OSchip
/
llvm-project
mirror of https://github.com/THU-DSP-LAB/llvm-project.git
13
0
Fork 6
Code Issues Packages Projects Releases Wiki Activity
llvm-project/llvm/lib/Analysis/MemoryBuiltins.cpp

989 lines
38 KiB
C++
Raw Blame History

//===- MemoryBuiltins.cpp - Identify calls to memory builtins -------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This family of functions identifies calls to builtin functions that allocate
// or free memory.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Analysis/TargetFolder.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/Utils/Local.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Argument.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalAlias.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Operator.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstdint>
#include <iterator>
#include <utility>
using namespace llvm;
#define DEBUG_TYPE "memory-builtins"
enum AllocType : uint8_t {
OpNewLike = 1<<0, // allocates; never returns null
MallocLike = 1<<1, // allocates; may return null
AlignedAllocLike = 1<<2, // allocates with alignment; may return null
CallocLike = 1<<3, // allocates + bzero
ReallocLike = 1<<4, // reallocates
StrDupLike = 1<<5,
MallocOrOpNewLike = MallocLike | OpNewLike,
MallocOrCallocLike = MallocLike | OpNewLike | CallocLike | AlignedAllocLike,
AllocLike = MallocOrCallocLike | StrDupLike,
AnyAlloc = AllocLike | ReallocLike
};
struct AllocFnsTy {
AllocType AllocTy;
unsigned NumParams;
// First and Second size parameters (or -1 if unused)
int FstParam, SndParam;
// Alignment parameter for aligned_alloc and aligned new
int AlignParam;
};
// FIXME: certain users need more information. E.g., SimplifyLibCalls needs to
// know which functions are nounwind, noalias, nocapture parameters, etc.
static const std::pair<LibFunc, AllocFnsTy> AllocationFnData[] = {
{LibFunc_malloc, {MallocLike, 1, 0, -1, -1}},
{LibFunc_vec_malloc, {MallocLike, 1, 0, -1, -1}},
{LibFunc_valloc, {MallocLike, 1, 0, -1, -1}},
{LibFunc_Znwj, {OpNewLike, 1, 0, -1, -1}}, // new(unsigned int)
{LibFunc_ZnwjRKSt9nothrow_t, {MallocLike, 2, 0, -1, -1}}, // new(unsigned int, nothrow)
{LibFunc_ZnwjSt11align_val_t, {OpNewLike, 2, 0, -1, 1}}, // new(unsigned int, align_val_t)
{LibFunc_ZnwjSt11align_val_tRKSt9nothrow_t, {MallocLike, 3, 0, -1, 1}}, // new(unsigned int, align_val_t, nothrow)
{LibFunc_Znwm, {OpNewLike, 1, 0, -1, -1}}, // new(unsigned long)
{LibFunc_ZnwmRKSt9nothrow_t, {MallocLike, 2, 0, -1, -1}}, // new(unsigned long, nothrow)
{LibFunc_ZnwmSt11align_val_t, {OpNewLike, 2, 0, -1, 1}}, // new(unsigned long, align_val_t)
{LibFunc_ZnwmSt11align_val_tRKSt9nothrow_t, {MallocLike, 3, 0, -1, 1}}, // new(unsigned long, align_val_t, nothrow)
{LibFunc_Znaj, {OpNewLike, 1, 0, -1, -1}}, // new[](unsigned int)
{LibFunc_ZnajRKSt9nothrow_t, {MallocLike, 2, 0, -1, -1}}, // new[](unsigned int, nothrow)
{LibFunc_ZnajSt11align_val_t, {OpNewLike, 2, 0, -1, 1}}, // new[](unsigned int, align_val_t)
{LibFunc_ZnajSt11align_val_tRKSt9nothrow_t, {MallocLike, 3, 0, -1, 1}}, // new[](unsigned int, align_val_t, nothrow)
{LibFunc_Znam, {OpNewLike, 1, 0, -1, -1}}, // new[](unsigned long)
{LibFunc_ZnamRKSt9nothrow_t, {MallocLike, 2, 0, -1, -1}}, // new[](unsigned long, nothrow)
{LibFunc_ZnamSt11align_val_t, {OpNewLike, 2, 0, -1, 1}}, // new[](unsigned long, align_val_t)
{LibFunc_ZnamSt11align_val_tRKSt9nothrow_t, {MallocLike, 3, 0, -1, 1}}, // new[](unsigned long, align_val_t, nothrow)
{LibFunc_msvc_new_int, {OpNewLike, 1, 0, -1, -1}}, // new(unsigned int)
{LibFunc_msvc_new_int_nothrow, {MallocLike, 2, 0, -1, -1}}, // new(unsigned int, nothrow)
{LibFunc_msvc_new_longlong, {OpNewLike, 1, 0, -1, -1}}, // new(unsigned long long)
{LibFunc_msvc_new_longlong_nothrow, {MallocLike, 2, 0, -1, -1}}, // new(unsigned long long, nothrow)
{LibFunc_msvc_new_array_int, {OpNewLike, 1, 0, -1, -1}}, // new[](unsigned int)
{LibFunc_msvc_new_array_int_nothrow, {MallocLike, 2, 0, -1, -1}}, // new[](unsigned int, nothrow)
{LibFunc_msvc_new_array_longlong, {OpNewLike, 1, 0, -1, -1}}, // new[](unsigned long long)
{LibFunc_msvc_new_array_longlong_nothrow, {MallocLike, 2, 0, -1, -1}}, // new[](unsigned long long, nothrow)
{LibFunc_aligned_alloc, {AlignedAllocLike, 2, 1, -1, 0}},
{LibFunc_memalign, {AlignedAllocLike, 2, 1, -1, 0}},
{LibFunc_calloc, {CallocLike, 2, 0, 1, -1}},
{LibFunc_vec_calloc, {CallocLike, 2, 0, 1, -1}},
{LibFunc_realloc, {ReallocLike, 2, 1, -1, -1}},
{LibFunc_vec_realloc, {ReallocLike, 2, 1, -1, -1}},
{LibFunc_reallocf, {ReallocLike, 2, 1, -1, -1}},
{LibFunc_strdup, {StrDupLike, 1, -1, -1, -1}},
{LibFunc_strndup, {StrDupLike, 2, 1, -1, -1}},
{LibFunc___kmpc_alloc_shared, {MallocLike, 1, 0, -1, -1}},
// TODO: Handle "int posix_memalign(void **, size_t, size_t)"
};
static const Function *getCalledFunction(const Value *V,
bool &IsNoBuiltin) {
// Don't care about intrinsics in this case.
if (isa<IntrinsicInst>(V))
return nullptr;
const auto *CB = dyn_cast<CallBase>(V);
if (!CB)
return nullptr;
IsNoBuiltin = CB->isNoBuiltin();
if (const Function *Callee = CB->getCalledFunction())
return Callee;
return nullptr;
}
/// Returns the allocation data for the given value if it's a call to a known
/// allocation function.
static Optional<AllocFnsTy>
getAllocationDataForFunction(const Function *Callee, AllocType AllocTy,
const TargetLibraryInfo *TLI) {
// Make sure that the function is available.
LibFunc TLIFn;
if (!TLI || !TLI->getLibFunc(*Callee, TLIFn) || !TLI->has(TLIFn))
return None;
const auto *Iter = find_if(
AllocationFnData, [TLIFn](const std::pair<LibFunc, AllocFnsTy> &P) {
return P.first == TLIFn;
});
if (Iter == std::end(AllocationFnData))
return None;
const AllocFnsTy *FnData = &Iter->second;
if ((FnData->AllocTy & AllocTy) != FnData->AllocTy)
return None;
// Check function prototype.
int FstParam = FnData->FstParam;
int SndParam = FnData->SndParam;
FunctionType *FTy = Callee->getFunctionType();
if (FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) &&
FTy->getNumParams() == FnData->NumParams &&
(FstParam < 0 ||
(FTy->getParamType(FstParam)->isIntegerTy(32) ||
FTy->getParamType(FstParam)->isIntegerTy(64))) &&
(SndParam < 0 ||
FTy->getParamType(SndParam)->isIntegerTy(32) ||
FTy->getParamType(SndParam)->isIntegerTy(64)))
return *FnData;
return None;
}
static Optional<AllocFnsTy> getAllocationData(const Value *V, AllocType AllocTy,
const TargetLibraryInfo *TLI) {
bool IsNoBuiltinCall;
if (const Function *Callee = getCalledFunction(V, IsNoBuiltinCall))
if (!IsNoBuiltinCall)
return getAllocationDataForFunction(Callee, AllocTy, TLI);
return None;
}
static Optional<AllocFnsTy>
getAllocationData(const Value *V, AllocType AllocTy,
function_ref<const TargetLibraryInfo &(Function &)> GetTLI) {
bool IsNoBuiltinCall;
if (const Function *Callee = getCalledFunction(V, IsNoBuiltinCall))
if (!IsNoBuiltinCall)
return getAllocationDataForFunction(
Callee, AllocTy, &GetTLI(const_cast<Function &>(*Callee)));
return None;
}
static Optional<AllocFnsTy> getAllocationSize(const Value *V,
const TargetLibraryInfo *TLI) {
bool IsNoBuiltinCall;
const Function *Callee =
getCalledFunction(V, IsNoBuiltinCall);
if (!Callee)
return None;
// Prefer to use existing information over allocsize. This will give us an
// accurate AllocTy.
if (!IsNoBuiltinCall)
if (Optional<AllocFnsTy> Data =
getAllocationDataForFunction(Callee, AnyAlloc, TLI))
return Data;
Attribute Attr = Callee->getFnAttribute(Attribute::AllocSize);
if (Attr == Attribute())
return None;
std::pair<unsigned, Optional<unsigned>> Args = Attr.getAllocSizeArgs();
AllocFnsTy Result;
// Because allocsize only tells us how many bytes are allocated, we're not
// really allowed to assume anything, so we use MallocLike.
Result.AllocTy = MallocLike;
Result.NumParams = Callee->getNumOperands();
Result.FstParam = Args.first;
Result.SndParam = Args.second.getValueOr(-1);
// Allocsize has no way to specify an alignment argument
Result.AlignParam = -1;
return Result;
}
/// Tests if a value is a call or invoke to a library function that
/// allocates or reallocates memory (either malloc, calloc, realloc, or strdup
/// like).
bool llvm::isAllocationFn(const Value *V, const TargetLibraryInfo *TLI) {
return getAllocationData(V, AnyAlloc, TLI).hasValue();
}
bool llvm::isAllocationFn(
const Value *V, function_ref<const TargetLibraryInfo &(Function &)> GetTLI) {
return getAllocationData(V, AnyAlloc, GetTLI).hasValue();
}
/// Tests if a value is a call or invoke to a library function that
/// allocates uninitialized memory (such as malloc).
static bool isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI) {
return getAllocationData(V, MallocOrOpNewLike, TLI).hasValue();
}
/// Tests if a value is a call or invoke to a library function that
/// allocates uninitialized memory with alignment (such as aligned_alloc).
static bool isAlignedAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI) {
return getAllocationData(V, AlignedAllocLike, TLI)
.hasValue();
}
/// Tests if a value is a call or invoke to a library function that
/// allocates zero-filled memory (such as calloc).
static bool isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI) {
return getAllocationData(V, CallocLike, TLI).hasValue();
}
/// Tests if a value is a call or invoke to a library function that
/// allocates memory similar to malloc or calloc.
bool llvm::isMallocOrCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI) {
return getAllocationData(V, MallocOrCallocLike, TLI).hasValue();
}
/// Tests if a value is a call or invoke to a library function that
/// allocates memory (either malloc, calloc, or strdup like).
bool llvm::isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI) {
return getAllocationData(V, AllocLike, TLI).hasValue();
}
/// Tests if a value is a call or invoke to a library function that
/// reallocates memory (e.g., realloc).
bool llvm::isReallocLikeFn(const Value *V, const TargetLibraryInfo *TLI) {
return getAllocationData(V, ReallocLike, TLI).hasValue();
}
/// Tests if a functions is a call or invoke to a library function that
/// reallocates memory (e.g., realloc).
bool llvm::isReallocLikeFn(const Function *F, const TargetLibraryInfo *TLI) {
return getAllocationDataForFunction(F, ReallocLike, TLI).hasValue();
}
bool llvm::isAllocRemovable(const CallBase *CB, const TargetLibraryInfo *TLI) {
assert(isAllocationFn(CB, TLI));
// Note: Removability is highly dependent on the source language. For
// example, recent C++ requires direct calls to the global allocation
// [basic.stc.dynamic.allocation] to be observable unless part of a new
// expression [expr.new paragraph 13].
// Historically we've treated the C family allocation routines as removable
return isAllocLikeFn(CB, TLI);
}
Value *llvm::getAllocAlignment(const CallBase *V,
const TargetLibraryInfo *TLI) {
assert(isAllocationFn(V, TLI));
const Optional<AllocFnsTy> FnData = getAllocationData(V, AnyAlloc, TLI);
if (!FnData.hasValue() || FnData->AlignParam < 0) {
return nullptr;
}
return V->getOperand(FnData->AlignParam);
}
/// When we're compiling N-bit code, and the user uses parameters that are
/// greater than N bits (e.g. uint64_t on a 32-bit build), we can run into
/// trouble with APInt size issues. This function handles resizing + overflow
/// checks for us. Check and zext or trunc \p I depending on IntTyBits and
/// I's value.
static bool CheckedZextOrTrunc(APInt &I, unsigned IntTyBits) {
// More bits than we can handle. Checking the bit width isn't necessary, but
// it's faster than checking active bits, and should give `false` in the
// vast majority of cases.
if (I.getBitWidth() > IntTyBits && I.getActiveBits() > IntTyBits)
return false;
if (I.getBitWidth() != IntTyBits)
I = I.zextOrTrunc(IntTyBits);
return true;
}
Optional<APInt>
llvm::getAllocSize(const CallBase *CB,
const TargetLibraryInfo *TLI,
std::function<const Value*(const Value*)> Mapper) {
// Note: This handles both explicitly listed allocation functions and
// allocsize. The code structure could stand to be cleaned up a bit.
Optional<AllocFnsTy> FnData = getAllocationSize(CB, TLI);
if (!FnData)
return None;
// Get the index type for this address space, results and intermediate
// computations are performed at that width.
auto &DL = CB->getModule()->getDataLayout();
const unsigned IntTyBits = DL.getIndexTypeSizeInBits(CB->getType());
// Handle strdup-like functions separately.
if (FnData->AllocTy == StrDupLike) {
APInt Size(IntTyBits, GetStringLength(Mapper(CB->getArgOperand(0))));
if (!Size)
return None;
// Strndup limits strlen.
if (FnData->FstParam > 0) {
const ConstantInt *Arg =
dyn_cast<ConstantInt>(Mapper(CB->getArgOperand(FnData->FstParam)));
if (!Arg)
return None;
APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits);
if (Size.ugt(MaxSize))
Size = MaxSize + 1;
}
return Size;
}
const ConstantInt *Arg =
dyn_cast<ConstantInt>(Mapper(CB->getArgOperand(FnData->FstParam)));
if (!Arg)
return None;
APInt Size = Arg->getValue();
if (!CheckedZextOrTrunc(Size, IntTyBits))
return None;
// Size is determined by just 1 parameter.
if (FnData->SndParam < 0)
return Size;
Arg = dyn_cast<ConstantInt>(Mapper(CB->getArgOperand(FnData->SndParam)));
if (!Arg)
return None;
APInt NumElems = Arg->getValue();
if (!CheckedZextOrTrunc(NumElems, IntTyBits))
return None;
bool Overflow;
Size = Size.umul_ov(NumElems, Overflow);
if (Overflow)
return None;
return Size;
}
Constant *llvm::getInitialValueOfAllocation(const CallBase *Alloc,
const TargetLibraryInfo *TLI,
Type *Ty) {
assert(isAllocationFn(Alloc, TLI));
// malloc and aligned_alloc are uninitialized (undef)
if (isMallocLikeFn(Alloc, TLI) || isAlignedAllocLikeFn(Alloc, TLI))
return UndefValue::get(Ty);
// calloc zero initializes
if (isCallocLikeFn(Alloc, TLI))
return Constant::getNullValue(Ty);
return nullptr;
}
/// isLibFreeFunction - Returns true if the function is a builtin free()
bool llvm::isLibFreeFunction(const Function *F, const LibFunc TLIFn) {
unsigned ExpectedNumParams;
if (TLIFn == LibFunc_free ||
TLIFn == LibFunc_ZdlPv || // operator delete(void*)
TLIFn == LibFunc_ZdaPv || // operator delete[](void*)
TLIFn == LibFunc_msvc_delete_ptr32 || // operator delete(void*)
TLIFn == LibFunc_msvc_delete_ptr64 || // operator delete(void*)
TLIFn == LibFunc_msvc_delete_array_ptr32 || // operator delete[](void*)
TLIFn == LibFunc_msvc_delete_array_ptr64) // operator delete[](void*)
ExpectedNumParams = 1;
else if (TLIFn == LibFunc_ZdlPvj || // delete(void*, uint)
TLIFn == LibFunc_ZdlPvm || // delete(void*, ulong)
TLIFn == LibFunc_ZdlPvRKSt9nothrow_t || // delete(void*, nothrow)
TLIFn == LibFunc_ZdlPvSt11align_val_t || // delete(void*, align_val_t)
TLIFn == LibFunc_ZdaPvj || // delete[](void*, uint)
TLIFn == LibFunc_ZdaPvm || // delete[](void*, ulong)
TLIFn == LibFunc_ZdaPvRKSt9nothrow_t || // delete[](void*, nothrow)
TLIFn == LibFunc_ZdaPvSt11align_val_t || // delete[](void*, align_val_t)
TLIFn == LibFunc_msvc_delete_ptr32_int || // delete(void*, uint)
TLIFn == LibFunc_msvc_delete_ptr64_longlong || // delete(void*, ulonglong)
TLIFn == LibFunc_msvc_delete_ptr32_nothrow || // delete(void*, nothrow)
TLIFn == LibFunc_msvc_delete_ptr64_nothrow || // delete(void*, nothrow)
TLIFn == LibFunc_msvc_delete_array_ptr32_int || // delete[](void*, uint)
TLIFn == LibFunc_msvc_delete_array_ptr64_longlong || // delete[](void*, ulonglong)
TLIFn == LibFunc_msvc_delete_array_ptr32_nothrow || // delete[](void*, nothrow)
TLIFn == LibFunc_msvc_delete_array_ptr64_nothrow || // delete[](void*, nothrow)
TLIFn == LibFunc___kmpc_free_shared) // OpenMP Offloading RTL free
ExpectedNumParams = 2;
else if (TLIFn == LibFunc_ZdaPvSt11align_val_tRKSt9nothrow_t || // delete(void*, align_val_t, nothrow)
TLIFn == LibFunc_ZdlPvSt11align_val_tRKSt9nothrow_t || // delete[](void*, align_val_t, nothrow)
TLIFn == LibFunc_ZdlPvjSt11align_val_t || // delete(void*, unsigned long, align_val_t)
TLIFn == LibFunc_ZdlPvmSt11align_val_t || // delete(void*, unsigned long, align_val_t)
TLIFn == LibFunc_ZdaPvjSt11align_val_t || // delete[](void*, unsigned int, align_val_t)
TLIFn == LibFunc_ZdaPvmSt11align_val_t) // delete[](void*, unsigned long, align_val_t)
ExpectedNumParams = 3;
else
return false;
// Check free prototype.
// FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
// attribute will exist.
FunctionType *FTy = F->getFunctionType();
if (!FTy->getReturnType()->isVoidTy())
return false;
if (FTy->getNumParams() != ExpectedNumParams)
return false;
if (FTy->getParamType(0) != Type::getInt8PtrTy(F->getContext()))
return false;
return true;
}
/// isFreeCall - Returns non-null if the value is a call to the builtin free()
const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) {
bool IsNoBuiltinCall;
const Function *Callee = getCalledFunction(I, IsNoBuiltinCall);
if (Callee == nullptr || IsNoBuiltinCall)
return nullptr;
LibFunc TLIFn;
if (!TLI || !TLI->getLibFunc(*Callee, TLIFn) || !TLI->has(TLIFn))
return nullptr;
return isLibFreeFunction(Callee, TLIFn) ? dyn_cast<CallInst>(I) : nullptr;
}
//===----------------------------------------------------------------------===//
// Utility functions to compute size of objects.
//
static APInt getSizeWithOverflow(const SizeOffsetType &Data) {
if (Data.second.isNegative() || Data.first.ult(Data.second))
return APInt(Data.first.getBitWidth(), 0);
return Data.first - Data.second;
}
/// Compute the size of the object pointed by Ptr. Returns true and the
/// object size in Size if successful, and false otherwise.
/// If RoundToAlign is true, then Size is rounded up to the alignment of
/// allocas, byval arguments, and global variables.
bool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
const TargetLibraryInfo *TLI, ObjectSizeOpts Opts) {
ObjectSizeOffsetVisitor Visitor(DL, TLI, Ptr->getContext(), Opts);
SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr));
if (!Visitor.bothKnown(Data))
return false;
Size = getSizeWithOverflow(Data).getZExtValue();
return true;
}
Value *llvm::lowerObjectSizeCall(IntrinsicInst *ObjectSize,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
bool MustSucceed) {
assert(ObjectSize->getIntrinsicID() == Intrinsic::objectsize &&
"ObjectSize must be a call to llvm.objectsize!");
bool MaxVal = cast<ConstantInt>(ObjectSize->getArgOperand(1))->isZero();
ObjectSizeOpts EvalOptions;
// Unless we have to fold this to something, try to be as accurate as
// possible.
if (MustSucceed)
EvalOptions.EvalMode =
MaxVal ? ObjectSizeOpts::Mode::Max : ObjectSizeOpts::Mode::Min;
else
EvalOptions.EvalMode = ObjectSizeOpts::Mode::Exact;
EvalOptions.NullIsUnknownSize =
cast<ConstantInt>(ObjectSize->getArgOperand(2))->isOne();
auto *ResultType = cast<IntegerType>(ObjectSize->getType());
bool StaticOnly = cast<ConstantInt>(ObjectSize->getArgOperand(3))->isZero();
if (StaticOnly) {
// FIXME: Does it make sense to just return a failure value if the size won't
// fit in the output and `!MustSucceed`?
uint64_t Size;
if (getObjectSize(ObjectSize->getArgOperand(0), Size, DL, TLI, EvalOptions) &&
isUIntN(ResultType->getBitWidth(), Size))
return ConstantInt::get(ResultType, Size);
} else {
LLVMContext &Ctx = ObjectSize->getFunction()->getContext();
ObjectSizeOffsetEvaluator Eval(DL, TLI, Ctx, EvalOptions);
SizeOffsetEvalType SizeOffsetPair =
Eval.compute(ObjectSize->getArgOperand(0));
if (SizeOffsetPair != ObjectSizeOffsetEvaluator::unknown()) {
IRBuilder<TargetFolder> Builder(Ctx, TargetFolder(DL));
Builder.SetInsertPoint(ObjectSize);
// If we've outside the end of the object, then we can always access
// exactly 0 bytes.
Value *ResultSize =
Builder.CreateSub(SizeOffsetPair.first, SizeOffsetPair.second);
Value *UseZero =
Builder.CreateICmpULT(SizeOffsetPair.first, SizeOffsetPair.second);
ResultSize = Builder.CreateZExtOrTrunc(ResultSize, ResultType);
Value *Ret = Builder.CreateSelect(
UseZero, ConstantInt::get(ResultType, 0), ResultSize);
// The non-constant size expression cannot evaluate to -1.
if (!isa<Constant>(SizeOffsetPair.first) ||
!isa<Constant>(SizeOffsetPair.second))
Builder.CreateAssumption(
Builder.CreateICmpNE(Ret, ConstantInt::get(ResultType, -1)));
return Ret;
}
}
if (!MustSucceed)
return nullptr;
return ConstantInt::get(ResultType, MaxVal ? -1ULL : 0);
}
STATISTIC(ObjectVisitorArgument,
"Number of arguments with unsolved size and offset");
STATISTIC(ObjectVisitorLoad,
"Number of load instructions with unsolved size and offset");
APInt ObjectSizeOffsetVisitor::align(APInt Size, MaybeAlign Alignment) {
if (Options.RoundToAlign && Alignment)
return APInt(IntTyBits, alignTo(Size.getZExtValue(), Alignment));
return Size;
}
ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout &DL,
const TargetLibraryInfo *TLI,
LLVMContext &Context,
ObjectSizeOpts Options)
: DL(DL), TLI(TLI), Options(Options) {
// Pointer size must be rechecked for each object visited since it could have
// a different address space.
}
SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
IntTyBits = DL.getIndexTypeSizeInBits(V->getType());
Zero = APInt::getZero(IntTyBits);
V = V->stripPointerCasts();
if (Instruction *I = dyn_cast<Instruction>(V)) {
// If we have already seen this instruction, bail out. Cycles can happen in
// unreachable code after constant propagation.
if (!SeenInsts.insert(I).second)
return unknown();
if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
return visitGEPOperator(*GEP);
return visit(*I);
}
if (Argument *A = dyn_cast<Argument>(V))
return visitArgument(*A);
if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
return visitConstantPointerNull(*P);
if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
return visitGlobalAlias(*GA);
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
return visitGlobalVariable(*GV);
if (UndefValue *UV = dyn_cast<UndefValue>(V))
return visitUndefValue(*UV);
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() == Instruction::IntToPtr)
return unknown(); // clueless
if (CE->getOpcode() == Instruction::GetElementPtr)
return visitGEPOperator(cast<GEPOperator>(*CE));
}
LLVM_DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: "
<< *V << '\n');
return unknown();
}
bool ObjectSizeOffsetVisitor::CheckedZextOrTrunc(APInt &I) {
return ::CheckedZextOrTrunc(I, IntTyBits);
}
SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) {
if (!I.getAllocatedType()->isSized())
return unknown();
if (isa<ScalableVectorType>(I.getAllocatedType()))
return unknown();
APInt Size(IntTyBits, DL.getTypeAllocSize(I.getAllocatedType()));
if (!I.isArrayAllocation())
return std::make_pair(align(Size, I.getAlign()), Zero);
Value *ArraySize = I.getArraySize();
if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) {
APInt NumElems = C->getValue();
if (!CheckedZextOrTrunc(NumElems))
return unknown();
bool Overflow;
Size = Size.umul_ov(NumElems, Overflow);
return Overflow ? unknown()
: std::make_pair(align(Size, I.getAlign()), Zero);
}
return unknown();
}
SizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) {
Type *MemoryTy = A.getPointeeInMemoryValueType();
// No interprocedural analysis is done at the moment.
if (!MemoryTy|| !MemoryTy->isSized()) {
++ObjectVisitorArgument;
return unknown();
}
APInt Size(IntTyBits, DL.getTypeAllocSize(MemoryTy));
return std::make_pair(align(Size, A.getParamAlign()), Zero);
}
SizeOffsetType ObjectSizeOffsetVisitor::visitCallBase(CallBase &CB) {
auto Mapper = [](const Value *V) { return V; };
if (Optional<APInt> Size = getAllocSize(&CB, TLI, Mapper))
return std::make_pair(*Size, Zero);
return unknown();
}
SizeOffsetType
ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull& CPN) {
// If null is unknown, there's nothing we can do. Additionally, non-zero
// address spaces can make use of null, so we don't presume to know anything
// about that.
//
// TODO: How should this work with address space casts? We currently just drop
// them on the floor, but it's unclear what we should do when a NULL from
// addrspace(1) gets casted to addrspace(0) (or vice-versa).
if (Options.NullIsUnknownSize || CPN.getType()->getAddressSpace())
return unknown();
return std::make_pair(Zero, Zero);
}
SizeOffsetType
ObjectSizeOffsetVisitor::visitExtractElementInst(ExtractElementInst&) {
return unknown();
}
SizeOffsetType
ObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst&) {
// Easy cases were already folded by previous passes.
return unknown();
}
SizeOffsetType ObjectSizeOffsetVisitor::visitGEPOperator(GEPOperator &GEP) {
SizeOffsetType PtrData = compute(GEP.getPointerOperand());
APInt Offset(DL.getIndexTypeSizeInBits(GEP.getPointerOperand()->getType()), 0);
if (!bothKnown(PtrData) || !GEP.accumulateConstantOffset(DL, Offset))
return unknown();
return std::make_pair(PtrData.first, PtrData.second + Offset);
}
SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalAlias(GlobalAlias &GA) {
if (GA.isInterposable())
return unknown();
return compute(GA.getAliasee());
}
SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){
if (!GV.hasDefinitiveInitializer())
return unknown();
APInt Size(IntTyBits, DL.getTypeAllocSize(GV.getValueType()));
return std::make_pair(align(Size, GV.getAlign()), Zero);
}
SizeOffsetType ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst&) {
// clueless
return unknown();
}
SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) {
++ObjectVisitorLoad;
return unknown();
}
SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) {
// too complex to analyze statically.
return unknown();
}
SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
SizeOffsetType TrueSide = compute(I.getTrueValue());
SizeOffsetType FalseSide = compute(I.getFalseValue());
if (bothKnown(TrueSide) && bothKnown(FalseSide)) {
if (TrueSide == FalseSide) {
return TrueSide;
}
APInt TrueResult = getSizeWithOverflow(TrueSide);
APInt FalseResult = getSizeWithOverflow(FalseSide);
if (TrueResult == FalseResult) {
return TrueSide;
}
if (Options.EvalMode == ObjectSizeOpts::Mode::Min) {
if (TrueResult.slt(FalseResult))
return TrueSide;
return FalseSide;
}
if (Options.EvalMode == ObjectSizeOpts::Mode::Max) {
if (TrueResult.sgt(FalseResult))
return TrueSide;
return FalseSide;
}
}
return unknown();
}
SizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) {
return std::make_pair(Zero, Zero);
}
SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) {
LLVM_DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I
<< '\n');
return unknown();
}
ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(
const DataLayout &DL, const TargetLibraryInfo *TLI, LLVMContext &Context,
ObjectSizeOpts EvalOpts)
: DL(DL), TLI(TLI), Context(Context),
Builder(Context, TargetFolder(DL),
IRBuilderCallbackInserter(
[&](Instruction *I) { InsertedInstructions.insert(I); })),
EvalOpts(EvalOpts) {
// IntTy and Zero must be set for each compute() since the address space may
// be different for later objects.
}
SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute(Value *V) {
// XXX - Are vectors of pointers possible here?
IntTy = cast<IntegerType>(DL.getIndexType(V->getType()));
Zero = ConstantInt::get(IntTy, 0);
SizeOffsetEvalType Result = compute_(V);
if (!bothKnown(Result)) {
// Erase everything that was computed in this iteration from the cache, so
// that no dangling references are left behind. We could be a bit smarter if
// we kept a dependency graph. It's probably not worth the complexity.
for (const Value *SeenVal : SeenVals) {
CacheMapTy::iterator CacheIt = CacheMap.find(SeenVal);
// non-computable results can be safely cached
if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second))
CacheMap.erase(CacheIt);
}
// Erase any instructions we inserted as part of the traversal.
for (Instruction *I : InsertedInstructions) {
I->replaceAllUsesWith(UndefValue::get(I->getType()));
I->eraseFromParent();
}
}
SeenVals.clear();
InsertedInstructions.clear();
return Result;
}
SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) {
ObjectSizeOffsetVisitor Visitor(DL, TLI, Context, EvalOpts);
SizeOffsetType Const = Visitor.compute(V);
if (Visitor.bothKnown(Const))
return std::make_pair(ConstantInt::get(Context, Const.first),
ConstantInt::get(Context, Const.second));
V = V->stripPointerCasts();
// Check cache.
CacheMapTy::iterator CacheIt = CacheMap.find(V);
if (CacheIt != CacheMap.end())
return CacheIt->second;
// Always generate code immediately before the instruction being
// processed, so that the generated code dominates the same BBs.
BuilderTy::InsertPointGuard Guard(Builder);
if (Instruction *I = dyn_cast<Instruction>(V))
Builder.SetInsertPoint(I);
// Now compute the size and offset.
SizeOffsetEvalType Result;
// Record the pointers that were handled in this run, so that they can be
// cleaned later if something fails. We also use this set to break cycles that
// can occur in dead code.
if (!SeenVals.insert(V).second) {
Result = unknown();
} else if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
Result = visitGEPOperator(*GEP);
} else if (Instruction *I = dyn_cast<Instruction>(V)) {
Result = visit(*I);
} else if (isa<Argument>(V) ||
(isa<ConstantExpr>(V) &&
cast<ConstantExpr>(V)->getOpcode() == Instruction::IntToPtr) ||
isa<GlobalAlias>(V) ||
isa<GlobalVariable>(V)) {
// Ignore values where we cannot do more than ObjectSizeVisitor.
Result = unknown();
} else {
LLVM_DEBUG(
dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: " << *V
<< '\n');
Result = unknown();
}
// Don't reuse CacheIt since it may be invalid at this point.
CacheMap[V] = Result;
return Result;
}
SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) {
if (!I.getAllocatedType()->isSized())
return unknown();
// must be a VLA
assert(I.isArrayAllocation());
// If needed, adjust the alloca's operand size to match the pointer size.
// Subsequent math operations expect the types to match.
Value *ArraySize = Builder.CreateZExtOrTrunc(
I.getArraySize(), DL.getIntPtrType(I.getContext()));
assert(ArraySize->getType() == Zero->getType() &&
"Expected zero constant to have pointer type");
Value *Size = ConstantInt::get(ArraySize->getType(),
DL.getTypeAllocSize(I.getAllocatedType()));
Size = Builder.CreateMul(Size, ArraySize);
return std::make_pair(Size, Zero);
}
SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallBase(CallBase &CB) {
Optional<AllocFnsTy> FnData = getAllocationSize(&CB, TLI);
if (!FnData)
return unknown();
// Handle strdup-like functions separately.
if (FnData->AllocTy == StrDupLike) {
// TODO: implement evaluation of strdup/strndup
return unknown();
}
Value *FirstArg = CB.getArgOperand(FnData->FstParam);
FirstArg = Builder.CreateZExtOrTrunc(FirstArg, IntTy);
if (FnData->SndParam < 0)
return std::make_pair(FirstArg, Zero);
Value *SecondArg = CB.getArgOperand(FnData->SndParam);
SecondArg = Builder.CreateZExtOrTrunc(SecondArg, IntTy);
Value *Size = Builder.CreateMul(FirstArg, SecondArg);
return std::make_pair(Size, Zero);
}
SizeOffsetEvalType
ObjectSizeOffsetEvaluator::visitExtractElementInst(ExtractElementInst&) {
return unknown();
}
SizeOffsetEvalType
ObjectSizeOffsetEvaluator::visitExtractValueInst(ExtractValueInst&) {
return unknown();
}
SizeOffsetEvalType
ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) {
SizeOffsetEvalType PtrData = compute_(GEP.getPointerOperand());
if (!bothKnown(PtrData))
return unknown();
Value *Offset = EmitGEPOffset(&Builder, DL, &GEP, /*NoAssumptions=*/true);
Offset = Builder.CreateAdd(PtrData.second, Offset);
return std::make_pair(PtrData.first, Offset);
}
SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst&) {
// clueless
return unknown();
}
SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst&) {
return unknown();
}
SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitPHINode(PHINode &PHI) {
// Create 2 PHIs: one for size and another for offset.
PHINode *SizePHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
PHINode *OffsetPHI = Builder.CreatePHI(IntTy, PHI.getNumIncomingValues());
// Insert right away in the cache to handle recursive PHIs.
CacheMap[&PHI] = std::make_pair(SizePHI, OffsetPHI);
// Compute offset/size for each PHI incoming pointer.
for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) {
Builder.SetInsertPoint(&*PHI.getIncomingBlock(i)->getFirstInsertionPt());
SizeOffsetEvalType EdgeData = compute_(PHI.getIncomingValue(i));
if (!bothKnown(EdgeData)) {
OffsetPHI->replaceAllUsesWith(UndefValue::get(IntTy));
OffsetPHI->eraseFromParent();
InsertedInstructions.erase(OffsetPHI);
SizePHI->replaceAllUsesWith(UndefValue::get(IntTy));
SizePHI->eraseFromParent();
InsertedInstructions.erase(SizePHI);
return unknown();
}
SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i));
OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i));
}
Value *Size = SizePHI, *Offset = OffsetPHI;
if (Value *Tmp = SizePHI->hasConstantValue()) {
Size = Tmp;
SizePHI->replaceAllUsesWith(Size);
SizePHI->eraseFromParent();
InsertedInstructions.erase(SizePHI);
}
if (Value *Tmp = OffsetPHI->hasConstantValue()) {
Offset = Tmp;
OffsetPHI->replaceAllUsesWith(Offset);
OffsetPHI->eraseFromParent();
InsertedInstructions.erase(OffsetPHI);
}
return std::make_pair(Size, Offset);
}
SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) {
SizeOffsetEvalType TrueSide = compute_(I.getTrueValue());
SizeOffsetEvalType FalseSide = compute_(I.getFalseValue());
if (!bothKnown(TrueSide) || !bothKnown(FalseSide))
return unknown();
if (TrueSide == FalseSide)
return TrueSide;
Value *Size = Builder.CreateSelect(I.getCondition(), TrueSide.first,
FalseSide.first);
Value *Offset = Builder.CreateSelect(I.getCondition(), TrueSide.second,
FalseSide.second);
return std::make_pair(Size, Offset);
}
SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) {
LLVM_DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I
<< '\n');
return unknown();
}
Reference in New Issue View Git Blame Copy Permalink