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 /// isArrayMalloc - Returns the corresponding CallInst if the instruction
236 /// is a call to malloc whose array size can be determined and the array size
237 /// is not constant 1. Otherwise, return NULL.
238 const CallInst *llvm::isArrayMalloc(const Value *I,
239 const DataLayout *DL,
240 const TargetLibraryInfo *TLI) {
241 const CallInst *CI = extractMallocCall(I, TLI);
242 Value *ArraySize = computeArraySize(CI, DL, TLI);
244 if (ConstantInt *ConstSize = dyn_cast_or_null<ConstantInt>(ArraySize))
245 if (ConstSize->isOne())
248 // CI is a non-array malloc or we can't figure out that it is an array malloc.
252 /// getMallocType - Returns the PointerType resulting from the malloc call.
253 /// The PointerType depends on the number of bitcast uses of the malloc call:
254 /// 0: PointerType is the calls' return type.
255 /// 1: PointerType is the bitcast's result type.
256 /// >1: Unique PointerType cannot be determined, return NULL.
257 PointerType *llvm::getMallocType(const CallInst *CI,
258 const TargetLibraryInfo *TLI) {
259 assert(isMallocLikeFn(CI, TLI) && "getMallocType and not malloc call");
261 PointerType *MallocType = nullptr;
262 unsigned NumOfBitCastUses = 0;
264 // Determine if CallInst has a bitcast use.
265 for (Value::const_user_iterator UI = CI->user_begin(), E = CI->user_end();
267 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
268 MallocType = cast<PointerType>(BCI->getDestTy());
272 // Malloc call has 1 bitcast use, so type is the bitcast's destination type.
273 if (NumOfBitCastUses == 1)
276 // Malloc call was not bitcast, so type is the malloc function's return type.
277 if (NumOfBitCastUses == 0)
278 return cast<PointerType>(CI->getType());
280 // Type could not be determined.
284 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
285 /// The Type depends on the number of bitcast uses of the malloc call:
286 /// 0: PointerType is the malloc calls' return type.
287 /// 1: PointerType is the bitcast's result type.
288 /// >1: Unique PointerType cannot be determined, return NULL.
289 Type *llvm::getMallocAllocatedType(const CallInst *CI,
290 const TargetLibraryInfo *TLI) {
291 PointerType *PT = getMallocType(CI, TLI);
292 return PT ? PT->getElementType() : nullptr;
295 /// getMallocArraySize - Returns the array size of a malloc call. If the
296 /// argument passed to malloc is a multiple of the size of the malloced type,
297 /// then return that multiple. For non-array mallocs, the multiple is
298 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
300 Value *llvm::getMallocArraySize(CallInst *CI, const DataLayout *DL,
301 const TargetLibraryInfo *TLI,
302 bool LookThroughSExt) {
303 assert(isMallocLikeFn(CI, TLI) && "getMallocArraySize and not malloc call");
304 return computeArraySize(CI, DL, TLI, LookThroughSExt);
308 /// extractCallocCall - Returns the corresponding CallInst if the instruction
309 /// is a calloc call.
310 const CallInst *llvm::extractCallocCall(const Value *I,
311 const TargetLibraryInfo *TLI) {
312 return isCallocLikeFn(I, TLI) ? cast<CallInst>(I) : nullptr;
316 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
317 const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) {
318 const CallInst *CI = dyn_cast<CallInst>(I);
319 if (!CI || isa<IntrinsicInst>(CI))
321 Function *Callee = CI->getCalledFunction();
322 if (Callee == nullptr)
325 StringRef FnName = Callee->getName();
327 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
330 unsigned ExpectedNumParams;
331 if (TLIFn == LibFunc::free ||
332 TLIFn == LibFunc::ZdlPv || // operator delete(void*)
333 TLIFn == LibFunc::ZdaPv) // operator delete[](void*)
334 ExpectedNumParams = 1;
335 else if (TLIFn == LibFunc::ZdlPvj || // delete(void*, uint)
336 TLIFn == LibFunc::ZdlPvm || // delete(void*, ulong)
337 TLIFn == LibFunc::ZdlPvRKSt9nothrow_t || // delete(void*, nothrow)
338 TLIFn == LibFunc::ZdaPvj || // delete[](void*, uint)
339 TLIFn == LibFunc::ZdaPvm || // delete[](void*, ulong)
340 TLIFn == LibFunc::ZdaPvRKSt9nothrow_t) // delete[](void*, nothrow)
341 ExpectedNumParams = 2;
345 // Check free prototype.
346 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
347 // attribute will exist.
348 FunctionType *FTy = Callee->getFunctionType();
349 if (!FTy->getReturnType()->isVoidTy())
351 if (FTy->getNumParams() != ExpectedNumParams)
353 if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext()))
361 //===----------------------------------------------------------------------===//
362 // Utility functions to compute size of objects.
366 /// \brief Compute the size of the object pointed by Ptr. Returns true and the
367 /// object size in Size if successful, and false otherwise.
368 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
369 /// byval arguments, and global variables.
370 bool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout *DL,
371 const TargetLibraryInfo *TLI, bool RoundToAlign) {
375 ObjectSizeOffsetVisitor Visitor(DL, TLI, Ptr->getContext(), RoundToAlign);
376 SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr));
377 if (!Visitor.bothKnown(Data))
380 APInt ObjSize = Data.first, Offset = Data.second;
381 // check for overflow
382 if (Offset.slt(0) || ObjSize.ult(Offset))
385 Size = (ObjSize - Offset).getZExtValue();
390 STATISTIC(ObjectVisitorArgument,
391 "Number of arguments with unsolved size and offset");
392 STATISTIC(ObjectVisitorLoad,
393 "Number of load instructions with unsolved size and offset");
396 APInt ObjectSizeOffsetVisitor::align(APInt Size, uint64_t Align) {
397 if (RoundToAlign && Align)
398 return APInt(IntTyBits, RoundUpToAlignment(Size.getZExtValue(), Align));
402 ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout *DL,
403 const TargetLibraryInfo *TLI,
404 LLVMContext &Context,
406 : DL(DL), TLI(TLI), RoundToAlign(RoundToAlign) {
407 // Pointer size must be rechecked for each object visited since it could have
408 // a different address space.
411 SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
412 IntTyBits = DL->getPointerTypeSizeInBits(V->getType());
413 Zero = APInt::getNullValue(IntTyBits);
415 V = V->stripPointerCasts();
416 if (Instruction *I = dyn_cast<Instruction>(V)) {
417 // If we have already seen this instruction, bail out. Cycles can happen in
418 // unreachable code after constant propagation.
419 if (!SeenInsts.insert(I).second)
422 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
423 return visitGEPOperator(*GEP);
426 if (Argument *A = dyn_cast<Argument>(V))
427 return visitArgument(*A);
428 if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
429 return visitConstantPointerNull(*P);
430 if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
431 return visitGlobalAlias(*GA);
432 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
433 return visitGlobalVariable(*GV);
434 if (UndefValue *UV = dyn_cast<UndefValue>(V))
435 return visitUndefValue(*UV);
436 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
437 if (CE->getOpcode() == Instruction::IntToPtr)
438 return unknown(); // clueless
439 if (CE->getOpcode() == Instruction::GetElementPtr)
440 return visitGEPOperator(cast<GEPOperator>(*CE));
443 DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V
448 SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) {
449 if (!I.getAllocatedType()->isSized())
452 APInt Size(IntTyBits, DL->getTypeAllocSize(I.getAllocatedType()));
453 if (!I.isArrayAllocation())
454 return std::make_pair(align(Size, I.getAlignment()), Zero);
456 Value *ArraySize = I.getArraySize();
457 if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) {
458 Size *= C->getValue().zextOrSelf(IntTyBits);
459 return std::make_pair(align(Size, I.getAlignment()), Zero);
464 SizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) {
465 // no interprocedural analysis is done at the moment
466 if (!A.hasByValOrInAllocaAttr()) {
467 ++ObjectVisitorArgument;
470 PointerType *PT = cast<PointerType>(A.getType());
471 APInt Size(IntTyBits, DL->getTypeAllocSize(PT->getElementType()));
472 return std::make_pair(align(Size, A.getParamAlignment()), Zero);
475 SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) {
476 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
481 // handle strdup-like functions separately
482 if (FnData->AllocTy == StrDupLike) {
483 APInt Size(IntTyBits, GetStringLength(CS.getArgument(0)));
487 // strndup limits strlen
488 if (FnData->FstParam > 0) {
489 ConstantInt *Arg= dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
493 APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits);
494 if (Size.ugt(MaxSize))
497 return std::make_pair(Size, Zero);
500 ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
504 APInt Size = Arg->getValue().zextOrSelf(IntTyBits);
505 // size determined by just 1 parameter
506 if (FnData->SndParam < 0)
507 return std::make_pair(Size, Zero);
509 Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam));
513 Size *= Arg->getValue().zextOrSelf(IntTyBits);
514 return std::make_pair(Size, Zero);
516 // TODO: handle more standard functions (+ wchar cousins):
517 // - strdup / strndup
518 // - strcpy / strncpy
519 // - strcat / strncat
520 // - memcpy / memmove
521 // - strcat / strncat
526 ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull&) {
527 return std::make_pair(Zero, Zero);
531 ObjectSizeOffsetVisitor::visitExtractElementInst(ExtractElementInst&) {
536 ObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst&) {
537 // Easy cases were already folded by previous passes.
541 SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) {
542 SizeOffsetType PtrData = compute(GEP.getPointerOperand());
543 APInt Offset(IntTyBits, 0);
544 if (!bothKnown(PtrData) || !GEP.accumulateConstantOffset(*DL, Offset))
547 return std::make_pair(PtrData.first, PtrData.second + Offset);
550 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalAlias(GlobalAlias &GA) {
551 if (GA.mayBeOverridden())
553 return compute(GA.getAliasee());
556 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){
557 if (!GV.hasDefinitiveInitializer())
560 APInt Size(IntTyBits, DL->getTypeAllocSize(GV.getType()->getElementType()));
561 return std::make_pair(align(Size, GV.getAlignment()), Zero);
564 SizeOffsetType ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst&) {
569 SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) {
574 SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) {
575 // too complex to analyze statically.
579 SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
580 SizeOffsetType TrueSide = compute(I.getTrueValue());
581 SizeOffsetType FalseSide = compute(I.getFalseValue());
582 if (bothKnown(TrueSide) && bothKnown(FalseSide) && TrueSide == FalseSide)
587 SizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) {
588 return std::make_pair(Zero, Zero);
591 SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) {
592 DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I << '\n');
596 ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(const DataLayout *DL,
597 const TargetLibraryInfo *TLI,
598 LLVMContext &Context,
600 : DL(DL), TLI(TLI), Context(Context), Builder(Context, TargetFolder(DL)),
601 RoundToAlign(RoundToAlign) {
602 // IntTy and Zero must be set for each compute() since the address space may
603 // be different for later objects.
606 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) {
607 // XXX - Are vectors of pointers possible here?
608 IntTy = cast<IntegerType>(DL->getIntPtrType(V->getType()));
609 Zero = ConstantInt::get(IntTy, 0);
611 SizeOffsetEvalType Result = compute_(V);
613 if (!bothKnown(Result)) {
614 // erase everything that was computed in this iteration from the cache, so
615 // that no dangling references are left behind. We could be a bit smarter if
616 // we kept a dependency graph. It's probably not worth the complexity.
617 for (PtrSetTy::iterator I=SeenVals.begin(), E=SeenVals.end(); I != E; ++I) {
618 CacheMapTy::iterator CacheIt = CacheMap.find(*I);
619 // non-computable results can be safely cached
620 if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second))
621 CacheMap.erase(CacheIt);
629 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) {
630 ObjectSizeOffsetVisitor Visitor(DL, TLI, Context, RoundToAlign);
631 SizeOffsetType Const = Visitor.compute(V);
632 if (Visitor.bothKnown(Const))
633 return std::make_pair(ConstantInt::get(Context, Const.first),
634 ConstantInt::get(Context, Const.second));
636 V = V->stripPointerCasts();
639 CacheMapTy::iterator CacheIt = CacheMap.find(V);
640 if (CacheIt != CacheMap.end())
641 return CacheIt->second;
643 // always generate code immediately before the instruction being
644 // processed, so that the generated code dominates the same BBs
645 Instruction *PrevInsertPoint = Builder.GetInsertPoint();
646 if (Instruction *I = dyn_cast<Instruction>(V))
647 Builder.SetInsertPoint(I);
649 // now compute the size and offset
650 SizeOffsetEvalType Result;
652 // Record the pointers that were handled in this run, so that they can be
653 // cleaned later if something fails. We also use this set to break cycles that
654 // can occur in dead code.
655 if (!SeenVals.insert(V).second) {
657 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
658 Result = visitGEPOperator(*GEP);
659 } else if (Instruction *I = dyn_cast<Instruction>(V)) {
661 } else if (isa<Argument>(V) ||
662 (isa<ConstantExpr>(V) &&
663 cast<ConstantExpr>(V)->getOpcode() == Instruction::IntToPtr) ||
664 isa<GlobalAlias>(V) ||
665 isa<GlobalVariable>(V)) {
666 // ignore values where we cannot do more than what ObjectSizeVisitor can
669 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: "
675 Builder.SetInsertPoint(PrevInsertPoint);
677 // Don't reuse CacheIt since it may be invalid at this point.
678 CacheMap[V] = Result;
682 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) {
683 if (!I.getAllocatedType()->isSized())
687 assert(I.isArrayAllocation());
688 Value *ArraySize = I.getArraySize();
689 Value *Size = ConstantInt::get(ArraySize->getType(),
690 DL->getTypeAllocSize(I.getAllocatedType()));
691 Size = Builder.CreateMul(Size, ArraySize);
692 return std::make_pair(Size, Zero);
695 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) {
696 const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
701 // handle strdup-like functions separately
702 if (FnData->AllocTy == StrDupLike) {
707 Value *FirstArg = CS.getArgument(FnData->FstParam);
708 FirstArg = Builder.CreateZExt(FirstArg, IntTy);
709 if (FnData->SndParam < 0)
710 return std::make_pair(FirstArg, Zero);
712 Value *SecondArg = CS.getArgument(FnData->SndParam);
713 SecondArg = Builder.CreateZExt(SecondArg, IntTy);
714 Value *Size = Builder.CreateMul(FirstArg, SecondArg);
715 return std::make_pair(Size, Zero);
717 // TODO: handle more standard functions (+ wchar cousins):
718 // - strdup / strndup
719 // - strcpy / strncpy
720 // - strcat / strncat
721 // - memcpy / memmove
722 // - strcat / strncat
727 ObjectSizeOffsetEvaluator::visitExtractElementInst(ExtractElementInst&) {
732 ObjectSizeOffsetEvaluator::visitExtractValueInst(ExtractValueInst&) {
737 ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) {
738 SizeOffsetEvalType PtrData = compute_(GEP.getPointerOperand());
739 if (!bothKnown(PtrData))
742 Value *Offset = EmitGEPOffset(&Builder, *DL, &GEP, /*NoAssumptions=*/true);
743 Offset = Builder.CreateAdd(PtrData.second, Offset);
744 return std::make_pair(PtrData.first, Offset);
747 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst&) {
752 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst&) {
756 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) {
757 // create 2 PHIs: one for size and another for offset
758 PHINode *SizePHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
759 PHINode *OffsetPHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
761 // insert right away in the cache to handle recursive PHIs
762 CacheMap[&PHI] = std::make_pair(SizePHI, OffsetPHI);
764 // compute offset/size for each PHI incoming pointer
765 for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) {
766 Builder.SetInsertPoint(PHI.getIncomingBlock(i)->getFirstInsertionPt());
767 SizeOffsetEvalType EdgeData = compute_(PHI.getIncomingValue(i));
769 if (!bothKnown(EdgeData)) {
770 OffsetPHI->replaceAllUsesWith(UndefValue::get(IntTy));
771 OffsetPHI->eraseFromParent();
772 SizePHI->replaceAllUsesWith(UndefValue::get(IntTy));
773 SizePHI->eraseFromParent();
776 SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i));
777 OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i));
780 Value *Size = SizePHI, *Offset = OffsetPHI, *Tmp;
781 if ((Tmp = SizePHI->hasConstantValue())) {
783 SizePHI->replaceAllUsesWith(Size);
784 SizePHI->eraseFromParent();
786 if ((Tmp = OffsetPHI->hasConstantValue())) {
788 OffsetPHI->replaceAllUsesWith(Offset);
789 OffsetPHI->eraseFromParent();
791 return std::make_pair(Size, Offset);
794 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) {
795 SizeOffsetEvalType TrueSide = compute_(I.getTrueValue());
796 SizeOffsetEvalType FalseSide = compute_(I.getFalseValue());
798 if (!bothKnown(TrueSide) || !bothKnown(FalseSide))
800 if (TrueSide == FalseSide)
803 Value *Size = Builder.CreateSelect(I.getCondition(), TrueSide.first,
805 Value *Offset = Builder.CreateSelect(I.getCondition(), TrueSide.second,
807 return std::make_pair(Size, Offset);
810 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) {
811 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I <<'\n');