793 lines
28 KiB
C++
793 lines
28 KiB
C++
//===------ MemoryBuiltins.cpp - Identify calls to memory builtins --------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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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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#include "llvm/Analysis/MemoryBuiltins.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/TargetLibraryInfo.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/GlobalVariable.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/Intrinsics.h"
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#include "llvm/IR/Metadata.h"
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#include "llvm/IR/Module.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/MathExtras.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/Utils/Local.h"
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using namespace llvm;
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#define DEBUG_TYPE "memory-builtins"
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enum AllocType {
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OpNewLike = 1<<0, // allocates; never returns null
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MallocLike = 1<<1 | OpNewLike, // allocates; may return null
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CallocLike = 1<<2, // allocates + bzero
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ReallocLike = 1<<3, // reallocates
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StrDupLike = 1<<4,
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AllocLike = MallocLike | CallocLike | StrDupLike,
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AnyAlloc = AllocLike | ReallocLike
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};
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struct AllocFnsTy {
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LibFunc::Func Func;
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AllocType AllocTy;
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unsigned char NumParams;
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// First and Second size parameters (or -1 if unused)
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signed char FstParam, SndParam;
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};
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// FIXME: certain users need more information. E.g., SimplifyLibCalls needs to
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// know which functions are nounwind, noalias, nocapture parameters, etc.
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static const AllocFnsTy AllocationFnData[] = {
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{LibFunc::malloc, MallocLike, 1, 0, -1},
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{LibFunc::valloc, MallocLike, 1, 0, -1},
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{LibFunc::Znwj, OpNewLike, 1, 0, -1}, // new(unsigned int)
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{LibFunc::ZnwjRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned int, nothrow)
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{LibFunc::Znwm, OpNewLike, 1, 0, -1}, // new(unsigned long)
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{LibFunc::ZnwmRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new(unsigned long, nothrow)
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{LibFunc::Znaj, OpNewLike, 1, 0, -1}, // new[](unsigned int)
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{LibFunc::ZnajRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned int, nothrow)
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{LibFunc::Znam, OpNewLike, 1, 0, -1}, // new[](unsigned long)
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{LibFunc::ZnamRKSt9nothrow_t, MallocLike, 2, 0, -1}, // new[](unsigned long, nothrow)
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{LibFunc::calloc, CallocLike, 2, 0, 1},
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{LibFunc::realloc, ReallocLike, 2, 1, -1},
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{LibFunc::reallocf, ReallocLike, 2, 1, -1},
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{LibFunc::strdup, StrDupLike, 1, -1, -1},
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{LibFunc::strndup, StrDupLike, 2, 1, -1}
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// TODO: Handle "int posix_memalign(void **, size_t, size_t)"
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};
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static Function *getCalledFunction(const Value *V, bool LookThroughBitCast) {
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if (LookThroughBitCast)
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V = V->stripPointerCasts();
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CallSite CS(const_cast<Value*>(V));
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if (!CS.getInstruction())
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return nullptr;
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if (CS.isNoBuiltin())
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return nullptr;
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Function *Callee = CS.getCalledFunction();
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if (!Callee || !Callee->isDeclaration())
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return nullptr;
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return Callee;
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}
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/// \brief Returns the allocation data for the given value if it is a call to a
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/// known allocation function, and NULL otherwise.
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static const AllocFnsTy *getAllocationData(const Value *V, AllocType AllocTy,
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const TargetLibraryInfo *TLI,
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bool LookThroughBitCast = false) {
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// Skip intrinsics
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if (isa<IntrinsicInst>(V))
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return nullptr;
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Function *Callee = getCalledFunction(V, LookThroughBitCast);
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if (!Callee)
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return nullptr;
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// Make sure that the function is available.
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StringRef FnName = Callee->getName();
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LibFunc::Func TLIFn;
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if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
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return nullptr;
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unsigned i = 0;
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bool found = false;
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for ( ; i < array_lengthof(AllocationFnData); ++i) {
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if (AllocationFnData[i].Func == TLIFn) {
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found = true;
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break;
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}
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}
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if (!found)
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return nullptr;
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const AllocFnsTy *FnData = &AllocationFnData[i];
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if ((FnData->AllocTy & AllocTy) != FnData->AllocTy)
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return nullptr;
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// Check function prototype.
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int FstParam = FnData->FstParam;
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int SndParam = FnData->SndParam;
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FunctionType *FTy = Callee->getFunctionType();
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if (FTy->getReturnType() == Type::getInt8PtrTy(FTy->getContext()) &&
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FTy->getNumParams() == FnData->NumParams &&
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(FstParam < 0 ||
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(FTy->getParamType(FstParam)->isIntegerTy(32) ||
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FTy->getParamType(FstParam)->isIntegerTy(64))) &&
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(SndParam < 0 ||
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FTy->getParamType(SndParam)->isIntegerTy(32) ||
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FTy->getParamType(SndParam)->isIntegerTy(64)))
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return FnData;
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return nullptr;
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}
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static bool hasNoAliasAttr(const Value *V, bool LookThroughBitCast) {
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ImmutableCallSite CS(LookThroughBitCast ? V->stripPointerCasts() : V);
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return CS && CS.hasFnAttr(Attribute::NoAlias);
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}
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/// \brief 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 llvm::isAllocationFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast) {
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return getAllocationData(V, AnyAlloc, TLI, LookThroughBitCast);
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}
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/// \brief 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 llvm::isNoAliasFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast) {
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// it's safe to consider realloc as noalias since accessing the original
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// pointer is undefined behavior
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return isAllocationFn(V, TLI, LookThroughBitCast) ||
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hasNoAliasAttr(V, LookThroughBitCast);
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}
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/// \brief 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 llvm::isMallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast) {
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return getAllocationData(V, MallocLike, TLI, LookThroughBitCast);
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}
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/// \brief 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 llvm::isCallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast) {
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return getAllocationData(V, CallocLike, TLI, LookThroughBitCast);
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}
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/// \brief 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 llvm::isAllocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast) {
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return getAllocationData(V, AllocLike, TLI, LookThroughBitCast);
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}
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/// \brief Tests if a value is a call or invoke to a library function that
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/// reallocates memory (such as realloc).
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bool llvm::isReallocLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast) {
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return getAllocationData(V, ReallocLike, TLI, LookThroughBitCast);
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}
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/// \brief Tests if a value is a call or invoke to a library function that
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/// allocates memory and never returns null (such as operator new).
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bool llvm::isOperatorNewLikeFn(const Value *V, const TargetLibraryInfo *TLI,
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bool LookThroughBitCast) {
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return getAllocationData(V, OpNewLike, TLI, LookThroughBitCast);
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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 *llvm::extractMallocCall(const Value *I,
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const TargetLibraryInfo *TLI) {
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return isMallocLikeFn(I, TLI) ? dyn_cast<CallInst>(I) : nullptr;
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}
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static Value *computeArraySize(const CallInst *CI, const DataLayout &DL,
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const TargetLibraryInfo *TLI,
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bool LookThroughSExt = false) {
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if (!CI)
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return nullptr;
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// The size of the malloc's result type must be known to determine array size.
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Type *T = getMallocAllocatedType(CI, TLI);
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if (!T || !T->isSized())
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return nullptr;
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unsigned ElementSize = DL.getTypeAllocSize(T);
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if (StructType *ST = dyn_cast<StructType>(T))
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ElementSize = DL.getStructLayout(ST)->getSizeInBytes();
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// If malloc call's arg can be determined to be a multiple of ElementSize,
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// return the multiple. Otherwise, return NULL.
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Value *MallocArg = CI->getArgOperand(0);
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Value *Multiple = nullptr;
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if (ComputeMultiple(MallocArg, ElementSize, Multiple,
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LookThroughSExt))
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return Multiple;
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return nullptr;
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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 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 *llvm::getMallocType(const CallInst *CI,
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const TargetLibraryInfo *TLI) {
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assert(isMallocLikeFn(CI, TLI) && "getMallocType and not malloc call");
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PointerType *MallocType = nullptr;
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unsigned NumOfBitCastUses = 0;
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// Determine if CallInst has a bitcast use.
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for (Value::const_user_iterator UI = CI->user_begin(), E = CI->user_end();
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UI != E;)
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if (const BitCastInst *BCI = dyn_cast<BitCastInst>(*UI++)) {
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MallocType = cast<PointerType>(BCI->getDestTy());
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NumOfBitCastUses++;
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}
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// Malloc call has 1 bitcast use, so type is the bitcast's destination type.
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if (NumOfBitCastUses == 1)
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return MallocType;
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// Malloc call was not bitcast, so type is the malloc function's return type.
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if (NumOfBitCastUses == 0)
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return cast<PointerType>(CI->getType());
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// Type could not be determined.
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return nullptr;
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}
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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 *llvm::getMallocAllocatedType(const CallInst *CI,
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const TargetLibraryInfo *TLI) {
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PointerType *PT = getMallocType(CI, TLI);
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return PT ? PT->getElementType() : nullptr;
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}
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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 *llvm::getMallocArraySize(CallInst *CI, const DataLayout &DL,
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const TargetLibraryInfo *TLI,
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bool LookThroughSExt) {
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assert(isMallocLikeFn(CI, TLI) && "getMallocArraySize and not malloc call");
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return computeArraySize(CI, DL, TLI, LookThroughSExt);
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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 *llvm::extractCallocCall(const Value *I,
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const TargetLibraryInfo *TLI) {
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return isCallocLikeFn(I, TLI) ? cast<CallInst>(I) : nullptr;
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}
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/// isFreeCall - Returns non-null if the value is a call to the builtin free()
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const CallInst *llvm::isFreeCall(const Value *I, const TargetLibraryInfo *TLI) {
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const CallInst *CI = dyn_cast<CallInst>(I);
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if (!CI || isa<IntrinsicInst>(CI))
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return nullptr;
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Function *Callee = CI->getCalledFunction();
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if (Callee == nullptr)
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return nullptr;
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StringRef FnName = Callee->getName();
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LibFunc::Func TLIFn;
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if (!TLI || !TLI->getLibFunc(FnName, TLIFn) || !TLI->has(TLIFn))
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return nullptr;
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unsigned ExpectedNumParams;
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if (TLIFn == LibFunc::free ||
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TLIFn == LibFunc::ZdlPv || // operator delete(void*)
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TLIFn == LibFunc::ZdaPv) // operator delete[](void*)
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ExpectedNumParams = 1;
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else if (TLIFn == LibFunc::ZdlPvj || // delete(void*, uint)
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TLIFn == LibFunc::ZdlPvm || // delete(void*, ulong)
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TLIFn == LibFunc::ZdlPvRKSt9nothrow_t || // delete(void*, nothrow)
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TLIFn == LibFunc::ZdaPvj || // delete[](void*, uint)
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TLIFn == LibFunc::ZdaPvm || // delete[](void*, ulong)
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TLIFn == LibFunc::ZdaPvRKSt9nothrow_t) // delete[](void*, nothrow)
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ExpectedNumParams = 2;
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else
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return nullptr;
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// Check free prototype.
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// FIXME: workaround for PR5130, this will be obsolete when a nobuiltin
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// attribute will exist.
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FunctionType *FTy = Callee->getFunctionType();
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if (!FTy->getReturnType()->isVoidTy())
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return nullptr;
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if (FTy->getNumParams() != ExpectedNumParams)
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return nullptr;
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if (FTy->getParamType(0) != Type::getInt8PtrTy(Callee->getContext()))
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return nullptr;
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return CI;
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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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/// \brief 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.
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/// If RoundToAlign is true, then Size is rounded up to the aligment of allocas,
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/// byval arguments, and global variables.
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bool llvm::getObjectSize(const Value *Ptr, uint64_t &Size, const DataLayout &DL,
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const TargetLibraryInfo *TLI, bool RoundToAlign) {
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ObjectSizeOffsetVisitor Visitor(DL, TLI, Ptr->getContext(), RoundToAlign);
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SizeOffsetType Data = Visitor.compute(const_cast<Value*>(Ptr));
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if (!Visitor.bothKnown(Data))
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return false;
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APInt ObjSize = Data.first, Offset = Data.second;
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// check for overflow
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if (Offset.slt(0) || ObjSize.ult(Offset))
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Size = 0;
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else
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Size = (ObjSize - Offset).getZExtValue();
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return true;
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}
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STATISTIC(ObjectVisitorArgument,
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"Number of arguments with unsolved size and offset");
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STATISTIC(ObjectVisitorLoad,
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"Number of load instructions with unsolved size and offset");
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APInt ObjectSizeOffsetVisitor::align(APInt Size, uint64_t Align) {
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if (RoundToAlign && Align)
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return APInt(IntTyBits, RoundUpToAlignment(Size.getZExtValue(), Align));
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return Size;
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}
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ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout &DL,
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const TargetLibraryInfo *TLI,
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LLVMContext &Context,
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bool RoundToAlign)
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: DL(DL), TLI(TLI), RoundToAlign(RoundToAlign) {
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// Pointer size must be rechecked for each object visited since it could have
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// a different address space.
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}
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SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) {
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IntTyBits = DL.getPointerTypeSizeInBits(V->getType());
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Zero = APInt::getNullValue(IntTyBits);
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V = V->stripPointerCasts();
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if (Instruction *I = dyn_cast<Instruction>(V)) {
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// If we have already seen this instruction, bail out. Cycles can happen in
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// unreachable code after constant propagation.
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if (!SeenInsts.insert(I).second)
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return unknown();
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if (GEPOperator *GEP = dyn_cast<GEPOperator>(V))
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return visitGEPOperator(*GEP);
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return visit(*I);
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}
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if (Argument *A = dyn_cast<Argument>(V))
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return visitArgument(*A);
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if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V))
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return visitConstantPointerNull(*P);
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if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
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return visitGlobalAlias(*GA);
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if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
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return visitGlobalVariable(*GV);
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if (UndefValue *UV = dyn_cast<UndefValue>(V))
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return visitUndefValue(*UV);
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if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
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if (CE->getOpcode() == Instruction::IntToPtr)
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return unknown(); // clueless
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if (CE->getOpcode() == Instruction::GetElementPtr)
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return visitGEPOperator(cast<GEPOperator>(*CE));
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}
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DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V
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<< '\n');
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return unknown();
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}
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SizeOffsetType ObjectSizeOffsetVisitor::visitAllocaInst(AllocaInst &I) {
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if (!I.getAllocatedType()->isSized())
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return unknown();
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APInt Size(IntTyBits, DL.getTypeAllocSize(I.getAllocatedType()));
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if (!I.isArrayAllocation())
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return std::make_pair(align(Size, I.getAlignment()), Zero);
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Value *ArraySize = I.getArraySize();
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if (const ConstantInt *C = dyn_cast<ConstantInt>(ArraySize)) {
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Size *= C->getValue().zextOrSelf(IntTyBits);
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return std::make_pair(align(Size, I.getAlignment()), Zero);
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}
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return unknown();
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}
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SizeOffsetType ObjectSizeOffsetVisitor::visitArgument(Argument &A) {
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// no interprocedural analysis is done at the moment
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if (!A.hasByValOrInAllocaAttr()) {
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++ObjectVisitorArgument;
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return unknown();
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}
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PointerType *PT = cast<PointerType>(A.getType());
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APInt Size(IntTyBits, DL.getTypeAllocSize(PT->getElementType()));
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return std::make_pair(align(Size, A.getParamAlignment()), Zero);
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}
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SizeOffsetType ObjectSizeOffsetVisitor::visitCallSite(CallSite CS) {
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const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
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TLI);
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if (!FnData)
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return unknown();
|
|
|
|
// handle strdup-like functions separately
|
|
if (FnData->AllocTy == StrDupLike) {
|
|
APInt Size(IntTyBits, GetStringLength(CS.getArgument(0)));
|
|
if (!Size)
|
|
return unknown();
|
|
|
|
// strndup limits strlen
|
|
if (FnData->FstParam > 0) {
|
|
ConstantInt *Arg= dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
|
|
if (!Arg)
|
|
return unknown();
|
|
|
|
APInt MaxSize = Arg->getValue().zextOrSelf(IntTyBits);
|
|
if (Size.ugt(MaxSize))
|
|
Size = MaxSize + 1;
|
|
}
|
|
return std::make_pair(Size, Zero);
|
|
}
|
|
|
|
ConstantInt *Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->FstParam));
|
|
if (!Arg)
|
|
return unknown();
|
|
|
|
APInt Size = Arg->getValue().zextOrSelf(IntTyBits);
|
|
// size determined by just 1 parameter
|
|
if (FnData->SndParam < 0)
|
|
return std::make_pair(Size, Zero);
|
|
|
|
Arg = dyn_cast<ConstantInt>(CS.getArgument(FnData->SndParam));
|
|
if (!Arg)
|
|
return unknown();
|
|
|
|
Size *= Arg->getValue().zextOrSelf(IntTyBits);
|
|
return std::make_pair(Size, Zero);
|
|
|
|
// TODO: handle more standard functions (+ wchar cousins):
|
|
// - strdup / strndup
|
|
// - strcpy / strncpy
|
|
// - strcat / strncat
|
|
// - memcpy / memmove
|
|
// - strcat / strncat
|
|
// - memset
|
|
}
|
|
|
|
SizeOffsetType
|
|
ObjectSizeOffsetVisitor::visitConstantPointerNull(ConstantPointerNull&) {
|
|
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(IntTyBits, 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.mayBeOverridden())
|
|
return unknown();
|
|
return compute(GA.getAliasee());
|
|
}
|
|
|
|
SizeOffsetType ObjectSizeOffsetVisitor::visitGlobalVariable(GlobalVariable &GV){
|
|
if (!GV.hasDefinitiveInitializer())
|
|
return unknown();
|
|
|
|
APInt Size(IntTyBits, DL.getTypeAllocSize(GV.getType()->getElementType()));
|
|
return std::make_pair(align(Size, GV.getAlignment()), 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) && TrueSide == FalseSide)
|
|
return TrueSide;
|
|
return unknown();
|
|
}
|
|
|
|
SizeOffsetType ObjectSizeOffsetVisitor::visitUndefValue(UndefValue&) {
|
|
return std::make_pair(Zero, Zero);
|
|
}
|
|
|
|
SizeOffsetType ObjectSizeOffsetVisitor::visitInstruction(Instruction &I) {
|
|
DEBUG(dbgs() << "ObjectSizeOffsetVisitor unknown instruction:" << I << '\n');
|
|
return unknown();
|
|
}
|
|
|
|
ObjectSizeOffsetEvaluator::ObjectSizeOffsetEvaluator(
|
|
const DataLayout &DL, const TargetLibraryInfo *TLI, LLVMContext &Context,
|
|
bool RoundToAlign)
|
|
: DL(DL), TLI(TLI), Context(Context), Builder(Context, TargetFolder(DL)),
|
|
RoundToAlign(RoundToAlign) {
|
|
// 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.getIntPtrType(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 (PtrSetTy::iterator I=SeenVals.begin(), E=SeenVals.end(); I != E; ++I) {
|
|
CacheMapTy::iterator CacheIt = CacheMap.find(*I);
|
|
// non-computable results can be safely cached
|
|
if (CacheIt != CacheMap.end() && anyKnown(CacheIt->second))
|
|
CacheMap.erase(CacheIt);
|
|
}
|
|
}
|
|
|
|
SeenVals.clear();
|
|
return Result;
|
|
}
|
|
|
|
SizeOffsetEvalType ObjectSizeOffsetEvaluator::compute_(Value *V) {
|
|
ObjectSizeOffsetVisitor Visitor(DL, TLI, Context, RoundToAlign);
|
|
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
|
|
Instruction *PrevInsertPoint = Builder.GetInsertPoint();
|
|
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 what ObjectSizeVisitor can
|
|
Result = unknown();
|
|
} else {
|
|
DEBUG(dbgs() << "ObjectSizeOffsetEvaluator::compute() unhandled value: "
|
|
<< *V << '\n');
|
|
Result = unknown();
|
|
}
|
|
|
|
if (PrevInsertPoint)
|
|
Builder.SetInsertPoint(PrevInsertPoint);
|
|
|
|
// 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());
|
|
Value *ArraySize = I.getArraySize();
|
|
Value *Size = ConstantInt::get(ArraySize->getType(),
|
|
DL.getTypeAllocSize(I.getAllocatedType()));
|
|
Size = Builder.CreateMul(Size, ArraySize);
|
|
return std::make_pair(Size, Zero);
|
|
}
|
|
|
|
SizeOffsetEvalType ObjectSizeOffsetEvaluator::visitCallSite(CallSite CS) {
|
|
const AllocFnsTy *FnData = getAllocationData(CS.getInstruction(), AnyAlloc,
|
|
TLI);
|
|
if (!FnData)
|
|
return unknown();
|
|
|
|
// handle strdup-like functions separately
|
|
if (FnData->AllocTy == StrDupLike) {
|
|
// TODO
|
|
return unknown();
|
|
}
|
|
|
|
Value *FirstArg = CS.getArgument(FnData->FstParam);
|
|
FirstArg = Builder.CreateZExt(FirstArg, IntTy);
|
|
if (FnData->SndParam < 0)
|
|
return std::make_pair(FirstArg, Zero);
|
|
|
|
Value *SecondArg = CS.getArgument(FnData->SndParam);
|
|
SecondArg = Builder.CreateZExt(SecondArg, IntTy);
|
|
Value *Size = Builder.CreateMul(FirstArg, SecondArg);
|
|
return std::make_pair(Size, Zero);
|
|
|
|
// TODO: handle more standard functions (+ wchar cousins):
|
|
// - strdup / strndup
|
|
// - strcpy / strncpy
|
|
// - strcat / strncat
|
|
// - memcpy / memmove
|
|
// - strcat / strncat
|
|
// - memset
|
|
}
|
|
|
|
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();
|
|
SizePHI->replaceAllUsesWith(UndefValue::get(IntTy));
|
|
SizePHI->eraseFromParent();
|
|
return unknown();
|
|
}
|
|
SizePHI->addIncoming(EdgeData.first, PHI.getIncomingBlock(i));
|
|
OffsetPHI->addIncoming(EdgeData.second, PHI.getIncomingBlock(i));
|
|
}
|
|
|
|
Value *Size = SizePHI, *Offset = OffsetPHI, *Tmp;
|
|
if ((Tmp = SizePHI->hasConstantValue())) {
|
|
Size = Tmp;
|
|
SizePHI->replaceAllUsesWith(Size);
|
|
SizePHI->eraseFromParent();
|
|
}
|
|
if ((Tmp = OffsetPHI->hasConstantValue())) {
|
|
Offset = Tmp;
|
|
OffsetPHI->replaceAllUsesWith(Offset);
|
|
OffsetPHI->eraseFromParent();
|
|
}
|
|
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) {
|
|
DEBUG(dbgs() << "ObjectSizeOffsetEvaluator unknown instruction:" << I <<'\n');
|
|
return unknown();
|
|
}
|