mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-21 00:32:23 +00:00
46e8312fb7
Reviewed by Eli Friedman. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82281 91177308-0d34-0410-b5e6-96231b3b80d8
266 lines
9.1 KiB
C++
266 lines
9.1 KiB
C++
//===- PointerTracking.cpp - Pointer Bounds Tracking ------------*- C++ -*-===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements tracking of pointer bounds.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
#include "llvm/Analysis/ConstantFolding.h"
|
|
#include "llvm/Analysis/Dominators.h"
|
|
#include "llvm/Analysis/LoopInfo.h"
|
|
#include "llvm/Analysis/MallocHelper.h"
|
|
#include "llvm/Analysis/PointerTracking.h"
|
|
#include "llvm/Analysis/ScalarEvolution.h"
|
|
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
|
|
#include "llvm/Constants.h"
|
|
#include "llvm/Module.h"
|
|
#include "llvm/Value.h"
|
|
#include "llvm/Support/CallSite.h"
|
|
#include "llvm/Support/InstIterator.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
#include "llvm/Target/TargetData.h"
|
|
using namespace llvm;
|
|
|
|
char PointerTracking::ID = 0;
|
|
PointerTracking::PointerTracking() : FunctionPass(&ID) {}
|
|
|
|
bool PointerTracking::runOnFunction(Function &F) {
|
|
predCache.clear();
|
|
assert(analyzing.empty());
|
|
FF = &F;
|
|
TD = getAnalysisIfAvailable<TargetData>();
|
|
SE = &getAnalysis<ScalarEvolution>();
|
|
LI = &getAnalysis<LoopInfo>();
|
|
DT = &getAnalysis<DominatorTree>();
|
|
return false;
|
|
}
|
|
|
|
void PointerTracking::getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AU.addRequiredTransitive<DominatorTree>();
|
|
AU.addRequiredTransitive<LoopInfo>();
|
|
AU.addRequiredTransitive<ScalarEvolution>();
|
|
AU.setPreservesAll();
|
|
}
|
|
|
|
bool PointerTracking::doInitialization(Module &M) {
|
|
const Type *PTy = PointerType::getUnqual(Type::getInt8Ty(M.getContext()));
|
|
|
|
// Find calloc(i64, i64) or calloc(i32, i32).
|
|
callocFunc = M.getFunction("calloc");
|
|
if (callocFunc) {
|
|
const FunctionType *Ty = callocFunc->getFunctionType();
|
|
|
|
std::vector<const Type*> args, args2;
|
|
args.push_back(Type::getInt64Ty(M.getContext()));
|
|
args.push_back(Type::getInt64Ty(M.getContext()));
|
|
args2.push_back(Type::getInt32Ty(M.getContext()));
|
|
args2.push_back(Type::getInt32Ty(M.getContext()));
|
|
const FunctionType *Calloc1Type =
|
|
FunctionType::get(PTy, args, false);
|
|
const FunctionType *Calloc2Type =
|
|
FunctionType::get(PTy, args2, false);
|
|
if (Ty != Calloc1Type && Ty != Calloc2Type)
|
|
callocFunc = 0; // Give up
|
|
}
|
|
|
|
// Find realloc(i8*, i64) or realloc(i8*, i32).
|
|
reallocFunc = M.getFunction("realloc");
|
|
if (reallocFunc) {
|
|
const FunctionType *Ty = reallocFunc->getFunctionType();
|
|
std::vector<const Type*> args, args2;
|
|
args.push_back(PTy);
|
|
args.push_back(Type::getInt64Ty(M.getContext()));
|
|
args2.push_back(PTy);
|
|
args2.push_back(Type::getInt32Ty(M.getContext()));
|
|
|
|
const FunctionType *Realloc1Type =
|
|
FunctionType::get(PTy, args, false);
|
|
const FunctionType *Realloc2Type =
|
|
FunctionType::get(PTy, args2, false);
|
|
if (Ty != Realloc1Type && Ty != Realloc2Type)
|
|
reallocFunc = 0; // Give up
|
|
}
|
|
return false;
|
|
}
|
|
|
|
// Calculates the number of elements allocated for pointer P,
|
|
// the type of the element is stored in Ty.
|
|
const SCEV *PointerTracking::computeAllocationCount(Value *P,
|
|
const Type *&Ty) const {
|
|
Value *V = P->stripPointerCasts();
|
|
if (AllocationInst *AI = dyn_cast<AllocationInst>(V)) {
|
|
Value *arraySize = AI->getArraySize();
|
|
Ty = AI->getAllocatedType();
|
|
// arraySize elements of type Ty.
|
|
return SE->getSCEV(arraySize);
|
|
}
|
|
|
|
if (CallInst *CI = extractMallocCall(V)) {
|
|
Value *arraySize = getMallocArraySize(CI, P->getContext(), TD);
|
|
Ty = getMallocAllocatedType(CI);
|
|
if (!Ty || !arraySize) return SE->getCouldNotCompute();
|
|
// arraySize elements of type Ty.
|
|
return SE->getSCEV(arraySize);
|
|
}
|
|
|
|
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
|
|
if (GV->hasDefinitiveInitializer()) {
|
|
Constant *C = GV->getInitializer();
|
|
if (const ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) {
|
|
Ty = ATy->getElementType();
|
|
return SE->getConstant(Type::getInt32Ty(P->getContext()),
|
|
ATy->getNumElements());
|
|
}
|
|
}
|
|
Ty = GV->getType();
|
|
return SE->getConstant(Type::getInt32Ty(P->getContext()), 1);
|
|
//TODO: implement more tracking for globals
|
|
}
|
|
|
|
if (CallInst *CI = dyn_cast<CallInst>(V)) {
|
|
CallSite CS(CI);
|
|
Function *F = dyn_cast<Function>(CS.getCalledValue()->stripPointerCasts());
|
|
const Loop *L = LI->getLoopFor(CI->getParent());
|
|
if (F == callocFunc) {
|
|
Ty = Type::getInt8Ty(P->getContext());
|
|
// calloc allocates arg0*arg1 bytes.
|
|
return SE->getSCEVAtScope(SE->getMulExpr(SE->getSCEV(CS.getArgument(0)),
|
|
SE->getSCEV(CS.getArgument(1))),
|
|
L);
|
|
} else if (F == reallocFunc) {
|
|
Ty = Type::getInt8Ty(P->getContext());
|
|
// realloc allocates arg1 bytes.
|
|
return SE->getSCEVAtScope(CS.getArgument(1), L);
|
|
}
|
|
}
|
|
|
|
return SE->getCouldNotCompute();
|
|
}
|
|
|
|
// Calculates the number of elements of type Ty allocated for P.
|
|
const SCEV *PointerTracking::computeAllocationCountForType(Value *P,
|
|
const Type *Ty)
|
|
const {
|
|
const Type *elementTy;
|
|
const SCEV *Count = computeAllocationCount(P, elementTy);
|
|
if (isa<SCEVCouldNotCompute>(Count))
|
|
return Count;
|
|
if (elementTy == Ty)
|
|
return Count;
|
|
|
|
if (!TD) // need TargetData from this point forward
|
|
return SE->getCouldNotCompute();
|
|
|
|
uint64_t elementSize = TD->getTypeAllocSize(elementTy);
|
|
uint64_t wantSize = TD->getTypeAllocSize(Ty);
|
|
if (elementSize == wantSize)
|
|
return Count;
|
|
if (elementSize % wantSize) //fractional counts not possible
|
|
return SE->getCouldNotCompute();
|
|
return SE->getMulExpr(Count, SE->getConstant(Count->getType(),
|
|
elementSize/wantSize));
|
|
}
|
|
|
|
const SCEV *PointerTracking::getAllocationElementCount(Value *V) const {
|
|
// We only deal with pointers.
|
|
const PointerType *PTy = cast<PointerType>(V->getType());
|
|
return computeAllocationCountForType(V, PTy->getElementType());
|
|
}
|
|
|
|
const SCEV *PointerTracking::getAllocationSizeInBytes(Value *V) const {
|
|
return computeAllocationCountForType(V, Type::getInt8Ty(V->getContext()));
|
|
}
|
|
|
|
// Helper for isLoopGuardedBy that checks the swapped and inverted predicate too
|
|
enum SolverResult PointerTracking::isLoopGuardedBy(const Loop *L,
|
|
Predicate Pred,
|
|
const SCEV *A,
|
|
const SCEV *B) const {
|
|
if (SE->isLoopGuardedByCond(L, Pred, A, B))
|
|
return AlwaysTrue;
|
|
Pred = ICmpInst::getSwappedPredicate(Pred);
|
|
if (SE->isLoopGuardedByCond(L, Pred, B, A))
|
|
return AlwaysTrue;
|
|
|
|
Pred = ICmpInst::getInversePredicate(Pred);
|
|
if (SE->isLoopGuardedByCond(L, Pred, B, A))
|
|
return AlwaysFalse;
|
|
Pred = ICmpInst::getSwappedPredicate(Pred);
|
|
if (SE->isLoopGuardedByCond(L, Pred, A, B))
|
|
return AlwaysTrue;
|
|
return Unknown;
|
|
}
|
|
|
|
enum SolverResult PointerTracking::checkLimits(const SCEV *Offset,
|
|
const SCEV *Limit,
|
|
BasicBlock *BB)
|
|
{
|
|
//FIXME: merge implementation
|
|
return Unknown;
|
|
}
|
|
|
|
void PointerTracking::getPointerOffset(Value *Pointer, Value *&Base,
|
|
const SCEV *&Limit,
|
|
const SCEV *&Offset) const
|
|
{
|
|
Pointer = Pointer->stripPointerCasts();
|
|
Base = Pointer->getUnderlyingObject();
|
|
Limit = getAllocationSizeInBytes(Base);
|
|
if (isa<SCEVCouldNotCompute>(Limit)) {
|
|
Base = 0;
|
|
Offset = Limit;
|
|
return;
|
|
}
|
|
|
|
Offset = SE->getMinusSCEV(SE->getSCEV(Pointer), SE->getSCEV(Base));
|
|
if (isa<SCEVCouldNotCompute>(Offset)) {
|
|
Base = 0;
|
|
Limit = Offset;
|
|
}
|
|
}
|
|
|
|
void PointerTracking::print(raw_ostream &OS, const Module* M) const {
|
|
// Calling some PT methods may cause caches to be updated, however
|
|
// this should be safe for the same reason its safe for SCEV.
|
|
PointerTracking &PT = *const_cast<PointerTracking*>(this);
|
|
for (inst_iterator I=inst_begin(*FF), E=inst_end(*FF); I != E; ++I) {
|
|
if (!isa<PointerType>(I->getType()))
|
|
continue;
|
|
Value *Base;
|
|
const SCEV *Limit, *Offset;
|
|
getPointerOffset(&*I, Base, Limit, Offset);
|
|
if (!Base)
|
|
continue;
|
|
|
|
if (Base == &*I) {
|
|
const SCEV *S = getAllocationElementCount(Base);
|
|
OS << *Base << " ==> " << *S << " elements, ";
|
|
OS << *Limit << " bytes allocated\n";
|
|
continue;
|
|
}
|
|
OS << &*I << " -- base: " << *Base;
|
|
OS << " offset: " << *Offset;
|
|
|
|
enum SolverResult res = PT.checkLimits(Offset, Limit, I->getParent());
|
|
switch (res) {
|
|
case AlwaysTrue:
|
|
OS << " always safe\n";
|
|
break;
|
|
case AlwaysFalse:
|
|
OS << " always unsafe\n";
|
|
break;
|
|
case Unknown:
|
|
OS << " <<unknown>>\n";
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
static RegisterPass<PointerTracking> X("pointertracking",
|
|
"Track pointer bounds", false, true);
|