lib/Transforms/Utils/BuildLibCalls.cpp

   1 //===- BuildLibCalls.cpp - Utility builder for libcalls -------------------===//
   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 some functions that will create standard C libcalls.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Transforms/Utils/BuildLibCalls.h"
  15 #include "llvm/Type.h"
  16 #include "llvm/Constants.h"
  17 #include "llvm/Function.h"
  18 #include "llvm/Module.h"
  19 #include "llvm/Support/IRBuilder.h"
  20 #include "llvm/Target/TargetData.h"
  21 #include "llvm/LLVMContext.h"
  22 #include "llvm/Intrinsics.h"
  23
  24 using namespace llvm;
  25
  26 /// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*.
  27 Value *llvm::CastToCStr(Value *V, IRBuilder<> &B) {
  28   return B.CreateBitCast(V, B.getInt8PtrTy(), "cstr");
  29 }
  30
  31 /// EmitStrLen - Emit a call to the strlen function to the builder, for the
  32 /// specified pointer.  This always returns an integer value of size intptr_t.
  33 Value *llvm::EmitStrLen(Value *Ptr, IRBuilder<> &B, const TargetData *TD) {
  34   Module *M = B.GetInsertBlock()->getParent()->getParent();
  35   AttributeWithIndex AWI[2];
  36   AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
  37   AWI[1] = AttributeWithIndex::get(~0u, Attribute::ReadOnly |
  38                                    Attribute::NoUnwind);
  39
  40   LLVMContext &Context = B.GetInsertBlock()->getContext();
  41   Constant *StrLen = M->getOrInsertFunction("strlen", AttrListPtr::get(AWI, 2),
  42                                             TD->getIntPtrType(Context),
  43                                             B.getInt8PtrTy(),
  44                                             NULL);
  45   CallInst *CI = B.CreateCall(StrLen, CastToCStr(Ptr, B), "strlen");
  46   if (const Function *F = dyn_cast<Function>(StrLen->stripPointerCasts()))
  47     CI->setCallingConv(F->getCallingConv());
  48
  49   return CI;
  50 }
  51
  52 /// EmitStrChr - Emit a call to the strchr function to the builder, for the
  53 /// specified pointer and character.  Ptr is required to be some pointer type,
  54 /// and the return value has 'i8*' type.
  55 Value *llvm::EmitStrChr(Value *Ptr, char C, IRBuilder<> &B,
  56                         const TargetData *TD) {
  57   Module *M = B.GetInsertBlock()->getParent()->getParent();
  58   AttributeWithIndex AWI =
  59     AttributeWithIndex::get(~0u, Attribute::ReadOnly | Attribute::NoUnwind);
  60
  61   const Type *I8Ptr = B.getInt8PtrTy();
  62   const Type *I32Ty = B.getInt32Ty();
  63   Constant *StrChr = M->getOrInsertFunction("strchr", AttrListPtr::get(&AWI, 1),
  64                                             I8Ptr, I8Ptr, I32Ty, NULL);
  65   CallInst *CI = B.CreateCall2(StrChr, CastToCStr(Ptr, B),
  66                                ConstantInt::get(I32Ty, C), "strchr");
  67   if (const Function *F = dyn_cast<Function>(StrChr->stripPointerCasts()))
  68     CI->setCallingConv(F->getCallingConv());
  69   return CI;
  70 }
  71
  72 /// EmitStrNCmp - Emit a call to the strncmp function to the builder.
  73 Value *llvm::EmitStrNCmp(Value *Ptr1, Value *Ptr2, Value *Len,
  74                          IRBuilder<> &B, const TargetData *TD) {
  75   Module *M = B.GetInsertBlock()->getParent()->getParent();
  76   AttributeWithIndex AWI[3];
  77   AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
  78   AWI[1] = AttributeWithIndex::get(2, Attribute::NoCapture);
  79   AWI[2] = AttributeWithIndex::get(~0u, Attribute::ReadOnly |
  80                                    Attribute::NoUnwind);
  81
  82   LLVMContext &Context = B.GetInsertBlock()->getContext();
  83   Value *StrNCmp = M->getOrInsertFunction("strncmp", AttrListPtr::get(AWI, 3),
  84                                           B.getInt32Ty(),
  85                                           B.getInt8PtrTy(),
  86                                           B.getInt8PtrTy(),
  87                                           TD->getIntPtrType(Context), NULL);
  88   CallInst *CI = B.CreateCall3(StrNCmp, CastToCStr(Ptr1, B),
  89                                CastToCStr(Ptr2, B), Len, "strncmp");
  90
  91   if (const Function *F = dyn_cast<Function>(StrNCmp->stripPointerCasts()))
  92     CI->setCallingConv(F->getCallingConv());
  93
  94   return CI;
  95 }
  96
  97 /// EmitStrCpy - Emit a call to the strcpy function to the builder, for the
  98 /// specified pointer arguments.
  99 Value *llvm::EmitStrCpy(Value *Dst, Value *Src, IRBuilder<> &B,
 100                         const TargetData *TD, StringRef Name) {
 101   Module *M = B.GetInsertBlock()->getParent()->getParent();
 102   AttributeWithIndex AWI[2];
 103   AWI[0] = AttributeWithIndex::get(2, Attribute::NoCapture);
 104   AWI[1] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
 105   const Type *I8Ptr = B.getInt8PtrTy();
 106   Value *StrCpy = M->getOrInsertFunction(Name, AttrListPtr::get(AWI, 2),
 107                                          I8Ptr, I8Ptr, I8Ptr, NULL);
 108   CallInst *CI = B.CreateCall2(StrCpy, CastToCStr(Dst, B), CastToCStr(Src, B),
 109                                Name);
 110   if (const Function *F = dyn_cast<Function>(StrCpy->stripPointerCasts()))
 111     CI->setCallingConv(F->getCallingConv());
 112   return CI;
 113 }
 114
 115 /// EmitStrNCpy - Emit a call to the strncpy function to the builder, for the
 116 /// specified pointer arguments.
 117 Value *llvm::EmitStrNCpy(Value *Dst, Value *Src, Value *Len,
 118                          IRBuilder<> &B, const TargetData *TD, StringRef Name) {
 119   Module *M = B.GetInsertBlock()->getParent()->getParent();
 120   AttributeWithIndex AWI[2];
 121   AWI[0] = AttributeWithIndex::get(2, Attribute::NoCapture);
 122   AWI[1] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
 123   const Type *I8Ptr = B.getInt8PtrTy();
 124   Value *StrNCpy = M->getOrInsertFunction(Name, AttrListPtr::get(AWI, 2),
 125                                           I8Ptr, I8Ptr, I8Ptr,
 126                                           Len->getType(), NULL);
 127   CallInst *CI = B.CreateCall3(StrNCpy, CastToCStr(Dst, B), CastToCStr(Src, B),
 128                                Len, "strncpy");
 129   if (const Function *F = dyn_cast<Function>(StrNCpy->stripPointerCasts()))
 130     CI->setCallingConv(F->getCallingConv());
 131   return CI;
 132 }
 133
 134 /// EmitMemCpyChk - Emit a call to the __memcpy_chk function to the builder.
 135 /// This expects that the Len and ObjSize have type 'intptr_t' and Dst/Src
 136 /// are pointers.
 137 Value *llvm::EmitMemCpyChk(Value *Dst, Value *Src, Value *Len, Value *ObjSize,
 138                            IRBuilder<> &B, const TargetData *TD) {
 139   Module *M = B.GetInsertBlock()->getParent()->getParent();
 140   AttributeWithIndex AWI;
 141   AWI = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
 142   LLVMContext &Context = B.GetInsertBlock()->getContext();
 143   Value *MemCpy = M->getOrInsertFunction("__memcpy_chk",
 144                                          AttrListPtr::get(&AWI, 1),
 145                                          B.getInt8PtrTy(),
 146                                          B.getInt8PtrTy(),
 147                                          B.getInt8PtrTy(),
 148                                          TD->getIntPtrType(Context),
 149                                          TD->getIntPtrType(Context), NULL);
 150   Dst = CastToCStr(Dst, B);
 151   Src = CastToCStr(Src, B);
 152   CallInst *CI = B.CreateCall4(MemCpy, Dst, Src, Len, ObjSize);
 153   if (const Function *F = dyn_cast<Function>(MemCpy->stripPointerCasts()))
 154     CI->setCallingConv(F->getCallingConv());
 155   return CI;
 156 }
 157
 158 /// EmitMemChr - Emit a call to the memchr function.  This assumes that Ptr is
 159 /// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
 160 Value *llvm::EmitMemChr(Value *Ptr, Value *Val,
 161                         Value *Len, IRBuilder<> &B, const TargetData *TD) {
 162   Module *M = B.GetInsertBlock()->getParent()->getParent();
 163   AttributeWithIndex AWI;
 164   AWI = AttributeWithIndex::get(~0u, Attribute::ReadOnly | Attribute::NoUnwind);
 165   LLVMContext &Context = B.GetInsertBlock()->getContext();
 166   Value *MemChr = M->getOrInsertFunction("memchr", AttrListPtr::get(&AWI, 1),
 167                                          B.getInt8PtrTy(),
 168                                          B.getInt8PtrTy(),
 169                                          B.getInt32Ty(),
 170                                          TD->getIntPtrType(Context),
 171                                          NULL);
 172   CallInst *CI = B.CreateCall3(MemChr, CastToCStr(Ptr, B), Val, Len, "memchr");
 173
 174   if (const Function *F = dyn_cast<Function>(MemChr->stripPointerCasts()))
 175     CI->setCallingConv(F->getCallingConv());
 176
 177   return CI;
 178 }
 179
 180 /// EmitMemCmp - Emit a call to the memcmp function.
 181 Value *llvm::EmitMemCmp(Value *Ptr1, Value *Ptr2,
 182                         Value *Len, IRBuilder<> &B, const TargetData *TD) {
 183   Module *M = B.GetInsertBlock()->getParent()->getParent();
 184   AttributeWithIndex AWI[3];
 185   AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
 186   AWI[1] = AttributeWithIndex::get(2, Attribute::NoCapture);
 187   AWI[2] = AttributeWithIndex::get(~0u, Attribute::ReadOnly |
 188                                    Attribute::NoUnwind);
 189
 190   LLVMContext &Context = B.GetInsertBlock()->getContext();
 191   Value *MemCmp = M->getOrInsertFunction("memcmp", AttrListPtr::get(AWI, 3),
 192                                          B.getInt32Ty(),
 193                                          B.getInt8PtrTy(),
 194                                          B.getInt8PtrTy(),
 195                                          TD->getIntPtrType(Context), NULL);
 196   CallInst *CI = B.CreateCall3(MemCmp, CastToCStr(Ptr1, B), CastToCStr(Ptr2, B),
 197                                Len, "memcmp");
 198
 199   if (const Function *F = dyn_cast<Function>(MemCmp->stripPointerCasts()))
 200     CI->setCallingConv(F->getCallingConv());
 201
 202   return CI;
 203 }
 204
 205 /// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g.
 206 /// 'floor').  This function is known to take a single of type matching 'Op' and
 207 /// returns one value with the same type.  If 'Op' is a long double, 'l' is
 208 /// added as the suffix of name, if 'Op' is a float, we add a 'f' suffix.
 209 Value *llvm::EmitUnaryFloatFnCall(Value *Op, const char *Name,
 210                                   IRBuilder<> &B, const AttrListPtr &Attrs) {
 211   char NameBuffer[20];
 212   if (!Op->getType()->isDoubleTy()) {
 213     // If we need to add a suffix, copy into NameBuffer.
 214     unsigned NameLen = strlen(Name);
 215     assert(NameLen < sizeof(NameBuffer)-2);
 216     memcpy(NameBuffer, Name, NameLen);
 217     if (Op->getType()->isFloatTy())
 218       NameBuffer[NameLen] = 'f';  // floorf
 219     else
 220       NameBuffer[NameLen] = 'l';  // floorl
 221     NameBuffer[NameLen+1] = 0;
 222     Name = NameBuffer;
 223   }
 224
 225   Module *M = B.GetInsertBlock()->getParent()->getParent();
 226   Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
 227                                          Op->getType(), NULL);
 228   CallInst *CI = B.CreateCall(Callee, Op, Name);
 229   CI->setAttributes(Attrs);
 230   if (const Function *F = dyn_cast<Function>(Callee->stripPointerCasts()))
 231     CI->setCallingConv(F->getCallingConv());
 232
 233   return CI;
 234 }
 235
 236 /// EmitPutChar - Emit a call to the putchar function.  This assumes that Char
 237 /// is an integer.
 238 Value *llvm::EmitPutChar(Value *Char, IRBuilder<> &B, const TargetData *TD) {
 239   Module *M = B.GetInsertBlock()->getParent()->getParent();
 240   Value *PutChar = M->getOrInsertFunction("putchar", B.getInt32Ty(),
 241                                           B.getInt32Ty(), NULL);
 242   CallInst *CI = B.CreateCall(PutChar,
 243                               B.CreateIntCast(Char,
 244                               B.getInt32Ty(),
 245                               /*isSigned*/true,
 246                               "chari"),
 247                               "putchar");
 248
 249   if (const Function *F = dyn_cast<Function>(PutChar->stripPointerCasts()))
 250     CI->setCallingConv(F->getCallingConv());
 251   return CI;
 252 }
 253
 254 /// EmitPutS - Emit a call to the puts function.  This assumes that Str is
 255 /// some pointer.
 256 void llvm::EmitPutS(Value *Str, IRBuilder<> &B, const TargetData *TD) {
 257   Module *M = B.GetInsertBlock()->getParent()->getParent();
 258   AttributeWithIndex AWI[2];
 259   AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
 260   AWI[1] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
 261
 262   Value *PutS = M->getOrInsertFunction("puts", AttrListPtr::get(AWI, 2),
 263                                        B.getInt32Ty(),
 264                                        B.getInt8PtrTy(),
 265                                        NULL);
 266   CallInst *CI = B.CreateCall(PutS, CastToCStr(Str, B), "puts");
 267   if (const Function *F = dyn_cast<Function>(PutS->stripPointerCasts()))
 268     CI->setCallingConv(F->getCallingConv());
 269
 270 }
 271
 272 /// EmitFPutC - Emit a call to the fputc function.  This assumes that Char is
 273 /// an integer and File is a pointer to FILE.
 274 void llvm::EmitFPutC(Value *Char, Value *File, IRBuilder<> &B,
 275                      const TargetData *TD) {
 276   Module *M = B.GetInsertBlock()->getParent()->getParent();
 277   AttributeWithIndex AWI[2];
 278   AWI[0] = AttributeWithIndex::get(2, Attribute::NoCapture);
 279   AWI[1] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
 280   Constant *F;
 281   if (File->getType()->isPointerTy())
 282     F = M->getOrInsertFunction("fputc", AttrListPtr::get(AWI, 2),
 283                                B.getInt32Ty(),
 284                                B.getInt32Ty(), File->getType(),
 285                                NULL);
 286   else
 287     F = M->getOrInsertFunction("fputc",
 288                                B.getInt32Ty(),
 289                                B.getInt32Ty(),
 290                                File->getType(), NULL);
 291   Char = B.CreateIntCast(Char, B.getInt32Ty(), /*isSigned*/true,
 292                          "chari");
 293   CallInst *CI = B.CreateCall2(F, Char, File, "fputc");
 294
 295   if (const Function *Fn = dyn_cast<Function>(F->stripPointerCasts()))
 296     CI->setCallingConv(Fn->getCallingConv());
 297 }
 298
 299 /// EmitFPutS - Emit a call to the puts function.  Str is required to be a
 300 /// pointer and File is a pointer to FILE.
 301 void llvm::EmitFPutS(Value *Str, Value *File, IRBuilder<> &B,
 302                      const TargetData *TD) {
 303   Module *M = B.GetInsertBlock()->getParent()->getParent();
 304   AttributeWithIndex AWI[3];
 305   AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
 306   AWI[1] = AttributeWithIndex::get(2, Attribute::NoCapture);
 307   AWI[2] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
 308   Constant *F;
 309   if (File->getType()->isPointerTy())
 310     F = M->getOrInsertFunction("fputs", AttrListPtr::get(AWI, 3),
 311                                B.getInt32Ty(),
 312                                B.getInt8PtrTy(),
 313                                File->getType(), NULL);
 314   else
 315     F = M->getOrInsertFunction("fputs", B.getInt32Ty(),
 316                                B.getInt8PtrTy(),
 317                                File->getType(), NULL);
 318   CallInst *CI = B.CreateCall2(F, CastToCStr(Str, B), File, "fputs");
 319
 320   if (const Function *Fn = dyn_cast<Function>(F->stripPointerCasts()))
 321     CI->setCallingConv(Fn->getCallingConv());
 322 }
 323
 324 /// EmitFWrite - Emit a call to the fwrite function.  This assumes that Ptr is
 325 /// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
 326 void llvm::EmitFWrite(Value *Ptr, Value *Size, Value *File,
 327                       IRBuilder<> &B, const TargetData *TD) {
 328   Module *M = B.GetInsertBlock()->getParent()->getParent();
 329   AttributeWithIndex AWI[3];
 330   AWI[0] = AttributeWithIndex::get(1, Attribute::NoCapture);
 331   AWI[1] = AttributeWithIndex::get(4, Attribute::NoCapture);
 332   AWI[2] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
 333   LLVMContext &Context = B.GetInsertBlock()->getContext();
 334   Constant *F;
 335   if (File->getType()->isPointerTy())
 336     F = M->getOrInsertFunction("fwrite", AttrListPtr::get(AWI, 3),
 337                                TD->getIntPtrType(Context),
 338                                B.getInt8PtrTy(),
 339                                TD->getIntPtrType(Context),
 340                                TD->getIntPtrType(Context),
 341                                File->getType(), NULL);
 342   else
 343     F = M->getOrInsertFunction("fwrite", TD->getIntPtrType(Context),
 344                                B.getInt8PtrTy(),
 345                                TD->getIntPtrType(Context),
 346                                TD->getIntPtrType(Context),
 347                                File->getType(), NULL);
 348   CallInst *CI = B.CreateCall4(F, CastToCStr(Ptr, B), Size,
 349                         ConstantInt::get(TD->getIntPtrType(Context), 1), File);
 350
 351   if (const Function *Fn = dyn_cast<Function>(F->stripPointerCasts()))
 352     CI->setCallingConv(Fn->getCallingConv());
 353 }
 354
 355 SimplifyFortifiedLibCalls::~SimplifyFortifiedLibCalls() { }
 356
 357 bool SimplifyFortifiedLibCalls::fold(CallInst *CI, const TargetData *TD) {
 358   // We really need TargetData for later.
 359   if (!TD) return false;
 360
 361   this->CI = CI;
 362   Function *Callee = CI->getCalledFunction();
 363   StringRef Name = Callee->getName();
 364   const FunctionType *FT = Callee->getFunctionType();
 365   BasicBlock *BB = CI->getParent();
 366   LLVMContext &Context = CI->getParent()->getContext();
 367   IRBuilder<> B(Context);
 368
 369   // Set the builder to the instruction after the call.
 370   B.SetInsertPoint(BB, CI);
 371
 372   if (Name == "__memcpy_chk") {
 373     // Check if this has the right signature.
 374     if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
 375         !FT->getParamType(0)->isPointerTy() ||
 376         !FT->getParamType(1)->isPointerTy() ||
 377         FT->getParamType(2) != TD->getIntPtrType(Context) ||
 378         FT->getParamType(3) != TD->getIntPtrType(Context))
 379       return false;
 380
 381     if (isFoldable(3, 2, false)) {
 382       B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
 383                      CI->getArgOperand(2), 1);
 384       replaceCall(CI->getArgOperand(0));
 385       return true;
 386     }
 387     return false;
 388   }
 389
 390   // Should be similar to memcpy.
 391   if (Name == "__mempcpy_chk") {
 392     return false;
 393   }
 394
 395   if (Name == "__memmove_chk") {
 396     // Check if this has the right signature.
 397     if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
 398         !FT->getParamType(0)->isPointerTy() ||
 399         !FT->getParamType(1)->isPointerTy() ||
 400         FT->getParamType(2) != TD->getIntPtrType(Context) ||
 401         FT->getParamType(3) != TD->getIntPtrType(Context))
 402       return false;
 403
 404     if (isFoldable(3, 2, false)) {
 405       B.CreateMemMove(CI->getArgOperand(0), CI->getArgOperand(1),
 406                       CI->getArgOperand(2), 1);
 407       replaceCall(CI->getArgOperand(0));
 408       return true;
 409     }
 410     return false;
 411   }
 412
 413   if (Name == "__memset_chk") {
 414     // Check if this has the right signature.
 415     if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
 416         !FT->getParamType(0)->isPointerTy() ||
 417         !FT->getParamType(1)->isIntegerTy() ||
 418         FT->getParamType(2) != TD->getIntPtrType(Context) ||
 419         FT->getParamType(3) != TD->getIntPtrType(Context))
 420       return false;
 421
 422     if (isFoldable(3, 2, false)) {
 423       Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(),
 424                                    false);
 425       B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1);
 426       replaceCall(CI->getArgOperand(0));
 427       return true;
 428     }
 429     return false;
 430   }
 431
 432   if (Name == "__strcpy_chk" || Name == "__stpcpy_chk") {
 433     // Check if this has the right signature.
 434     if (FT->getNumParams() != 3 ||
 435         FT->getReturnType() != FT->getParamType(0) ||
 436         FT->getParamType(0) != FT->getParamType(1) ||
 437         FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
 438         FT->getParamType(2) != TD->getIntPtrType(Context))
 439       return 0;
 440
 441
 442     // If a) we don't have any length information, or b) we know this will
 443     // fit then just lower to a plain st[rp]cpy. Otherwise we'll keep our
 444     // st[rp]cpy_chk call which may fail at runtime if the size is too long.
 445     // TODO: It might be nice to get a maximum length out of the possible
 446     // string lengths for varying.
 447     if (isFoldable(2, 1, true)) {
 448       Value *Ret = EmitStrCpy(CI->getArgOperand(0), CI->getArgOperand(1), B, TD,
 449                               Name.substr(2, 6));
 450       replaceCall(Ret);
 451       return true;
 452     }
 453     return false;
 454   }
 455
 456   if (Name == "__strncpy_chk" || Name == "__stpncpy_chk") {
 457     // Check if this has the right signature.
 458     if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
 459         FT->getParamType(0) != FT->getParamType(1) ||
 460         FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
 461         !FT->getParamType(2)->isIntegerTy() ||
 462         FT->getParamType(3) != TD->getIntPtrType(Context))
 463       return false;
 464
 465     if (isFoldable(3, 2, false)) {
 466       Value *Ret = EmitStrNCpy(CI->getArgOperand(0), CI->getArgOperand(1),
 467                                CI->getArgOperand(2), B, TD, Name.substr(2, 7));
 468       replaceCall(Ret);
 469       return true;
 470     }
 471     return false;
 472   }
 473
 474   if (Name == "__strcat_chk") {
 475     return false;
 476   }
 477
 478   if (Name == "__strncat_chk") {
 479     return false;
 480   }
 481
 482   return false;
 483 }