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/Constants.h"
16 #include "llvm/Function.h"
17 #include "llvm/IRBuilder.h"
18 #include "llvm/Intrinsics.h"
19 #include "llvm/Intrinsics.h"
20 #include "llvm/LLVMContext.h"
21 #include "llvm/LLVMContext.h"
22 #include "llvm/Module.h"
23 #include "llvm/Type.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/DataLayout.h"
26 #include "llvm/Target/TargetLibraryInfo.h"
27 
28 using namespace llvm;
29 
30 /// CastToCStr - Return V if it is an i8*, otherwise cast it to i8*.
31 Value *llvm::CastToCStr(Value *V, IRBuilder<> &B) {
32   return B.CreateBitCast(V, B.getInt8PtrTy(), "cstr");
33 }
34 
35 /// EmitStrLen - Emit a call to the strlen function to the builder, for the
36 /// specified pointer.  This always returns an integer value of size intptr_t.
37 Value *llvm::EmitStrLen(Value *Ptr, IRBuilder<> &B, const DataLayout *TD,
38                         const TargetLibraryInfo *TLI) {
39   if (!TLI->has(LibFunc::strlen))
40     return 0;
41 
42   Module *M = B.GetInsertBlock()->getParent()->getParent();
43   AttributeWithIndex AWI[2];
44   AWI[0] = AttributeWithIndex::get(M->getContext(), 1, Attributes::NoCapture);
45   Attributes::AttrVal AVs[2] = { Attributes::ReadOnly, Attributes::NoUnwind };
46   AWI[1] = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
47                                    ArrayRef<Attributes::AttrVal>(AVs, 2));
48 
49   Constant *StrLen = M->getOrInsertFunction("strlen", AttrListPtr::get(AWI),
50                                             TD->getIntPtrType(Ptr->getType()),
51                                             B.getInt8PtrTy(),
52                                             NULL);
53   CallInst *CI = B.CreateCall(StrLen, CastToCStr(Ptr, B), "strlen");
54   if (const Function *F = dyn_cast<Function>(StrLen->stripPointerCasts()))
55     CI->setCallingConv(F->getCallingConv());
56 
57   return CI;
58 }
59 
60 /// EmitStrNLen - Emit a call to the strnlen function to the builder, for the
61 /// specified pointer.  Ptr is required to be some pointer type, MaxLen must
62 /// be of size_t type, and the return value has 'intptr_t' type.
63 Value *llvm::EmitStrNLen(Value *Ptr, Value *MaxLen, IRBuilder<> &B,
64                          const DataLayout *TD, const TargetLibraryInfo *TLI) {
65   if (!TLI->has(LibFunc::strnlen))
66     return 0;
67 
68   Module *M = B.GetInsertBlock()->getParent()->getParent();
69   AttributeWithIndex AWI[2];
70   AWI[0] = AttributeWithIndex::get(M->getContext(), 1, Attributes::NoCapture);
71   Attributes::AttrVal AVs[2] = { Attributes::ReadOnly, Attributes::NoUnwind };
72   AWI[1] = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
73                                    ArrayRef<Attributes::AttrVal>(AVs, 2));
74 
75   Constant *StrNLen = M->getOrInsertFunction("strnlen", AttrListPtr::get(AWI),
76                                              TD->getIntPtrType(Ptr->getType()),
77                                              B.getInt8PtrTy(),
78                                              TD->getIntPtrType(Ptr->getType()),
79                                              NULL);
80   CallInst *CI = B.CreateCall2(StrNLen, CastToCStr(Ptr, B), MaxLen, "strnlen");
81   if (const Function *F = dyn_cast<Function>(StrNLen->stripPointerCasts()))
82     CI->setCallingConv(F->getCallingConv());
83 
84   return CI;
85 }
86 
87 /// EmitStrChr - Emit a call to the strchr function to the builder, for the
88 /// specified pointer and character.  Ptr is required to be some pointer type,
89 /// and the return value has 'i8*' type.
90 Value *llvm::EmitStrChr(Value *Ptr, char C, IRBuilder<> &B,
91                         const DataLayout *TD, const TargetLibraryInfo *TLI) {
92   if (!TLI->has(LibFunc::strchr))
93     return 0;
94 
95   Module *M = B.GetInsertBlock()->getParent()->getParent();
96   Attributes::AttrVal AVs[2] = { Attributes::ReadOnly, Attributes::NoUnwind };
97   AttributeWithIndex AWI =
98     AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
99                             ArrayRef<Attributes::AttrVal>(AVs, 2));
100 
101   Type *I8Ptr = B.getInt8PtrTy();
102   Type *I32Ty = B.getInt32Ty();
103   Constant *StrChr = M->getOrInsertFunction("strchr", AttrListPtr::get(AWI),
104                                             I8Ptr, I8Ptr, I32Ty, NULL);
105   CallInst *CI = B.CreateCall2(StrChr, CastToCStr(Ptr, B),
106                                ConstantInt::get(I32Ty, C), "strchr");
107   if (const Function *F = dyn_cast<Function>(StrChr->stripPointerCasts()))
108     CI->setCallingConv(F->getCallingConv());
109   return CI;
110 }
111 
112 /// EmitStrNCmp - Emit a call to the strncmp function to the builder.
113 Value *llvm::EmitStrNCmp(Value *Ptr1, Value *Ptr2, Value *Len,
114                          IRBuilder<> &B, const DataLayout *TD,
115                          const TargetLibraryInfo *TLI) {
116   if (!TLI->has(LibFunc::strncmp))
117     return 0;
118 
119   Module *M = B.GetInsertBlock()->getParent()->getParent();
120   AttributeWithIndex AWI[3];
121   AWI[0] = AttributeWithIndex::get(M->getContext(), 1, Attributes::NoCapture);
122   AWI[1] = AttributeWithIndex::get(M->getContext(), 2, Attributes::NoCapture);
123   Attributes::AttrVal AVs[2] = { Attributes::ReadOnly, Attributes::NoUnwind };
124   AWI[2] = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
125                                    ArrayRef<Attributes::AttrVal>(AVs, 2));
126 
127   Value *StrNCmp = M->getOrInsertFunction("strncmp", AttrListPtr::get(AWI),
128                                           B.getInt32Ty(),
129                                           B.getInt8PtrTy(),
130                                           B.getInt8PtrTy(),
131                                           TD->getIntPtrType(Ptr1->getType()),
132                                           NULL);
133   CallInst *CI = B.CreateCall3(StrNCmp, CastToCStr(Ptr1, B),
134                                CastToCStr(Ptr2, B), Len, "strncmp");
135 
136   if (const Function *F = dyn_cast<Function>(StrNCmp->stripPointerCasts()))
137     CI->setCallingConv(F->getCallingConv());
138 
139   return CI;
140 }
141 
142 /// EmitStrCpy - Emit a call to the strcpy function to the builder, for the
143 /// specified pointer arguments.
144 Value *llvm::EmitStrCpy(Value *Dst, Value *Src, IRBuilder<> &B,
145                         const DataLayout *TD, const TargetLibraryInfo *TLI,
146                         StringRef Name) {
147   if (!TLI->has(LibFunc::strcpy))
148     return 0;
149 
150   Module *M = B.GetInsertBlock()->getParent()->getParent();
151   AttributeWithIndex AWI[2];
152   AWI[0] = AttributeWithIndex::get(M->getContext(), 2, Attributes::NoCapture);
153   AWI[1] = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
154                                    Attributes::NoUnwind);
155   Type *I8Ptr = B.getInt8PtrTy();
156   Value *StrCpy = M->getOrInsertFunction(Name, AttrListPtr::get(AWI),
157                                          I8Ptr, I8Ptr, I8Ptr, NULL);
158   CallInst *CI = B.CreateCall2(StrCpy, CastToCStr(Dst, B), CastToCStr(Src, B),
159                                Name);
160   if (const Function *F = dyn_cast<Function>(StrCpy->stripPointerCasts()))
161     CI->setCallingConv(F->getCallingConv());
162   return CI;
163 }
164 
165 /// EmitStrNCpy - Emit a call to the strncpy function to the builder, for the
166 /// specified pointer arguments.
167 Value *llvm::EmitStrNCpy(Value *Dst, Value *Src, Value *Len,
168                          IRBuilder<> &B, const DataLayout *TD,
169                          const TargetLibraryInfo *TLI, StringRef Name) {
170   if (!TLI->has(LibFunc::strncpy))
171     return 0;
172 
173   Module *M = B.GetInsertBlock()->getParent()->getParent();
174   AttributeWithIndex AWI[2];
175   AWI[0] = AttributeWithIndex::get(M->getContext(), 2, Attributes::NoCapture);
176   AWI[1] = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
177                                    Attributes::NoUnwind);
178   Type *I8Ptr = B.getInt8PtrTy();
179   Value *StrNCpy = M->getOrInsertFunction(Name, AttrListPtr::get(AWI),
180                                           I8Ptr, I8Ptr, I8Ptr,
181                                           Len->getType(), NULL);
182   CallInst *CI = B.CreateCall3(StrNCpy, CastToCStr(Dst, B), CastToCStr(Src, B),
183                                Len, "strncpy");
184   if (const Function *F = dyn_cast<Function>(StrNCpy->stripPointerCasts()))
185     CI->setCallingConv(F->getCallingConv());
186   return CI;
187 }
188 
189 /// EmitMemCpyChk - Emit a call to the __memcpy_chk function to the builder.
190 /// This expects that the Len and ObjSize have type 'intptr_t' and Dst/Src
191 /// are pointers.
192 Value *llvm::EmitMemCpyChk(Value *Dst, Value *Src, Value *Len, Value *ObjSize,
193                            IRBuilder<> &B, const DataLayout *TD,
194                            const TargetLibraryInfo *TLI) {
195   if (!TLI->has(LibFunc::memcpy_chk))
196     return 0;
197 
198   Module *M = B.GetInsertBlock()->getParent()->getParent();
199   AttributeWithIndex AWI;
200   AWI = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
201                                 Attributes::NoUnwind);
202   Value *MemCpy = M->getOrInsertFunction("__memcpy_chk",
203                                          AttrListPtr::get(AWI),
204                                          B.getInt8PtrTy(),
205                                          B.getInt8PtrTy(),
206                                          B.getInt8PtrTy(),
207                                          TD->getIntPtrType(Dst->getType()),
208                                          TD->getIntPtrType(Src->getType()),
209                                          NULL);
210   Dst = CastToCStr(Dst, B);
211   Src = CastToCStr(Src, B);
212   CallInst *CI = B.CreateCall4(MemCpy, Dst, Src, Len, ObjSize);
213   if (const Function *F = dyn_cast<Function>(MemCpy->stripPointerCasts()))
214     CI->setCallingConv(F->getCallingConv());
215   return CI;
216 }
217 
218 /// EmitMemChr - Emit a call to the memchr function.  This assumes that Ptr is
219 /// a pointer, Val is an i32 value, and Len is an 'intptr_t' value.
220 Value *llvm::EmitMemChr(Value *Ptr, Value *Val,
221                         Value *Len, IRBuilder<> &B, const DataLayout *TD,
222                         const TargetLibraryInfo *TLI) {
223   if (!TLI->has(LibFunc::memchr))
224     return 0;
225 
226   Module *M = B.GetInsertBlock()->getParent()->getParent();
227   AttributeWithIndex AWI;
228   Attributes::AttrVal AVs[2] = { Attributes::ReadOnly, Attributes::NoUnwind };
229   AWI = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
230                                 ArrayRef<Attributes::AttrVal>(AVs, 2));
231   Value *MemChr = M->getOrInsertFunction("memchr", AttrListPtr::get(AWI),
232                                          B.getInt8PtrTy(),
233                                          B.getInt8PtrTy(),
234                                          B.getInt32Ty(),
235                                          TD->getIntPtrType(Ptr->getType()),
236                                          NULL);
237   CallInst *CI = B.CreateCall3(MemChr, CastToCStr(Ptr, B), Val, Len, "memchr");
238 
239   if (const Function *F = dyn_cast<Function>(MemChr->stripPointerCasts()))
240     CI->setCallingConv(F->getCallingConv());
241 
242   return CI;
243 }
244 
245 /// EmitMemCmp - Emit a call to the memcmp function.
246 Value *llvm::EmitMemCmp(Value *Ptr1, Value *Ptr2,
247                         Value *Len, IRBuilder<> &B, const DataLayout *TD,
248                         const TargetLibraryInfo *TLI) {
249   if (!TLI->has(LibFunc::memcmp))
250     return 0;
251 
252   Module *M = B.GetInsertBlock()->getParent()->getParent();
253   AttributeWithIndex AWI[3];
254   AWI[0] = AttributeWithIndex::get(M->getContext(), 1, Attributes::NoCapture);
255   AWI[1] = AttributeWithIndex::get(M->getContext(), 2, Attributes::NoCapture);
256   Attributes::AttrVal AVs[2] = { Attributes::ReadOnly, Attributes::NoUnwind };
257   AWI[2] = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
258                                    ArrayRef<Attributes::AttrVal>(AVs, 2));
259 
260   Value *MemCmp = M->getOrInsertFunction("memcmp", AttrListPtr::get(AWI),
261                                          B.getInt32Ty(),
262                                          B.getInt8PtrTy(),
263                                          B.getInt8PtrTy(),
264                                          TD->getIntPtrType(Ptr1->getType()),
265                                          NULL);
266   CallInst *CI = B.CreateCall3(MemCmp, CastToCStr(Ptr1, B), CastToCStr(Ptr2, B),
267                                Len, "memcmp");
268 
269   if (const Function *F = dyn_cast<Function>(MemCmp->stripPointerCasts()))
270     CI->setCallingConv(F->getCallingConv());
271 
272   return CI;
273 }
274 
275 /// EmitUnaryFloatFnCall - Emit a call to the unary function named 'Name' (e.g.
276 /// 'floor').  This function is known to take a single of type matching 'Op' and
277 /// returns one value with the same type.  If 'Op' is a long double, 'l' is
278 /// added as the suffix of name, if 'Op' is a float, we add a 'f' suffix.
279 Value *llvm::EmitUnaryFloatFnCall(Value *Op, StringRef Name, IRBuilder<> &B,
280                                   const AttrListPtr &Attrs) {
281   SmallString<20> NameBuffer;
282   if (!Op->getType()->isDoubleTy()) {
283     // If we need to add a suffix, copy into NameBuffer.
284     NameBuffer += Name;
285     if (Op->getType()->isFloatTy())
286       NameBuffer += 'f'; // floorf
287     else
288       NameBuffer += 'l'; // floorl
289     Name = NameBuffer;
290   }
291 
292   Module *M = B.GetInsertBlock()->getParent()->getParent();
293   Value *Callee = M->getOrInsertFunction(Name, Op->getType(),
294                                          Op->getType(), NULL);
295   CallInst *CI = B.CreateCall(Callee, Op, Name);
296   CI->setAttributes(Attrs);
297   if (const Function *F = dyn_cast<Function>(Callee->stripPointerCasts()))
298     CI->setCallingConv(F->getCallingConv());
299 
300   return CI;
301 }
302 
303 /// EmitPutChar - Emit a call to the putchar function.  This assumes that Char
304 /// is an integer.
305 Value *llvm::EmitPutChar(Value *Char, IRBuilder<> &B, const DataLayout *TD,
306                          const TargetLibraryInfo *TLI) {
307   if (!TLI->has(LibFunc::putchar))
308     return 0;
309 
310   Module *M = B.GetInsertBlock()->getParent()->getParent();
311   Value *PutChar = M->getOrInsertFunction("putchar", B.getInt32Ty(),
312                                           B.getInt32Ty(), NULL);
313   CallInst *CI = B.CreateCall(PutChar,
314                               B.CreateIntCast(Char,
315                               B.getInt32Ty(),
316                               /*isSigned*/true,
317                               "chari"),
318                               "putchar");
319 
320   if (const Function *F = dyn_cast<Function>(PutChar->stripPointerCasts()))
321     CI->setCallingConv(F->getCallingConv());
322   return CI;
323 }
324 
325 /// EmitPutS - Emit a call to the puts function.  This assumes that Str is
326 /// some pointer.
327 Value *llvm::EmitPutS(Value *Str, IRBuilder<> &B, const DataLayout *TD,
328                       const TargetLibraryInfo *TLI) {
329   if (!TLI->has(LibFunc::puts))
330     return 0;
331 
332   Module *M = B.GetInsertBlock()->getParent()->getParent();
333   AttributeWithIndex AWI[2];
334   AWI[0] = AttributeWithIndex::get(M->getContext(), 1, Attributes::NoCapture);
335   AWI[1] = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
336                                    Attributes::NoUnwind);
337 
338   Value *PutS = M->getOrInsertFunction("puts", AttrListPtr::get(AWI),
339                                        B.getInt32Ty(),
340                                        B.getInt8PtrTy(),
341                                        NULL);
342   CallInst *CI = B.CreateCall(PutS, CastToCStr(Str, B), "puts");
343   if (const Function *F = dyn_cast<Function>(PutS->stripPointerCasts()))
344     CI->setCallingConv(F->getCallingConv());
345   return CI;
346 }
347 
348 /// EmitFPutC - Emit a call to the fputc function.  This assumes that Char is
349 /// an integer and File is a pointer to FILE.
350 Value *llvm::EmitFPutC(Value *Char, Value *File, IRBuilder<> &B,
351                        const DataLayout *TD, const TargetLibraryInfo *TLI) {
352   if (!TLI->has(LibFunc::fputc))
353     return 0;
354 
355   Module *M = B.GetInsertBlock()->getParent()->getParent();
356   AttributeWithIndex AWI[2];
357   AWI[0] = AttributeWithIndex::get(M->getContext(), 2, Attributes::NoCapture);
358   AWI[1] = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
359                                    Attributes::NoUnwind);
360   Constant *F;
361   if (File->getType()->isPointerTy())
362     F = M->getOrInsertFunction("fputc", AttrListPtr::get(AWI),
363                                B.getInt32Ty(),
364                                B.getInt32Ty(), File->getType(),
365                                NULL);
366   else
367     F = M->getOrInsertFunction("fputc",
368                                B.getInt32Ty(),
369                                B.getInt32Ty(),
370                                File->getType(), NULL);
371   Char = B.CreateIntCast(Char, B.getInt32Ty(), /*isSigned*/true,
372                          "chari");
373   CallInst *CI = B.CreateCall2(F, Char, File, "fputc");
374 
375   if (const Function *Fn = dyn_cast<Function>(F->stripPointerCasts()))
376     CI->setCallingConv(Fn->getCallingConv());
377   return CI;
378 }
379 
380 /// EmitFPutS - Emit a call to the puts function.  Str is required to be a
381 /// pointer and File is a pointer to FILE.
382 Value *llvm::EmitFPutS(Value *Str, Value *File, IRBuilder<> &B,
383                        const DataLayout *TD, const TargetLibraryInfo *TLI) {
384   if (!TLI->has(LibFunc::fputs))
385     return 0;
386 
387   Module *M = B.GetInsertBlock()->getParent()->getParent();
388   AttributeWithIndex AWI[3];
389   AWI[0] = AttributeWithIndex::get(M->getContext(), 1, Attributes::NoCapture);
390   AWI[1] = AttributeWithIndex::get(M->getContext(), 2, Attributes::NoCapture);
391   AWI[2] = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
392                                    Attributes::NoUnwind);
393   StringRef FPutsName = TLI->getName(LibFunc::fputs);
394   Constant *F;
395   if (File->getType()->isPointerTy())
396     F = M->getOrInsertFunction(FPutsName, AttrListPtr::get(AWI),
397                                B.getInt32Ty(),
398                                B.getInt8PtrTy(),
399                                File->getType(), NULL);
400   else
401     F = M->getOrInsertFunction(FPutsName, B.getInt32Ty(),
402                                B.getInt8PtrTy(),
403                                File->getType(), NULL);
404   CallInst *CI = B.CreateCall2(F, CastToCStr(Str, B), File, "fputs");
405 
406   if (const Function *Fn = dyn_cast<Function>(F->stripPointerCasts()))
407     CI->setCallingConv(Fn->getCallingConv());
408   return CI;
409 }
410 
411 /// EmitFWrite - Emit a call to the fwrite function.  This assumes that Ptr is
412 /// a pointer, Size is an 'intptr_t', and File is a pointer to FILE.
413 Value *llvm::EmitFWrite(Value *Ptr, Value *Size, Value *File,
414                         IRBuilder<> &B, const DataLayout *TD,
415                         const TargetLibraryInfo *TLI) {
416   if (!TLI->has(LibFunc::fwrite))
417     return 0;
418 
419   Module *M = B.GetInsertBlock()->getParent()->getParent();
420   AttributeWithIndex AWI[3];
421   AWI[0] = AttributeWithIndex::get(M->getContext(), 1, Attributes::NoCapture);
422   AWI[1] = AttributeWithIndex::get(M->getContext(), 4, Attributes::NoCapture);
423   AWI[2] = AttributeWithIndex::get(M->getContext(), AttrListPtr::FunctionIndex,
424                                    Attributes::NoUnwind);
425   StringRef FWriteName = TLI->getName(LibFunc::fwrite);
426   Constant *F;
427   Type *PtrTy = Ptr->getType();
428   if (File->getType()->isPointerTy())
429     F = M->getOrInsertFunction(FWriteName, AttrListPtr::get(AWI),
430                                TD->getIntPtrType(PtrTy),
431                                B.getInt8PtrTy(),
432                                TD->getIntPtrType(PtrTy),
433                                TD->getIntPtrType(PtrTy),
434                                File->getType(), NULL);
435   else
436     F = M->getOrInsertFunction(FWriteName, TD->getIntPtrType(PtrTy),
437                                B.getInt8PtrTy(),
438                                TD->getIntPtrType(PtrTy),
439                                TD->getIntPtrType(PtrTy),
440                                File->getType(), NULL);
441   CallInst *CI = B.CreateCall4(F, CastToCStr(Ptr, B), Size,
442                         ConstantInt::get(TD->getIntPtrType(PtrTy), 1), File);
443 
444   if (const Function *Fn = dyn_cast<Function>(F->stripPointerCasts()))
445     CI->setCallingConv(Fn->getCallingConv());
446   return CI;
447 }
448 
449 SimplifyFortifiedLibCalls::~SimplifyFortifiedLibCalls() { }
450 
451 bool SimplifyFortifiedLibCalls::fold(CallInst *CI, const DataLayout *TD,
452                                      const TargetLibraryInfo *TLI) {
453   // We really need DataLayout for later.
454   if (!TD) return false;
455 
456   this->CI = CI;
457   Function *Callee = CI->getCalledFunction();
458   StringRef Name = Callee->getName();
459   FunctionType *FT = Callee->getFunctionType();
460   LLVMContext &Context = CI->getParent()->getContext();
461   IRBuilder<> B(CI);
462 
463   if (Name == "__memcpy_chk") {
464     Type *PT = FT->getParamType(0);
465     // Check if this has the right signature.
466     if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
467         !FT->getParamType(0)->isPointerTy() ||
468         !FT->getParamType(1)->isPointerTy() ||
469         FT->getParamType(2) != TD->getIntPtrType(PT) ||
470         FT->getParamType(3) != TD->getIntPtrType(PT))
471       return false;
472 
473     if (isFoldable(3, 2, false)) {
474       B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
475                      CI->getArgOperand(2), 1);
476       replaceCall(CI->getArgOperand(0));
477       return true;
478     }
479     return false;
480   }
481 
482   // Should be similar to memcpy.
483   if (Name == "__mempcpy_chk") {
484     return false;
485   }
486 
487   if (Name == "__memmove_chk") {
488     // Check if this has the right signature.
489     Type *PT = FT->getParamType(0);
490     if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
491         !FT->getParamType(0)->isPointerTy() ||
492         !FT->getParamType(1)->isPointerTy() ||
493         FT->getParamType(2) != TD->getIntPtrType(PT) ||
494         FT->getParamType(3) != TD->getIntPtrType(PT))
495       return false;
496 
497     if (isFoldable(3, 2, false)) {
498       B.CreateMemMove(CI->getArgOperand(0), CI->getArgOperand(1),
499                       CI->getArgOperand(2), 1);
500       replaceCall(CI->getArgOperand(0));
501       return true;
502     }
503     return false;
504   }
505 
506   if (Name == "__memset_chk") {
507     // Check if this has the right signature.
508     Type *PT = FT->getParamType(0);
509     if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
510         !FT->getParamType(0)->isPointerTy() ||
511         !FT->getParamType(1)->isIntegerTy() ||
512         FT->getParamType(2) != TD->getIntPtrType(PT) ||
513         FT->getParamType(3) != TD->getIntPtrType(PT))
514       return false;
515 
516     if (isFoldable(3, 2, false)) {
517       Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(),
518                                    false);
519       B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1);
520       replaceCall(CI->getArgOperand(0));
521       return true;
522     }
523     return false;
524   }
525 
526   if (Name == "__strcpy_chk" || Name == "__stpcpy_chk") {
527     // Check if this has the right signature.
528     Type *PT = FT->getParamType(0);
529     if (FT->getNumParams() != 3 ||
530         FT->getReturnType() != FT->getParamType(0) ||
531         FT->getParamType(0) != FT->getParamType(1) ||
532         FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
533         FT->getParamType(2) != TD->getIntPtrType(PT))
534       return 0;
535 
536 
537     // If a) we don't have any length information, or b) we know this will
538     // fit then just lower to a plain st[rp]cpy. Otherwise we'll keep our
539     // st[rp]cpy_chk call which may fail at runtime if the size is too long.
540     // TODO: It might be nice to get a maximum length out of the possible
541     // string lengths for varying.
542     if (isFoldable(2, 1, true)) {
543       Value *Ret = EmitStrCpy(CI->getArgOperand(0), CI->getArgOperand(1), B, TD,
544                               TLI, Name.substr(2, 6));
545       if (!Ret)
546         return false;
547       replaceCall(Ret);
548       return true;
549     }
550     return false;
551   }
552 
553   if (Name == "__strncpy_chk" || Name == "__stpncpy_chk") {
554     // Check if this has the right signature.
555     Type *PT = FT->getParamType(0);
556     if (FT->getNumParams() != 4 || FT->getReturnType() != FT->getParamType(0) ||
557         FT->getParamType(0) != FT->getParamType(1) ||
558         FT->getParamType(0) != Type::getInt8PtrTy(Context) ||
559         !FT->getParamType(2)->isIntegerTy() ||
560         FT->getParamType(3) != TD->getIntPtrType(PT))
561       return false;
562 
563     if (isFoldable(3, 2, false)) {
564       Value *Ret = EmitStrNCpy(CI->getArgOperand(0), CI->getArgOperand(1),
565                                CI->getArgOperand(2), B, TD, TLI,
566                                Name.substr(2, 7));
567       if (!Ret)
568         return false;
569       replaceCall(Ret);
570       return true;
571     }
572     return false;
573   }
574 
575   if (Name == "__strcat_chk") {
576     return false;
577   }
578 
579   if (Name == "__strncat_chk") {
580     return false;
581   }
582 
583   return false;
584 }
585