1 //===------ MemoryBuiltins.cpp - Identify calls to memory builtins --------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This family of functions identifies calls to builtin functions that allocate
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Analysis/MemoryBuiltins.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/Statistic.h"
18 #include "llvm/Analysis/TargetLibraryInfo.h"
19 #include "llvm/Analysis/ValueTracking.h"
20 #include "llvm/IR/DataLayout.h"
21 #include "llvm/IR/GlobalVariable.h"
22 #include "llvm/IR/Instructions.h"
23 #include "llvm/IR/Intrinsics.h"
24 #include "llvm/IR/Metadata.h"
25 #include "llvm/IR/Module.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/MathExtras.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include "llvm/Transforms/Utils/Local.h"
32 #define DEBUG_TYPE "memory-builtins"
34 enum AllocType : uint8_t {
35 OpNewLike = 1<<0, // allocates; never returns null
36 MallocLike = 1<<1 | OpNewLike, // allocates; may return null
37 CallocLike = 1<<2, // allocates + bzero
38 ReallocLike = 1<<3, // reallocates
40 AllocLike = MallocLike | CallocLike | StrDupLike,
41 AnyAlloc = AllocLike | ReallocLike
47 unsigned char NumParams;
48 // First and Second size parameters (or -1 if unused)
49 signed char FstParam, SndParam;
52 // FIXME: certain users need more information. E.g., SimplifyLibCalls needs to
53 // know which functions are nounwind, noalias, nocapture parameters, etc.
54 static const AllocFnsTy AllocationFnData[] = {
55 {LibFunc::malloc, MallocLike, 1, 0, -1},
56 {LibFunc::valloc, MallocLike, 1, 0, -1},
57 {LibFunc::Znwj, OpNewLike, 1, 0, -1}, // new(unsigned int)
58 {LibFunc::ZnwjRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned int, nothrow)
59 {LibFunc::Znwm, OpNewLike, 1, 0, -1}, // new(unsigned long)
60 {LibFunc::ZnwmRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned long, nothrow)
61 {LibFunc::Znaj, OpNewLike, 1, 0, -1}, // new[](unsigned int)
62 {LibFunc::ZnajRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned int, nothrow)
63 {LibFunc::Znam, OpNewLike, 1, 0, -1}, // new[](unsigned long)
64 {LibFunc::ZnamRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned long, nothrow)
65 {LibFunc::msvc_new_int, OpNewLike, 1, 0, -1}, // new(unsigned int)
66 {LibFunc::msvc_new_int_nothrow, MallocLike, 2, 0, -1}, // new(unsigned int, nothrow)
67 {LibFunc::msvc_new_longlong, OpNewLike, 1, 0, -1}, // new(unsigned long long)
68 {LibFunc::msvc_new_longlong_nothrow, MallocLike, 2, 0, -1}, // new(unsigned long long, nothrow)
69 {LibFunc::msvc_new_array_int, OpNewLike, 1, 0, -1}, // new[](unsigned int)
70 {LibFunc::msvc_new_array_int_nothrow, MallocLike, 2, 0, -1}, // new[](unsigned int, nothrow)
71 {LibFunc::msvc_new_array_longlong, OpNewLike, 1, 0, -1}, // new[](unsigned long long)
72 {LibFunc::msvc_new_array_longlong_nothrow, MallocLike, 2, 0, -1}, // new[](unsigned long long, nothrow)
73 {LibFunc::calloc, CallocLike, 2, 0, 1},
74 {LibFunc::realloc, ReallocLike, 2, 1, -1},
75 {LibFunc::reallocf, ReallocLike, 2, 1, -1},
76 {LibFunc::strdup, StrDupLike, 1, -1, -1},
77 {LibFunc::strndup, StrDupLike, 2, 1, -1}
78 // TODO: Handle "int posix_memalign(void **, size_t, size_t)"
82 static Function *getCalledFunction(const Value *V, bool LookThroughBitCast) {
83 if (LookThroughBitCast)
84 V = V->stripPointerCasts();
86 CallSite CS(const_cast<Value*>(V));
87 if (!CS.getInstruction())
93 Function *Callee = CS.getCalledFunction();
94 if (!Callee || !Callee->isDeclaration())
99 /// \brief Returns the allocation data for the given value if it is a call to a
100 /// known allocation function, and NULL otherwise.
101 static const AllocFnsTy *getAllocationData(const Value *V, AllocType AllocTy,
102 const TargetLibraryInfo *TLI,
103 bool LookThroughBitCast = false) {
105 if (isa<IntrinsicInst>(V))
108 Function *Callee = getCalledFunction(V, LookThroughBitCast);
112 // Make sure that the function is available.
113 StringRef FnName = Callee->getName();
115 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
118 const AllocFnsTy *FnData =
119 std::find_if(std::begin(AllocationFnData), std::end(AllocationFnData),
120 [TLIFn](const AllocFnsTy &Fn) { return Fn.Func == TLIFn; });
122 if (FnData == std::end(AllocationFnData))
125 if ((FnData->AllocTy & AllocTy) != FnData->AllocTy)
128 // Check function prototype.
129 int FstParam = FnData->FstParam;
130 int SndParam = FnData->SndParam;
131 FunctionType *FTy = Callee->getFunctionType();
133 if (FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) &&
134 FTy->getNumParams() == FnData->NumParams &&
136 (FTy->getParamType(FstParam)->isIntegerTy(32) ||
137 FTy->getParamType(FstParam)->isIntegerTy(64))) &&
139 FTy->getParamType(SndParam)->isIntegerTy(32) ||
140 FTy->getParamType(SndParam)->isIntegerTy(64)))
145 static bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) {
146 ImmutableCallSite CS(LookThroughBitCast ? V->stripPointerCasts() : V);
147 return CS && CS.hasFnAttr(Attribute::NoAlias);
151 /// \brief Tests if a value is a call or invoke to a library function that
152 /// allocates or reallocates memory (either malloc, calloc, realloc, or strdup
154 bool llvm::isAllocationFn(const Value *V, const TargetLibraryInfo *TLI,
155 bool LookThroughBitCast) {
156 return getAllocationData(V, AnyAlloc, TLI, LookThroughBitCast);
159 /// \brief Tests if a value is a call or invoke to a function that returns a
160 /// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions).
161 bool llvm::isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI,
162 bool LookThroughBitCast) {
163 // it's safe to consider realloc as noalias since accessing the original
164 // pointer is undefined behavior
165 return isAllocationFn(V, TLI, LookThroughBitCast) ||
166 hasNoAliasAttr(V, LookThroughBitCast);
169 /// \brief Tests if a value is a call or invoke to a library function that
170 /// allocates uninitialized memory (such as malloc).
171 bool llvm::isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
172 bool LookThroughBitCast) {
173 return getAllocationData(V, MallocLike, TLI, LookThroughBitCast);
176 /// \brief Tests if a value is a call or invoke to a library function that
177 /// allocates zero-filled memory (such as calloc).
178 bool llvm::isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
179 bool LookThroughBitCast) {
180 return getAllocationData(V, CallocLike, TLI, LookThroughBitCast);
183 /// \brief Tests if a value is a call or invoke to a library function that
184 /// allocates memory (either malloc, calloc, or strdup like).
185 bool llvm::isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
186 bool LookThroughBitCast) {
187 return getAllocationData(V, AllocLike, TLI, LookThroughBitCast);
190 /// \brief Tests if a value is a call or invoke to a library function that
191 /// allocates memory and never returns null (such as operator new).
192 bool llvm::isOperatorNewLikeFn(const Value *V, const TargetLibraryInfo *TLI,
193 bool LookThroughBitCast) {
194 return getAllocationData(V, OpNewLike, TLI, LookThroughBitCast);
197 /// extractMallocCall - Returns the corresponding CallInst if the instruction
198 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
199 /// ignore InvokeInst here.
200 const CallInst *llvm::extractMallocCall(const Value *I,
201 const TargetLibraryInfo *TLI) {
202 return isMallocLikeFn(I, TLI) ? dyn_cast<CallInst>(I) : nullptr;
205 static Value *computeArraySize(const CallInst *CI, const DataLayout &DL,
206 const TargetLibraryInfo *TLI,
207 bool LookThroughSExt = false) {
211 // The size of the malloc's result type must be known to determine array size.
212 Type *T = getMallocAllocatedType(CI, TLI);
213 if (!T || !T->isSized())
216 unsigned ElementSize = DL.getTypeAllocSize(T);
217 if (StructType *ST = dyn_cast<StructType>(T))
218 ElementSize = DL.getStructLayout(ST)->getSizeInBytes();
220 // If malloc call's arg can be determined to be a multiple of ElementSize,
221 // return the multiple. Otherwise, return NULL.
222 Value *MallocArg = CI->getArgOperand(0);
223 Value *Multiple = nullptr;
224 if (ComputeMultiple(MallocArg, ElementSize, Multiple,
231 /// getMallocType - Returns the PointerType resulting from the malloc call.
232 /// The PointerType depends on the number of bitcast uses of the malloc call:
233 /// 0: PointerType is the calls' return type.
234 /// 1: PointerType is the bitcast's result type.
235 /// >1: Unique PointerType cannot be determined, return NULL.
236 PointerType *llvm::getMallocType(const CallInst *CI,
237 const TargetLibraryInfo *TLI) {
238 assert(isMallocLikeFn(CI, TLI) && "getMallocType and not malloc call");
240 PointerType *MallocType = nullptr;
241 unsigned NumOfBitCastUses = 0;
243 // Determine if CallInst has a bitcast use.
244 for (Value::const_user_iterator UI = CI->user_begin(), E = CI->user_end();
246 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
247 MallocType = cast<PointerType>(BCI->getDestTy());
251 // Malloc call has 1 bitcast use, so type is the bitcast's destination type.
252 if (NumOfBitCastUses == 1)
255 // Malloc call was not bitcast, so type is the malloc function's return type.
256 if (NumOfBitCastUses == 0)
257 return cast<PointerType>(CI->getType());
259 // Type could not be determined.
263 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
264 /// The Type depends on the number of bitcast uses of the malloc call:
265 /// 0: PointerType is the malloc calls' return type.
266 /// 1: PointerType is the bitcast's result type.
267 /// >1: Unique PointerType cannot be determined, return NULL.
268 Type *llvm::getMallocAllocatedType(const CallInst *CI,
269 const TargetLibraryInfo *TLI) {
270 PointerType *PT = getMallocType(CI, TLI);
271 return PT ? PT->getElementType() : nullptr;
274 /// getMallocArraySize - Returns the array size of a malloc call. If the
275 /// argument passed to malloc is a multiple of the size of the malloced type,
276 /// then return that multiple. For non-array mallocs, the multiple is
277 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
279 Value *llvm::getMallocArraySize(CallInst *CI, const DataLayout &DL,
280 const TargetLibraryInfo *TLI,
281 bool LookThroughSExt) {
282 assert(isMallocLikeFn(CI, TLI) && "getMallocArraySize and not malloc call");
283 return computeArraySize(CI, DL, TLI, LookThroughSExt);
287 /// extractCallocCall - Returns the corresponding CallInst if the instruction
288 /// is a calloc call.
289 const CallInst *llvm::extractCallocCall(const Value *I,
290 const TargetLibraryInfo *TLI) {
291 return isCallocLikeFn(I, TLI) ? cast<CallInst>(I) : nullptr;
295 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
296 const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) {
297 const CallInst *CI = dyn_cast<CallInst>(I);
298 if (!CI || isa<IntrinsicInst>(CI))
300 Function *Callee = CI->getCalledFunction();
301 if (Callee == nullptr)
304 StringRef FnName = Callee->getName();
306 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
309 unsigned ExpectedNumParams;
310 if (TLIFn == LibFunc::free ||
311 TLIFn == LibFunc::ZdlPv || // operator delete(void*)
312 TLIFn == LibFunc::ZdaPv || // operator delete[](void*)
313 TLIFn == LibFunc::msvc_delete_ptr32 || // operator delete(void*)
314 TLIFn == LibFunc::msvc_delete_ptr64 || // operator delete(void*)
315 TLIFn == LibFunc::msvc_delete_array_ptr32 || // operator delete[](void*)
316 TLIFn == LibFunc::msvc_delete_array_ptr64) // operator delete[](void*)
317 ExpectedNumParams = 1;
318 else if (TLIFn == LibFunc::ZdlPvj || // delete(void*, uint)
319 TLIFn == LibFunc::ZdlPvm || // delete(void*, ulong)
320 TLIFn == LibFunc::ZdlPvRKSt9nothrow_t || // delete(void*, nothrow)
321 TLIFn == LibFunc::ZdaPvj || // delete[](void*, uint)
322 TLIFn == LibFunc::ZdaPvm || // delete[](void*, ulong)
323 TLIFn == LibFunc::ZdaPvRKSt9nothrow_t || // delete[](void*, nothrow)
324 TLIFn == LibFunc::msvc_delete_ptr32_int || // delete(void*, uint)
325 TLIFn == LibFunc::msvc_delete_ptr64_longlong || // delete(void*, ulonglong)
326 TLIFn == LibFunc::msvc_delete_ptr32_nothrow || // delete(void*, nothrow)
327 TLIFn == LibFunc::msvc_delete_ptr64_nothrow || // delete(void*, nothrow)
328 TLIFn == LibFunc::msvc_delete_array_ptr32_int || // delete[](void*, uint)
329 TLIFn == LibFunc::msvc_delete_array_ptr64_longlong || // delete[](void*, ulonglong)
330 TLIFn == LibFunc::msvc_delete_array_ptr32_nothrow || // delete[](void*, nothrow)
331 TLIFn == LibFunc::msvc_delete_array_ptr64_nothrow) // delete[](void*, nothrow)
332 ExpectedNumParams = 2;
336 // Check free prototype.
337 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
338 // attribute will exist.
339 FunctionType *FTy = Callee->getFunctionType();
340 if (!FTy->getReturnType()->isVoidTy())
342 if (FTy->getNumParams() != ExpectedNumParams)
344 if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext()))
352 //===----------------------------------------------------------------------===//
353 // Utility functions to compute size of objects.
357 /// \brief Compute the size of the object pointed by Ptr. Returns true and the
358 /// object size in Size if successful, and false otherwise.
359 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
360 /// byval arguments, and global variables.
361 bool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
362 const TargetLibraryInfo *TLI, bool RoundToAlign) {
363 ObjectSizeOffsetVisitor Visitor(DL, TLI, Ptr->getContext(), RoundToAlign);
364 SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr));
365 if (!Visitor.bothKnown(Data))
368 APInt ObjSize = Data.first, Offset = Data.second;
369 // check for overflow
370 if (Offset.slt(0) || ObjSize.ult(Offset))
373 Size = (ObjSize - Offset).getZExtValue();
378 STATISTIC(ObjectVisitorArgument,
379 "Number of arguments with unsolved size and offset");
380 STATISTIC(ObjectVisitorLoad,
381 "Number of load instructions with unsolved size and offset");
384 APInt ObjectSizeOffsetVisitor::align(APInt Size, uint64_t Align) {
385 if (RoundToAlign && Align)
386 return APInt(IntTyBits, RoundUpToAlignment(Size.getZExtValue(), Align));
390 ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout &DL,
391 const TargetLibraryInfo *TLI,
392 LLVMContext &Context,
394 : DL(DL), TLI(TLI), RoundToAlign(RoundToAlign) {
395 // Pointer size must be rechecked for each object visited since it could have
396 // a different address space.
399 SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
400 IntTyBits = DL.getPointerTypeSizeInBits(V->getType());
401 Zero = APInt::getNullValue(IntTyBits);
403 V = V->stripPointerCasts();
404 if (Instruction *I = dyn_cast<Instruction>(V)) {
405 // If we have already seen this instruction, bail out. Cycles can happen in
406 // unreachable code after constant propagation.
407 if (!SeenInsts.insert(I).second)
410 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
411 return visitGEPOperator(*GEP);
414 if (Argument *A = dyn_cast<Argument>(V))
415 return visitArgument(*A);
416 if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
417 return visitConstantPointerNull(*P);
418 if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
419 return visitGlobalAlias(*GA);
420 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
421 return visitGlobalVariable(*GV);
422 if (UndefValue *UV = dyn_cast<UndefValue>(V))
423 return visitUndefValue(*UV);
424 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
425 if (CE->getOpcode() == Instruction::IntToPtr)
426 return unknown(); // clueless
427 if (CE->getOpcode() == Instruction::GetElementPtr)
428 return visitGEPOperator(cast<GEPOperator>(*CE));
431 DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V
436 SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) {
437 if (!I.getAllocatedType()->isSized())
440 APInt Size(IntTyBits, DL.getTypeAllocSize(I.getAllocatedType()));
441 if (!I.isArrayAllocation())
442 return std::make_pair(align(Size, I.getAlignment()), Zero);
444 Value *ArraySize = I.getArraySize();
445 if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) {
446 Size *= C->getValue().zextOrSelf(IntTyBits);
447 return std::make_pair(align(Size, I.getAlignment()), Zero);
452 SizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) {
453 // no interprocedural analysis is done at the moment
454 if (!A.hasByValOrInAllocaAttr()) {
455 ++ObjectVisitorArgument;
458 PointerType *PT = cast<PointerType>(A.getType());
459 APInt Size(IntTyBits, DL.getTypeAllocSize(PT->getElementType()));
460 return std::make_pair(align(Size, A.getParamAlignment()), Zero);
463 SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) {
464 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
469 // handle strdup-like functions separately
470 if (FnData->AllocTy == StrDupLike) {
471 APInt Size(IntTyBits, GetStringLength(CS.getArgument(0)));
475 // strndup limits strlen
476 if (FnData->FstParam > 0) {
477 ConstantInt *Arg= dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
481 APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits);
482 if (Size.ugt(MaxSize))
485 return std::make_pair(Size, Zero);
488 ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
492 APInt Size = Arg->getValue().zextOrSelf(IntTyBits);
493 // size determined by just 1 parameter
494 if (FnData->SndParam < 0)
495 return std::make_pair(Size, Zero);
497 Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam));
501 Size *= Arg->getValue().zextOrSelf(IntTyBits);
502 return std::make_pair(Size, Zero);
504 // TODO: handle more standard functions (+ wchar cousins):
505 // - strdup / strndup
506 // - strcpy / strncpy
507 // - strcat / strncat
508 // - memcpy / memmove
509 // - strcat / strncat
514 ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull&) {
515 return std::make_pair(Zero, Zero);
519 ObjectSizeOffsetVisitor::visitExtractElementInst(ExtractElementInst&) {
524 ObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst&) {
525 // Easy cases were already folded by previous passes.
529 SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) {
530 SizeOffsetType PtrData = compute(GEP.getPointerOperand());
531 APInt Offset(IntTyBits, 0);
532 if (!bothKnown(PtrData) || !GEP.accumulateConstantOffset(DL, Offset))
535 return std::make_pair(PtrData.first, PtrData.second + Offset);
538 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalAlias(GlobalAlias &GA) {
539 if (GA.mayBeOverridden())
541 return compute(GA.getAliasee());
544 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){
545 if (!GV.hasDefinitiveInitializer())
548 APInt Size(IntTyBits, DL.getTypeAllocSize(GV.getType()->getElementType()));
549 return std::make_pair(align(Size, GV.getAlignment()), Zero);
552 SizeOffsetType ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst&) {
557 SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) {
562 SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) {
563 // too complex to analyze statically.
567 SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
568 SizeOffsetType TrueSide = compute(I.getTrueValue());
569 SizeOffsetType FalseSide = compute(I.getFalseValue());
570 if (bothKnown(TrueSide) && bothKnown(FalseSide) && TrueSide == FalseSide)
575 SizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) {
576 return std::make_pair(Zero, Zero);
579 SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) {
580 DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I << '\n');
584 ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(
585 const DataLayout &DL, const TargetLibraryInfo *TLI, LLVMContext &Context,
587 : DL(DL), TLI(TLI), Context(Context), Builder(Context, TargetFolder(DL)),
588 RoundToAlign(RoundToAlign) {
589 // IntTy and Zero must be set for each compute() since the address space may
590 // be different for later objects.
593 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) {
594 // XXX - Are vectors of pointers possible here?
595 IntTy = cast<IntegerType>(DL.getIntPtrType(V->getType()));
596 Zero = ConstantInt::get(IntTy, 0);
598 SizeOffsetEvalType Result = compute_(V);
600 if (!bothKnown(Result)) {
601 // erase everything that was computed in this iteration from the cache, so
602 // that no dangling references are left behind. We could be a bit smarter if
603 // we kept a dependency graph. It's probably not worth the complexity.
604 for (PtrSetTy::iterator I=SeenVals.begin(), E=SeenVals.end(); I != E; ++I) {
605 CacheMapTy::iterator CacheIt = CacheMap.find(*I);
606 // non-computable results can be safely cached
607 if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second))
608 CacheMap.erase(CacheIt);
616 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) {
617 ObjectSizeOffsetVisitor Visitor(DL, TLI, Context, RoundToAlign);
618 SizeOffsetType Const = Visitor.compute(V);
619 if (Visitor.bothKnown(Const))
620 return std::make_pair(ConstantInt::get(Context, Const.first),
621 ConstantInt::get(Context, Const.second));
623 V = V->stripPointerCasts();
626 CacheMapTy::iterator CacheIt = CacheMap.find(V);
627 if (CacheIt != CacheMap.end())
628 return CacheIt->second;
630 // always generate code immediately before the instruction being
631 // processed, so that the generated code dominates the same BBs
632 BuilderTy::InsertPointGuard Guard(Builder);
633 if (Instruction *I = dyn_cast<Instruction>(V))
634 Builder.SetInsertPoint(I);
636 // now compute the size and offset
637 SizeOffsetEvalType Result;
639 // Record the pointers that were handled in this run, so that they can be
640 // cleaned later if something fails. We also use this set to break cycles that
641 // can occur in dead code.
642 if (!SeenVals.insert(V).second) {
644 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
645 Result = visitGEPOperator(*GEP);
646 } else if (Instruction *I = dyn_cast<Instruction>(V)) {
648 } else if (isa<Argument>(V) ||
649 (isa<ConstantExpr>(V) &&
650 cast<ConstantExpr>(V)->getOpcode() == Instruction::IntToPtr) ||
651 isa<GlobalAlias>(V) ||
652 isa<GlobalVariable>(V)) {
653 // ignore values where we cannot do more than what ObjectSizeVisitor can
656 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: "
661 // Don't reuse CacheIt since it may be invalid at this point.
662 CacheMap[V] = Result;
666 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) {
667 if (!I.getAllocatedType()->isSized())
671 assert(I.isArrayAllocation());
672 Value *ArraySize = I.getArraySize();
673 Value *Size = ConstantInt::get(ArraySize->getType(),
674 DL.getTypeAllocSize(I.getAllocatedType()));
675 Size = Builder.CreateMul(Size, ArraySize);
676 return std::make_pair(Size, Zero);
679 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) {
680 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
685 // handle strdup-like functions separately
686 if (FnData->AllocTy == StrDupLike) {
691 Value *FirstArg = CS.getArgument(FnData->FstParam);
692 FirstArg = Builder.CreateZExt(FirstArg, IntTy);
693 if (FnData->SndParam < 0)
694 return std::make_pair(FirstArg, Zero);
696 Value *SecondArg = CS.getArgument(FnData->SndParam);
697 SecondArg = Builder.CreateZExt(SecondArg, IntTy);
698 Value *Size = Builder.CreateMul(FirstArg, SecondArg);
699 return std::make_pair(Size, Zero);
701 // TODO: handle more standard functions (+ wchar cousins):
702 // - strdup / strndup
703 // - strcpy / strncpy
704 // - strcat / strncat
705 // - memcpy / memmove
706 // - strcat / strncat
711 ObjectSizeOffsetEvaluator::visitExtractElementInst(ExtractElementInst&) {
716 ObjectSizeOffsetEvaluator::visitExtractValueInst(ExtractValueInst&) {
721 ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) {
722 SizeOffsetEvalType PtrData = compute_(GEP.getPointerOperand());
723 if (!bothKnown(PtrData))
726 Value *Offset = EmitGEPOffset(&Builder, DL, &GEP, /*NoAssumptions=*/true);
727 Offset = Builder.CreateAdd(PtrData.second, Offset);
728 return std::make_pair(PtrData.first, Offset);
731 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst&) {
736 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst&) {
740 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) {
741 // create 2 PHIs: one for size and another for offset
742 PHINode *SizePHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
743 PHINode *OffsetPHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
745 // insert right away in the cache to handle recursive PHIs
746 CacheMap[&PHI] = std::make_pair(SizePHI, OffsetPHI);
748 // compute offset/size for each PHI incoming pointer
749 for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) {
750 Builder.SetInsertPoint(&*PHI.getIncomingBlock(i)->getFirstInsertionPt());
751 SizeOffsetEvalType EdgeData = compute_(PHI.getIncomingValue(i));
753 if (!bothKnown(EdgeData)) {
754 OffsetPHI->replaceAllUsesWith(UndefValue::get(IntTy));
755 OffsetPHI->eraseFromParent();
756 SizePHI->replaceAllUsesWith(UndefValue::get(IntTy));
757 SizePHI->eraseFromParent();
760 SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i));
761 OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i));
764 Value *Size = SizePHI, *Offset = OffsetPHI, *Tmp;
765 if ((Tmp = SizePHI->hasConstantValue())) {
767 SizePHI->replaceAllUsesWith(Size);
768 SizePHI->eraseFromParent();
770 if ((Tmp = OffsetPHI->hasConstantValue())) {
772 OffsetPHI->replaceAllUsesWith(Offset);
773 OffsetPHI->eraseFromParent();
775 return std::make_pair(Size, Offset);
778 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) {
779 SizeOffsetEvalType TrueSide = compute_(I.getTrueValue());
780 SizeOffsetEvalType FalseSide = compute_(I.getFalseValue());
782 if (!bothKnown(TrueSide) || !bothKnown(FalseSide))
784 if (TrueSide == FalseSide)
787 Value *Size = Builder.CreateSelect(I.getCondition(), TrueSide.first,
789 Value *Offset = Builder.CreateSelect(I.getCondition(), TrueSide.second,
791 return std::make_pair(Size, Offset);
794 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) {
795 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I <<'\n');