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llvm-project/llvm/lib/Analysis/MemoryBuiltins.cpp
Bill Wendling fc6b5666db
[NFC][ObjectSizeOffset] Use classes instead of std::pair (#76882) 
The use of std::pair makes the values it holds opaque. Using classes
improves this while keeping the POD aspect of a std::pair. As a nice
addition, the "known" functions held inappropriately in the Visitor
classes can now properly reside in the value classes. :-)
2024-01-05 18:08:53 -08:00

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//===- 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/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.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/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstdint>
#include <iterator>
#include <numeric>
#include <optional>
#include <type_traits>
#include <utility>
using namespace llvm;
#define DEBUG_TYPE "memory-builtins"
static cl::opt<unsigned> ObjectSizeOffsetVisitorMaxVisitInstructions(
"object-size-offset-visitor-max-visit-instructions",
cl::desc("Maximum number of instructions for ObjectSizeOffsetVisitor to "
"look at"),
cl::init(100));
enum AllocType : uint8_t {
OpNewLike = 1<<0, // allocates; never returns null
MallocLike = 1<<1, // allocates; may return null
StrDupLike = 1<<2,
MallocOrOpNewLike = MallocLike | OpNewLike,
AllocLike = MallocOrOpNewLike | StrDupLike,
AnyAlloc = AllocLike
};
enum class MallocFamily {
Malloc,
CPPNew, // new(unsigned int)
CPPNewAligned, // new(unsigned int, align_val_t)
CPPNewArray, // new[](unsigned int)
CPPNewArrayAligned, // new[](unsigned long, align_val_t)
MSVCNew, // new(unsigned int)
MSVCArrayNew, // new[](unsigned int)
VecMalloc,
KmpcAllocShared,
};
StringRef mangledNameForMallocFamily(const MallocFamily &Family) {
switch (Family) {
case MallocFamily::Malloc:
return "malloc";
case MallocFamily::CPPNew:
return "_Znwm";
case MallocFamily::CPPNewAligned:
return "_ZnwmSt11align_val_t";
case MallocFamily::CPPNewArray:
return "_Znam";
case MallocFamily::CPPNewArrayAligned:
return "_ZnamSt11align_val_t";
case MallocFamily::MSVCNew:
return "??2@YAPAXI@Z";
case MallocFamily::MSVCArrayNew:
return "??_U@YAPAXI@Z";
case MallocFamily::VecMalloc:
return "vec_malloc";
case MallocFamily::KmpcAllocShared:
return "__kmpc_alloc_shared";
}
llvm_unreachable("missing an alloc family");
}
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;
// Name of default allocator function to group malloc/free calls by family
MallocFamily Family;
};
// clang-format off
// 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_Znwj, {OpNewLike, 1, 0, -1, -1, MallocFamily::CPPNew}}, // new(unsigned int)
{LibFunc_ZnwjRKSt9nothrow_t, {MallocLike, 2, 0, -1, -1, MallocFamily::CPPNew}}, // new(unsigned int, nothrow)
{LibFunc_ZnwjSt11align_val_t, {OpNewLike, 2, 0, -1, 1, MallocFamily::CPPNewAligned}}, // new(unsigned int, align_val_t)
{LibFunc_ZnwjSt11align_val_tRKSt9nothrow_t, {MallocLike, 3, 0, -1, 1, MallocFamily::CPPNewAligned}}, // new(unsigned int, align_val_t, nothrow)
{LibFunc_Znwm, {OpNewLike, 1, 0, -1, -1, MallocFamily::CPPNew}}, // new(unsigned long)
{LibFunc_Znwm12__hot_cold_t, {OpNewLike, 2, 0, -1, -1, MallocFamily::CPPNew}}, // new(unsigned long, __hot_cold_t)
{LibFunc_ZnwmRKSt9nothrow_t, {MallocLike, 2, 0, -1, -1, MallocFamily::CPPNew}}, // new(unsigned long, nothrow)
{LibFunc_ZnwmRKSt9nothrow_t12__hot_cold_t, {MallocLike, 3, 0, -1, -1, MallocFamily::CPPNew}}, // new(unsigned long, nothrow, __hot_cold_t)
{LibFunc_ZnwmSt11align_val_t, {OpNewLike, 2, 0, -1, 1, MallocFamily::CPPNewAligned}}, // new(unsigned long, align_val_t)
{LibFunc_ZnwmSt11align_val_t12__hot_cold_t, {OpNewLike, 3, 0, -1, 1, MallocFamily::CPPNewAligned}}, // new(unsigned long, align_val_t, __hot_cold_t)
{LibFunc_ZnwmSt11align_val_tRKSt9nothrow_t, {MallocLike, 3, 0, -1, 1, MallocFamily::CPPNewAligned}}, // new(unsigned long, align_val_t, nothrow)
{LibFunc_ZnwmSt11align_val_tRKSt9nothrow_t12__hot_cold_t, {MallocLike, 4, 0, -1, 1, MallocFamily::CPPNewAligned}}, // new(unsigned long, align_val_t, nothrow, __hot_cold_t)
{LibFunc_Znaj, {OpNewLike, 1, 0, -1, -1, MallocFamily::CPPNewArray}}, // new[](unsigned int)
{LibFunc_ZnajRKSt9nothrow_t, {MallocLike, 2, 0, -1, -1, MallocFamily::CPPNewArray}}, // new[](unsigned int, nothrow)
{LibFunc_ZnajSt11align_val_t, {OpNewLike, 2, 0, -1, 1, MallocFamily::CPPNewArrayAligned}}, // new[](unsigned int, align_val_t)
{LibFunc_ZnajSt11align_val_tRKSt9nothrow_t, {MallocLike, 3, 0, -1, 1, MallocFamily::CPPNewArrayAligned}}, // new[](unsigned int, align_val_t, nothrow)
{LibFunc_Znam, {OpNewLike, 1, 0, -1, -1, MallocFamily::CPPNewArray}}, // new[](unsigned long)
{LibFunc_Znam12__hot_cold_t, {OpNewLike, 2, 0, -1, -1, MallocFamily::CPPNew}}, // new[](unsigned long, __hot_cold_t)
{LibFunc_ZnamRKSt9nothrow_t, {MallocLike, 2, 0, -1, -1, MallocFamily::CPPNewArray}}, // new[](unsigned long, nothrow)
{LibFunc_ZnamRKSt9nothrow_t12__hot_cold_t, {MallocLike, 3, 0, -1, -1, MallocFamily::CPPNew}}, // new[](unsigned long, nothrow, __hot_cold_t)
{LibFunc_ZnamSt11align_val_t, {OpNewLike, 2, 0, -1, 1, MallocFamily::CPPNewArrayAligned}}, // new[](unsigned long, align_val_t)
{LibFunc_ZnamSt11align_val_t12__hot_cold_t, {OpNewLike, 3, 0, -1, 1, MallocFamily::CPPNewAligned}}, // new[](unsigned long, align_val_t, __hot_cold_t)
{LibFunc_ZnamSt11align_val_tRKSt9nothrow_t, {MallocLike, 3, 0, -1, 1, MallocFamily::CPPNewArrayAligned}}, // new[](unsigned long, align_val_t, nothrow)
{LibFunc_ZnamSt11align_val_tRKSt9nothrow_t12__hot_cold_t, {MallocLike, 4, 0, -1, 1, MallocFamily::CPPNewAligned}}, // new[](unsigned long, align_val_t, nothrow, __hot_cold_t)
{LibFunc_msvc_new_int, {OpNewLike, 1, 0, -1, -1, MallocFamily::MSVCNew}}, // new(unsigned int)
{LibFunc_msvc_new_int_nothrow, {MallocLike, 2, 0, -1, -1, MallocFamily::MSVCNew}}, // new(unsigned int, nothrow)
{LibFunc_msvc_new_longlong, {OpNewLike, 1, 0, -1, -1, MallocFamily::MSVCNew}}, // new(unsigned long long)
{LibFunc_msvc_new_longlong_nothrow, {MallocLike, 2, 0, -1, -1, MallocFamily::MSVCNew}}, // new(unsigned long long, nothrow)
{LibFunc_msvc_new_array_int, {OpNewLike, 1, 0, -1, -1, MallocFamily::MSVCArrayNew}}, // new[](unsigned int)
{LibFunc_msvc_new_array_int_nothrow, {MallocLike, 2, 0, -1, -1, MallocFamily::MSVCArrayNew}}, // new[](unsigned int, nothrow)
{LibFunc_msvc_new_array_longlong, {OpNewLike, 1, 0, -1, -1, MallocFamily::MSVCArrayNew}}, // new[](unsigned long long)
{LibFunc_msvc_new_array_longlong_nothrow, {MallocLike, 2, 0, -1, -1, MallocFamily::MSVCArrayNew}}, // new[](unsigned long long, nothrow)
{LibFunc_strdup, {StrDupLike, 1, -1, -1, -1, MallocFamily::Malloc}},
{LibFunc_dunder_strdup, {StrDupLike, 1, -1, -1, -1, MallocFamily::Malloc}},
{LibFunc_strndup, {StrDupLike, 2, 1, -1, -1, MallocFamily::Malloc}},
{LibFunc_dunder_strndup, {StrDupLike, 2, 1, -1, -1, MallocFamily::Malloc}},
{LibFunc___kmpc_alloc_shared, {MallocLike, 1, 0, -1, -1, MallocFamily::KmpcAllocShared}},
};
// clang-format on
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 std::optional<AllocFnsTy>
getAllocationDataForFunction(const Function *Callee, AllocType AllocTy,
const TargetLibraryInfo *TLI) {
// Don't perform a slow TLI lookup, if this function doesn't return a pointer
// and thus can't be an allocation function.
if (!Callee->getReturnType()->isPointerTy())
return std::nullopt;
// Make sure that the function is available.
LibFunc TLIFn;
if (!TLI || !TLI->getLibFunc(*Callee, TLIFn) || !TLI->has(TLIFn))
return std::nullopt;
const auto *Iter = find_if(
AllocationFnData, [TLIFn](const std::pair<LibFunc, AllocFnsTy> &P) {
return P.first == TLIFn;
});
if (Iter == std::end(AllocationFnData))
return std::nullopt;
const AllocFnsTy *FnData = &Iter->second;
if ((FnData->AllocTy & AllocTy) != FnData->AllocTy)
return std::nullopt;
// Check function prototype.
int FstParam = FnData->FstParam;
int SndParam = FnData->SndParam;
FunctionType *FTy = Callee->getFunctionType();
if (FTy->getReturnType()->isPointerTy() &&
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 std::nullopt;
}
static std::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 std::nullopt;
}
static std::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 std::nullopt;
}
static std::optional<AllocFnsTy>
getAllocationSize(const Value *V, const TargetLibraryInfo *TLI) {
bool IsNoBuiltinCall;
const Function *Callee =
getCalledFunction(V, IsNoBuiltinCall);
if (!Callee)
return std::nullopt;
// Prefer to use existing information over allocsize. This will give us an
// accurate AllocTy.
if (!IsNoBuiltinCall)
if (std::optional<AllocFnsTy> Data =
getAllocationDataForFunction(Callee, AnyAlloc, TLI))
return Data;
Attribute Attr = Callee->getFnAttribute(Attribute::AllocSize);
if (Attr == Attribute())
return std::nullopt;
std::pair<unsigned, std::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.value_or(-1);
// Allocsize has no way to specify an alignment argument
Result.AlignParam = -1;
return Result;
}
static AllocFnKind getAllocFnKind(const Value *V) {
if (const auto *CB = dyn_cast<CallBase>(V)) {
Attribute Attr = CB->getFnAttr(Attribute::AllocKind);
if (Attr.isValid())
return AllocFnKind(Attr.getValueAsInt());
}
return AllocFnKind::Unknown;
}
static AllocFnKind getAllocFnKind(const Function *F) {
return F->getAttributes().getAllocKind();
}
static bool checkFnAllocKind(const Value *V, AllocFnKind Wanted) {
return (getAllocFnKind(V) & Wanted) != AllocFnKind::Unknown;
}
static bool checkFnAllocKind(const Function *F, AllocFnKind Wanted) {
return (getAllocFnKind(F) & Wanted) != AllocFnKind::Unknown;
}
/// 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).has_value() ||
checkFnAllocKind(V, AllocFnKind::Alloc | AllocFnKind::Realloc);
}
bool llvm::isAllocationFn(
const Value *V,
function_ref<const TargetLibraryInfo &(Function &)> GetTLI) {
return getAllocationData(V, AnyAlloc, GetTLI).has_value() ||
checkFnAllocKind(V, AllocFnKind::Alloc | AllocFnKind::Realloc);
}
/// Tests if a value is a call or invoke to a library function that
/// allocates memory via new.
bool llvm::isNewLikeFn(const Value *V, const TargetLibraryInfo *TLI) {
return getAllocationData(V, OpNewLike, TLI).has_value();
}
/// 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) {
// TODO: Function behavior does not match name.
return getAllocationData(V, MallocOrOpNewLike, TLI).has_value();
}
/// 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).has_value() ||
checkFnAllocKind(V, AllocFnKind::Alloc);
}
/// 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) {
return checkFnAllocKind(F, AllocFnKind::Realloc);
}
Value *llvm::getReallocatedOperand(const CallBase *CB) {
if (checkFnAllocKind(CB, AllocFnKind::Realloc))
return CB->getArgOperandWithAttribute(Attribute::AllocatedPointer);
return nullptr;
}
bool llvm::isRemovableAlloc(const CallBase *CB, const TargetLibraryInfo *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 and operator
// new as removable
return isAllocLikeFn(CB, TLI);
}
Value *llvm::getAllocAlignment(const CallBase *V,
const TargetLibraryInfo *TLI) {
const std::optional<AllocFnsTy> FnData = getAllocationData(V, AnyAlloc, TLI);
if (FnData && FnData->AlignParam >= 0) {
return V->getOperand(FnData->AlignParam);
}
return V->getArgOperandWithAttribute(Attribute::AllocAlign);
}
/// 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;
}
std::optional<APInt>
llvm::getAllocSize(const CallBase *CB, const TargetLibraryInfo *TLI,
function_ref<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.
std::optional<AllocFnsTy> FnData = getAllocationSize(CB, TLI);
if (!FnData)
return std::nullopt;
// 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 std::nullopt;
// Strndup limits strlen.
if (FnData->FstParam > 0) {
const ConstantInt *Arg =
dyn_cast<ConstantInt>(Mapper(CB->getArgOperand(FnData->FstParam)));
if (!Arg)
return std::nullopt;
APInt MaxSize = Arg->getValue().zext(IntTyBits);
if (Size.ugt(MaxSize))
Size = MaxSize + 1;
}
return Size;
}
const ConstantInt *Arg =
dyn_cast<ConstantInt>(Mapper(CB->getArgOperand(FnData->FstParam)));
if (!Arg)
return std::nullopt;
APInt Size = Arg->getValue();
if (!CheckedZextOrTrunc(Size, IntTyBits))
return std::nullopt;
// 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 std::nullopt;
APInt NumElems = Arg->getValue();
if (!CheckedZextOrTrunc(NumElems, IntTyBits))
return std::nullopt;
bool Overflow;
Size = Size.umul_ov(NumElems, Overflow);
if (Overflow)
return std::nullopt;
return Size;
}
Constant *llvm::getInitialValueOfAllocation(const Value *V,
const TargetLibraryInfo *TLI,
Type *Ty) {
auto *Alloc = dyn_cast<CallBase>(V);
if (!Alloc)
return nullptr;
// malloc are uninitialized (undef)
if (getAllocationData(Alloc, MallocOrOpNewLike, TLI).has_value())
return UndefValue::get(Ty);
AllocFnKind AK = getAllocFnKind(Alloc);
if ((AK & AllocFnKind::Uninitialized) != AllocFnKind::Unknown)
return UndefValue::get(Ty);
if ((AK & AllocFnKind::Zeroed) != AllocFnKind::Unknown)
return Constant::getNullValue(Ty);
return nullptr;
}
struct FreeFnsTy {
unsigned NumParams;
// Name of default allocator function to group malloc/free calls by family
MallocFamily Family;
};
// clang-format off
static const std::pair<LibFunc, FreeFnsTy> FreeFnData[] = {
{LibFunc_ZdlPv, {1, MallocFamily::CPPNew}}, // operator delete(void*)
{LibFunc_ZdaPv, {1, MallocFamily::CPPNewArray}}, // operator delete[](void*)
{LibFunc_msvc_delete_ptr32, {1, MallocFamily::MSVCNew}}, // operator delete(void*)
{LibFunc_msvc_delete_ptr64, {1, MallocFamily::MSVCNew}}, // operator delete(void*)
{LibFunc_msvc_delete_array_ptr32, {1, MallocFamily::MSVCArrayNew}}, // operator delete[](void*)
{LibFunc_msvc_delete_array_ptr64, {1, MallocFamily::MSVCArrayNew}}, // operator delete[](void*)
{LibFunc_ZdlPvj, {2, MallocFamily::CPPNew}}, // delete(void*, uint)
{LibFunc_ZdlPvm, {2, MallocFamily::CPPNew}}, // delete(void*, ulong)
{LibFunc_ZdlPvRKSt9nothrow_t, {2, MallocFamily::CPPNew}}, // delete(void*, nothrow)
{LibFunc_ZdlPvSt11align_val_t, {2, MallocFamily::CPPNewAligned}}, // delete(void*, align_val_t)
{LibFunc_ZdaPvj, {2, MallocFamily::CPPNewArray}}, // delete[](void*, uint)
{LibFunc_ZdaPvm, {2, MallocFamily::CPPNewArray}}, // delete[](void*, ulong)
{LibFunc_ZdaPvRKSt9nothrow_t, {2, MallocFamily::CPPNewArray}}, // delete[](void*, nothrow)
{LibFunc_ZdaPvSt11align_val_t, {2, MallocFamily::CPPNewArrayAligned}}, // delete[](void*, align_val_t)
{LibFunc_msvc_delete_ptr32_int, {2, MallocFamily::MSVCNew}}, // delete(void*, uint)
{LibFunc_msvc_delete_ptr64_longlong, {2, MallocFamily::MSVCNew}}, // delete(void*, ulonglong)
{LibFunc_msvc_delete_ptr32_nothrow, {2, MallocFamily::MSVCNew}}, // delete(void*, nothrow)
{LibFunc_msvc_delete_ptr64_nothrow, {2, MallocFamily::MSVCNew}}, // delete(void*, nothrow)
{LibFunc_msvc_delete_array_ptr32_int, {2, MallocFamily::MSVCArrayNew}}, // delete[](void*, uint)
{LibFunc_msvc_delete_array_ptr64_longlong, {2, MallocFamily::MSVCArrayNew}}, // delete[](void*, ulonglong)
{LibFunc_msvc_delete_array_ptr32_nothrow, {2, MallocFamily::MSVCArrayNew}}, // delete[](void*, nothrow)
{LibFunc_msvc_delete_array_ptr64_nothrow, {2, MallocFamily::MSVCArrayNew}}, // delete[](void*, nothrow)
{LibFunc___kmpc_free_shared, {2, MallocFamily::KmpcAllocShared}}, // OpenMP Offloading RTL free
{LibFunc_ZdlPvSt11align_val_tRKSt9nothrow_t, {3, MallocFamily::CPPNewAligned}}, // delete(void*, align_val_t, nothrow)
{LibFunc_ZdaPvSt11align_val_tRKSt9nothrow_t, {3, MallocFamily::CPPNewArrayAligned}}, // delete[](void*, align_val_t, nothrow)
{LibFunc_ZdlPvjSt11align_val_t, {3, MallocFamily::CPPNewAligned}}, // delete(void*, unsigned int, align_val_t)
{LibFunc_ZdlPvmSt11align_val_t, {3, MallocFamily::CPPNewAligned}}, // delete(void*, unsigned long, align_val_t)
{LibFunc_ZdaPvjSt11align_val_t, {3, MallocFamily::CPPNewArrayAligned}}, // delete[](void*, unsigned int, align_val_t)
{LibFunc_ZdaPvmSt11align_val_t, {3, MallocFamily::CPPNewArrayAligned}}, // delete[](void*, unsigned long, align_val_t)
};
// clang-format on
std::optional<FreeFnsTy> getFreeFunctionDataForFunction(const Function *Callee,
const LibFunc TLIFn) {
const auto *Iter =
find_if(FreeFnData, [TLIFn](const std::pair<LibFunc, FreeFnsTy> &P) {
return P.first == TLIFn;
});
if (Iter == std::end(FreeFnData))
return std::nullopt;
return Iter->second;
}
std::optional<StringRef>
llvm::getAllocationFamily(const Value *I, const TargetLibraryInfo *TLI) {
bool IsNoBuiltin;
const Function *Callee = getCalledFunction(I, IsNoBuiltin);
if (Callee == nullptr || IsNoBuiltin)
return std::nullopt;
LibFunc TLIFn;
if (TLI && TLI->getLibFunc(*Callee, TLIFn) && TLI->has(TLIFn)) {
// Callee is some known library function.
const auto AllocData = getAllocationDataForFunction(Callee, AnyAlloc, TLI);
if (AllocData)
return mangledNameForMallocFamily(AllocData->Family);
const auto FreeData = getFreeFunctionDataForFunction(Callee, TLIFn);
if (FreeData)
return mangledNameForMallocFamily(FreeData->Family);
}
// Callee isn't a known library function, still check attributes.
if (checkFnAllocKind(I, AllocFnKind::Free | AllocFnKind::Alloc |
AllocFnKind::Realloc)) {
Attribute Attr = cast<CallBase>(I)->getFnAttr("alloc-family");
if (Attr.isValid())
return Attr.getValueAsString();
}
return std::nullopt;
}
/// isLibFreeFunction - Returns true if the function is a builtin free()
bool llvm::isLibFreeFunction(const Function *F, const LibFunc TLIFn) {
std::optional<FreeFnsTy> FnData = getFreeFunctionDataForFunction(F, TLIFn);
if (!FnData)
return checkFnAllocKind(F, AllocFnKind::Free);
// 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() != FnData->NumParams)
return false;
if (!FTy->getParamType(0)->isPointerTy())
return false;
return true;
}
Value *llvm::getFreedOperand(const CallBase *CB, const TargetLibraryInfo *TLI) {
bool IsNoBuiltinCall;
const Function *Callee = getCalledFunction(CB, IsNoBuiltinCall);
if (Callee == nullptr || IsNoBuiltinCall)
return nullptr;
LibFunc TLIFn;
if (TLI && TLI->getLibFunc(*Callee, TLIFn) && TLI->has(TLIFn) &&
isLibFreeFunction(Callee, TLIFn)) {
// All currently supported free functions free the first argument.
return CB->getArgOperand(0);
}
if (checkFnAllocKind(CB, AllocFnKind::Free))
return CB->getArgOperandWithAttribute(Attribute::AllocatedPointer);
return nullptr;
}
//===----------------------------------------------------------------------===//
// Utility functions to compute size of objects.
//
static APInt getSizeWithOverflow(const SizeOffsetAPInt &Data) {
APInt Size = Data.Size;
APInt Offset = Data.Offset;
if (Offset.isNegative() || Size.ult(Offset))
return APInt(Size.getBitWidth(), 0);
return Size - Offset;
}
/// 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);
SizeOffsetAPInt Data = Visitor.compute(const_cast<Value *>(Ptr));
if (!Data.bothKnown())
return false;
Size = getSizeWithOverflow(Data).getZExtValue();
return true;
}
Value *llvm::lowerObjectSizeCall(IntrinsicInst *ObjectSize,
const DataLayout &DL,
const TargetLibraryInfo *TLI,
bool MustSucceed) {
return lowerObjectSizeCall(ObjectSize, DL, TLI, /*AAResults=*/nullptr,
MustSucceed);
}
Value *llvm::lowerObjectSizeCall(
IntrinsicInst *ObjectSize, const DataLayout &DL,
const TargetLibraryInfo *TLI, AAResults *AA, bool MustSucceed,
SmallVectorImpl<Instruction *> *InsertedInstructions) {
assert(ObjectSize->getIntrinsicID() == Intrinsic::objectsize &&
"ObjectSize must be a call to llvm.objectsize!");
bool MaxVal = cast<ConstantInt>(ObjectSize->getArgOperand(1))->isZero();
ObjectSizeOpts EvalOptions;
EvalOptions.AA = AA;
// 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::ExactSizeFromOffset;
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);
SizeOffsetValue SizeOffsetPair = Eval.compute(ObjectSize->getArgOperand(0));
if (SizeOffsetPair != ObjectSizeOffsetEvaluator::unknown()) {
IRBuilder<TargetFolder, IRBuilderCallbackInserter> Builder(
Ctx, TargetFolder(DL), IRBuilderCallbackInserter([&](Instruction *I) {
if (InsertedInstructions)
InsertedInstructions->push_back(I);
}));
Builder.SetInsertPoint(ObjectSize);
Value *Size = SizeOffsetPair.Size;
Value *Offset = SizeOffsetPair.Offset;
// If we've outside the end of the object, then we can always access
// exactly 0 bytes.
Value *ResultSize = Builder.CreateSub(Size, Offset);
Value *UseZero = Builder.CreateICmpULT(Size, Offset);
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>(Size) || !isa<Constant>(Offset))
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.
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::compute(Value *V) {
InstructionsVisited = 0;
return computeImpl(V);
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::computeImpl(Value *V) {
unsigned InitialIntTyBits = DL.getIndexTypeSizeInBits(V->getType());
// Stripping pointer casts can strip address space casts which can change the
// index type size. The invariant is that we use the value type to determine
// the index type size and if we stripped address space casts we have to
// readjust the APInt as we pass it upwards in order for the APInt to match
// the type the caller passed in.
APInt Offset(InitialIntTyBits, 0);
V = V->stripAndAccumulateConstantOffsets(
DL, Offset, /* AllowNonInbounds */ true, /* AllowInvariantGroup */ true);
// Later we use the index type size and zero but it will match the type of the
// value that is passed to computeImpl.
IntTyBits = DL.getIndexTypeSizeInBits(V->getType());
Zero = APInt::getZero(IntTyBits);
SizeOffsetAPInt SOT = computeValue(V);
bool IndexTypeSizeChanged = InitialIntTyBits != IntTyBits;
if (!IndexTypeSizeChanged && Offset.isZero())
return SOT;
// We stripped an address space cast that changed the index type size or we
// accumulated some constant offset (or both). Readjust the bit width to match
// the argument index type size and apply the offset, as required.
if (IndexTypeSizeChanged) {
if (SOT.knownSize() && !::CheckedZextOrTrunc(SOT.Size, InitialIntTyBits))
SOT.Size = APInt();
if (SOT.knownOffset() &&
!::CheckedZextOrTrunc(SOT.Offset, InitialIntTyBits))
SOT.Offset = APInt();
}
// If the computed offset is "unknown" we cannot add the stripped offset.
return {SOT.Size,
SOT.Offset.getBitWidth() > 1 ? SOT.Offset + Offset : SOT.Offset};
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::computeValue(Value *V) {
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.
auto P = SeenInsts.try_emplace(I, ObjectSizeOffsetVisitor::unknown());
if (!P.second)
return P.first->second;
++InstructionsVisited;
if (InstructionsVisited > ObjectSizeOffsetVisitorMaxVisitInstructions)
return ObjectSizeOffsetVisitor::unknown();
SizeOffsetAPInt Res = visit(*I);
// Cache the result for later visits. If we happened to visit this during
// the above recursion, we would consider it unknown until now.
SeenInsts[I] = Res;
return Res;
}
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);
LLVM_DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: "
<< *V << '\n');
return ObjectSizeOffsetVisitor::unknown();
}
bool ObjectSizeOffsetVisitor::CheckedZextOrTrunc(APInt &I) {
return ::CheckedZextOrTrunc(I, IntTyBits);
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) {
TypeSize ElemSize = DL.getTypeAllocSize(I.getAllocatedType());
if (ElemSize.isScalable() && Options.EvalMode != ObjectSizeOpts::Mode::Min)
return ObjectSizeOffsetVisitor::unknown();
APInt Size(IntTyBits, ElemSize.getKnownMinValue());
if (!I.isArrayAllocation())
return SizeOffsetAPInt(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 ObjectSizeOffsetVisitor::unknown();
bool Overflow;
Size = Size.umul_ov(NumElems, Overflow);
return Overflow ? ObjectSizeOffsetVisitor::unknown()
: SizeOffsetAPInt(align(Size, I.getAlign()), Zero);
}
return ObjectSizeOffsetVisitor::unknown();
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::visitArgument(Argument &A) {
Type *MemoryTy = A.getPointeeInMemoryValueType();
// No interprocedural analysis is done at the moment.
if (!MemoryTy|| !MemoryTy->isSized()) {
++ObjectVisitorArgument;
return ObjectSizeOffsetVisitor::unknown();
}
APInt Size(IntTyBits, DL.getTypeAllocSize(MemoryTy));
return SizeOffsetAPInt(align(Size, A.getParamAlign()), Zero);
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::visitCallBase(CallBase &CB) {
if (std::optional<APInt> Size = getAllocSize(&CB, TLI))
return SizeOffsetAPInt(*Size, Zero);
return ObjectSizeOffsetVisitor::unknown();
}
SizeOffsetAPInt
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 ObjectSizeOffsetVisitor::unknown();
return SizeOffsetAPInt(Zero, Zero);
}
SizeOffsetAPInt
ObjectSizeOffsetVisitor::visitExtractElementInst(ExtractElementInst &) {
return ObjectSizeOffsetVisitor::unknown();
}
SizeOffsetAPInt
ObjectSizeOffsetVisitor::visitExtractValueInst(ExtractValueInst &) {
// Easy cases were already folded by previous passes.
return ObjectSizeOffsetVisitor::unknown();
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::visitGlobalAlias(GlobalAlias &GA) {
if (GA.isInterposable())
return ObjectSizeOffsetVisitor::unknown();
return computeImpl(GA.getAliasee());
}
SizeOffsetAPInt
ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV) {
if (!GV.getValueType()->isSized() || GV.hasExternalWeakLinkage() ||
((!GV.hasInitializer() || GV.isInterposable()) &&
Options.EvalMode != ObjectSizeOpts::Mode::Min))
return ObjectSizeOffsetVisitor::unknown();
APInt Size(IntTyBits, DL.getTypeAllocSize(GV.getValueType()));
return SizeOffsetAPInt(align(Size, GV.getAlign()), Zero);
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::visitIntToPtrInst(IntToPtrInst &) {
// clueless
return ObjectSizeOffsetVisitor::unknown();
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::findLoadSizeOffset(
LoadInst &Load, BasicBlock &BB, BasicBlock::iterator From,
SmallDenseMap<BasicBlock *, SizeOffsetAPInt, 8> &VisitedBlocks,
unsigned &ScannedInstCount) {
constexpr unsigned MaxInstsToScan = 128;
auto Where = VisitedBlocks.find(&BB);
if (Where != VisitedBlocks.end())
return Where->second;
auto Unknown = [&BB, &VisitedBlocks]() {
return VisitedBlocks[&BB] = ObjectSizeOffsetVisitor::unknown();
};
auto Known = [&BB, &VisitedBlocks](SizeOffsetAPInt SO) {
return VisitedBlocks[&BB] = SO;
};
do {
Instruction &I = *From;
if (I.isDebugOrPseudoInst())
continue;
if (++ScannedInstCount > MaxInstsToScan)
return Unknown();
if (!I.mayWriteToMemory())
continue;
if (auto *SI = dyn_cast<StoreInst>(&I)) {
AliasResult AR =
Options.AA->alias(SI->getPointerOperand(), Load.getPointerOperand());
switch ((AliasResult::Kind)AR) {
case AliasResult::NoAlias:
continue;
case AliasResult::MustAlias:
if (SI->getValueOperand()->getType()->isPointerTy())
return Known(computeImpl(SI->getValueOperand()));
else
return Unknown(); // No handling of non-pointer values by `compute`.
default:
return Unknown();
}
}
if (auto *CB = dyn_cast<CallBase>(&I)) {
Function *Callee = CB->getCalledFunction();
// Bail out on indirect call.
if (!Callee)
return Unknown();
LibFunc TLIFn;
if (!TLI || !TLI->getLibFunc(*CB->getCalledFunction(), TLIFn) ||
!TLI->has(TLIFn))
return Unknown();
// TODO: There's probably more interesting case to support here.
if (TLIFn != LibFunc_posix_memalign)
return Unknown();
AliasResult AR =
Options.AA->alias(CB->getOperand(0), Load.getPointerOperand());
switch ((AliasResult::Kind)AR) {
case AliasResult::NoAlias:
continue;
case AliasResult::MustAlias:
break;
default:
return Unknown();
}
// Is the error status of posix_memalign correctly checked? If not it
// would be incorrect to assume it succeeds and load doesn't see the
// previous value.
std::optional<bool> Checked = isImpliedByDomCondition(
ICmpInst::ICMP_EQ, CB, ConstantInt::get(CB->getType(), 0), &Load, DL);
if (!Checked || !*Checked)
return Unknown();
Value *Size = CB->getOperand(2);
auto *C = dyn_cast<ConstantInt>(Size);
if (!C)
return Unknown();
return Known({C->getValue(), APInt(C->getValue().getBitWidth(), 0)});
}
return Unknown();
} while (From-- != BB.begin());
SmallVector<SizeOffsetAPInt> PredecessorSizeOffsets;
for (auto *PredBB : predecessors(&BB)) {
PredecessorSizeOffsets.push_back(findLoadSizeOffset(
Load, *PredBB, BasicBlock::iterator(PredBB->getTerminator()),
VisitedBlocks, ScannedInstCount));
if (!PredecessorSizeOffsets.back().bothKnown())
return Unknown();
}
if (PredecessorSizeOffsets.empty())
return Unknown();
return Known(std::accumulate(
PredecessorSizeOffsets.begin() + 1, PredecessorSizeOffsets.end(),
PredecessorSizeOffsets.front(),
[this](SizeOffsetAPInt LHS, SizeOffsetAPInt RHS) {
return combineSizeOffset(LHS, RHS);
}));
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::visitLoadInst(LoadInst &LI) {
if (!Options.AA) {
++ObjectVisitorLoad;
return ObjectSizeOffsetVisitor::unknown();
}
SmallDenseMap<BasicBlock *, SizeOffsetAPInt, 8> VisitedBlocks;
unsigned ScannedInstCount = 0;
SizeOffsetAPInt SO =
findLoadSizeOffset(LI, *LI.getParent(), BasicBlock::iterator(LI),
VisitedBlocks, ScannedInstCount);
if (!SO.bothKnown())
++ObjectVisitorLoad;
return SO;
}
SizeOffsetAPInt
ObjectSizeOffsetVisitor::combineSizeOffset(SizeOffsetAPInt LHS,
SizeOffsetAPInt RHS) {
if (!LHS.bothKnown() || !RHS.bothKnown())
return ObjectSizeOffsetVisitor::unknown();
switch (Options.EvalMode) {
case ObjectSizeOpts::Mode::Min:
return (getSizeWithOverflow(LHS).slt(getSizeWithOverflow(RHS))) ? LHS : RHS;
case ObjectSizeOpts::Mode::Max:
return (getSizeWithOverflow(LHS).sgt(getSizeWithOverflow(RHS))) ? LHS : RHS;
case ObjectSizeOpts::Mode::ExactSizeFromOffset:
return (getSizeWithOverflow(LHS).eq(getSizeWithOverflow(RHS)))
? LHS
: ObjectSizeOffsetVisitor::unknown();
case ObjectSizeOpts::Mode::ExactUnderlyingSizeAndOffset:
return LHS == RHS ? LHS : ObjectSizeOffsetVisitor::unknown();
}
llvm_unreachable("missing an eval mode");
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::visitPHINode(PHINode &PN) {
if (PN.getNumIncomingValues() == 0)
return ObjectSizeOffsetVisitor::unknown();
auto IncomingValues = PN.incoming_values();
return std::accumulate(IncomingValues.begin() + 1, IncomingValues.end(),
computeImpl(*IncomingValues.begin()),
[this](SizeOffsetAPInt LHS, Value *VRHS) {
return combineSizeOffset(LHS, computeImpl(VRHS));
});
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) {
return combineSizeOffset(computeImpl(I.getTrueValue()),
computeImpl(I.getFalseValue()));
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::visitUndefValue(UndefValue &) {
return SizeOffsetAPInt(Zero, Zero);
}
SizeOffsetAPInt ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) {
LLVM_DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I
<< '\n');
return ObjectSizeOffsetVisitor::unknown();
}
// Just set these right here...
SizeOffsetValue::SizeOffsetValue(const SizeOffsetWeakTrackingVH &SOT)
: SizeOffsetType(SOT.Size, SOT.Offset) {}
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.
}
SizeOffsetValue ObjectSizeOffsetEvaluator::compute(Value *V) {
// XXX - Are vectors of pointers possible here?
IntTy = cast<IntegerType>(DL.getIndexType(V->getType()));
Zero = ConstantInt::get(IntTy, 0);
SizeOffsetValue Result = compute_(V);
if (!Result.bothKnown()) {
// 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() && CacheIt->second.anyKnown())
CacheMap.erase(CacheIt);
}
// Erase any instructions we inserted as part of the traversal.
for (Instruction *I : InsertedInstructions) {
I->replaceAllUsesWith(PoisonValue::get(I->getType()));
I->eraseFromParent();
}
}
SeenVals.clear();
InsertedInstructions.clear();
return Result;
}
SizeOffsetValue ObjectSizeOffsetEvaluator::compute_(Value *V) {
ObjectSizeOffsetVisitor Visitor(DL, TLI, Context, EvalOpts);
SizeOffsetAPInt Const = Visitor.compute(V);
if (Const.bothKnown())
return SizeOffsetValue(ConstantInt::get(Context, Const.Size),
ConstantInt::get(Context, Const.Offset));
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.
SizeOffsetValue 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 = ObjectSizeOffsetEvaluator::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 = ObjectSizeOffsetEvaluator::unknown();
} else {
LLVM_DEBUG(
dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: " << *V
<< '\n');
Result = ObjectSizeOffsetEvaluator::unknown();
}
// Don't reuse CacheIt since it may be invalid at this point.
CacheMap[V] = SizeOffsetWeakTrackingVH(Result);
return Result;
}
SizeOffsetValue ObjectSizeOffsetEvaluator::visitAllocaInst(AllocaInst &I) {
if (!I.getAllocatedType()->isSized())
return ObjectSizeOffsetEvaluator::unknown();
// must be a VLA
assert(I.isArrayAllocation());
// If needed, adjust the alloca's operand size to match the pointer indexing
// size. Subsequent math operations expect the types to match.
Value *ArraySize = Builder.CreateZExtOrTrunc(
I.getArraySize(),
DL.getIndexType(I.getContext(), DL.getAllocaAddrSpace()));
assert(ArraySize->getType() == Zero->getType() &&
"Expected zero constant to have pointer index type");
Value *Size = ConstantInt::get(ArraySize->getType(),
DL.getTypeAllocSize(I.getAllocatedType()));
Size = Builder.CreateMul(Size, ArraySize);
return SizeOffsetValue(Size, Zero);
}
SizeOffsetValue ObjectSizeOffsetEvaluator::visitCallBase(CallBase &CB) {
std::optional<AllocFnsTy> FnData = getAllocationSize(&CB, TLI);
if (!FnData)
return ObjectSizeOffsetEvaluator::unknown();
// Handle strdup-like functions separately.
if (FnData->AllocTy == StrDupLike) {
// TODO: implement evaluation of strdup/strndup
return ObjectSizeOffsetEvaluator::unknown();
}
Value *FirstArg = CB.getArgOperand(FnData->FstParam);
FirstArg = Builder.CreateZExtOrTrunc(FirstArg, IntTy);
if (FnData->SndParam < 0)
return SizeOffsetValue(FirstArg, Zero);
Value *SecondArg = CB.getArgOperand(FnData->SndParam);
SecondArg = Builder.CreateZExtOrTrunc(SecondArg, IntTy);
Value *Size = Builder.CreateMul(FirstArg, SecondArg);
return SizeOffsetValue(Size, Zero);
}
SizeOffsetValue
ObjectSizeOffsetEvaluator::visitExtractElementInst(ExtractElementInst &) {
return ObjectSizeOffsetEvaluator::unknown();
}
SizeOffsetValue
ObjectSizeOffsetEvaluator::visitExtractValueInst(ExtractValueInst &) {
return ObjectSizeOffsetEvaluator::unknown();
}
SizeOffsetValue ObjectSizeOffsetEvaluator::visitGEPOperator(GEPOperator &GEP) {
SizeOffsetValue PtrData = compute_(GEP.getPointerOperand());
if (!PtrData.bothKnown())
return ObjectSizeOffsetEvaluator::unknown();
Value *Offset = emitGEPOffset(&Builder, DL, &GEP, /*NoAssumptions=*/true);
Offset = Builder.CreateAdd(PtrData.Offset, Offset);
return SizeOffsetValue(PtrData.Size, Offset);
}
SizeOffsetValue ObjectSizeOffsetEvaluator::visitIntToPtrInst(IntToPtrInst &) {
// clueless
return ObjectSizeOffsetEvaluator::unknown();
}
SizeOffsetValue ObjectSizeOffsetEvaluator::visitLoadInst(LoadInst &LI) {
return ObjectSizeOffsetEvaluator::unknown();
}
SizeOffsetValue 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] = SizeOffsetWeakTrackingVH(SizePHI, OffsetPHI);
// Compute offset/size for each PHI incoming pointer.
for (unsigned i = 0, e = PHI.getNumIncomingValues(); i != e; ++i) {
BasicBlock *IncomingBlock = PHI.getIncomingBlock(i);
Builder.SetInsertPoint(IncomingBlock, IncomingBlock->getFirstInsertionPt());
SizeOffsetValue EdgeData = compute_(PHI.getIncomingValue(i));
if (!EdgeData.bothKnown()) {
OffsetPHI->replaceAllUsesWith(PoisonValue::get(IntTy));
OffsetPHI->eraseFromParent();
InsertedInstructions.erase(OffsetPHI);
SizePHI->replaceAllUsesWith(PoisonValue::get(IntTy));
SizePHI->eraseFromParent();
InsertedInstructions.erase(SizePHI);
return ObjectSizeOffsetEvaluator::unknown();
}
SizePHI->addIncoming(EdgeData.Size, IncomingBlock);
OffsetPHI->addIncoming(EdgeData.Offset, IncomingBlock);
}
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 SizeOffsetValue(Size, Offset);
}
SizeOffsetValue ObjectSizeOffsetEvaluator::visitSelectInst(SelectInst &I) {
SizeOffsetValue TrueSide = compute_(I.getTrueValue());
SizeOffsetValue FalseSide = compute_(I.getFalseValue());
if (!TrueSide.bothKnown() || !FalseSide.bothKnown())
return ObjectSizeOffsetEvaluator::unknown();
if (TrueSide == FalseSide)
return TrueSide;
Value *Size =
Builder.CreateSelect(I.getCondition(), TrueSide.Size, FalseSide.Size);
Value *Offset =
Builder.CreateSelect(I.getCondition(), TrueSide.Offset, FalseSide.Offset);
return SizeOffsetValue(Size, Offset);
}
SizeOffsetValue ObjectSizeOffsetEvaluator::visitInstruction(Instruction &I) {
LLVM_DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I
<< '\n');
return ObjectSizeOffsetEvaluator::unknown();
}
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