printf return value
1103     // is used, in general the printf return value is not compatible with either
1104     // putchar() or puts().
1105     if (!CI->use_empty())
1106       return 0;
1107
1108     // printf("x") -> putchar('x'), even for '%'.
1109     if (FormatStr.size() == 1) {
1110       Value *Res = EmitPutChar(B.getInt32(FormatStr[0]), B, TD);
1111       if (CI->use_empty()) return CI;
1112       return B.CreateIntCast(Res, CI->getType(), true);
1113     }
1114
1115     // printf("foo\n") --> puts("foo")
1116     if (FormatStr[FormatStr.size()-1] == '\n' &&
1117         FormatStr.find('%') == std::string::npos) {  // no format characters.
1118       // Create a string literal with no \n on it.  We expect the constant merge
1119       // pass to be run after this pass, to merge duplicate strings.
1120       FormatStr.erase(FormatStr.end()-1);
1121       Constant *C = ConstantArray::get(*Context, FormatStr, true);
1122       C = new GlobalVariable(*Callee->getParent(), C->getType(), true,
1123                              GlobalVariable::InternalLinkage, C, "str");
1124       EmitPutS(C, B, TD);
1125       return CI->use_empty() ? (Value*)CI :
1126                     ConstantInt::get(CI->getType(), FormatStr.size()+1);
1127     }
1128
1129     // Optimize specific format strings.
1130     // printf("%c", chr) --> putchar(chr)
1131     if (FormatStr == "%c" && CI->getNumArgOperands() > 1 &&
1132         CI->getArgOperand(1)->getType()->isIntegerTy()) {
1133       Value *Res = EmitPutChar(CI->getArgOperand(1), B, TD);
1134
1135       if (CI->use_empty()) return CI;
1136       return B.CreateIntCast(Res, CI->getType(), true);
1137     }
1138
1139     // printf("%s\n", str) --> puts(str)
1140     if (FormatStr == "%s\n" && CI->getNumArgOperands() > 1 &&
1141         CI->getArgOperand(1)->getType()->isPointerTy()) {
1142       EmitPutS(CI->getArgOperand(1), B, TD);
1143       return CI;
1144     }
1145     return 0;
1146   }
1147
1148   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
1149     // Require one fixed pointer argument and an integer/void result.
1150     const FunctionType *FT = Callee->getFunctionType();
1151     if (FT->getNumParams() < 1 || !FT->getParamType(0)->isPointerTy() ||
1152         !(FT->getReturnType()->isIntegerTy() ||
1153           FT->getReturnType()->isVoidTy()))
1154       return 0;
1155
1156     if (Value *V = OptimizeFixedFormatString(Callee, CI, B)) {
1157       return V;
1158     }
1159
1160     // printf(format, ...) -> iprintf(format, ...) if no floating point
1161     // arguments.
1162     if (TLI->has(LibFunc::iprintf) && !CallHasFloatingPointArgument(CI)) {
1163       Module *M = B.GetInsertBlock()->getParent()->getParent();
1164       Constant *IPrintFFn =
1165         M->getOrInsertFunction("iprintf", FT, Callee->getAttributes());
1166       CallInst *New = cast<CallInst>(CI->clone());
1167       New->setCalledFunction(IPrintFFn);
1168       B.Insert(New);
1169       return New;
1170     }
1171     return 0;
1172   }
1173 };
1174
1175 //===---------------------------------------===//
1176 // 'sprintf' Optimizations
1177
1178 struct SPrintFOpt : public LibCallOptimization {
1179   Value *OptimizeFixedFormatString(Function *Callee, CallInst *CI,
1180                                    IRBuilder<> &B) {
1181     // Check for a fixed format string.
1182     std::string FormatStr;
1183     if (!GetConstantStringInfo(CI->getArgOperand(1), FormatStr))
1184       return 0;
1185
1186     // If we just have a format string (nothing else crazy) transform it.
1187     if (CI->getNumArgOperands() == 2) {
1188       // Make sure there's no % in the constant array.  We could try to handle
1189       // %% -> % in the future if we cared.
1190       for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
1191         if (FormatStr[i] == '%')
1192           return 0; // we found a format specifier, bail out.
1193
1194       // These optimizations require TargetData.
1195       if (!TD) return 0;
1196
1197       // sprintf(str, fmt) -> llvm.memcpy(str, fmt, strlen(fmt)+1, 1)
1198       B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
1199                      ConstantInt::get(TD->getIntPtrType(*Context), // Copy the
1200                                       FormatStr.size() + 1), 1);   // nul byte.
1201       return ConstantInt::get(CI->getType(), FormatStr.size());
1202     }
1203
1204     // The remaining optimizations require the format string to be "%s" or "%c"
1205     // and have an extra operand.
1206     if (FormatStr.size() != 2 || FormatStr[0] != '%' ||
1207         CI->getNumArgOperands() < 3)
1208       return 0;
1209
1210     // Decode the second character of the format string.
1211     if (FormatStr[1] == 'c') {
1212       // sprintf(dst, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0
1213       if (!CI->getArgOperand(2)->getType()->isIntegerTy()) return 0;
1214       Value *V = B.CreateTrunc(CI->getArgOperand(2), B.getInt8Ty(), "char");
1215       Value *Ptr = CastToCStr(CI->getArgOperand(0), B);
1216       B.CreateStore(V, Ptr);
1217       Ptr = B.CreateGEP(Ptr, B.getInt32(1), "nul");
1218       B.CreateStore(B.getInt8(0), Ptr);
1219
1220       return ConstantInt::get(CI->getType(), 1);
1221     }
1222
1223     if (FormatStr[1] == 's') {
1224       // These optimizations require TargetData.
1225       if (!TD) return 0;
1226
1227       // sprintf(dest, "%s", str) -> llvm.memcpy(dest, str, strlen(str)+1, 1)
1228       if (!CI->getArgOperand(2)->getType()->isPointerTy()) return 0;
1229
1230       Value *Len = EmitStrLen(CI->getArgOperand(2), B, TD);
1231       Value *IncLen = B.CreateAdd(Len,
1232                                   ConstantInt::get(Len->getType(), 1),
1233                                   "leninc");
1234       B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(2), IncLen, 1);
1235
1236       // The sprintf result is the unincremented number of bytes in the string.
1237       return B.CreateIntCast(Len, CI->getType(), false);
1238     }
1239     return 0;
1240   }
1241
1242   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
1243     // Require two fixed pointer arguments and an integer result.
1244     const FunctionType *FT = Callee->getFunctionType();
1245     if (FT->getNumParams() != 2 || !FT->getParamType(0)->isPointerTy() ||
1246         !FT->getParamType(1)->isPointerTy() ||
1247         !FT->getReturnType()->isIntegerTy())
1248       return 0;
1249
1250     if (Value *V = OptimizeFixedFormatString(Callee, CI, B)) {
1251       return V;
1252     }
1253
1254     // sprintf(str, format, ...) -> siprintf(str, format, ...) if no floating
1255     // point arguments.
1256     if (TLI->has(LibFunc::siprintf) && !CallHasFloatingPointArgument(CI)) {
1257       Module *M = B.GetInsertBlock()->getParent()->getParent();
1258       Constant *SIPrintFFn =
1259         M->getOrInsertFunction("siprintf", FT, Callee->getAttributes());
1260       CallInst *New = cast<CallInst>(CI->clone());
1261       New->setCalledFunction(SIPrintFFn);
1262       B.Insert(New);
1263       return New;
1264     }
1265     return 0;
1266   }
1267 };
1268
1269 //===---------------------------------------===//
1270 // 'fwrite' Optimizations
1271
1272 struct FWriteOpt : public LibCallOptimization {
1273   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
1274     // Require a pointer, an integer, an integer, a pointer, returning integer.
1275     const FunctionType *FT = Callee->getFunctionType();
1276     if (FT->getNumParams() != 4 || !FT->getParamType(0)->isPointerTy() ||
1277         !FT->getParamType(1)->isIntegerTy() ||
1278         !FT->getParamType(2)->isIntegerTy() ||
1279         !FT->getParamType(3)->isPointerTy() ||
1280         !FT->getReturnType()->isIntegerTy())
1281       return 0;
1282
1283     // Get the element size and count.
1284     ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getArgOperand(1));
1285     ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getArgOperand(2));
1286     if (!SizeC || !CountC) return 0;
1287     uint64_t Bytes = SizeC->getZExtValue()*CountC->getZExtValue();
1288
1289     // If this is writing zero records, remove the call (it's a noop).
1290     if (Bytes == 0)
1291       return ConstantInt::get(CI->getType(), 0);
1292
1293     // If this is writing one byte, turn it into fputc.
1294     if (Bytes == 1) {  // fwrite(S,1,1,F) -> fputc(S[0],F)
1295       Value *Char = B.CreateLoad(CastToCStr(CI->getArgOperand(0), B), "char");
1296       EmitFPutC(Char, CI->getArgOperand(3), B, TD);
1297       return ConstantInt::get(CI->getType(), 1);
1298     }
1299
1300     return 0;
1301   }
1302 };
1303
1304 //===---------------------------------------===//
1305 // 'fputs' Optimizations
1306
1307 struct FPutsOpt : public LibCallOptimization {
1308   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
1309     // These optimizations require TargetData.
1310     if (!TD) return 0;
1311
1312     // Require two pointers.  Also, we can't optimize if return value is used.
1313     const FunctionType *FT = Callee->getFunctionType();
1314     if (FT->getNumParams() != 2 || !FT->getParamType(0)->isPointerTy() ||
1315         !FT->getParamType(1)->isPointerTy() ||
1316         !CI->use_empty())
1317       return 0;
1318
1319     // fputs(s,F) --> fwrite(s,1,strlen(s),F)
1320     uint64_t Len = GetStringLength(CI->getArgOperand(0));
1321     if (!Len) return 0;
1322     EmitFWrite(CI->getArgOperand(0),
1323                ConstantInt::get(TD->getIntPtrType(*Context), Len-1),
1324                CI->getArgOperand(1), B, TD);
1325     return CI;  // Known to have no uses (see above).
1326   }
1327 };
1328
1329 //===---------------------------------------===//
1330 // 'fprintf' Optimizations
1331
1332 struct FPrintFOpt : public LibCallOptimization {
1333   Value *OptimizeFixedFormatString(Function *Callee, CallInst *CI,
1334                                    IRBuilder<> &B) {
1335     // All the optimizations depend on the format string.
1336     std::string FormatStr;
1337     if (!GetConstantStringInfo(CI->getArgOperand(1), FormatStr))
1338       return 0;
1339
1340     // fprintf(F, "foo") --> fwrite("foo", 3, 1, F)
1341     if (CI->getNumArgOperands() == 2) {
1342       for (unsigned i = 0, e = FormatStr.size(); i != e; ++i)
1343         if (FormatStr[i] == '%')  // Could handle %% -> % if we cared.
1344           return 0; // We found a format specifier.
1345
1346       // These optimizations require TargetData.
1347       if (!TD) return 0;
1348
1349       EmitFWrite(CI->getArgOperand(1),
1350                  ConstantInt::get(TD->getIntPtrType(*Context),
1351                                   FormatStr.size()),
1352                  CI->getArgOperand(0), B, TD);
1353       return ConstantInt::get(CI->getType(), FormatStr.size());
1354     }
1355
1356     // The remaining optimizations require the format string to be "%s" or "%c"
1357     // and have an extra operand.
1358     if (FormatStr.size() != 2 || FormatStr[0] != '%' ||
1359         CI->getNumArgOperands() < 3)
1360       return 0;
1361
1362     // Decode the second character of the format string.
1363     if (FormatStr[1] == 'c') {
1364       // fprintf(F, "%c", chr) --> fputc(chr, F)
1365       if (!CI->getArgOperand(2)->getType()->isIntegerTy()) return 0;
1366       EmitFPutC(CI->getArgOperand(2), CI->getArgOperand(0), B, TD);
1367       return ConstantInt::get(CI->getType(), 1);
1368     }
1369
1370     if (FormatStr[1] == 's') {
1371       // fprintf(F, "%s", str) --> fputs(str, F)
1372       if (!CI->getArgOperand(2)->getType()->isPointerTy() || !CI->use_empty())
1373         return 0;
1374       EmitFPutS(CI->getArgOperand(2), CI->getArgOperand(0), B, TD);
1375       return CI;
1376     }
1377     return 0;
1378   }
1379
1380   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
1381     // Require two fixed paramters as pointers and integer result.
1382     const FunctionType *FT = Callee->getFunctionType();
1383     if (FT->getNumParams() != 2 || !FT->getParamType(0)->isPointerTy() ||
1384         !FT->getParamType(1)->isPointerTy() ||
1385         !FT->getReturnType()->isIntegerTy())
1386       return 0;
1387
1388     if (Value *V = OptimizeFixedFormatString(Callee, CI, B)) {
1389       return V;
1390     }
1391
1392     // fprintf(stream, format, ...) -> fiprintf(stream, format, ...) if no
1393     // floating point arguments.
1394     if (TLI->has(LibFunc::fiprintf) && !CallHasFloatingPointArgument(CI)) {
1395       Module *M = B.GetInsertBlock()->getParent()->getParent();
1396       Constant *FIPrintFFn =
1397         M->getOrInsertFunction("fiprintf", FT, Callee->getAttributes());
1398       CallInst *New = cast<CallInst>(CI->clone());
1399       New->setCalledFunction(FIPrintFFn);
1400       B.Insert(New);
1401       return New;
1402     }
1403     return 0;
1404   }
1405 };
1406
1407 //===---------------------------------------===//
1408 // 'puts' Optimizations
1409
1410 struct PutsOpt : public LibCallOptimization {
1411   virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
1412     // Require one fixed pointer argument and an integer/void result.
1413     const FunctionType *FT = Callee->getFunctionType();
1414     if (FT->getNumParams() < 1 || !FT->getParamType(0)->isPointerTy() ||
1415         !(FT->getReturnType()->isIntegerTy() ||
1416           FT->getReturnType()->isVoidTy()))
1417       return 0;
1418
1419     // Check for a constant string.
1420     std::string Str;
1421     if (!GetConstantStringInfo(CI->getArgOperand(0), Str))
1422       return 0;
1423
1424     if (Str.empty() && CI->use_empty()) {
1425       // puts("") -> putchar('\n')
1426       Value *Res = EmitPutChar(B.getInt32('\n'), B, TD);
1427       if (CI->use_empty()) return CI;
1428       return B.CreateIntCast(Res, CI->getType(), true);
1429     }
1430
1431     return 0;
1432   }
1433 };
1434
1435 } // end anonymous namespace.
1436
1437 //===----------------------------------------------------------------------===//
1438 // SimplifyLibCalls Pass Implementation
1439 //===----------------------------------------------------------------------===//
1440
1441 namespace {
1442   /// This pass optimizes well known library functions from libc and libm.
1443   ///
1444   class SimplifyLibCalls : public FunctionPass {
1445     TargetLibraryInfo *TLI;
1446
1447     StringMap<LibCallOptimization*> Optimizations;
1448     // String and Memory LibCall Optimizations
1449     StrCatOpt StrCat; StrNCatOpt StrNCat; StrChrOpt StrChr; StrRChrOpt StrRChr;
1450     StrCmpOpt StrCmp; StrNCmpOpt StrNCmp; StrCpyOpt StrCpy; StrCpyOpt StrCpyChk;
1451     StrNCpyOpt StrNCpy; StrLenOpt StrLen; StrPBrkOpt StrPBrk;
1452     StrToOpt StrTo; StrSpnOpt StrSpn; StrCSpnOpt StrCSpn; StrStrOpt StrStr;
1453     MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
1454     // Math Library Optimizations
1455     PowOpt Pow; Exp2Opt Exp2; UnaryDoubleFPOpt UnaryDoubleFP;
1456     // Integer Optimizations
1457     FFSOpt FFS; AbsOpt Abs; IsDigitOpt IsDigit; IsAsciiOpt IsAscii;
1458     ToAsciiOpt ToAscii;
1459     // Formatting and IO Optimizations
1460     SPrintFOpt SPrintF; PrintFOpt PrintF;
1461     FWriteOpt FWrite; FPutsOpt FPuts; FPrintFOpt FPrintF;
1462     PutsOpt Puts;
1463
1464     bool Modified;  // This is only used by doInitialization.
1465   public:
1466     static char ID; // Pass identification
1467     SimplifyLibCalls() : FunctionPass(ID), StrCpy(false), StrCpyChk(true) {
1468       initializeSimplifyLibCallsPass(*PassRegistry::getPassRegistry());
1469     }
1470     void InitOptimizations();
1471     bool runOnFunction(Function &F);
1472
1473     void setDoesNotAccessMemory(Function &F);
1474     void setOnlyReadsMemory(Function &F);
1475     void setDoesNotThrow(Function &F);
1476     void setDoesNotCapture(Function &F, unsigned n);
1477     void setDoesNotAlias(Function &F, unsigned n);
1478     bool doInitialization(Module &M);
1479
1480     void inferPrototypeAttributes(Function &F);
1481     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
1482       AU.addRequired<TargetLibraryInfo>();
1483     }
1484   };
1485 } // end anonymous namespace.
1486
1487 char SimplifyLibCalls::ID = 0;
1488
1489 INITIALIZE_PASS_BEGIN(SimplifyLibCalls, "simplify-libcalls",
1490                       "Simplify well-known library calls", false, false)
1491 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
1492 INITIALIZE_PASS_END(SimplifyLibCalls, "simplify-libcalls",
1493                     "Simplify well-known library calls", false, false)
1494
1495 // Public interface to the Simplify LibCalls pass.
1496 FunctionPass *llvm::createSimplifyLibCallsPass() {
1497   return new SimplifyLibCalls();
1498 }
1499
1500 /// Optimizations - Populate the Optimizations map with all the optimizations
1501 /// we know.
1502 void SimplifyLibCalls::InitOptimizations() {
1503   // String and Memory LibCall Optimizations
1504   Optimizations["strcat"] = &StrCat;
1505   Optimizations["strncat"] = &StrNCat;
1506   Optimizations["strchr"] = &StrChr;
1507   Optimizations["strrchr"] = &StrRChr;
1508   Optimizations["strcmp"] = &StrCmp;
1509   Optimizations["strncmp"] = &StrNCmp;
1510   Optimizations["strcpy"] = &StrCpy;
1511   Optimizations["strncpy"] = &StrNCpy;
1512   Optimizations["strlen"] = &StrLen;
1513   Optimizations["strpbrk"] = &StrPBrk;
1514   Optimizations["strtol"] = &StrTo;
1515   Optimizations["strtod"] = &StrTo;
1516   Optimizations["strtof"] = &StrTo;
1517   Optimizations["strtoul"] = &StrTo;
1518   Optimizations["strtoll"] = &StrTo;
1519   Optimizations["strtold"] = &StrTo;
1520   Optimizations["strtoull"] = &StrTo;
1521   Optimizations["strspn"] = &StrSpn;
1522   Optimizations["strcspn"] = &StrCSpn;
1523   Optimizations["strstr"] = &StrStr;
1524   Optimizations["memcmp"] = &MemCmp;
1525   if (TLI->has(LibFunc::memcpy)) Optimizations["memcpy"] = &MemCpy;
1526   Optimizations["memmove"] = &MemMove;
1527   if (TLI->has(LibFunc::memset)) Optimizations["memset"] = &MemSet;
1528
1529   // _chk variants of String and Memory LibCall Optimizations.
1530   Optimizations["__strcpy_chk"] = &StrCpyChk;
1531
1532   // Math Library Optimizations
1533   Optimizations["powf"] = &Pow;
1534   Optimizations["pow"] = &Pow;
1535   Optimizations["powl"] = &Pow;
1536   Optimizations["llvm.pow.f32"] = &Pow;
1537   Optimizations["llvm.pow.f64"] = &Pow;
1538   Optimizations["llvm.pow.f80"] = &Pow;
1539   Optimizations["llvm.pow.f128"] = &Pow;
1540   Optimizations["llvm.pow.ppcf128"] = &Pow;
1541   Optimizations["exp2l"] = &Exp2;
1542   Optimizations["exp2"] = &Exp2;
1543   Optimizations["exp2f"] = &Exp2;
1544   Optimizations["llvm.exp2.ppcf128"] = &Exp2;
1545   Optimizations["llvm.exp2.f128"] = &Exp2;
1546   Optimizations["llvm.exp2.f80"] = &Exp2;
1547   Optimizations["llvm.exp2.f64"] = &Exp2;
1548   Optimizations["llvm.exp2.f32"] = &Exp2;
1549
1550 #ifdef HAVE_FLOORF
1551   Optimizations["floor"] = &UnaryDoubleFP;
1552 #endif
1553 #ifdef HAVE_CEILF
1554   Optimizations["ceil"] = &UnaryDoubleFP;
1555 #endif
1556 #ifdef HAVE_ROUNDF
1557   Optimizations["round"] = &UnaryDoubleFP;
1558 #endif
1559 #ifdef HAVE_RINTF
1560   Optimizations["rint"] = &UnaryDoubleFP;
1561 #endif
1562 #ifdef HAVE_NEARBYINTF
1563   Optimizations["nearbyint"] = &UnaryDoubleFP;
1564 #endif
1565
1566   // Integer Optimizations
1567   Optimizations["ffs"] = &FFS;
1568   Optimizations["ffsl"] = &FFS;
1569   Optimizations["ffsll"] = &FFS;
1570   Optimizations["abs"] = &Abs;
1571   Optimizations["labs"] = &Abs;
1572   Optimizations["llabs"] = &Abs;
1573   Optimizations["isdigit"] = &IsDigit;
1574   Optimizations["isascii"] = &IsAscii;
1575   Optimizations["toascii"] = &ToAscii;
1576
1577   // Formatting and IO Optimizations
1578   Optimizations["sprintf"] = &SPrintF;
1579   Optimizations["printf"] = &PrintF;
1580   Optimizations["fwrite"] = &FWrite;
1581   Optimizations["fputs"] = &FPuts;
1582   Optimizations["fprintf"] = &FPrintF;
1583   Optimizations["puts"] = &Puts;
1584 }
1585
1586
1587 /// runOnFunction - Top level algorithm.
1588 ///
1589 bool SimplifyLibCalls::runOnFunction(Function &F) {
1590   TLI = &getAnalysis<TargetLibraryInfo>();
1591
1592   if (Optimizations.empty())
1593     InitOptimizations();
1594
1595   const TargetData *TD = getAnalysisIfAvailable<TargetData>();
1596
1597   IRBuilder<> Builder(F.getContext());
1598
1599   bool Changed = false;
1600   for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
1601     for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
1602       // Ignore non-calls.
1603       CallInst *CI = dyn_cast<CallInst>(I++);
1604       if (!CI) continue;
1605
1606       // Ignore indirect calls and calls to non-external functions.
1607       Function *Callee = CI->getCalledFunction();
1608       if (Callee == 0 || !Callee->isDeclaration() ||
1609           !(Callee->hasExternalLinkage() || Callee->hasDLLImportLinkage()))
1610         continue;
1611
1612       // Ignore unknown calls.
1613       LibCallOptimization *LCO = Optimizations.lookup(Callee->getName());
1614       if (!LCO) continue;
1615
1616       // Set the builder to the instruction after the call.
1617       Builder.SetInsertPoint(BB, I);
1618
1619       // Use debug location of CI for all new instructions.
1620       Builder.SetCurrentDebugLocation(CI->getDebugLoc());
1621
1622       // Try to optimize this call.
1623       Value *Result = LCO->OptimizeCall(CI, TD, TLI, Builder);
1624       if (Result == 0) continue;
1625
1626       DEBUG(dbgs() << "SimplifyLibCalls simplified: " << *CI;
1627             dbgs() << "  into: " << *Result << "\n");
1628
1629       // Something changed!
1630       Changed = true;
1631       ++NumSimplified;
1632
1633       // Inspect the instruction after the call (which was potentially just
1634       // added) next.
1635       I = CI; ++I;
1636
1637       if (CI != Result && !CI->use_empty()) {
1638         CI->replaceAllUsesWith(Result);
1639         if (!Result->hasName())
1640           Result->takeName(CI);
1641       }
1642       CI->eraseFromParent();
1643     }
1644   }
1645   return Changed;
1646 }
1647
1648 // Utility methods for doInitialization.
1649
1650 void SimplifyLibCalls::setDoesNotAccessMemory(Function &F) {
1651   if (!F.doesNotAccessMemory()) {
1652     F.setDoesNotAccessMemory();
1653     ++NumAnnotated;
1654     Modified = true;
1655   }
1656 }
1657 void SimplifyLibCalls::setOnlyReadsMemory(Function &F) {
1658   if (!F.onlyReadsMemory()) {
1659     F.setOnlyReadsMemory();
1660     ++NumAnnotated;
1661     Modified = true;
1662   }
1663 }
1664 void SimplifyLibCalls::setDoesNotThrow(Function &F) {
1665   if (!F.doesNotThrow()) {
1666     F.setDoesNotThrow();
1667     ++NumAnnotated;
1668     Modified = true;
1669   }
1670 }
1671 void SimplifyLibCalls::setDoesNotCapture(Function &F, unsigned n) {
1672   if (!F.doesNotCapture(n)) {
1673     F.setDoesNotCapture(n);
1674     ++NumAnnotated;
1675     Modified = true;
1676   }
1677 }
1678 void SimplifyLibCalls::setDoesNotAlias(Function &F, unsigned n) {
1679   if (!F.doesNotAlias(n)) {
1680     F.setDoesNotAlias(n);
1681     ++NumAnnotated;
1682     Modified = true;
1683   }
1684 }
1685
1686
1687 void SimplifyLibCalls::inferPrototypeAttributes(Function &F) {
1688   const FunctionType *FTy = F.getFunctionType();
1689
1690   StringRef Name = F.getName();
1691   switch (Name[0]) {
1692   case 's':
1693     if (Name == "strlen") {
1694       if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1695         return;
1696       setOnlyReadsMemory(F);
1697       setDoesNotThrow(F);
1698       setDoesNotCapture(F, 1);
1699     } else if (Name == "strchr" ||
1700                Name == "strrchr") {
1701       if (FTy->getNumParams() != 2 ||
1702           !FTy->getParamType(0)->isPointerTy() ||
1703           !FTy->getParamType(1)->isIntegerTy())
1704         return;
1705       setOnlyReadsMemory(F);
1706       setDoesNotThrow(F);
1707     } else if (Name == "strcpy" ||
1708                Name == "stpcpy" ||
1709                Name == "strcat" ||
1710                Name == "strtol" ||
1711                Name == "strtod" ||
1712                Name == "strtof" ||
1713                Name == "strtoul" ||
1714                Name == "strtoll" ||
1715                Name == "strtold" ||
1716                Name == "strncat" ||
1717                Name == "strncpy" ||
1718                Name == "strtoull") {
1719       if (FTy->getNumParams() < 2 ||
1720           !FTy->getParamType(1)->isPointerTy())
1721         return;
1722       setDoesNotThrow(F);
1723       setDoesNotCapture(F, 2);
1724     } else if (Name == "strxfrm") {
1725       if (FTy->getNumParams() != 3 ||
1726           !FTy->getParamType(0)->isPointerTy() ||
1727           !FTy->getParamType(1)->isPointerTy())
1728         return;
1729       setDoesNotThrow(F);
1730       setDoesNotCapture(F, 1);
1731       setDoesNotCapture(F, 2);
1732     } else if (Name == "strcmp" ||
1733                Name == "strspn" ||
1734                Name == "strncmp" ||
1735                Name == "strcspn" ||
1736                Name == "strcoll" ||
1737                Name == "strcasecmp" ||
1738                Name == "strncasecmp") {
1739       if (FTy->getNumParams() < 2 ||
1740           !FTy->getParamType(0)->isPointerTy() ||
1741           !FTy->getParamType(1)->isPointerTy())
1742         return;
1743       setOnlyReadsMemory(F);
1744       setDoesNotThrow(F);
1745       setDoesNotCapture(F, 1);
1746       setDoesNotCapture(F, 2);
1747     } else if (Name == "strstr" ||
1748                Name == "strpbrk") {
1749       if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
1750         return;
1751       setOnlyReadsMemory(F);
1752       setDoesNotThrow(F);
1753       setDoesNotCapture(F, 2);
1754     } else if (Name == "strtok" ||
1755                Name == "strtok_r") {
1756       if (FTy->getNumParams() < 2 || !FTy->getParamType(1)->isPointerTy())
1757         return;
1758       setDoesNotThrow(F);
1759       setDoesNotCapture(F, 2);
1760     } else if (Name == "scanf" ||
1761                Name == "setbuf" ||
1762                Name == "setvbuf") {
1763       if (FTy->getNumParams() < 1 || !FTy->getParamType(0)->isPointerTy())
1764         return;
1765       setDoesNotThrow(F);
1766       setDoesNotCapture(F, 1);
1767     } else if (Name == "strdup" ||
1768                Name == "strndup") {
1769       if (FTy->getNumParams() < 1 || !FTy->getReturnType()->isPointerTy() ||
1770           !FTy->getParamType(0)->isPointerTy())
1771         return;
1772       setDoesNotThrow(F);
1773       setDoesNotAlias(F, 0);
1774       setDoesNotCapture(F, 1);
1775     } else if (Name == "stat" ||
1776                Name == "sscanf" ||
1777                Name == "sprintf" ||
1778                Name == "statvfs") {
1779       if (FTy->getNumParams() < 2 ||
1780           !FTy->getParamType(0)->isPointerTy() ||
1781           !FTy->getParamType(1)->isPointerTy())
1782         return;
1783       setDoesNotThrow(F);
1784       setDoesNotCapture(F, 1);
1785       setDoesNotCapture(F, 2);
1786     } else if (Name == "snprintf") {
1787       if (FTy->getNumParams() != 3 ||
1788           !FTy->getParamType(0)->isPointerTy() ||
1789           !FTy->getParamType(2)->isPointerTy())
1790         return;
1791       setDoesNotThrow(F);
1792       setDoesNotCapture(F, 1);
1793       setDoesNotCapture(F, 3);
1794     } else if (Name == "setitimer") {
1795       if (FTy->getNumParams() != 3 ||
1796           !FTy->getParamType(1)->isPointerTy() ||
1797           !FTy->getParamType(2)->isPointerTy())
1798         return;
1799       setDoesNotThrow(F);
1800       setDoesNotCapture(F, 2);
1801       setDoesNotCapture(F, 3);
1802     } else if (Name == "system") {
1803       if (FTy->getNumParams() != 1 ||
1804           !FTy->getParamType(0)->isPointerTy())
1805         return;
1806       // May throw; "system" is a valid pthread cancellation point.
1807       setDoesNotCapture(F, 1);
1808     }
1809     break;
1810   case 'm':
1811     if (Name == "malloc") {
1812       if (FTy->getNumParams() != 1 ||
1813           !FTy->getReturnType()->isPointerTy())
1814         return;
1815       setDoesNotThrow(F);
1816       setDoesNotAlias(F, 0);
1817     } else if (Name == "memcmp") {
1818       if (FTy->getNumParams() != 3 ||
1819           !FTy->getParamType(0)->isPointerTy() ||
1820           !FTy->getParamType(1)->isPointerTy())
1821         return;
1822       setOnlyReadsMemory(F);
1823       setDoesNotThrow(F);
1824       setDoesNotCapture(F, 1);
1825       setDoesNotCapture(F, 2);
1826     } else if (Name == "memchr" ||
1827                Name == "memrchr") {
1828       if (FTy->getNumParams() != 3)
1829         return;
1830       setOnlyReadsMemory(F);
1831       setDoesNotThrow(F);
1832     } else if (Name == "modf" ||
1833                Name == "modff" ||
1834                Name == "modfl" ||
1835                Name == "memcpy" ||
1836                Name == "memccpy" ||
1837                Name == "memmove") {
1838       if (FTy->getNumParams() < 2 ||
1839           !FTy->getParamType(1)->isPointerTy())
1840         return;
1841       setDoesNotThrow(F);
1842       setDoesNotCapture(F, 2);
1843     } else if (Name == "memalign") {
1844       if (!FTy->getReturnType()->isPointerTy())
1845         return;
1846       setDoesNotAlias(F, 0);
1847     } else if (Name == "mkdir" ||
1848                Name == "mktime") {
1849       if (FTy->getNumParams() == 0 ||
1850           !FTy->getParamType(0)->isPointerTy())
1851         return;
1852       setDoesNotThrow(F);
1853       setDoesNotCapture(F, 1);
1854     }
1855     break;
1856   case 'r':
1857     if (Name == "realloc") {
1858       if (FTy->getNumParams() != 2 ||
1859           !FTy->getParamType(0)->isPointerTy() ||
1860           !FTy->getReturnType()->isPointerTy())
1861         return;
1862       setDoesNotThrow(F);
1863       setDoesNotAlias(F, 0);
1864       setDoesNotCapture(F, 1);
1865     } else if (Name == "read") {
1866       if (FTy->getNumParams() != 3 ||
1867           !FTy->getParamType(1)->isPointerTy())
1868         return;
1869       // May throw; "read" is a valid pthread cancellation point.
1870       setDoesNotCapture(F, 2);
1871     } else if (Name == "rmdir" ||
1872                Name == "rewind" ||
1873                Name == "remove" ||
1874                Name == "realpath") {
1875       if (FTy->getNumParams() < 1 ||
1876           !FTy->getParamType(0)->isPointerTy())
1877         return;
1878       setDoesNotThrow(F);
1879       setDoesNotCapture(F, 1);
1880     } else if (Name == "rename" ||
1881                Name == "readlink") {
1882       if (FTy->getNumParams() < 2 ||
1883           !FTy->getParamType(0)->isPointerTy() ||
1884           !FTy->getParamType(1)->isPointerTy())
1885         return;
1886       setDoesNotThrow(F);
1887       setDoesNotCapture(F, 1);
1888       setDoesNotCapture(F, 2);
1889     }
1890     break;
1891   case 'w':
1892     if (Name == "write") {
1893       if (FTy->getNumParams() != 3 || !FTy->getParamType(1)->isPointerTy())
1894         return;
1895       // May throw; "write" is a valid pthread cancellation point.
1896       setDoesNotCapture(F, 2);
1897     }
1898     break;
1899   case 'b':
1900     if (Name == "bcopy") {
1901       if (FTy->getNumParams() != 3 ||
1902           !FTy->getParamType(0)->isPointerTy() ||
1903           !FTy->getParamType(1)->isPointerTy())
1904         return;
1905       setDoesNotThrow(F);
1906       setDoesNotCapture(F, 1);
1907       setDoesNotCapture(F, 2);
1908     } else if (Name == "bcmp") {
1909       if (FTy->getNumParams() != 3 ||
1910           !FTy->getParamType(0)->isPointerTy() ||
1911           !FTy->getParamType(1)->isPointerTy())
1912         return;
1913       setDoesNotThrow(F);
1914       setOnlyReadsMemory(F);
1915       setDoesNotCapture(F, 1);
1916       setDoesNotCapture(F, 2);
1917     } else if (Name == "bzero") {
1918       if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy())
1919         return;
1920       setDoesNotThrow(F);
1921       setDoesNotCapture(F, 1);
1922     }
1923     break;
1924   case 'c':
1925     if (Name == "calloc") {
1926       if (FTy->getNumParams() != 2 ||
1927           !FTy->getReturnType()->isPointerTy())
1928         return;
1929       setDoesNotThrow(F);
1930       setDoesNotAlias(F, 0);
1931     } else if (Name == "chmod" ||
1932                Name == "chown" ||
1933                Name == "ctermid" ||
1934                Name == "clearerr" ||
1935                Name == "closedir") {
1936       if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
1937         return;
1938       setDoesNotThrow(F);
1939       setDoesNotCapture(F, 1);
1940     }
1941     break;
1942   case 'a':
1943     if (Name == "atoi" ||
1944         Name == "atol" ||
1945         Name == "atof" ||
1946         Name == "atoll") {
1947       if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1948         return;
1949       setDoesNotThrow(F);
1950       setOnlyReadsMemory(F);
1951       setDoesNotCapture(F, 1);
1952     } else if (Name == "access") {
1953       if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy())
1954         return;
1955       setDoesNotThrow(F);
1956       setDoesNotCapture(F, 1);
1957     }
1958     break;
1959   case 'f':
1960     if (Name == "fopen") {
1961       if (FTy->getNumParams() != 2 ||
1962           !FTy->getReturnType()->isPointerTy() ||
1963           !FTy->getParamType(0)->isPointerTy() ||
1964           !FTy->getParamType(1)->isPointerTy())
1965         return;
1966       setDoesNotThrow(F);
1967       setDoesNotAlias(F, 0);
1968       setDoesNotCapture(F, 1);
1969       setDoesNotCapture(F, 2);
1970     } else if (Name == "fdopen") {
1971       if (FTy->getNumParams() != 2 ||
1972           !FTy->getReturnType()->isPointerTy() ||
1973           !FTy->getParamType(1)->isPointerTy())
1974         return;
1975       setDoesNotThrow(F);
1976       setDoesNotAlias(F, 0);
1977       setDoesNotCapture(F, 2);
1978     } else if (Name == "feof" ||
1979                Name == "free" ||
1980                Name == "fseek" ||
1981                Name == "ftell" ||
1982                Name == "fgetc" ||
1983                Name == "fseeko" ||
1984                Name == "ftello" ||
1985                Name == "fileno" ||
1986                Name == "fflush" ||
1987                Name == "fclose" ||
1988                Name == "fsetpos" ||
1989                Name == "flockfile" ||
1990                Name == "funlockfile" ||
1991                Name == "ftrylockfile") {
1992       if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
1993         return;
1994       setDoesNotThrow(F);
1995       setDoesNotCapture(F, 1);
1996     } else if (Name == "ferror") {
1997       if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
1998         return;
1999       setDoesNotThrow(F);
2000       setDoesNotCapture(F, 1);
2001       setOnlyReadsMemory(F);
2002     } else if (Name == "fputc" ||
2003                Name == "fstat" ||
2004                Name == "frexp" ||
2005                Name == "frexpf" ||
2006                Name == "frexpl" ||
2007                Name == "fstatvfs") {
2008       if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
2009         return;
2010       setDoesNotThrow(F);
2011       setDoesNotCapture(F, 2);
2012     } else if (Name == "fgets") {
2013       if (FTy->getNumParams() != 3 ||
2014           !FTy->getParamType(0)->isPointerTy() ||
2015           !FTy->getParamType(2)->isPointerTy())
2016         return;
2017       setDoesNotThrow(F);
2018       setDoesNotCapture(F, 3);
2019     } else if (Name == "fread" ||
2020                Name == "fwrite") {
2021       if (FTy->getNumParams() != 4 ||
2022           !FTy->getParamType(0)->isPointerTy() ||
2023           !FTy->getParamType(3)->isPointerTy())
2024         return;
2025       setDoesNotThrow(F);
2026       setDoesNotCapture(F, 1);
2027       setDoesNotCapture(F, 4);
2028     } else if (Name == "fputs" ||
2029                Name == "fscanf" ||
2030                Name == "fprintf" ||
2031                Name == "fgetpos") {
2032       if (FTy->getNumParams() < 2 ||
2033           !FTy->getParamType(0)->isPointerTy() ||
2034           !FTy->getParamType(1)->isPointerTy())
2035         return;
2036       setDoesNotThrow(F);
2037       setDoesNotCapture(F, 1);
2038       setDoesNotCapture(F, 2);
2039     }
2040     break;
2041   case 'g':
2042     if (Name == "getc" ||
2043         Name == "getlogin_r" ||
2044         Name == "getc_unlocked") {
2045       if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
2046         return;
2047       setDoesNotThrow(F);
2048       setDoesNotCapture(F, 1);
2049     } else if (Name == "getenv") {
2050       if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
2051         return;
2052       setDoesNotThrow(F);
2053       setOnlyReadsMemory(F);
2054       setDoesNotCapture(F, 1);
2055     } else if (Name == "gets" ||
2056                Name == "getchar") {
2057       setDoesNotThrow(F);
2058     } else if (Name == "getitimer") {
2059       if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
2060         return;
2061       setDoesNotThrow(F);
2062       setDoesNotCapture(F, 2);
2063     } else if (Name == "getpwnam") {
2064       if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
2065         return;
2066       setDoesNotThrow(F);
2067       setDoesNotCapture(F, 1);
2068     }
2069     break;
2070   case 'u':
2071     if (Name == "ungetc") {
2072       if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
2073         return;
2074       setDoesNotThrow(F);
2075       setDoesNotCapture(F, 2);
2076     } else if (Name == "uname" ||
2077                Name == "unlink" ||
2078                Name == "unsetenv") {
2079       if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
2080         return;
2081       setDoesNotThrow(F);
2082       setDoesNotCapture(F, 1);
2083     } else if (Name == "utime" ||
2084                Name == "utimes") {
2085       if (FTy->getNumParams() != 2 ||
2086           !FTy->getParamType(0)->isPointerTy() ||
2087           !FTy->getParamType(1)->isPointerTy())
2088         return;
2089       setDoesNotThrow(F);
2090       setDoesNotCapture(F, 1);
2091       setDoesNotCapture(F, 2);
2092     }
2093     break;
2094   case 'p':
2095     if (Name == "putc") {
2096       if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
2097         return;
2098       setDoesNotThrow(F);
2099       setDoesNotCapture(F, 2);
2100     } else if (Name == "puts" ||
2101                Name == "printf" ||
2102                Name == "perror") {
2103       if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
2104         return;
2105       setDoesNotThrow(F);
2106       setDoesNotCapture(F, 1);
2107     } else if (Name == "pread" ||
2108                Name == "pwrite") {
2109       if (FTy->getNumParams() != 4 || !FTy->getParamType(1)->isPointerTy())
2110         return;
2111       // May throw; these are valid pthread cancellation points.
2112       setDoesNotCapture(F, 2);
2113     } else if (Name == "putchar") {
2114       setDoesNotThrow(F);
2115     } else if (Name == "popen") {
2116       if (FTy->getNumParams() != 2 ||
2117           !FTy->getReturnType()->isPointerTy() ||
2118           !FTy->getParamType(0)->isPointerTy() ||
2119           !FTy->getParamType(1)->isPointerTy())
2120         return;
2121       setDoesNotThrow(F);
2122       setDoesNotAlias(F, 0);
2123       setDoesNotCapture(F, 1);
2124       setDoesNotCapture(F, 2);
2125     } else if (Name == "pclose") {
2126       if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
2127         return;
2128       setDoesNotThrow(F);
2129       setDoesNotCapture(F, 1);
2130     }
2131     break;
2132   case 'v':
2133     if (Name == "vscanf") {
2134       if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
2135         return;
2136       setDoesNotThrow(F);
2137       setDoesNotCapture(F, 1);
2138     } else if (Name == "vsscanf" ||
2139                Name == "vfscanf") {
2140       if (FTy->getNumParams() != 3 ||
2141           !FTy->getParamType(1)->isPointerTy() ||
2142           !FTy->getParamType(2)->isPointerTy())
2143         return;
2144       setDoesNotThrow(F);
2145       setDoesNotCapture(F, 1);
2146       setDoesNotCapture(F, 2);
2147     } else if (Name == "valloc") {
2148       if (!FTy->getReturnType()->isPointerTy())
2149         return;
2150       setDoesNotThrow(F);
2151       setDoesNotAlias(F, 0);
2152     } else if (Name == "vprintf") {
2153       if (FTy->getNumParams() != 2 || !FTy->getParamType(0)->isPointerTy())
2154         return;
2155       setDoesNotThrow(F);
2156       setDoesNotCapture(F, 1);
2157     } else if (Name == "vfprintf" ||
2158                Name == "vsprintf") {
2159       if (FTy->getNumParams() != 3 ||
2160           !FTy->getParamType(0)->isPointerTy() ||
2161           !FTy->getParamType(1)->isPointerTy())
2162         return;
2163       setDoesNotThrow(F);
2164       setDoesNotCapture(F, 1);
2165       setDoesNotCapture(F, 2);
2166     } else if (Name == "vsnprintf") {
2167       if (FTy->getNumParams() != 4 ||
2168           !FTy->getParamType(0)->isPointerTy() ||
2169           !FTy->getParamType(2)->isPointerTy())
2170         return;
2171       setDoesNotThrow(F);
2172       setDoesNotCapture(F, 1);
2173       setDoesNotCapture(F, 3);
2174     }
2175     break;
2176   case 'o':
2177     if (Name == "open") {
2178       if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy())
2179         return;
2180       // May throw; "open" is a valid pthread cancellation point.
2181       setDoesNotCapture(F, 1);
2182     } else if (Name == "opendir") {
2183       if (FTy->getNumParams() != 1 ||
2184           !FTy->getReturnType()->isPointerTy() ||
2185           !FTy->getParamType(0)->isPointerTy())
2186         return;
2187       setDoesNotThrow(F);
2188       setDoesNotAlias(F, 0);
2189       setDoesNotCapture(F, 1);
2190     }
2191     break;
2192   case 't':
2193     if (Name == "tmpfile") {
2194       if (!FTy->getReturnType()->isPointerTy())
2195         return;
2196       setDoesNotThrow(F);
2197       setDoesNotAlias(F, 0);
2198     } else if (Name == "times") {
2199       if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
2200         return;
2201       setDoesNotThrow(F);
2202       setDoesNotCapture(F, 1);
2203     }
2204     break;
2205   case 'h':
2206     if (Name == "htonl" ||
2207         Name == "htons") {
2208       setDoesNotThrow(F);
2209       setDoesNotAccessMemory(F);
2210     }
2211     break;
2212   case 'n':
2213     if (Name == "ntohl" ||
2214         Name == "ntohs") {
2215       setDoesNotThrow(F);
2216       setDoesNotAccessMemory(F);
2217     }
2218     break;
2219   case 'l':
2220     if (Name == "lstat") {
2221       if (FTy->getNumParams() != 2 ||
2222           !FTy->getParamType(0)->isPointerTy() ||
2223           !FTy->getParamType(1)->isPointerTy())
2224         return;
2225       setDoesNotThrow(F);
2226       setDoesNotCapture(F, 1);
2227       setDoesNotCapture(F, 2);
2228     } else if (Name == "lchown") {
2229       if (FTy->getNumParams() != 3 || !FTy->getParamType(0)->isPointerTy())
2230         return;
2231       setDoesNotThrow(F);
2232       setDoesNotCapture(F, 1);
2233     }
2234     break;
2235   case 'q':
2236     if (Name == "qsort") {
2237       if (FTy->getNumParams() != 4 || !FTy->getParamType(3)->isPointerTy())
2238         return;
2239       // May throw; places call through function pointer.
2240       setDoesNotCapture(F, 4);
2241     }
2242     break;
2243   case '_':
2244     if (Name == "__strdup" ||
2245         Name == "__strndup") {
2246       if (FTy->getNumParams() < 1 ||
2247           !FTy->getReturnType()->isPointerTy() ||
2248           !FTy->getParamType(0)->isPointerTy())
2249         return;
2250       setDoesNotThrow(F);
2251       setDoesNotAlias(F, 0);
2252       setDoesNotCapture(F, 1);
2253     } else if (Name == "__strtok_r") {
2254       if (FTy->getNumParams() != 3 ||
2255           !FTy->getParamType(1)->isPointerTy())
2256         return;
2257       setDoesNotThrow(F);
2258       setDoesNotCapture(F, 2);
2259     } else if (Name == "_IO_getc") {
2260       if (FTy->getNumParams() != 1 || !FTy->getParamType(0)->isPointerTy())
2261         return;
2262       setDoesNotThrow(F);
2263       setDoesNotCapture(F, 1);
2264     } else if (Name == "_IO_putc") {
2265       if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
2266         return;
2267       setDoesNotThrow(F);
2268       setDoesNotCapture(F, 2);
2269     }
2270     break;
2271   case 1:
2272     if (Name == "\1__isoc99_scanf") {
2273       if (FTy->getNumParams() < 1 ||
2274           !FTy->getParamType(0)->isPointerTy())
2275         return;
2276       setDoesNotThrow(F);
2277       setDoesNotCapture(F, 1);
2278     } else if (Name == "\1stat64" ||
2279                Name == "\1lstat64" ||
2280                Name == "\1statvfs64" ||
2281                Name == "\1__isoc99_sscanf") {
2282       if (FTy->getNumParams() < 1 ||
2283           !FTy->getParamType(0)->isPointerTy() ||
2284           !FTy->getParamType(1)->isPointerTy())
2285         return;
2286       setDoesNotThrow(F);
2287       setDoesNotCapture(F, 1);
2288       setDoesNotCapture(F, 2);
2289     } else if (Name == "\1fopen64") {
2290       if (FTy->getNumParams() != 2 ||
2291           !FTy->getReturnType()->isPointerTy() ||
2292           !FTy->getParamType(0)->isPointerTy() ||
2293           !FTy->getParamType(1)->isPointerTy())
2294         return;
2295       setDoesNotThrow(F);
2296       setDoesNotAlias(F, 0);
2297       setDoesNotCapture(F, 1);
2298       setDoesNotCapture(F, 2);
2299     } else if (Name == "\1fseeko64" ||
2300                Name == "\1ftello64") {
2301       if (FTy->getNumParams() == 0 || !FTy->getParamType(0)->isPointerTy())
2302         return;
2303       setDoesNotThrow(F);
2304       setDoesNotCapture(F, 1);
2305     } else if (Name == "\1tmpfile64") {
2306       if (!FTy->getReturnType()->isPointerTy())
2307         return;
2308       setDoesNotThrow(F);
2309       setDoesNotAlias(F, 0);
2310     } else if (Name == "\1fstat64" ||
2311                Name == "\1fstatvfs64") {
2312       if (FTy->getNumParams() != 2 || !FTy->getParamType(1)->isPointerTy())
2313         return;
2314       setDoesNotThrow(F);
2315       setDoesNotCapture(F, 2);
2316     } else if (Name == "\1open64") {
2317       if (FTy->getNumParams() < 2 || !FTy->getParamType(0)->isPointerTy())
2318         return;
2319       // May throw; "open" is a valid pthread cancellation point.
2320       setDoesNotCapture(F, 1);
2321     }
2322     break;
2323   }
2324 }
2325
2326 /// doInitialization - Add attributes to well-known functions.
2327 ///
2328 bool SimplifyLibCalls::doInitialization(Module &M) {
2329   Modified = false;
2330   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
2331     Function &F = *I;
2332     if (F.isDeclaration() && F.hasName())
2333       inferPrototypeAttributes(F);
2334   }
2335   return Modified;
2336 }
2337
2338 // TODO:
2339 //   Additional cases that we need to add to this file:
2340 //
2341 // cbrt:
2342 //   * cbrt(expN(X))  -> expN(x/3)
2343 //   * cbrt(sqrt(x))  -> pow(x,1/6)
2344 //   * cbrt(sqrt(x))  -> pow(x,1/9)
2345 //
2346 // cos, cosf, cosl:
2347 //   * cos(-x)  -> cos(x)
2348 //
2349 // exp, expf, expl:
2350 //   * exp(log(x))  -> x
2351 //
2352 // log, logf, logl:
2353 //   * log(exp(x))   -> x
2354 //   * log(x**y)     -> y*log(x)
2355 //   * log(exp(y))   -> y*log(e)
2356 //   * log(exp2(y))  -> y*log(2)
2357 //   * log(exp10(y)) -> y*log(10)
2358 //   * log(sqrt(x))  -> 0.5*log(x)
2359 //   * log(pow(x,y)) -> y*log(x)
2360 //
2361 // lround, lroundf, lroundl:
2362 //   * lround(cnst) -> cnst'
2363 //
2364 // pow, powf, powl:
2365 //   * pow(exp(x),y)  -> exp(x*y)
2366 //   * pow(sqrt(x),y) -> pow(x,y*0.5)
2367 //   * pow(pow(x,y),z)-> pow(x,y*z)
2368 //
2369 // round, roundf, roundl:
2370 //   * round(cnst) -> cnst'
2371 //
2372 // signbit:
2373 //   * signbit(cnst) -> cnst'
2374 //   * signbit(nncst) -> 0 (if pstv is a non-negative constant)
2375 //
2376 // sqrt, sqrtf, sqrtl:
2377 //   * sqrt(expN(x))  -> expN(x*0.5)
2378 //   * sqrt(Nroot(x)) -> pow(x,1/(2*N))
2379 //   * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
2380 //
2381 // stpcpy:
2382 //   * stpcpy(str, "literal") ->
2383 //           llvm.memcpy(str,"literal",strlen("literal")+1,1)
2384 //
2385 // tan, tanf, tanl:
2386 //   * tan(atan(x)) -> x
2387 //
2388 // trunc, truncf, truncl:
2389 //   * trunc(cnst) -> cnst'
2390 //
2391 //