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346 lines
13 KiB
C++
346 lines
13 KiB
C++
//==- llvm/Analysis/MemoryBuiltins.h - Calls to memory builtins --*- C++ -*-==//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This family of functions identifies calls to builtin functions that allocate
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// or free memory.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_MEMORYBUILTINS_H
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#define LLVM_ANALYSIS_MEMORYBUILTINS_H
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#include "llvm/ADT/APInt.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/Analysis/TargetFolder.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include "llvm/IR/CallSite.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/InstVisitor.h"
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#include "llvm/IR/ValueHandle.h"
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#include <cstdint>
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#include <utility>
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namespace llvm {
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class AllocaInst;
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class Argument;
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class CallInst;
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class ConstantInt;
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class ConstantPointerNull;
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class DataLayout;
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class ExtractElementInst;
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class ExtractValueInst;
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class GEPOperator;
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class GlobalAlias;
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class GlobalVariable;
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class Instruction;
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class IntegerType;
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class IntrinsicInst;
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class IntToPtrInst;
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class LLVMContext;
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class LoadInst;
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class PHINode;
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class PointerType;
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class SelectInst;
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class TargetLibraryInfo;
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class Type;
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class UndefValue;
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class Value;
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/// Tests if a value is a call or invoke to a library function that
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/// allocates or reallocates memory (either malloc, calloc, realloc, or strdup
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/// like).
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bool isAllocationFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast = false);
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bool isAllocationFn(const Value *V,
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function_ref<const TargetLibraryInfo &(Function &)> GetTLI,
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bool LookThroughBitCast = false);
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/// Tests if a value is a call or invoke to a function that returns a
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/// NoAlias pointer (including malloc/calloc/realloc/strdup-like functions).
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bool isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast = false);
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/// Tests if a value is a call or invoke to a library function that
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/// allocates uninitialized memory (such as malloc).
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bool isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast = false);
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bool isMallocLikeFn(const Value *V,
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function_ref<const TargetLibraryInfo &(Function &)> GetTLI,
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bool LookThroughBitCast = false);
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/// Tests if a value is a call or invoke to a library function that
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/// allocates zero-filled memory (such as calloc).
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bool isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast = false);
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/// Tests if a value is a call or invoke to a library function that
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/// allocates memory similar to malloc or calloc.
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bool isMallocOrCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast = false);
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/// Tests if a value is a call or invoke to a library function that
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/// allocates memory (either malloc, calloc, or strdup like).
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bool isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast = false);
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/// Tests if a value is a call or invoke to a library function that
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/// reallocates memory (e.g., realloc).
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bool isReallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast = false);
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/// Tests if a function is a call or invoke to a library function that
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/// reallocates memory (e.g., realloc).
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bool isReallocLikeFn(const Function *F, const TargetLibraryInfo *TLI);
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/// Tests if a value is a call or invoke to a library function that
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/// allocates memory and throws if an allocation failed (e.g., new).
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bool isOpNewLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast = false);
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/// Tests if a value is a call or invoke to a library function that
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/// allocates memory (strdup, strndup).
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bool isStrdupLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast = false);
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//===----------------------------------------------------------------------===//
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// malloc Call Utility Functions.
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//
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/// extractMallocCall - Returns the corresponding CallInst if the instruction
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/// is a malloc call. Since CallInst::CreateMalloc() only creates calls, we
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/// ignore InvokeInst here.
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const CallInst *
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extractMallocCall(const Value *I,
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function_ref<const TargetLibraryInfo &(Function &)> GetTLI);
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inline CallInst *
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extractMallocCall(Value *I,
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function_ref<const TargetLibraryInfo &(Function &)> GetTLI) {
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return const_cast<CallInst *>(extractMallocCall((const Value *)I, GetTLI));
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}
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/// getMallocType - Returns the PointerType resulting from the malloc call.
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/// The PointerType depends on the number of bitcast uses of the malloc call:
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/// 0: PointerType is the malloc calls' return type.
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/// 1: PointerType is the bitcast's result type.
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/// >1: Unique PointerType cannot be determined, return NULL.
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PointerType *getMallocType(const CallInst *CI, const TargetLibraryInfo *TLI);
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/// getMallocAllocatedType - Returns the Type allocated by malloc call.
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/// The Type depends on the number of bitcast uses of the malloc call:
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/// 0: PointerType is the malloc calls' return type.
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/// 1: PointerType is the bitcast's result type.
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/// >1: Unique PointerType cannot be determined, return NULL.
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Type *getMallocAllocatedType(const CallInst *CI, const TargetLibraryInfo *TLI);
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/// getMallocArraySize - Returns the array size of a malloc call. If the
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/// argument passed to malloc is a multiple of the size of the malloced type,
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/// then return that multiple. For non-array mallocs, the multiple is
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/// constant 1. Otherwise, return NULL for mallocs whose array size cannot be
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/// determined.
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Value *getMallocArraySize(CallInst *CI, const DataLayout &DL,
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const TargetLibraryInfo *TLI,
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bool LookThroughSExt = false);
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//===----------------------------------------------------------------------===//
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// calloc Call Utility Functions.
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//
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/// extractCallocCall - Returns the corresponding CallInst if the instruction
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/// is a calloc call.
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const CallInst *extractCallocCall(const Value *I, const TargetLibraryInfo *TLI);
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inline CallInst *extractCallocCall(Value *I, const TargetLibraryInfo *TLI) {
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return const_cast<CallInst*>(extractCallocCall((const Value*)I, TLI));
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}
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//===----------------------------------------------------------------------===//
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// free Call Utility Functions.
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//
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/// isLibFreeFunction - Returns true if the function is a builtin free()
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bool isLibFreeFunction(const Function *F, const LibFunc TLIFn);
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/// isFreeCall - Returns non-null if the value is a call to the builtin free()
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const CallInst *isFreeCall(const Value *I, const TargetLibraryInfo *TLI);
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inline CallInst *isFreeCall(Value *I, const TargetLibraryInfo *TLI) {
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return const_cast<CallInst*>(isFreeCall((const Value*)I, TLI));
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}
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//===----------------------------------------------------------------------===//
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// Utility functions to compute size of objects.
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//
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/// Various options to control the behavior of getObjectSize.
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struct ObjectSizeOpts {
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/// Controls how we handle conditional statements with unknown conditions.
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enum class Mode : uint8_t {
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/// Fail to evaluate an unknown condition.
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Exact,
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/// Evaluate all branches of an unknown condition. If all evaluations
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/// succeed, pick the minimum size.
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Min,
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/// Same as Min, except we pick the maximum size of all of the branches.
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Max
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};
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/// How we want to evaluate this object's size.
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Mode EvalMode = Mode::Exact;
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/// Whether to round the result up to the alignment of allocas, byval
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/// arguments, and global variables.
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bool RoundToAlign = false;
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/// If this is true, null pointers in address space 0 will be treated as
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/// though they can't be evaluated. Otherwise, null is always considered to
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/// point to a 0 byte region of memory.
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bool NullIsUnknownSize = false;
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};
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/// Compute the size of the object pointed by Ptr. Returns true and the
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/// object size in Size if successful, and false otherwise. In this context, by
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/// object we mean the region of memory starting at Ptr to the end of the
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/// underlying object pointed to by Ptr.
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bool getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
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const TargetLibraryInfo *TLI, ObjectSizeOpts Opts = {});
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/// Try to turn a call to \@llvm.objectsize into an integer value of the given
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/// Type. Returns null on failure. If MustSucceed is true, this function will
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/// not return null, and may return conservative values governed by the second
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/// argument of the call to objectsize.
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Value *lowerObjectSizeCall(IntrinsicInst *ObjectSize, const DataLayout &DL,
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const TargetLibraryInfo *TLI, bool MustSucceed);
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using SizeOffsetType = std::pair<APInt, APInt>;
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/// Evaluate the size and offset of an object pointed to by a Value*
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/// statically. Fails if size or offset are not known at compile time.
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class ObjectSizeOffsetVisitor
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: public InstVisitor<ObjectSizeOffsetVisitor, SizeOffsetType> {
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const DataLayout &DL;
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const TargetLibraryInfo *TLI;
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ObjectSizeOpts Options;
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unsigned IntTyBits;
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APInt Zero;
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SmallPtrSet<Instruction *, 8> SeenInsts;
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APInt align(APInt Size, uint64_t Align);
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SizeOffsetType unknown() {
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return std::make_pair(APInt(), APInt());
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}
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public:
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ObjectSizeOffsetVisitor(const DataLayout &DL, const TargetLibraryInfo *TLI,
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LLVMContext &Context, ObjectSizeOpts Options = {});
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SizeOffsetType compute(Value *V);
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static bool knownSize(const SizeOffsetType &SizeOffset) {
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return SizeOffset.first.getBitWidth() > 1;
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}
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static bool knownOffset(const SizeOffsetType &SizeOffset) {
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return SizeOffset.second.getBitWidth() > 1;
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}
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static bool bothKnown(const SizeOffsetType &SizeOffset) {
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return knownSize(SizeOffset) && knownOffset(SizeOffset);
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}
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// These are "private", except they can't actually be made private. Only
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// compute() should be used by external users.
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SizeOffsetType visitAllocaInst(AllocaInst &I);
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SizeOffsetType visitArgument(Argument &A);
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SizeOffsetType visitCallSite(CallSite CS);
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SizeOffsetType visitConstantPointerNull(ConstantPointerNull&);
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SizeOffsetType visitExtractElementInst(ExtractElementInst &I);
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SizeOffsetType visitExtractValueInst(ExtractValueInst &I);
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SizeOffsetType visitGEPOperator(GEPOperator &GEP);
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SizeOffsetType visitGlobalAlias(GlobalAlias &GA);
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SizeOffsetType visitGlobalVariable(GlobalVariable &GV);
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SizeOffsetType visitIntToPtrInst(IntToPtrInst&);
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SizeOffsetType visitLoadInst(LoadInst &I);
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SizeOffsetType visitPHINode(PHINode&);
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SizeOffsetType visitSelectInst(SelectInst &I);
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SizeOffsetType visitUndefValue(UndefValue&);
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SizeOffsetType visitInstruction(Instruction &I);
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private:
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bool CheckedZextOrTrunc(APInt &I);
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};
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using SizeOffsetEvalType = std::pair<Value *, Value *>;
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/// Evaluate the size and offset of an object pointed to by a Value*.
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/// May create code to compute the result at run-time.
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class ObjectSizeOffsetEvaluator
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: public InstVisitor<ObjectSizeOffsetEvaluator, SizeOffsetEvalType> {
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using BuilderTy = IRBuilder<TargetFolder, IRBuilderCallbackInserter>;
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using WeakEvalType = std::pair<WeakTrackingVH, WeakTrackingVH>;
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using CacheMapTy = DenseMap<const Value *, WeakEvalType>;
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using PtrSetTy = SmallPtrSet<const Value *, 8>;
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const DataLayout &DL;
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const TargetLibraryInfo *TLI;
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LLVMContext &Context;
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BuilderTy Builder;
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IntegerType *IntTy;
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Value *Zero;
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CacheMapTy CacheMap;
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PtrSetTy SeenVals;
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ObjectSizeOpts EvalOpts;
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SmallPtrSet<Instruction *, 8> InsertedInstructions;
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SizeOffsetEvalType compute_(Value *V);
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public:
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static SizeOffsetEvalType unknown() {
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return std::make_pair(nullptr, nullptr);
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}
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ObjectSizeOffsetEvaluator(const DataLayout &DL, const TargetLibraryInfo *TLI,
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LLVMContext &Context, ObjectSizeOpts EvalOpts = {});
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SizeOffsetEvalType compute(Value *V);
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bool knownSize(SizeOffsetEvalType SizeOffset) {
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return SizeOffset.first;
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}
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bool knownOffset(SizeOffsetEvalType SizeOffset) {
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return SizeOffset.second;
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}
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bool anyKnown(SizeOffsetEvalType SizeOffset) {
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return knownSize(SizeOffset) || knownOffset(SizeOffset);
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}
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bool bothKnown(SizeOffsetEvalType SizeOffset) {
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return knownSize(SizeOffset) && knownOffset(SizeOffset);
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}
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// The individual instruction visitors should be treated as private.
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SizeOffsetEvalType visitAllocaInst(AllocaInst &I);
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SizeOffsetEvalType visitCallSite(CallSite CS);
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SizeOffsetEvalType visitExtractElementInst(ExtractElementInst &I);
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SizeOffsetEvalType visitExtractValueInst(ExtractValueInst &I);
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SizeOffsetEvalType visitGEPOperator(GEPOperator &GEP);
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SizeOffsetEvalType visitIntToPtrInst(IntToPtrInst&);
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SizeOffsetEvalType visitLoadInst(LoadInst &I);
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SizeOffsetEvalType visitPHINode(PHINode &PHI);
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SizeOffsetEvalType visitSelectInst(SelectInst &I);
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SizeOffsetEvalType visitInstruction(Instruction &I);
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};
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} // end namespace llvm
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#endif // LLVM_ANALYSIS_MEMORYBUILTINS_H
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