void GraphBuilder::visitInsertValueInst(InsertValueInst& I) {
setDestTo(I, createNode()->setAllocaMarker());
Type *StoredTy = I.getInsertedValueOperand()->getType();
DSNodeHandle Dest = getValueDest(&I);
Dest.mergeWith(getValueDest(I.getAggregateOperand()));
// Mark that the node is written to...
Dest.getNode()->setModifiedMarker();
unsigned Offset = 0;
Type* STy = I.getAggregateOperand()->getType();
llvm::InsertValueInst::idx_iterator i = I.idx_begin(), e = I.idx_end();
for (; i != e; i++) {
const StructLayout *SL = TD.getStructLayout(cast<StructType>(STy));
Offset += SL->getElementOffset(*i);
STy = (cast<StructType>(STy))->getTypeAtIndex(*i);
}
// Ensure a type-record exists...
Dest.getNode()->mergeTypeInfo(StoredTy, Offset);
// Avoid adding edges from null, or processing non-"pointer" stores
if (isa<PointerType>(StoredTy))
Dest.addEdgeTo(getValueDest(I.getInsertedValueOperand()));
}
bool CallAnalyzer::visitInsertValue(InsertValueInst &I) {
// Constant folding for insert value is trivial.
Constant *AggC = dyn_cast<Constant>(I.getAggregateOperand());
if (!AggC)
AggC = SimplifiedValues.lookup(I.getAggregateOperand());
Constant *InsertedC = dyn_cast<Constant>(I.getInsertedValueOperand());
if (!InsertedC)
InsertedC = SimplifiedValues.lookup(I.getInsertedValueOperand());
if (AggC && InsertedC) {
SimplifiedValues[&I] = ConstantExpr::getInsertValue(AggC, InsertedC,
I.getIndices());
return true;
}
// SROA can look through these but give them a cost.
return false;
}
//
// Method: runOnModule()
//
// Description:
// Entry point for this LLVM pass. Search for insertvalue instructions
// that can be simplified.
//
// Inputs:
// M - A reference to the LLVM module to transform.
//
// Outputs:
// M - The transformed LLVM module.
//
// Return value:
// true - The module was modified.
// false - The module was not modified.
//
bool SimplifyIV::runOnModule(Module& M) {
// Repeat till no change
bool changed;
do {
changed = false;
std::vector<StoreInst*> worklist;
for (Module::iterator F = M.begin(); F != M.end(); ++F) {
for (Function::iterator B = F->begin(), FE = F->end(); B != FE; ++B) {
for (BasicBlock::iterator I = B->begin(), BE = B->end(); I != BE;) {
InsertValueInst *IV = dyn_cast<InsertValueInst>(I++);
if(!IV)
continue;
// Find all insert value instructions.
if(!IV->hasOneUse())
continue;
// Check that its only use is a StoreInst
StoreInst *SI = dyn_cast<StoreInst>(*(IV->use_begin()));
if(!SI)
continue;
// Check that it is the stored value
if(SI->getOperand(0) != IV)
continue;
changed = true;
numErased++;
do {
// replace by a series of gep/stores
SmallVector<Value*, 8> Indices;
Type *Int32Ty = Type::getInt32Ty(M.getContext());
Indices.push_back(Constant::getNullValue(Int32Ty));
for (InsertValueInst::idx_iterator I = IV->idx_begin(), E = IV->idx_end();
I != E; ++I) {
Indices.push_back(ConstantInt::get(Int32Ty, *I));
}
GetElementPtrInst *GEP = GetElementPtrInst::CreateInBounds(SI->getOperand(1), Indices,
SI->getName(), SI) ;
new StoreInst(IV->getInsertedValueOperand(), GEP, SI);
IV = dyn_cast<InsertValueInst>(IV->getAggregateOperand());
} while(IV);
worklist.push_back(SI);
}
}
}
while(!worklist.empty()) {
StoreInst *SI = worklist.back();
worklist.pop_back();
SI->eraseFromParent();
}
} while(changed);
return (numErased > 0);
}
// This is the recursive version of BuildSubAggregate. It takes a few different
// arguments. Idxs is the index within the nested struct From that we are
// looking at now (which is of type IndexedType). IdxSkip is the number of
// indices from Idxs that should be left out when inserting into the resulting
// struct. To is the result struct built so far, new insertvalue instructions
// build on that.
Value *BuildSubAggregate(Value *From, Value* To, const Type *IndexedType,
SmallVector<unsigned, 10> &Idxs,
unsigned IdxSkip,
Instruction *InsertBefore) {
const llvm::StructType *STy = llvm::dyn_cast<llvm::StructType>(IndexedType);
if (STy) {
// Save the original To argument so we can modify it
Value *OrigTo = To;
// General case, the type indexed by Idxs is a struct
for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
// Process each struct element recursively
Idxs.push_back(i);
Value *PrevTo = To;
To = BuildSubAggregate(From, To, STy->getElementType(i), Idxs, IdxSkip,
InsertBefore);
Idxs.pop_back();
if (!To) {
// Couldn't find any inserted value for this index? Cleanup
while (PrevTo != OrigTo) {
InsertValueInst* Del = cast<InsertValueInst>(PrevTo);
PrevTo = Del->getAggregateOperand();
Del->eraseFromParent();
}
// Stop processing elements
break;
}
}
// If we succesfully found a value for each of our subaggregates
if (To)
return To;
}
// Base case, the type indexed by SourceIdxs is not a struct, or not all of
// the struct's elements had a value that was inserted directly. In the latter
// case, perhaps we can't determine each of the subelements individually, but
// we might be able to find the complete struct somewhere.
// Find the value that is at that particular spot
Value *V = FindInsertedValue(From, Idxs.begin(), Idxs.end());
if (!V)
return NULL;
// Insert the value in the new (sub) aggregrate
return llvm::InsertValueInst::Create(To, V, Idxs.begin() + IdxSkip,
Idxs.end(), "tmp", InsertBefore);
}