bool LLPE::runOnModule(Module &M) {
vector<int> argv = readInputFile();
for (Module::iterator F = M.begin(), F_end = M.end(); F != F_end; ++F) {
for (Function::arg_iterator A = F->arg_begin(), A_end = F->arg_end(); A != A_end; ++A) {
//Search for variables referencing argv
if (A->getName() == "argv") {
//Iterate through uses of argv
for (Value::use_iterator U = A->use_begin(), U_end = A->use_end(); U != U_end; ++U) {
Instruction *User = dyn_cast<Instruction>(*U);
StoreInst *SI = dyn_cast<StoreInst>(User);
AllocaInst *OrigAlloca = dyn_cast<AllocaInst>(SI->getOperand(1));
for (Value::use_iterator U2 = OrigAlloca->use_begin(), U2_end = OrigAlloca->use_end(); U2 != U2_end; ++U2) {
Instruction *User2 = dyn_cast<Instruction>(*U2);
for (Value::use_iterator U3 = User2->use_begin(), U3_end = OrigAlloca->use_end(); U3 != U3_end; ++U3) {
searchForStoreInstruction(dyn_cast<Instruction>(*U3)->getParent(), argv);
}
}
}
}
}
}
return true;
}
AllocaInst* Variables::changeLocal(Value* value, ArrayType* newType) {
AllocaInst* oldTarget = dyn_cast<AllocaInst>(value);
PointerType* oldPointerType = dyn_cast<PointerType>(oldTarget->getType());
ArrayType* oldType = dyn_cast<ArrayType>(oldPointerType->getElementType());
AllocaInst* newTarget = NULL;
errs() << "Changing the precision of variable \"" << oldTarget->getName() << "\" from " << *oldType
<< " to " << *newType << ".\n";
if (newType->getElementType()->getTypeID() != oldType->getElementType()->getTypeID()) {
newTarget = new AllocaInst(newType, getInt32(1), "", oldTarget);
// we are not calling getAlignment because in this case double requires 16. Investigate further.
unsigned alignment;
switch(newType->getElementType()->getTypeID()) {
case Type::FloatTyID:
alignment = 4;
break;
case Type::DoubleTyID:
alignment = 16;
break;
case Type::X86_FP80TyID:
alignment = 16;
break;
default:
alignment = 0;
}
newTarget->setAlignment(alignment); // depends on type? 8 for float? 16 for double?
newTarget->takeName(oldTarget);
// iterating through instructions using old AllocaInst
vector<Instruction*> erase;
Value::use_iterator it = oldTarget->use_begin();
for(; it != oldTarget->use_end(); it++) {
bool is_erased = Transformer::transform(it, newTarget, oldTarget, newType, oldType, alignment);
if (!is_erased)
erase.push_back(dyn_cast<Instruction>(*it));
}
// erasing uses of old instructions
for(unsigned int i = 0; i < erase.size(); i++) {
erase[i]->eraseFromParent();
}
// erase old instruction
//oldTarget->eraseFromParent();
}
else {
errs() << "\tNo changes required.\n";
}
return newTarget;
}
/// performCallSlotOptzn - takes a memcpy and a call that it depends on,
/// and checks for the possibility of a call slot optimization by having
/// the call write its result directly into the destination of the memcpy.
bool MemCpyOpt::performCallSlotOptzn(Instruction *cpy,
Value *cpyDest, Value *cpySrc,
uint64_t cpyLen, unsigned cpyAlign,
CallInst *C) {
// The general transformation to keep in mind is
//
// call @func(..., src, ...)
// memcpy(dest, src, ...)
//
// ->
//
// memcpy(dest, src, ...)
// call @func(..., dest, ...)
//
// Since moving the memcpy is technically awkward, we additionally check that
// src only holds uninitialized values at the moment of the call, meaning that
// the memcpy can be discarded rather than moved.
// Deliberately get the source and destination with bitcasts stripped away,
// because we'll need to do type comparisons based on the underlying type.
CallSite CS(C);
// Require that src be an alloca. This simplifies the reasoning considerably.
AllocaInst *srcAlloca = dyn_cast<AllocaInst>(cpySrc);
if (!srcAlloca)
return false;
// Check that all of src is copied to dest.
if (TD == 0) return false;
ConstantInt *srcArraySize = dyn_cast<ConstantInt>(srcAlloca->getArraySize());
if (!srcArraySize)
return false;
uint64_t srcSize = TD->getTypeAllocSize(srcAlloca->getAllocatedType()) *
srcArraySize->getZExtValue();
if (cpyLen < srcSize)
return false;
// Check that dest points to memory that is at least as aligned as src.
unsigned srcAlign = srcAlloca->getAlignment();
if (!srcAlign)
srcAlign = TD->getABITypeAlignment(srcAlloca->getAllocatedType());
bool isDestSufficientlyAligned = srcAlign <= cpyAlign;
// If dest is not aligned enough and we can't increase its alignment then
// bail out.
if (!isDestSufficientlyAligned && !isa<AllocaInst>(cpyDest))
return false;
// Check that accessing the first srcSize bytes of dest will not cause a
// trap. Otherwise the transform is invalid since it might cause a trap
// to occur earlier than it otherwise would.
if (AllocaInst *A = dyn_cast<AllocaInst>(cpyDest)) {
// The destination is an alloca. Check it is larger than srcSize.
ConstantInt *destArraySize = dyn_cast<ConstantInt>(A->getArraySize());
if (!destArraySize)
return false;
uint64_t destSize = TD->getTypeAllocSize(A->getAllocatedType()) *
destArraySize->getZExtValue();
if (destSize < srcSize)
return false;
} else if (Argument *A = dyn_cast<Argument>(cpyDest)) {
// If the destination is an sret parameter then only accesses that are
// outside of the returned struct type can trap.
if (!A->hasStructRetAttr())
return false;
Type *StructTy = cast<PointerType>(A->getType())->getElementType();
uint64_t destSize = TD->getTypeAllocSize(StructTy);
if (destSize < srcSize)
return false;
} else {
return false;
}
// Check that src is not accessed except via the call and the memcpy. This
// guarantees that it holds only undefined values when passed in (so the final
// memcpy can be dropped), that it is not read or written between the call and
// the memcpy, and that writing beyond the end of it is undefined.
SmallVector<User*, 8> srcUseList(srcAlloca->use_begin(),
srcAlloca->use_end());
while (!srcUseList.empty()) {
User *UI = srcUseList.pop_back_val();
if (isa<BitCastInst>(UI)) {
for (User::use_iterator I = UI->use_begin(), E = UI->use_end();
I != E; ++I)
srcUseList.push_back(*I);
} else if (GetElementPtrInst *G = dyn_cast<GetElementPtrInst>(UI)) {
if (G->hasAllZeroIndices())
for (User::use_iterator I = UI->use_begin(), E = UI->use_end();
I != E; ++I)
srcUseList.push_back(*I);
else
return false;
} else if (UI != C && UI != cpy) {
return false;
}
}
// Since we're changing the parameter to the callsite, we need to make sure
// that what would be the new parameter dominates the callsite.
DominatorTree &DT = getAnalysis<DominatorTree>();
if (Instruction *cpyDestInst = dyn_cast<Instruction>(cpyDest))
if (!DT.dominates(cpyDestInst, C))
return false;
// In addition to knowing that the call does not access src in some
// unexpected manner, for example via a global, which we deduce from
// the use analysis, we also need to know that it does not sneakily
// access dest. We rely on AA to figure this out for us.
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
AliasAnalysis::ModRefResult MR = AA.getModRefInfo(C, cpyDest, srcSize);
// If necessary, perform additional analysis.
if (MR != AliasAnalysis::NoModRef)
MR = AA.callCapturesBefore(C, cpyDest, srcSize, &DT);
if (MR != AliasAnalysis::NoModRef)
return false;
// All the checks have passed, so do the transformation.
bool changedArgument = false;
for (unsigned i = 0; i < CS.arg_size(); ++i)
if (CS.getArgument(i)->stripPointerCasts() == cpySrc) {
Value *Dest = cpySrc->getType() == cpyDest->getType() ? cpyDest
: CastInst::CreatePointerCast(cpyDest, cpySrc->getType(),
cpyDest->getName(), C);
changedArgument = true;
if (CS.getArgument(i)->getType() == Dest->getType())
CS.setArgument(i, Dest);
else
CS.setArgument(i, CastInst::CreatePointerCast(Dest,
CS.getArgument(i)->getType(), Dest->getName(), C));
}
if (!changedArgument)
return false;
// If the destination wasn't sufficiently aligned then increase its alignment.
if (!isDestSufficientlyAligned) {
assert(isa<AllocaInst>(cpyDest) && "Can only increase alloca alignment!");
cast<AllocaInst>(cpyDest)->setAlignment(srcAlign);
}
// Drop any cached information about the call, because we may have changed
// its dependence information by changing its parameter.
MD->removeInstruction(C);
// Remove the memcpy.
MD->removeInstruction(cpy);
++NumMemCpyInstr;
return true;
}
bool SpDefUseInstrumenter::runOnModule(Module &M) {
cerr << "instrument: --- Def-Use pair Spectrum ---\n";
Function *Main = M.getFunction("main");
LLVMContext &C = M.getContext();
if (Main == 0) {
cerr << "WARNING: cannot insert def-use instrumentation into a module"
<< " with no main function!\n";
return false; // No main, no instrumentation!
}
// Add library function prototype
Constant *SpFn = M.getOrInsertFunction("_updateSpectrum",
Type::getVoidTy(C),
Type::getInt32Ty(C), // spectrum index
Type::getInt32Ty(C), // component index
NULL);
unsigned spectrumIndex = IndexManager::getSpectrumIndex();
unsigned nDefs = 0;
unsigned nUses = 0;
// Loop through all functions within module
for (Module::iterator F = M.begin(), ME = M.end(); F != ME; ++F) {
// skip function declarations
if(F->isDeclaration())
continue;
// skip the _registerAll function
if(F->getName()=="_registerAll")
continue;
// Loop through all basic blocks within function
for (Function::iterator B = F->begin(), FE = F->end(); B != FE; ++B) {
//skip dead blocks
//is this really safe??
BasicBlock *bb = B;
if (B!=F->begin() && (pred_begin(bb)==pred_end(bb))) continue; //skip dead blocks
// Loop through all instructions within basic block
for (BasicBlock::iterator I = B->begin(), BE = B->end(); I != BE; I++) {
if(isa<DbgDeclareInst>(*I)) {
// extract source file information from debug intrinsic
DbgDeclareInst &DDI = cast<DbgDeclareInst>(*I);
std::string file, dir;
std::string name;
GlobalVariable *gv = cast<GlobalVariable>(DDI.getVariable());
if(!gv->hasInitializer()) continue;
ConstantStruct *cs = cast<ConstantStruct>(gv->getInitializer());
llvm::GetConstantStringInfo(cs->getOperand(2), name);
unsigned int line = unsigned(cast<ConstantInt>(cs->getOperand(4))->getZExtValue());
Value *V = cast<Value>(cs->getOperand(3));
GlobalVariable *gv2 = cast<GlobalVariable>(cast<ConstantExpr>(V)->getOperand(0));
if(!gv2->hasInitializer()) continue;
ConstantStruct *cs2 = cast<ConstantStruct>(gv2->getInitializer());
llvm::GetConstantStringInfo(cs2->getOperand(3), file);
llvm::GetConstantStringInfo(cs2->getOperand(4), dir);
// get the allocation instruction of the variable definition
AllocaInst *AI;
if(isa<AllocaInst>(DDI.getAddress())) {
AI = cast<AllocaInst>(DDI.getAddress());
} else if (isa<BitCastInst>(DDI.getAddress())) {
AI = cast<AllocaInst>(cast<BitCastInst>(DDI.getAddress())->getOperand(0));
} else {
continue;
}
nDefs++;
// add calls to lib function for each use of the variable
int currUses = 0;
for(AllocaInst::use_iterator U = AI->use_begin(), UE = AI->use_end(); U != UE; ++U) {
if(isa<Instruction>(*U)) {
User *user = *U;
Instruction *insertInst = (Instruction*)user;
// find most likely context location of use
int useline = line;
std::string usefile = file, usedir = dir;
BasicBlock *parent = insertInst->getParent();
BasicBlock::iterator inst = parent->begin();
while(((Instruction *)inst) != insertInst && inst != parent->end()) {
/*TODO: solve DbgStopPointInst problem*/
/*if(isa<DbgStopPointInst>(*inst)) {
DbgStopPointInst &DSPI = cast<DbgStopPointInst>(*inst);
llvm::GetConstantStringInfo(DSPI.getDirectory(), usedir);
llvm::GetConstantStringInfo(DSPI.getFileName(), usefile);
useline = DSPI.getLine();
}*/
inst++;
}
std::stringstream usename;
usename << name << "(use_" << currUses << ")";
// add source context of this invariant to context file
ContextManager::addSpectrumContext(
spectrumIndex, // spectrumIndex
nUses, // componentIndex
usedir, // path
usefile, // file
useline, // line
usename.str()); // name
currUses++;
std::vector<Value*> Args(2);
Args[0] = ConstantInt::get(Type::getInt32Ty(C), spectrumIndex);
Args[1] = ConstantInt::get(Type::getInt32Ty(C), nUses++);
CallInst::Create(SpFn, Args.begin(), Args.end(), "", insertInst);
}
}
}
}
}
}
// add the registration of the instrumented spectrum points in the _registerAll() function
addSpectrumRegistration(M, spectrumIndex, nUses, "Def-Use_Pairs");
std::cerr << "instrument: " << nDefs << " defines with a total number of " << nUses << " uses instrumented\n";
// notify change of program
return true;
}
