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 // First and Second size parameters (or -1 if unused)
48 int FstParam, SndParam;
51 // FIXME: certain users need more information. E.g., SimplifyLibCalls needs to
52 // know which functions are nounwind, noalias, nocapture parameters, etc.
53 static const std::pair<LibFunc::Func, AllocFnsTy> AllocationFnData[] = {
54 {LibFunc::malloc, {MallocLike, 1, 0, -1}},
55 {LibFunc::valloc, {MallocLike, 1, 0, -1}},
56 {LibFunc::Znwj, {OpNewLike, 1, 0, -1}}, // new(unsigned int)
57 {LibFunc::ZnwjRKSt9nothrow_t, {MallocLike, 2, 0, -1}}, // new(unsigned int, nothrow)
58 {LibFunc::Znwm, {OpNewLike, 1, 0, -1}}, // new(unsigned long)
59 {LibFunc::ZnwmRKSt9nothrow_t, {MallocLike, 2, 0, -1}}, // new(unsigned long, nothrow)
60 {LibFunc::Znaj, {OpNewLike, 1, 0, -1}}, // new[](unsigned int)
61 {LibFunc::ZnajRKSt9nothrow_t, {MallocLike, 2, 0, -1}}, // new[](unsigned int, nothrow)
62 {LibFunc::Znam, {OpNewLike, 1, 0, -1}}, // new[](unsigned long)
63 {LibFunc::ZnamRKSt9nothrow_t, {MallocLike, 2, 0, -1}}, // new[](unsigned long, nothrow)
64 {LibFunc::msvc_new_int, {OpNewLike, 1, 0, -1}}, // new(unsigned int)
65 {LibFunc::msvc_new_int_nothrow, {MallocLike, 2, 0, -1}}, // new(unsigned int, nothrow)
66 {LibFunc::msvc_new_longlong, {OpNewLike, 1, 0, -1}}, // new(unsigned long long)
67 {LibFunc::msvc_new_longlong_nothrow, {MallocLike, 2, 0, -1}}, // new(unsigned long long, nothrow)
68 {LibFunc::msvc_new_array_int, {OpNewLike, 1, 0, -1}}, // new[](unsigned int)
69 {LibFunc::msvc_new_array_int_nothrow, {MallocLike, 2, 0, -1}}, // new[](unsigned int, nothrow)
70 {LibFunc::msvc_new_array_longlong, {OpNewLike, 1, 0, -1}}, // new[](unsigned long long)
71 {LibFunc::msvc_new_array_longlong_nothrow, {MallocLike, 2, 0, -1}}, // new[](unsigned long long, nothrow)
72 {LibFunc::calloc, {CallocLike, 2, 0, 1}},
73 {LibFunc::realloc, {ReallocLike, 2, 1, -1}},
74 {LibFunc::reallocf, {ReallocLike, 2, 1, -1}},
75 {LibFunc::strdup, {StrDupLike, 1, -1, -1}},
76 {LibFunc::strndup, {StrDupLike, 2, 1, -1}}
77 // TODO: Handle "int posix_memalign(void **, size_t, size_t)"
80 static Function *getCalledFunction(const Value *V, bool LookThroughBitCast,
82 // Don't care about intrinsics in this case.
83 if (isa<IntrinsicInst>(V))
86 if (LookThroughBitCast)
87 V = V->stripPointerCasts();
89 CallSite CS(const_cast<Value*>(V));
90 if (!CS.getInstruction())
93 IsNoBuiltin = CS.isNoBuiltin();
95 Function *Callee = CS.getCalledFunction();
96 if (!Callee || !Callee->isDeclaration())
101 /// Returns the allocation data for the given value if it's either a call to a
102 /// known allocation function, or a call to a function with the allocsize
104 static Optional<AllocFnsTy>
105 getAllocationDataForFunction(const Function *Callee, AllocType AllocTy,
106 const TargetLibraryInfo *TLI) {
107 // Make sure that the function is available.
108 StringRef FnName = Callee->getName();
110 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
113 const auto *Iter = find_if(
114 AllocationFnData, [TLIFn](const std::pair<LibFunc::Func, AllocFnsTy> &P) {
115 return P.first == TLIFn;
118 if (Iter == std::end(AllocationFnData))
121 const AllocFnsTy *FnData = &Iter->second;
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 Optional<AllocFnsTy> getAllocationData(const Value *V, AllocType AllocTy,
143 const TargetLibraryInfo *TLI,
144 bool LookThroughBitCast = false) {
145 bool IsNoBuiltinCall;
146 if (const Function *Callee =
147 getCalledFunction(V, LookThroughBitCast, IsNoBuiltinCall))
148 if (!IsNoBuiltinCall)
149 return getAllocationDataForFunction(Callee, AllocTy, TLI);
153 static Optional<AllocFnsTy> getAllocationSize(const Value *V,
154 const TargetLibraryInfo *TLI) {
155 bool IsNoBuiltinCall;
156 const Function *Callee =
157 getCalledFunction(V, /*LookThroughBitCast=*/false, IsNoBuiltinCall);
161 // Prefer to use existing information over allocsize. This will give us an
163 if (!IsNoBuiltinCall)
164 if (Optional<AllocFnsTy> Data =
165 getAllocationDataForFunction(Callee, AnyAlloc, TLI))
168 Attribute Attr = Callee->getFnAttribute(Attribute::AllocSize);
169 if (Attr == Attribute())
172 std::pair<unsigned, Optional<unsigned>> Args = Attr.getAllocSizeArgs();
175 // Because allocsize only tells us how many bytes are allocated, we're not
176 // really allowed to assume anything, so we use MallocLike.
177 Result.AllocTy = MallocLike;
178 Result.NumParams = Callee->getNumOperands();
179 Result.FstParam = Args.first;
180 Result.SndParam = Args.second.getValueOr(-1);
184 static bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) {
185 ImmutableCallSite CS(LookThroughBitCast ? V->stripPointerCasts() : V);
186 return CS && CS.paramHasAttr(AttributeSet::ReturnIndex, Attribute::NoAlias);
190 /// \brief Tests if a value is a call or invoke to a library function that
191 /// allocates or reallocates memory (either malloc, calloc, realloc, or strdup
193 bool llvm::isAllocationFn(const Value *V, const TargetLibraryInfo *TLI,
194 bool LookThroughBitCast) {
195 return getAllocationData(V, AnyAlloc, TLI, LookThroughBitCast).hasValue();
198 /// \brief Tests if a value is a call or invoke to a function that returns a
199 /// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions).
200 bool llvm::isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI,
201 bool LookThroughBitCast) {
202 // it's safe to consider realloc as noalias since accessing the original
203 // pointer is undefined behavior
204 return isAllocationFn(V, TLI, LookThroughBitCast) ||
205 hasNoAliasAttr(V, LookThroughBitCast);
208 /// \brief Tests if a value is a call or invoke to a library function that
209 /// allocates uninitialized memory (such as malloc).
210 bool llvm::isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
211 bool LookThroughBitCast) {
212 return getAllocationData(V, MallocLike, TLI, LookThroughBitCast).hasValue();
215 /// \brief Tests if a value is a call or invoke to a library function that
216 /// allocates zero-filled memory (such as calloc).
217 bool llvm::isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
218 bool LookThroughBitCast) {
219 return getAllocationData(V, CallocLike, TLI, LookThroughBitCast).hasValue();
222 /// \brief Tests if a value is a call or invoke to a library function that
223 /// allocates memory (either malloc, calloc, or strdup like).
224 bool llvm::isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
225 bool LookThroughBitCast) {
226 return getAllocationData(V, AllocLike, TLI, LookThroughBitCast).hasValue();
229 /// extractMallocCall - Returns the corresponding CallInst if the instruction
230 /// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
231 /// ignore InvokeInst here.
232 const CallInst *llvm::extractMallocCall(const Value *I,
233 const TargetLibraryInfo *TLI) {
234 return isMallocLikeFn(I, TLI) ? dyn_cast<CallInst>(I) : nullptr;
237 static Value *computeArraySize(const CallInst *CI, const DataLayout &DL,
238 const TargetLibraryInfo *TLI,
239 bool LookThroughSExt = false) {
243 // The size of the malloc's result type must be known to determine array size.
244 Type *T = getMallocAllocatedType(CI, TLI);
245 if (!T || !T->isSized())
248 unsigned ElementSize = DL.getTypeAllocSize(T);
249 if (StructType *ST = dyn_cast<StructType>(T))
250 ElementSize = DL.getStructLayout(ST)->getSizeInBytes();
252 // If malloc call's arg can be determined to be a multiple of ElementSize,
253 // return the multiple. Otherwise, return NULL.
254 Value *MallocArg = CI->getArgOperand(0);
255 Value *Multiple = nullptr;
256 if (ComputeMultiple(MallocArg, ElementSize, Multiple, LookThroughSExt))
262 /// getMallocType - Returns the PointerType resulting from the malloc call.
263 /// The PointerType depends on the number of bitcast uses of the malloc call:
264 /// 0: PointerType is the calls' return type.
265 /// 1: PointerType is the bitcast's result type.
266 /// >1: Unique PointerType cannot be determined, return NULL.
267 PointerType *llvm::getMallocType(const CallInst *CI,
268 const TargetLibraryInfo *TLI) {
269 assert(isMallocLikeFn(CI, TLI) && "getMallocType and not malloc call");
271 PointerType *MallocType = nullptr;
272 unsigned NumOfBitCastUses = 0;
274 // Determine if CallInst has a bitcast use.
275 for (Value::const_user_iterator UI = CI->user_begin(), E = CI->user_end();
277 if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
278 MallocType = cast<PointerType>(BCI->getDestTy());
282 // Malloc call has 1 bitcast use, so type is the bitcast's destination type.
283 if (NumOfBitCastUses == 1)
286 // Malloc call was not bitcast, so type is the malloc function's return type.
287 if (NumOfBitCastUses == 0)
288 return cast<PointerType>(CI->getType());
290 // Type could not be determined.
294 /// getMallocAllocatedType - Returns the Type allocated by malloc call.
295 /// The Type depends on the number of bitcast uses of the malloc call:
296 /// 0: PointerType is the malloc calls' return type.
297 /// 1: PointerType is the bitcast's result type.
298 /// >1: Unique PointerType cannot be determined, return NULL.
299 Type *llvm::getMallocAllocatedType(const CallInst *CI,
300 const TargetLibraryInfo *TLI) {
301 PointerType *PT = getMallocType(CI, TLI);
302 return PT ? PT->getElementType() : nullptr;
305 /// getMallocArraySize - Returns the array size of a malloc call. If the
306 /// argument passed to malloc is a multiple of the size of the malloced type,
307 /// then return that multiple. For non-array mallocs, the multiple is
308 /// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
310 Value *llvm::getMallocArraySize(CallInst *CI, const DataLayout &DL,
311 const TargetLibraryInfo *TLI,
312 bool LookThroughSExt) {
313 assert(isMallocLikeFn(CI, TLI) && "getMallocArraySize and not malloc call");
314 return computeArraySize(CI, DL, TLI, LookThroughSExt);
318 /// extractCallocCall - Returns the corresponding CallInst if the instruction
319 /// is a calloc call.
320 const CallInst *llvm::extractCallocCall(const Value *I,
321 const TargetLibraryInfo *TLI) {
322 return isCallocLikeFn(I, TLI) ? cast<CallInst>(I) : nullptr;
326 /// isFreeCall - Returns non-null if the value is a call to the builtin free()
327 const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) {
328 const CallInst *CI = dyn_cast<CallInst>(I);
329 if (!CI || isa<IntrinsicInst>(CI))
331 Function *Callee = CI->getCalledFunction();
332 if (Callee == nullptr)
335 StringRef FnName = Callee->getName();
337 if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
340 unsigned ExpectedNumParams;
341 if (TLIFn == LibFunc::free ||
342 TLIFn == LibFunc::ZdlPv || // operator delete(void*)
343 TLIFn == LibFunc::ZdaPv || // operator delete[](void*)
344 TLIFn == LibFunc::msvc_delete_ptr32 || // operator delete(void*)
345 TLIFn == LibFunc::msvc_delete_ptr64 || // operator delete(void*)
346 TLIFn == LibFunc::msvc_delete_array_ptr32 || // operator delete[](void*)
347 TLIFn == LibFunc::msvc_delete_array_ptr64) // operator delete[](void*)
348 ExpectedNumParams = 1;
349 else if (TLIFn == LibFunc::ZdlPvj || // delete(void*, uint)
350 TLIFn == LibFunc::ZdlPvm || // delete(void*, ulong)
351 TLIFn == LibFunc::ZdlPvRKSt9nothrow_t || // delete(void*, nothrow)
352 TLIFn == LibFunc::ZdaPvj || // delete[](void*, uint)
353 TLIFn == LibFunc::ZdaPvm || // delete[](void*, ulong)
354 TLIFn == LibFunc::ZdaPvRKSt9nothrow_t || // delete[](void*, nothrow)
355 TLIFn == LibFunc::msvc_delete_ptr32_int || // delete(void*, uint)
356 TLIFn == LibFunc::msvc_delete_ptr64_longlong || // delete(void*, ulonglong)
357 TLIFn == LibFunc::msvc_delete_ptr32_nothrow || // delete(void*, nothrow)
358 TLIFn == LibFunc::msvc_delete_ptr64_nothrow || // delete(void*, nothrow)
359 TLIFn == LibFunc::msvc_delete_array_ptr32_int || // delete[](void*, uint)
360 TLIFn == LibFunc::msvc_delete_array_ptr64_longlong || // delete[](void*, ulonglong)
361 TLIFn == LibFunc::msvc_delete_array_ptr32_nothrow || // delete[](void*, nothrow)
362 TLIFn == LibFunc::msvc_delete_array_ptr64_nothrow) // delete[](void*, nothrow)
363 ExpectedNumParams = 2;
367 // Check free prototype.
368 // FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
369 // attribute will exist.
370 FunctionType *FTy = Callee->getFunctionType();
371 if (!FTy->getReturnType()->isVoidTy())
373 if (FTy->getNumParams() != ExpectedNumParams)
375 if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext()))
383 //===----------------------------------------------------------------------===//
384 // Utility functions to compute size of objects.
386 static APInt getSizeWithOverflow(const SizeOffsetType &Data) {
387 if (Data.second.isNegative() || Data.first.ult(Data.second))
388 return APInt(Data.first.getBitWidth(), 0);
389 return Data.first - Data.second;
392 /// \brief Compute the size of the object pointed by Ptr. Returns true and the
393 /// object size in Size if successful, and false otherwise.
394 /// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
395 /// byval arguments, and global variables.
396 bool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
397 const TargetLibraryInfo *TLI, bool RoundToAlign,
398 llvm::ObjSizeMode Mode) {
399 ObjectSizeOffsetVisitor Visitor(DL, TLI, Ptr->getContext(),
401 SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr));
402 if (!Visitor.bothKnown(Data))
405 Size = getSizeWithOverflow(Data).getZExtValue();
409 ConstantInt *llvm::lowerObjectSizeCall(IntrinsicInst *ObjectSize,
410 const DataLayout &DL,
411 const TargetLibraryInfo *TLI,
413 assert(ObjectSize->getIntrinsicID() == Intrinsic::objectsize &&
414 "ObjectSize must be a call to llvm.objectsize!");
416 bool MaxVal = cast<ConstantInt>(ObjectSize->getArgOperand(1))->isZero();
418 // Unless we have to fold this to something, try to be as accurate as
421 Mode = MaxVal ? ObjSizeMode::Max : ObjSizeMode::Min;
423 Mode = ObjSizeMode::Exact;
425 // FIXME: Does it make sense to just return a failure value if the size won't
426 // fit in the output and `!MustSucceed`?
428 auto *ResultType = cast<IntegerType>(ObjectSize->getType());
429 if (getObjectSize(ObjectSize->getArgOperand(0), Size, DL, TLI, false, Mode) &&
430 isUIntN(ResultType->getBitWidth(), Size))
431 return ConstantInt::get(ResultType, Size);
436 return ConstantInt::get(ResultType, MaxVal ? -1ULL : 0);
439 STATISTIC(ObjectVisitorArgument,
440 "Number of arguments with unsolved size and offset");
441 STATISTIC(ObjectVisitorLoad,
442 "Number of load instructions with unsolved size and offset");
445 APInt ObjectSizeOffsetVisitor::align(APInt Size, uint64_t Align) {
446 if (RoundToAlign && Align)
447 return APInt(IntTyBits, alignTo(Size.getZExtValue(), Align));
451 ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout &DL,
452 const TargetLibraryInfo *TLI,
453 LLVMContext &Context,
456 : DL(DL), TLI(TLI), RoundToAlign(RoundToAlign), Mode(Mode) {
457 // Pointer size must be rechecked for each object visited since it could have
458 // a different address space.
461 SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
462 IntTyBits = DL.getPointerTypeSizeInBits(V->getType());
463 Zero = APInt::getNullValue(IntTyBits);
465 V = V->stripPointerCasts();
466 if (Instruction *I = dyn_cast<Instruction>(V)) {
467 // If we have already seen this instruction, bail out. Cycles can happen in
468 // unreachable code after constant propagation.
469 if (!SeenInsts.insert(I).second)
472 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
473 return visitGEPOperator(*GEP);
476 if (Argument *A = dyn_cast<Argument>(V))
477 return visitArgument(*A);
478 if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
479 return visitConstantPointerNull(*P);
480 if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
481 return visitGlobalAlias(*GA);
482 if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
483 return visitGlobalVariable(*GV);
484 if (UndefValue *UV = dyn_cast<UndefValue>(V))
485 return visitUndefValue(*UV);
486 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
487 if (CE->getOpcode() == Instruction::IntToPtr)
488 return unknown(); // clueless
489 if (CE->getOpcode() == Instruction::GetElementPtr)
490 return visitGEPOperator(cast<GEPOperator>(*CE));
493 DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V
498 SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) {
499 if (!I.getAllocatedType()->isSized())
502 APInt Size(IntTyBits, DL.getTypeAllocSize(I.getAllocatedType()));
503 if (!I.isArrayAllocation())
504 return std::make_pair(align(Size, I.getAlignment()), Zero);
506 Value *ArraySize = I.getArraySize();
507 if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) {
508 Size *= C->getValue().zextOrSelf(IntTyBits);
509 return std::make_pair(align(Size, I.getAlignment()), Zero);
514 SizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) {
515 // No interprocedural analysis is done at the moment.
516 if (!A.hasByValOrInAllocaAttr()) {
517 ++ObjectVisitorArgument;
520 PointerType *PT = cast<PointerType>(A.getType());
521 APInt Size(IntTyBits, DL.getTypeAllocSize(PT->getElementType()));
522 return std::make_pair(align(Size, A.getParamAlignment()), Zero);
525 SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) {
526 Optional<AllocFnsTy> FnData = getAllocationSize(CS.getInstruction(), TLI);
530 // Handle strdup-like functions separately.
531 if (FnData->AllocTy == StrDupLike) {
532 APInt Size(IntTyBits, GetStringLength(CS.getArgument(0)));
536 // Strndup limits strlen.
537 if (FnData->FstParam > 0) {
539 dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
543 APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits);
544 if (Size.ugt(MaxSize))
547 return std::make_pair(Size, Zero);
550 ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
554 // When we're compiling N-bit code, and the user uses parameters that are
555 // greater than N bits (e.g. uint64_t on a 32-bit build), we can run into
556 // trouble with APInt size issues. This function handles resizing + overflow
558 auto CheckedZextOrTrunc = [&](APInt &I) {
559 // More bits than we can handle. Checking the bit width isn't necessary, but
560 // it's faster than checking active bits, and should give `false` in the
561 // vast majority of cases.
562 if (I.getBitWidth() > IntTyBits && I.getActiveBits() > IntTyBits)
564 if (I.getBitWidth() != IntTyBits)
565 I = I.zextOrTrunc(IntTyBits);
569 APInt Size = Arg->getValue();
570 if (!CheckedZextOrTrunc(Size))
573 // Size is determined by just 1 parameter.
574 if (FnData->SndParam < 0)
575 return std::make_pair(Size, Zero);
577 Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam));
581 APInt NumElems = Arg->getValue();
582 if (!CheckedZextOrTrunc(NumElems))
586 Size = Size.umul_ov(NumElems, Overflow);
587 return Overflow ? unknown() : std::make_pair(Size, Zero);
589 // TODO: handle more standard functions (+ wchar cousins):
590 // - strdup / strndup
591 // - strcpy / strncpy
592 // - strcat / strncat
593 // - memcpy / memmove
594 // - strcat / strncat
599 ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull&) {
600 return std::make_pair(Zero, Zero);
604 ObjectSizeOffsetVisitor::visitExtractElementInst(ExtractElementInst&) {
609 ObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst&) {
610 // Easy cases were already folded by previous passes.
614 SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) {
615 SizeOffsetType PtrData = compute(GEP.getPointerOperand());
616 APInt Offset(IntTyBits, 0);
617 if (!bothKnown(PtrData) || !GEP.accumulateConstantOffset(DL, Offset))
620 return std::make_pair(PtrData.first, PtrData.second + Offset);
623 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalAlias(GlobalAlias &GA) {
624 if (GA.isInterposable())
626 return compute(GA.getAliasee());
629 SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){
630 if (!GV.hasDefinitiveInitializer())
633 APInt Size(IntTyBits, DL.getTypeAllocSize(GV.getType()->getElementType()));
634 return std::make_pair(align(Size, GV.getAlignment()), Zero);
637 SizeOffsetType ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst&) {
642 SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) {
647 SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) {
648 // too complex to analyze statically.
652 SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
653 SizeOffsetType TrueSide = compute(I.getTrueValue());
654 SizeOffsetType FalseSide = compute(I.getFalseValue());
655 if (bothKnown(TrueSide) && bothKnown(FalseSide)) {
656 if (TrueSide == FalseSide) {
660 APInt TrueResult = getSizeWithOverflow(TrueSide);
661 APInt FalseResult = getSizeWithOverflow(FalseSide);
663 if (TrueResult == FalseResult) {
666 if (Mode == ObjSizeMode::Min) {
667 if (TrueResult.slt(FalseResult))
671 if (Mode == ObjSizeMode::Max) {
672 if (TrueResult.sgt(FalseResult))
680 SizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) {
681 return std::make_pair(Zero, Zero);
684 SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) {
685 DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I << '\n');
689 ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(
690 const DataLayout &DL, const TargetLibraryInfo *TLI, LLVMContext &Context,
692 : DL(DL), TLI(TLI), Context(Context), Builder(Context, TargetFolder(DL)),
693 RoundToAlign(RoundToAlign) {
694 // IntTy and Zero must be set for each compute() since the address space may
695 // be different for later objects.
698 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) {
699 // XXX - Are vectors of pointers possible here?
700 IntTy = cast<IntegerType>(DL.getIntPtrType(V->getType()));
701 Zero = ConstantInt::get(IntTy, 0);
703 SizeOffsetEvalType Result = compute_(V);
705 if (!bothKnown(Result)) {
706 // Erase everything that was computed in this iteration from the cache, so
707 // that no dangling references are left behind. We could be a bit smarter if
708 // we kept a dependency graph. It's probably not worth the complexity.
709 for (const Value *SeenVal : SeenVals) {
710 CacheMapTy::iterator CacheIt = CacheMap.find(SeenVal);
711 // non-computable results can be safely cached
712 if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second))
713 CacheMap.erase(CacheIt);
721 SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) {
722 ObjectSizeOffsetVisitor Visitor(DL, TLI, Context, RoundToAlign);
723 SizeOffsetType Const = Visitor.compute(V);
724 if (Visitor.bothKnown(Const))
725 return std::make_pair(ConstantInt::get(Context, Const.first),
726 ConstantInt::get(Context, Const.second));
728 V = V->stripPointerCasts();
731 CacheMapTy::iterator CacheIt = CacheMap.find(V);
732 if (CacheIt != CacheMap.end())
733 return CacheIt->second;
735 // Always generate code immediately before the instruction being
736 // processed, so that the generated code dominates the same BBs.
737 BuilderTy::InsertPointGuard Guard(Builder);
738 if (Instruction *I = dyn_cast<Instruction>(V))
739 Builder.SetInsertPoint(I);
741 // Now compute the size and offset.
742 SizeOffsetEvalType Result;
744 // Record the pointers that were handled in this run, so that they can be
745 // cleaned later if something fails. We also use this set to break cycles that
746 // can occur in dead code.
747 if (!SeenVals.insert(V).second) {
749 } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
750 Result = visitGEPOperator(*GEP);
751 } else if (Instruction *I = dyn_cast<Instruction>(V)) {
753 } else if (isa<Argument>(V) ||
754 (isa<ConstantExpr>(V) &&
755 cast<ConstantExpr>(V)->getOpcode() == Instruction::IntToPtr) ||
756 isa<GlobalAlias>(V) ||
757 isa<GlobalVariable>(V)) {
758 // Ignore values where we cannot do more than ObjectSizeVisitor.
761 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: "
766 // Don't reuse CacheIt since it may be invalid at this point.
767 CacheMap[V] = Result;
771 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) {
772 if (!I.getAllocatedType()->isSized())
776 assert(I.isArrayAllocation());
777 Value *ArraySize = I.getArraySize();
778 Value *Size = ConstantInt::get(ArraySize->getType(),
779 DL.getTypeAllocSize(I.getAllocatedType()));
780 Size = Builder.CreateMul(Size, ArraySize);
781 return std::make_pair(Size, Zero);
784 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) {
785 Optional<AllocFnsTy> FnData = getAllocationSize(CS.getInstruction(), TLI);
789 // Handle strdup-like functions separately.
790 if (FnData->AllocTy == StrDupLike) {
795 Value *FirstArg = CS.getArgument(FnData->FstParam);
796 FirstArg = Builder.CreateZExt(FirstArg, IntTy);
797 if (FnData->SndParam < 0)
798 return std::make_pair(FirstArg, Zero);
800 Value *SecondArg = CS.getArgument(FnData->SndParam);
801 SecondArg = Builder.CreateZExt(SecondArg, IntTy);
802 Value *Size = Builder.CreateMul(FirstArg, SecondArg);
803 return std::make_pair(Size, Zero);
805 // TODO: handle more standard functions (+ wchar cousins):
806 // - strdup / strndup
807 // - strcpy / strncpy
808 // - strcat / strncat
809 // - memcpy / memmove
810 // - strcat / strncat
815 ObjectSizeOffsetEvaluator::visitExtractElementInst(ExtractElementInst&) {
820 ObjectSizeOffsetEvaluator::visitExtractValueInst(ExtractValueInst&) {
825 ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) {
826 SizeOffsetEvalType PtrData = compute_(GEP.getPointerOperand());
827 if (!bothKnown(PtrData))
830 Value *Offset = EmitGEPOffset(&Builder, DL, &GEP, /*NoAssumptions=*/true);
831 Offset = Builder.CreateAdd(PtrData.second, Offset);
832 return std::make_pair(PtrData.first, Offset);
835 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst&) {
840 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst&) {
844 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) {
845 // Create 2 PHIs: one for size and another for offset.
846 PHINode *SizePHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
847 PHINode *OffsetPHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
849 // Insert right away in the cache to handle recursive PHIs.
850 CacheMap[&PHI] = std::make_pair(SizePHI, OffsetPHI);
852 // Compute offset/size for each PHI incoming pointer.
853 for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) {
854 Builder.SetInsertPoint(&*PHI.getIncomingBlock(i)->getFirstInsertionPt());
855 SizeOffsetEvalType EdgeData = compute_(PHI.getIncomingValue(i));
857 if (!bothKnown(EdgeData)) {
858 OffsetPHI->replaceAllUsesWith(UndefValue::get(IntTy));
859 OffsetPHI->eraseFromParent();
860 SizePHI->replaceAllUsesWith(UndefValue::get(IntTy));
861 SizePHI->eraseFromParent();
864 SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i));
865 OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i));
868 Value *Size = SizePHI, *Offset = OffsetPHI, *Tmp;
869 if ((Tmp = SizePHI->hasConstantValue())) {
871 SizePHI->replaceAllUsesWith(Size);
872 SizePHI->eraseFromParent();
874 if ((Tmp = OffsetPHI->hasConstantValue())) {
876 OffsetPHI->replaceAllUsesWith(Offset);
877 OffsetPHI->eraseFromParent();
879 return std::make_pair(Size, Offset);
882 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) {
883 SizeOffsetEvalType TrueSide = compute_(I.getTrueValue());
884 SizeOffsetEvalType FalseSide = compute_(I.getFalseValue());
886 if (!bothKnown(TrueSide) || !bothKnown(FalseSide))
888 if (TrueSide == FalseSide)
891 Value *Size = Builder.CreateSelect(I.getCondition(), TrueSide.first,
893 Value *Offset = Builder.CreateSelect(I.getCondition(), TrueSide.second,
895 return std::make_pair(Size, Offset);
898 SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) {
899 DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I <<'\n');