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"
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::calloc, CallocLike, 2, 0, 1},
66 {LibFunc::realloc, ReallocLike, 2, 1, -1},
67 {LibFunc::reallocf, ReallocLike, 2, 1, -1},
68 {LibFunc::strdup, StrDupLike, 1, -1, -1},
69 {LibFunc::strndup, StrDupLike, 2, 1, -1}
70 // TODO: Handle "int posix_memalign(void **, size_t, size_t)"
74 static Function *getCalledFunction(const Value *V, bool LookThroughBitCast) {
75 if (LookThroughBitCast)
76 V = V->stripPointerCasts();
78 CallSite CS(const_cast<Value*>(V));
79 if (!CS.getInstruction())
85 Function *Callee = CS.getCalledFunction();
86 if (!Callee || !Callee->isDeclaration())
91 /// \brief Returns the allocation data for the given value if it is a call to a
92 /// known allocation function, and NULL otherwise.
93 static const AllocFnsTy *getAllocationData(const Value *V, AllocType AllocTy,
94 const TargetLibraryInfo *TLI,
95 bool LookThroughBitCast = false) {
97 if (isa<IntrinsicInst>(V))
100 Function *Callee = getCalledFunction(V, LookThroughBitCast);
104 // Make sure that the function is available.
105 StringRef FnName = Callee->getName();
107 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
112 for ( ; i < array_lengthof(AllocationFnData); ++i) {
113 if (AllocationFnData[i].Func == TLIFn) {
121 const AllocFnsTy *FnData = &AllocationFnData[i];
122 if ((FnData->AllocTy & AllocTy) != FnData->AllocTy)
125 // Check function prototype.
126 int FstParam = FnData->FstParam;
127 int SndParam = FnData->SndParam;
128 FunctionType *FTy = Callee->getFunctionType();
130 if (FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) &&
131 FTy->getNumParams() == FnData->NumParams &&
133 (FTy->getParamType(FstParam)->isIntegerTy(32) ||
134 FTy->getParamType(FstParam)->isIntegerTy(64))) &&
136 FTy->getParamType(SndParam)->isIntegerTy(32) ||
137 FTy->getParamType(SndParam)->isIntegerTy(64)))
142 static bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) {
143 ImmutableCallSite CS(LookThroughBitCast ? V->stripPointerCasts() : V);
144 return CS && CS.hasFnAttr(Attribute::NoAlias);
148 /// \brief Tests if a value is a call or invoke to a library function that
149 /// allocates or reallocates memory (either malloc, calloc, realloc, or strdup
151 bool llvm::isAllocationFn(const Value *V, const TargetLibraryInfo *TLI,
152 bool LookThroughBitCast) {
153 return getAllocationData(V, AnyAlloc, TLI, LookThroughBitCast);
156 /// \brief Tests if a value is a call or invoke to a function that returns a
157 /// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions).
158 bool llvm::isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI,
159 bool LookThroughBitCast) {
160 // it's safe to consider realloc as noalias since accessing the original
161 // pointer is undefined behavior
162 return isAllocationFn(V, TLI, LookThroughBitCast) ||
163 hasNoAliasAttr(V, LookThroughBitCast);
166 /// \brief Tests if a value is a call or invoke to a library function that
167 /// allocates uninitialized memory (such as malloc).
168 bool llvm::isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
169 bool LookThroughBitCast) {
170 return getAllocationData(V, MallocLike, TLI, LookThroughBitCast);
173 /// \brief Tests if a value is a call or invoke to a library function that
174 /// allocates zero-filled memory (such as calloc).
175 bool llvm::isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
176 bool LookThroughBitCast) {
177 return getAllocationData(V, CallocLike, TLI, LookThroughBitCast);
180 /// \brief Tests if a value is a call or invoke to a library function that
181 /// allocates memory (either malloc, calloc, or strdup like).
182 bool llvm::isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
183 bool LookThroughBitCast) {
184 return getAllocationData(V, AllocLike, TLI, LookThroughBitCast);
187 /// \brief Tests if a value is a call or invoke to a library function that
188 /// reallocates memory (such as realloc).
189 bool llvm::isReallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
190 bool LookThroughBitCast) {
191 return getAllocationData(V, ReallocLike, TLI, LookThroughBitCast);
194 /// \brief Tests if a value is a call or invoke to a library function that
195 /// allocates memory and never returns null (such as operator new).
196 bool llvm::isOperatorNewLikeFn(const Value *V, const TargetLibraryInfo *TLI,
197 bool LookThroughBitCast) {
198 return getAllocationData(V, OpNewLike, TLI, LookThroughBitCast);
201 /// extractMallocCall - Returns the corresponding CallInst if the instruction
202 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
203 /// ignore InvokeInst here.
204 const CallInst *llvm::extractMallocCall(const Value *I,
205 const TargetLibraryInfo *TLI) {
206 return isMallocLikeFn(I, TLI) ? dyn_cast<CallInst>(I) : nullptr;
209 static Value *computeArraySize(const CallInst *CI, const DataLayout *DL,
210 const TargetLibraryInfo *TLI,
211 bool LookThroughSExt = false) {
215 // The size of the malloc's result type must be known to determine array size.
216 Type *T = getMallocAllocatedType(CI, TLI);
217 if (!T || !T->isSized() || !DL)
220 unsigned ElementSize = DL->getTypeAllocSize(T);
221 if (StructType *ST = dyn_cast<StructType>(T))
222 ElementSize = DL->getStructLayout(ST)->getSizeInBytes();
224 // If malloc call's arg can be determined to be a multiple of ElementSize,
225 // return the multiple. Otherwise, return NULL.
226 Value *MallocArg = CI->getArgOperand(0);
227 Value *Multiple = nullptr;
228 if (ComputeMultiple(MallocArg, ElementSize, Multiple,
235 /// getMallocType - Returns the PointerType resulting from the malloc call.
236 /// The PointerType depends on the number of bitcast uses of the malloc call:
237 /// 0: PointerType is the calls' return type.
238 /// 1: PointerType is the bitcast's result type.
239 /// >1: Unique PointerType cannot be determined, return NULL.
240 PointerType *llvm::getMallocType(const CallInst *CI,
241 const TargetLibraryInfo *TLI) {
242 assert(isMallocLikeFn(CI, TLI) && "getMallocType and not malloc call");
244 PointerType *MallocType = nullptr;
245 unsigned NumOfBitCastUses = 0;
247 // Determine if CallInst has a bitcast use.
248 for (Value::const_user_iterator UI = CI->user_begin(), E = CI->user_end();
250 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
251 MallocType = cast<PointerType>(BCI->getDestTy());
255 // Malloc call has 1 bitcast use, so type is the bitcast's destination type.
256 if (NumOfBitCastUses == 1)
259 // Malloc call was not bitcast, so type is the malloc function's return type.
260 if (NumOfBitCastUses == 0)
261 return cast<PointerType>(CI->getType());
263 // Type could not be determined.
267 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
268 /// The Type depends on the number of bitcast uses of the malloc call:
269 /// 0: PointerType is the malloc calls' return type.
270 /// 1: PointerType is the bitcast's result type.
271 /// >1: Unique PointerType cannot be determined, return NULL.
272 Type *llvm::getMallocAllocatedType(const CallInst *CI,
273 const TargetLibraryInfo *TLI) {
274 PointerType *PT = getMallocType(CI, TLI);
275 return PT ? PT->getElementType() : nullptr;
278 /// getMallocArraySize - Returns the array size of a malloc call. If the
279 /// argument passed to malloc is a multiple of the size of the malloced type,
280 /// then return that multiple. For non-array mallocs, the multiple is
281 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
283 Value *llvm::getMallocArraySize(CallInst *CI, const DataLayout *DL,
284 const TargetLibraryInfo *TLI,
285 bool LookThroughSExt) {
286 assert(isMallocLikeFn(CI, TLI) && "getMallocArraySize and not malloc call");
287 return computeArraySize(CI, DL, TLI, LookThroughSExt);
291 /// extractCallocCall - Returns the corresponding CallInst if the instruction
292 /// is a calloc call.
293 const CallInst *llvm::extractCallocCall(const Value *I,
294 const TargetLibraryInfo *TLI) {
295 return isCallocLikeFn(I, TLI) ? cast<CallInst>(I) : nullptr;
299 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
300 const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) {
301 const CallInst *CI = dyn_cast<CallInst>(I);
302 if (!CI || isa<IntrinsicInst>(CI))
304 Function *Callee = CI->getCalledFunction();
305 if (Callee == nullptr)
308 StringRef FnName = Callee->getName();
310 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
313 unsigned ExpectedNumParams;
314 if (TLIFn == LibFunc::free ||
315 TLIFn == LibFunc::ZdlPv || // operator delete(void*)
316 TLIFn == LibFunc::ZdaPv) // 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 ExpectedNumParams = 2;
328 // Check free prototype.
329 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
330 // attribute will exist.
331 FunctionType *FTy = Callee->getFunctionType();
332 if (!FTy->getReturnType()->isVoidTy())
334 if (FTy->getNumParams() != ExpectedNumParams)
336 if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext()))
344 //===----------------------------------------------------------------------===//
345 // Utility functions to compute size of objects.
349 /// \brief Compute the size of the object pointed by Ptr. Returns true and the
350 /// object size in Size if successful, and false otherwise.
351 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
352 /// byval arguments, and global variables.
353 bool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout *DL,
354 const TargetLibraryInfo *TLI, bool RoundToAlign) {
358 ObjectSizeOffsetVisitor Visitor(DL, TLI, Ptr->getContext(), RoundToAlign);
359 SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr));
360 if (!Visitor.bothKnown(Data))
363 APInt ObjSize = Data.first, Offset = Data.second;
364 // check for overflow
365 if (Offset.slt(0) || ObjSize.ult(Offset))
368 Size = (ObjSize - Offset).getZExtValue();
373 STATISTIC(ObjectVisitorArgument,
374 "Number of arguments with unsolved size and offset");
375 STATISTIC(ObjectVisitorLoad,
376 "Number of load instructions with unsolved size and offset");
379 APInt ObjectSizeOffsetVisitor::align(APInt Size, uint64_t Align) {
380 if (RoundToAlign && Align)
381 return APInt(IntTyBits, RoundUpToAlignment(Size.getZExtValue(), Align));
385 ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout *DL,
386 const TargetLibraryInfo *TLI,
387 LLVMContext &Context,
389 : DL(DL), TLI(TLI), RoundToAlign(RoundToAlign) {
390 // Pointer size must be rechecked for each object visited since it could have
391 // a different address space.
394 SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
395 IntTyBits = DL->getPointerTypeSizeInBits(V->getType());
396 Zero = APInt::getNullValue(IntTyBits);
398 V = V->stripPointerCasts();
399 if (Instruction *I = dyn_cast<Instruction>(V)) {
400 // If we have already seen this instruction, bail out. Cycles can happen in
401 // unreachable code after constant propagation.
402 if (!SeenInsts.insert(I).second)
405 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
406 return visitGEPOperator(*GEP);
409 if (Argument *A = dyn_cast<Argument>(V))
410 return visitArgument(*A);
411 if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
412 return visitConstantPointerNull(*P);
413 if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
414 return visitGlobalAlias(*GA);
415 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
416 return visitGlobalVariable(*GV);
417 if (UndefValue *UV = dyn_cast<UndefValue>(V))
418 return visitUndefValue(*UV);
419 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
420 if (CE->getOpcode() == Instruction::IntToPtr)
421 return unknown(); // clueless
422 if (CE->getOpcode() == Instruction::GetElementPtr)
423 return visitGEPOperator(cast<GEPOperator>(*CE));
426 DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V
431 SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) {
432 if (!I.getAllocatedType()->isSized())
435 APInt Size(IntTyBits, DL->getTypeAllocSize(I.getAllocatedType()));
436 if (!I.isArrayAllocation())
437 return std::make_pair(align(Size, I.getAlignment()), Zero);
439 Value *ArraySize = I.getArraySize();
440 if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) {
441 Size *= C->getValue().zextOrSelf(IntTyBits);
442 return std::make_pair(align(Size, I.getAlignment()), Zero);
447 SizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) {
448 // no interprocedural analysis is done at the moment
449 if (!A.hasByValOrInAllocaAttr()) {
450 ++ObjectVisitorArgument;
453 PointerType *PT = cast<PointerType>(A.getType());
454 APInt Size(IntTyBits, DL->getTypeAllocSize(PT->getElementType()));
455 return std::make_pair(align(Size, A.getParamAlignment()), Zero);
458 SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) {
459 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
464 // handle strdup-like functions separately
465 if (FnData->AllocTy == StrDupLike) {
466 APInt Size(IntTyBits, GetStringLength(CS.getArgument(0)));
470 // strndup limits strlen
471 if (FnData->FstParam > 0) {
472 ConstantInt *Arg= dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
476 APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits);
477 if (Size.ugt(MaxSize))
480 return std::make_pair(Size, Zero);
483 ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
487 APInt Size = Arg->getValue().zextOrSelf(IntTyBits);
488 // size determined by just 1 parameter
489 if (FnData->SndParam < 0)
490 return std::make_pair(Size, Zero);
492 Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam));
496 Size *= Arg->getValue().zextOrSelf(IntTyBits);
497 return std::make_pair(Size, Zero);
499 // TODO: handle more standard functions (+ wchar cousins):
500 // - strdup / strndup
501 // - strcpy / strncpy
502 // - strcat / strncat
503 // - memcpy / memmove
504 // - strcat / strncat
509 ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull&) {
510 return std::make_pair(Zero, Zero);
514 ObjectSizeOffsetVisitor::visitExtractElementInst(ExtractElementInst&) {
519 ObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst&) {
520 // Easy cases were already folded by previous passes.
524 SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) {
525 SizeOffsetType PtrData = compute(GEP.getPointerOperand());
526 APInt Offset(IntTyBits, 0);
527 if (!bothKnown(PtrData) || !GEP.accumulateConstantOffset(*DL, Offset))
530 return std::make_pair(PtrData.first, PtrData.second + Offset);
533 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalAlias(GlobalAlias &GA) {
534 if (GA.mayBeOverridden())
536 return compute(GA.getAliasee());
539 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){
540 if (!GV.hasDefinitiveInitializer())
543 APInt Size(IntTyBits, DL->getTypeAllocSize(GV.getType()->getElementType()));
544 return std::make_pair(align(Size, GV.getAlignment()), Zero);
547 SizeOffsetType ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst&) {
552 SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) {
557 SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) {
558 // too complex to analyze statically.
562 SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
563 SizeOffsetType TrueSide = compute(I.getTrueValue());
564 SizeOffsetType FalseSide = compute(I.getFalseValue());
565 if (bothKnown(TrueSide) && bothKnown(FalseSide) && TrueSide == FalseSide)
570 SizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) {
571 return std::make_pair(Zero, Zero);
574 SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) {
575 DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I << '\n');
579 ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(const DataLayout *DL,
580 const TargetLibraryInfo *TLI,
581 LLVMContext &Context,
583 : DL(DL), TLI(TLI), Context(Context), Builder(Context, TargetFolder(DL)),
584 RoundToAlign(RoundToAlign) {
585 // IntTy and Zero must be set for each compute() since the address space may
586 // be different for later objects.
589 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) {
590 // XXX - Are vectors of pointers possible here?
591 IntTy = cast<IntegerType>(DL->getIntPtrType(V->getType()));
592 Zero = ConstantInt::get(IntTy, 0);
594 SizeOffsetEvalType Result = compute_(V);
596 if (!bothKnown(Result)) {
597 // erase everything that was computed in this iteration from the cache, so
598 // that no dangling references are left behind. We could be a bit smarter if
599 // we kept a dependency graph. It's probably not worth the complexity.
600 for (PtrSetTy::iterator I=SeenVals.begin(), E=SeenVals.end(); I != E; ++I) {
601 CacheMapTy::iterator CacheIt = CacheMap.find(*I);
602 // non-computable results can be safely cached
603 if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second))
604 CacheMap.erase(CacheIt);
612 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) {
613 ObjectSizeOffsetVisitor Visitor(DL, TLI, Context, RoundToAlign);
614 SizeOffsetType Const = Visitor.compute(V);
615 if (Visitor.bothKnown(Const))
616 return std::make_pair(ConstantInt::get(Context, Const.first),
617 ConstantInt::get(Context, Const.second));
619 V = V->stripPointerCasts();
622 CacheMapTy::iterator CacheIt = CacheMap.find(V);
623 if (CacheIt != CacheMap.end())
624 return CacheIt->second;
626 // always generate code immediately before the instruction being
627 // processed, so that the generated code dominates the same BBs
628 Instruction *PrevInsertPoint = Builder.GetInsertPoint();
629 if (Instruction *I = dyn_cast<Instruction>(V))
630 Builder.SetInsertPoint(I);
632 // now compute the size and offset
633 SizeOffsetEvalType Result;
635 // Record the pointers that were handled in this run, so that they can be
636 // cleaned later if something fails. We also use this set to break cycles that
637 // can occur in dead code.
638 if (!SeenVals.insert(V).second) {
640 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
641 Result = visitGEPOperator(*GEP);
642 } else if (Instruction *I = dyn_cast<Instruction>(V)) {
644 } else if (isa<Argument>(V) ||
645 (isa<ConstantExpr>(V) &&
646 cast<ConstantExpr>(V)->getOpcode() == Instruction::IntToPtr) ||
647 isa<GlobalAlias>(V) ||
648 isa<GlobalVariable>(V)) {
649 // ignore values where we cannot do more than what ObjectSizeVisitor can
652 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: "
658 Builder.SetInsertPoint(PrevInsertPoint);
660 // Don't reuse CacheIt since it may be invalid at this point.
661 CacheMap[V] = Result;
665 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) {
666 if (!I.getAllocatedType()->isSized())
670 assert(I.isArrayAllocation());
671 Value *ArraySize = I.getArraySize();
672 Value *Size = ConstantInt::get(ArraySize->getType(),
673 DL->getTypeAllocSize(I.getAllocatedType()));
674 Size = Builder.CreateMul(Size, ArraySize);
675 return std::make_pair(Size, Zero);
678 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) {
679 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
684 // handle strdup-like functions separately
685 if (FnData->AllocTy == StrDupLike) {
690 Value *FirstArg = CS.getArgument(FnData->FstParam);
691 FirstArg = Builder.CreateZExt(FirstArg, IntTy);
692 if (FnData->SndParam < 0)
693 return std::make_pair(FirstArg, Zero);
695 Value *SecondArg = CS.getArgument(FnData->SndParam);
696 SecondArg = Builder.CreateZExt(SecondArg, IntTy);
697 Value *Size = Builder.CreateMul(FirstArg, SecondArg);
698 return std::make_pair(Size, Zero);
700 // TODO: handle more standard functions (+ wchar cousins):
701 // - strdup / strndup
702 // - strcpy / strncpy
703 // - strcat / strncat
704 // - memcpy / memmove
705 // - strcat / strncat
710 ObjectSizeOffsetEvaluator::visitExtractElementInst(ExtractElementInst&) {
715 ObjectSizeOffsetEvaluator::visitExtractValueInst(ExtractValueInst&) {
720 ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) {
721 SizeOffsetEvalType PtrData = compute_(GEP.getPointerOperand());
722 if (!bothKnown(PtrData))
725 Value *Offset = EmitGEPOffset(&Builder, *DL, &GEP, /*NoAssumptions=*/true);
726 Offset = Builder.CreateAdd(PtrData.second, Offset);
727 return std::make_pair(PtrData.first, Offset);
730 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst&) {
735 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst&) {
739 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) {
740 // create 2 PHIs: one for size and another for offset
741 PHINode *SizePHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
742 PHINode *OffsetPHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
744 // insert right away in the cache to handle recursive PHIs
745 CacheMap[&PHI] = std::make_pair(SizePHI, OffsetPHI);
747 // compute offset/size for each PHI incoming pointer
748 for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) {
749 Builder.SetInsertPoint(PHI.getIncomingBlock(i)->getFirstInsertionPt());
750 SizeOffsetEvalType EdgeData = compute_(PHI.getIncomingValue(i));
752 if (!bothKnown(EdgeData)) {
753 OffsetPHI->replaceAllUsesWith(UndefValue::get(IntTy));
754 OffsetPHI->eraseFromParent();
755 SizePHI->replaceAllUsesWith(UndefValue::get(IntTy));
756 SizePHI->eraseFromParent();
759 SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i));
760 OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i));
763 Value *Size = SizePHI, *Offset = OffsetPHI, *Tmp;
764 if ((Tmp = SizePHI->hasConstantValue())) {
766 SizePHI->replaceAllUsesWith(Size);
767 SizePHI->eraseFromParent();
769 if ((Tmp = OffsetPHI->hasConstantValue())) {
771 OffsetPHI->replaceAllUsesWith(Offset);
772 OffsetPHI->eraseFromParent();
774 return std::make_pair(Size, Offset);
777 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) {
778 SizeOffsetEvalType TrueSide = compute_(I.getTrueValue());
779 SizeOffsetEvalType FalseSide = compute_(I.getFalseValue());
781 if (!bothKnown(TrueSide) || !bothKnown(FalseSide))
783 if (TrueSide == FalseSide)
786 Value *Size = Builder.CreateSelect(I.getCondition(), TrueSide.first,
788 Value *Offset = Builder.CreateSelect(I.getCondition(), TrueSide.second,
790 return std::make_pair(Size, Offset);
793 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) {
794 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I <<'\n');