// Peephole Malloc instructions: we take a look at the use chain of the
// malloc instruction, and try to find out if the following conditions hold:
// 1. The malloc is of the form: 'malloc [sbyte], uint <constant>'
// 2. The only users of the malloc are cast & add instructions
// 3. Of the cast instructions, there is only one destination pointer type
// [RTy] where the size of the pointed to object is equal to the number
// of bytes allocated.
//
// If these conditions hold, we convert the malloc to allocate an [RTy]
// element. TODO: This comment is out of date WRT arrays
//
static bool MallocConvertibleToType(MallocInst *MI, const Type *Ty,
ValueTypeCache &CTMap,
const TargetData &TD) {
if (!isa<PointerType>(Ty)) return false; // Malloc always returns pointers
// Deal with the type to allocate, not the pointer type...
Ty = cast<PointerType>(Ty)->getElementType();
if (!Ty->isSized()) return false; // Can only alloc something with a size
// Analyze the number of bytes allocated...
ExprType Expr = ClassifyExpr(MI->getArraySize());
// Get information about the base datatype being allocated, before & after
int ReqTypeSize = TD.getTypeSize(Ty);
if (ReqTypeSize == 0) return false;
unsigned OldTypeSize = TD.getTypeSize(MI->getType()->getElementType());
// Must have a scale or offset to analyze it...
if (!Expr.Offset && !Expr.Scale && OldTypeSize == 1) return false;
// Get the offset and scale of the allocation...
int64_t OffsetVal = Expr.Offset ? getConstantValue(Expr.Offset) : 0;
int64_t ScaleVal = Expr.Scale ? getConstantValue(Expr.Scale) :(Expr.Var != 0);
// The old type might not be of unit size, take old size into consideration
// here...
int64_t Offset = OffsetVal * OldTypeSize;
int64_t Scale = ScaleVal * OldTypeSize;
// In order to be successful, both the scale and the offset must be a multiple
// of the requested data type's size.
//
if (Offset/ReqTypeSize*ReqTypeSize != Offset ||
Scale/ReqTypeSize*ReqTypeSize != Scale)
return false; // Nope.
return true;
}
/// IsConstantOffsetFromGlobal - If this constant is actually a constant offset
/// from a global, return the global and the constant. Because of
/// constantexprs, this function is recursive.
static bool IsConstantOffsetFromGlobal(Constant *C, GlobalValue *&GV,
int64_t &Offset, const TargetData &TD) {
// Trivial case, constant is the global.
if ((GV = dyn_cast<GlobalValue>(C))) {
Offset = 0;
return true;
}
// Otherwise, if this isn't a constant expr, bail out.
ConstantExpr *CE = dyn_cast<ConstantExpr>(C);
if (!CE) return false;
// Look through ptr->int and ptr->ptr casts.
if (CE->getOpcode() == Instruction::PtrToInt ||
CE->getOpcode() == Instruction::BitCast)
return IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD);
// i32* getelementptr ([5 x i32]* @a, i32 0, i32 5)
if (CE->getOpcode() == Instruction::GetElementPtr) {
// Cannot compute this if the element type of the pointer is missing size
// info.
if (!cast<PointerType>(CE->getOperand(0)->getType())->getElementType()->isSized())
return false;
// If the base isn't a global+constant, we aren't either.
if (!IsConstantOffsetFromGlobal(CE->getOperand(0), GV, Offset, TD))
return false;
// Otherwise, add any offset that our operands provide.
gep_type_iterator GTI = gep_type_begin(CE);
for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i, ++GTI) {
ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(i));
if (!CI) return false; // Index isn't a simple constant?
if (CI->getZExtValue() == 0) continue; // Not adding anything.
if (const StructType *ST = dyn_cast<StructType>(*GTI)) {
// N = N + Offset
Offset += TD.getStructLayout(ST)->getElementOffset(CI->getZExtValue());
} else {
const SequentialType *SQT = cast<SequentialType>(*GTI);
Offset += TD.getTypeSize(SQT->getElementType())*CI->getSExtValue();
}
}
return true;
}
return false;
}
static void ConvertOperandToType(User *U, Value *OldVal, Value *NewVal,
ValueMapCache &VMC, const TargetData &TD) {
if (isa<ValueHandle>(U)) return; // Valuehandles don't let go of operands...
if (VMC.OperandsMapped.count(U)) return;
VMC.OperandsMapped.insert(U);
ValueMapCache::ExprMapTy::iterator VMCI = VMC.ExprMap.find(U);
if (VMCI != VMC.ExprMap.end())
return;
Instruction *I = cast<Instruction>(U); // Only Instructions convertible
BasicBlock *BB = I->getParent();
assert(BB != 0 && "Instruction not embedded in basic block!");
std::string Name = I->getName();
I->setName("");
Instruction *Res; // Result of conversion
//std::cerr << endl << endl << "Type:\t" << Ty << "\nInst: " << I
// << "BB Before: " << BB << endl;
// Prevent I from being removed...
ValueHandle IHandle(VMC, I);
const Type *NewTy = NewVal->getType();
Constant *Dummy = (NewTy != Type::VoidTy) ?
Constant::getNullValue(NewTy) : 0;
switch (I->getOpcode()) {
case Instruction::Cast:
if (VMC.NewCasts.count(ValueHandle(VMC, I))) {
// This cast has already had it's value converted, causing a new cast to
// be created. We don't want to create YET ANOTHER cast instruction
// representing the original one, so just modify the operand of this cast
// instruction, which we know is newly created.
I->setOperand(0, NewVal);
I->setName(Name); // give I its name back
return;
} else {
Res = new CastInst(NewVal, I->getType(), Name);
}
break;
case Instruction::Add:
if (isa<PointerType>(NewTy)) {
Value *IndexVal = I->getOperand(OldVal == I->getOperand(0) ? 1 : 0);
std::vector<Value*> Indices;
BasicBlock::iterator It = I;
if (const Type *ETy = ConvertibleToGEP(NewTy, IndexVal, Indices, TD,&It)){
// If successful, convert the add to a GEP
//const Type *RetTy = PointerType::get(ETy);
// First operand is actually the given pointer...
Res = new GetElementPtrInst(NewVal, Indices, Name);
assert(cast<PointerType>(Res->getType())->getElementType() == ETy &&
"ConvertibleToGEP broken!");
break;
}
}
// FALLTHROUGH
case Instruction::Sub:
case Instruction::SetEQ:
case Instruction::SetNE: {
Res = BinaryOperator::create(cast<BinaryOperator>(I)->getOpcode(),
Dummy, Dummy, Name);
VMC.ExprMap[I] = Res; // Add node to expression eagerly
unsigned OtherIdx = (OldVal == I->getOperand(0)) ? 1 : 0;
Value *OtherOp = I->getOperand(OtherIdx);
Res->setOperand(!OtherIdx, NewVal);
Value *NewOther = ConvertExpressionToType(OtherOp, NewTy, VMC, TD);
Res->setOperand(OtherIdx, NewOther);
break;
}
case Instruction::Shl:
case Instruction::Shr:
assert(I->getOperand(0) == OldVal);
Res = new ShiftInst(cast<ShiftInst>(I)->getOpcode(), NewVal,
I->getOperand(1), Name);
break;
case Instruction::Free: // Free can free any pointer type!
assert(I->getOperand(0) == OldVal);
Res = new FreeInst(NewVal);
break;
case Instruction::Load: {
assert(I->getOperand(0) == OldVal && isa<PointerType>(NewVal->getType()));
const Type *LoadedTy =
cast<PointerType>(NewVal->getType())->getElementType();
Value *Src = NewVal;
if (const CompositeType *CT = dyn_cast<CompositeType>(LoadedTy)) {
std::vector<Value*> Indices;
Indices.push_back(Constant::getNullValue(Type::UIntTy));
unsigned Offset = 0; // No offset, get first leaf.
LoadedTy = getStructOffsetType(CT, Offset, Indices, TD, false);
assert(LoadedTy->isFirstClassType());
if (Indices.size() != 1) { // Do not generate load X, 0
// Insert the GEP instruction before this load.
Src = new GetElementPtrInst(Src, Indices, Name+".idx", I);
}
}
Res = new LoadInst(Src, Name);
assert(Res->getType()->isFirstClassType() && "Load of structure or array!");
break;
}
case Instruction::Store: {
if (I->getOperand(0) == OldVal) { // Replace the source value
// Check to see if operand #1 has already been converted...
ValueMapCache::ExprMapTy::iterator VMCI =
VMC.ExprMap.find(I->getOperand(1));
if (VMCI != VMC.ExprMap.end()) {
// Comments describing this stuff are in the OperandConvertibleToType
// switch statement for Store...
//
const Type *ElTy =
cast<PointerType>(VMCI->second->getType())->getElementType();
Value *SrcPtr = VMCI->second;
if (ElTy != NewTy) {
// We check that this is a struct in the initial scan...
const StructType *SElTy = cast<StructType>(ElTy);
std::vector<Value*> Indices;
Indices.push_back(Constant::getNullValue(Type::UIntTy));
unsigned Offset = 0;
const Type *Ty = getStructOffsetType(ElTy, Offset, Indices, TD,false);
assert(Offset == 0 && "Offset changed!");
assert(NewTy == Ty && "Did not convert to correct type!");
// Insert the GEP instruction before this store.
SrcPtr = new GetElementPtrInst(SrcPtr, Indices,
SrcPtr->getName()+".idx", I);
}
Res = new StoreInst(NewVal, SrcPtr);
VMC.ExprMap[I] = Res;
} else {
// Otherwise, we haven't converted Operand #1 over yet...
const PointerType *NewPT = PointerType::get(NewTy);
Res = new StoreInst(NewVal, Constant::getNullValue(NewPT));
VMC.ExprMap[I] = Res;
Res->setOperand(1, ConvertExpressionToType(I->getOperand(1),
NewPT, VMC, TD));
}
} else { // Replace the source pointer
const Type *ValTy = cast<PointerType>(NewTy)->getElementType();
Value *SrcPtr = NewVal;
if (isa<StructType>(ValTy)) {
std::vector<Value*> Indices;
Indices.push_back(Constant::getNullValue(Type::UIntTy));
unsigned Offset = 0;
ValTy = getStructOffsetType(ValTy, Offset, Indices, TD, false);
assert(Offset == 0 && ValTy);
// Insert the GEP instruction before this store.
SrcPtr = new GetElementPtrInst(SrcPtr, Indices,
SrcPtr->getName()+".idx", I);
}
Res = new StoreInst(Constant::getNullValue(ValTy), SrcPtr);
VMC.ExprMap[I] = Res;
Res->setOperand(0, ConvertExpressionToType(I->getOperand(0),
ValTy, VMC, TD));
}
break;
}
case Instruction::GetElementPtr: {
// Convert a one index getelementptr into just about anything that is
// desired.
//
BasicBlock::iterator It = I;
const Type *OldElTy = cast<PointerType>(I->getType())->getElementType();
unsigned DataSize = TD.getTypeSize(OldElTy);
Value *Index = I->getOperand(1);
if (DataSize != 1) {
// Insert a multiply of the old element type is not a unit size...
Value *CST;
if (Index->getType()->isSigned())
CST = ConstantSInt::get(Index->getType(), DataSize);
else
CST = ConstantUInt::get(Index->getType(), DataSize);
Index = BinaryOperator::create(Instruction::Mul, Index, CST, "scale", It);
}
// Perform the conversion now...
//
std::vector<Value*> Indices;
const Type *ElTy = ConvertibleToGEP(NewVal->getType(),Index,Indices,TD,&It);
assert(ElTy != 0 && "GEP Conversion Failure!");
Res = new GetElementPtrInst(NewVal, Indices, Name);
assert(Res->getType() == PointerType::get(ElTy) &&
"ConvertibleToGet failed!");
}
#if 0
if (I->getType() == PointerType::get(Type::SByteTy)) {
// Convert a getelementptr sbyte * %reg111, uint 16 freely back to
// anything that is a pointer type...
//
BasicBlock::iterator It = I;
// Check to see if the second argument is an expression that can
// be converted to the appropriate size... if so, allow it.
//
std::vector<Value*> Indices;
const Type *ElTy = ConvertibleToGEP(NewVal->getType(), I->getOperand(1),
Indices, TD, &It);
assert(ElTy != 0 && "GEP Conversion Failure!");
Res = new GetElementPtrInst(NewVal, Indices, Name);
} else {
// Convert a getelementptr ulong * %reg123, uint %N
// to getelementptr long * %reg123, uint %N
// ... where the type must simply stay the same size...
//
GetElementPtrInst *GEP = cast<GetElementPtrInst>(I);
std::vector<Value*> Indices(GEP->idx_begin(), GEP->idx_end());
Res = new GetElementPtrInst(NewVal, Indices, Name);
}
#endif
break;
case Instruction::PHI: {
PHINode *OldPN = cast<PHINode>(I);
PHINode *NewPN = new PHINode(NewTy, Name);
VMC.ExprMap[I] = NewPN;
while (OldPN->getNumOperands()) {
BasicBlock *BB = OldPN->getIncomingBlock(0);
Value *OldVal = OldPN->getIncomingValue(0);
ValueHandle OldValHandle(VMC, OldVal);
OldPN->removeIncomingValue(BB, false);
Value *V = ConvertExpressionToType(OldVal, NewTy, VMC, TD);
NewPN->addIncoming(V, BB);
}
Res = NewPN;
break;
}
case Instruction::Call: {
Value *Meth = I->getOperand(0);
std::vector<Value*> Params(I->op_begin()+1, I->op_end());
if (Meth == OldVal) { // Changing the function pointer?
const PointerType *NewPTy = cast<PointerType>(NewVal->getType());
const FunctionType *NewTy = cast<FunctionType>(NewPTy->getElementType());
if (NewTy->getReturnType() == Type::VoidTy)
Name = ""; // Make sure not to name a void call!
// Get an iterator to the call instruction so that we can insert casts for
// operands if need be. Note that we do not require operands to be
// convertible, we can insert casts if they are convertible but not
// compatible. The reason for this is that we prefer to have resolved
// functions but casted arguments if possible.
//
BasicBlock::iterator It = I;
// Convert over all of the call operands to their new types... but only
// convert over the part that is not in the vararg section of the call.
//
for (unsigned i = 0; i != NewTy->getNumParams(); ++i)
if (Params[i]->getType() != NewTy->getParamType(i)) {
// Create a cast to convert it to the right type, we know that this
// is a lossless cast...
//
Params[i] = new CastInst(Params[i], NewTy->getParamType(i),
"callarg.cast." +
Params[i]->getName(), It);
}
Meth = NewVal; // Update call destination to new value
} else { // Changing an argument, must be in vararg area
std::vector<Value*>::iterator OI =
find(Params.begin(), Params.end(), OldVal);
assert (OI != Params.end() && "Not using value!");
*OI = NewVal;
}
Res = new CallInst(Meth, Params, Name);
break;
}
default:
assert(0 && "Expression convertible, but don't know how to convert?");
return;
}
// If the instruction was newly created, insert it into the instruction
// stream.
//
BasicBlock::iterator It = I;
assert(It != BB->end() && "Instruction not in own basic block??");
BB->getInstList().insert(It, Res); // Keep It pointing to old instruction
DEBUG(std::cerr << "COT CREATED: " << (void*)Res << " " << *Res
<< "In: " << (void*)I << " " << *I << "Out: " << (void*)Res
<< " " << *Res);
// Add the instruction to the expression map
VMC.ExprMap[I] = Res;
if (I->getType() != Res->getType())
ConvertValueToNewType(I, Res, VMC, TD);
else {
bool FromStart = true;
Value::use_iterator UI;
while (1) {
if (FromStart) UI = I->use_begin();
if (UI == I->use_end()) break;
if (isa<ValueHandle>(*UI)) {
++UI;
FromStart = false;
} else {
User *U = *UI;
if (!FromStart) --UI;
U->replaceUsesOfWith(I, Res);
if (!FromStart) ++UI;
}
}
}
}
// OperandConvertibleToType - Return true if it is possible to convert operand
// V of User (instruction) U to the specified type. This is true iff it is
// possible to change the specified instruction to accept this. CTMap is a map
// of converted types, so that circular definitions will see the future type of
// the expression, not the static current type.
//
static bool OperandConvertibleToType(User *U, Value *V, const Type *Ty,
ValueTypeCache &CTMap,
const TargetData &TD) {
// if (V->getType() == Ty) return true; // Operand already the right type?
// Expression type must be holdable in a register.
if (!Ty->isFirstClassType())
return false;
Instruction *I = dyn_cast<Instruction>(U);
if (I == 0) return false; // We can't convert!
switch (I->getOpcode()) {
case Instruction::Cast:
assert(I->getOperand(0) == V);
// We can convert the expr if the cast destination type is losslessly
// convertible to the requested type.
// Also, do not change a cast that is a noop cast. For all intents and
// purposes it should be eliminated.
if (!Ty->isLosslesslyConvertibleTo(I->getOperand(0)->getType()) ||
I->getType() == I->getOperand(0)->getType())
return false;
// Do not allow a 'cast ushort %V to uint' to have it's first operand be
// converted to a 'short' type. Doing so changes the way sign promotion
// happens, and breaks things. Only allow the cast to take place if the
// signedness doesn't change... or if the current cast is not a lossy
// conversion.
//
if (!I->getType()->isLosslesslyConvertibleTo(I->getOperand(0)->getType()) &&
I->getOperand(0)->getType()->isSigned() != Ty->isSigned())
return false;
// We also do not allow conversion of a cast that casts from a ptr to array
// of X to a *X. For example: cast [4 x %List *] * %val to %List * *
//
if (const PointerType *SPT =
dyn_cast<PointerType>(I->getOperand(0)->getType()))
if (const PointerType *DPT = dyn_cast<PointerType>(I->getType()))
if (const ArrayType *AT = dyn_cast<ArrayType>(SPT->getElementType()))
if (AT->getElementType() == DPT->getElementType())
return false;
return true;
case Instruction::Add:
if (isa<PointerType>(Ty)) {
Value *IndexVal = I->getOperand(V == I->getOperand(0) ? 1 : 0);
std::vector<Value*> Indices;
if (const Type *ETy = ConvertibleToGEP(Ty, IndexVal, Indices, TD)) {
const Type *RetTy = PointerType::get(ETy);
// Only successful if we can convert this type to the required type
if (ValueConvertibleToType(I, RetTy, CTMap, TD)) {
CTMap[I] = RetTy;
return true;
}
// We have to return failure here because ValueConvertibleToType could
// have polluted our map
return false;
}
}
// FALLTHROUGH
case Instruction::Sub: {
if (!Ty->isInteger() && !Ty->isFloatingPoint()) return false;
Value *OtherOp = I->getOperand((V == I->getOperand(0)) ? 1 : 0);
return ValueConvertibleToType(I, Ty, CTMap, TD) &&
ExpressionConvertibleToType(OtherOp, Ty, CTMap, TD);
}
case Instruction::SetEQ:
case Instruction::SetNE: {
Value *OtherOp = I->getOperand((V == I->getOperand(0)) ? 1 : 0);
return ExpressionConvertibleToType(OtherOp, Ty, CTMap, TD);
}
case Instruction::Shr:
if (Ty->isSigned() != V->getType()->isSigned()) return false;
// FALL THROUGH
case Instruction::Shl:
if (I->getOperand(1) == V) return false; // Cannot change shift amount type
if (!Ty->isInteger()) return false;
return ValueConvertibleToType(I, Ty, CTMap, TD);
case Instruction::Free:
assert(I->getOperand(0) == V);
return isa<PointerType>(Ty); // Free can free any pointer type!
case Instruction::Load:
// Cannot convert the types of any subscripts...
if (I->getOperand(0) != V) return false;
if (const PointerType *PT = dyn_cast<PointerType>(Ty)) {
LoadInst *LI = cast<LoadInst>(I);
const Type *LoadedTy = PT->getElementType();
// They could be loading the first element of a composite type...
if (const CompositeType *CT = dyn_cast<CompositeType>(LoadedTy)) {
unsigned Offset = 0; // No offset, get first leaf.
std::vector<Value*> Indices; // Discarded...
LoadedTy = getStructOffsetType(CT, Offset, Indices, TD, false);
assert(Offset == 0 && "Offset changed from zero???");
}
if (!LoadedTy->isFirstClassType())
return false;
if (TD.getTypeSize(LoadedTy) != TD.getTypeSize(LI->getType()))
return false;
return ValueConvertibleToType(LI, LoadedTy, CTMap, TD);
}
return false;
case Instruction::Store: {
StoreInst *SI = cast<StoreInst>(I);
if (V == I->getOperand(0)) {
ValueTypeCache::iterator CTMI = CTMap.find(I->getOperand(1));
if (CTMI != CTMap.end()) { // Operand #1 is in the table already?
// If so, check to see if it's Ty*, or, more importantly, if it is a
// pointer to a structure where the first element is a Ty... this code
// is necessary because we might be trying to change the source and
// destination type of the store (they might be related) and the dest
// pointer type might be a pointer to structure. Below we allow pointer
// to structures where the 0th element is compatible with the value,
// now we have to support the symmetrical part of this.
//
const Type *ElTy = cast<PointerType>(CTMI->second)->getElementType();
// Already a pointer to what we want? Trivially accept...
if (ElTy == Ty) return true;
// Tricky case now, if the destination is a pointer to structure,
// obviously the source is not allowed to be a structure (cannot copy
// a whole structure at a time), so the level raiser must be trying to
// store into the first field. Check for this and allow it now:
//
if (const StructType *SElTy = dyn_cast<StructType>(ElTy)) {
unsigned Offset = 0;
std::vector<Value*> Indices;
ElTy = getStructOffsetType(ElTy, Offset, Indices, TD, false);
assert(Offset == 0 && "Offset changed!");
if (ElTy == 0) // Element at offset zero in struct doesn't exist!
return false; // Can only happen for {}*
if (ElTy == Ty) // Looks like the 0th element of structure is
return true; // compatible! Accept now!
// Otherwise we know that we can't work, so just stop trying now.
return false;
}
}
// Can convert the store if we can convert the pointer operand to match
// the new value type...
return ExpressionConvertibleToType(I->getOperand(1), PointerType::get(Ty),
CTMap, TD);
} else if (const PointerType *PT = dyn_cast<PointerType>(Ty)) {
const Type *ElTy = PT->getElementType();
assert(V == I->getOperand(1));
if (isa<StructType>(ElTy)) {
// We can change the destination pointer if we can store our first
// argument into the first element of the structure...
//
unsigned Offset = 0;
std::vector<Value*> Indices;
ElTy = getStructOffsetType(ElTy, Offset, Indices, TD, false);
assert(Offset == 0 && "Offset changed!");
if (ElTy == 0) // Element at offset zero in struct doesn't exist!
return false; // Can only happen for {}*
}
// Must move the same amount of data...
if (!ElTy->isSized() ||
TD.getTypeSize(ElTy) != TD.getTypeSize(I->getOperand(0)->getType()))
return false;
// Can convert store if the incoming value is convertible and if the
// result will preserve semantics...
const Type *Op0Ty = I->getOperand(0)->getType();
if (!(Op0Ty->isIntegral() ^ ElTy->isIntegral()) &&
!(Op0Ty->isFloatingPoint() ^ ElTy->isFloatingPoint()))
return ExpressionConvertibleToType(I->getOperand(0), ElTy, CTMap, TD);
}
return false;
}
case Instruction::GetElementPtr:
if (V != I->getOperand(0) || !isa<PointerType>(Ty)) return false;
// If we have a two operand form of getelementptr, this is really little
// more than a simple addition. As with addition, check to see if the
// getelementptr instruction can be changed to index into the new type.
//
if (I->getNumOperands() == 2) {
const Type *OldElTy = cast<PointerType>(I->getType())->getElementType();
unsigned DataSize = TD.getTypeSize(OldElTy);
Value *Index = I->getOperand(1);
Instruction *TempScale = 0;
// If the old data element is not unit sized, we have to create a scale
// instruction so that ConvertibleToGEP will know the REAL amount we are
// indexing by. Note that this is never inserted into the instruction
// stream, so we have to delete it when we're done.
//
if (DataSize != 1) {
Value *CST;
if (Index->getType()->isSigned())
CST = ConstantSInt::get(Index->getType(), DataSize);
else
CST = ConstantUInt::get(Index->getType(), DataSize);
TempScale = BinaryOperator::create(Instruction::Mul, Index, CST);
Index = TempScale;
}
// Check to see if the second argument is an expression that can
// be converted to the appropriate size... if so, allow it.
//
std::vector<Value*> Indices;
const Type *ElTy = ConvertibleToGEP(Ty, Index, Indices, TD);
delete TempScale; // Free our temporary multiply if we made it
if (ElTy == 0) return false; // Cannot make conversion...
return ValueConvertibleToType(I, PointerType::get(ElTy), CTMap, TD);
}
return false;
case Instruction::PHI: {
PHINode *PN = cast<PHINode>(I);
// Be conservative if we find a giant PHI node.
if (PN->getNumIncomingValues() > 32) return false;
for (unsigned i = 0; i < PN->getNumIncomingValues(); ++i)
if (!ExpressionConvertibleToType(PN->getIncomingValue(i), Ty, CTMap, TD))
return false;
return ValueConvertibleToType(PN, Ty, CTMap, TD);
}
case Instruction::Call: {
User::op_iterator OI = find(I->op_begin(), I->op_end(), V);
assert (OI != I->op_end() && "Not using value!");
unsigned OpNum = OI - I->op_begin();
// Are we trying to change the function pointer value to a new type?
if (OpNum == 0) {
const PointerType *PTy = dyn_cast<PointerType>(Ty);
if (PTy == 0) return false; // Can't convert to a non-pointer type...
const FunctionType *FTy = dyn_cast<FunctionType>(PTy->getElementType());
if (FTy == 0) return false; // Can't convert to a non ptr to function...
// Do not allow converting to a call where all of the operands are ...'s
if (FTy->getNumParams() == 0 && FTy->isVarArg())
return false; // Do not permit this conversion!
// Perform sanity checks to make sure that new function type has the
// correct number of arguments...
//
unsigned NumArgs = I->getNumOperands()-1; // Don't include function ptr
// Cannot convert to a type that requires more fixed arguments than
// the call provides...
//
if (NumArgs < FTy->getNumParams()) return false;
// Unless this is a vararg function type, we cannot provide more arguments
// than are desired...
//
if (!FTy->isVarArg() && NumArgs > FTy->getNumParams())
return false;
// Okay, at this point, we know that the call and the function type match
// number of arguments. Now we see if we can convert the arguments
// themselves. Note that we do not require operands to be convertible,
// we can insert casts if they are convertible but not compatible. The
// reason for this is that we prefer to have resolved functions but casted
// arguments if possible.
//
for (unsigned i = 0, NA = FTy->getNumParams(); i < NA; ++i)
if (!FTy->getParamType(i)->isLosslesslyConvertibleTo(I->getOperand(i+1)->getType()))
return false; // Operands must have compatible types!
// Okay, at this point, we know that all of the arguments can be
// converted. We succeed if we can change the return type if
// necessary...
//
return ValueConvertibleToType(I, FTy->getReturnType(), CTMap, TD);
}
const PointerType *MPtr = cast<PointerType>(I->getOperand(0)->getType());
const FunctionType *FTy = cast<FunctionType>(MPtr->getElementType());
if (!FTy->isVarArg()) return false;
if ((OpNum-1) < FTy->getNumParams())
return false; // It's not in the varargs section...
// If we get this far, we know the value is in the varargs section of the
// function! We can convert if we don't reinterpret the value...
//
return Ty->isLosslesslyConvertibleTo(V->getType());
}
}
return false;
}
// ExpressionConvertibleToType - Return true if it is possible
bool llvm::ExpressionConvertibleToType(Value *V, const Type *Ty,
ValueTypeCache &CTMap, const TargetData &TD) {
// Expression type must be holdable in a register.
if (!Ty->isFirstClassType())
return false;
ValueTypeCache::iterator CTMI = CTMap.find(V);
if (CTMI != CTMap.end()) return CTMI->second == Ty;
// If it's a constant... all constants can be converted to a different
// type.
//
if (isa<Constant>(V) && !isa<GlobalValue>(V))
return true;
CTMap[V] = Ty;
if (V->getType() == Ty) return true; // Expression already correct type!
Instruction *I = dyn_cast<Instruction>(V);
if (I == 0) return false; // Otherwise, we can't convert!
switch (I->getOpcode()) {
case Instruction::Cast:
// We can convert the expr if the cast destination type is losslessly
// convertible to the requested type.
if (!Ty->isLosslesslyConvertibleTo(I->getType())) return false;
// We also do not allow conversion of a cast that casts from a ptr to array
// of X to a *X. For example: cast [4 x %List *] * %val to %List * *
//
if (const PointerType *SPT =
dyn_cast<PointerType>(I->getOperand(0)->getType()))
if (const PointerType *DPT = dyn_cast<PointerType>(I->getType()))
if (const ArrayType *AT = dyn_cast<ArrayType>(SPT->getElementType()))
if (AT->getElementType() == DPT->getElementType())
return false;
break;
case Instruction::Add:
case Instruction::Sub:
if (!Ty->isInteger() && !Ty->isFloatingPoint()) return false;
if (!ExpressionConvertibleToType(I->getOperand(0), Ty, CTMap, TD) ||
!ExpressionConvertibleToType(I->getOperand(1), Ty, CTMap, TD))
return false;
break;
case Instruction::Shr:
if (!Ty->isInteger()) return false;
if (Ty->isSigned() != V->getType()->isSigned()) return false;
// FALL THROUGH
case Instruction::Shl:
if (!Ty->isInteger()) return false;
if (!ExpressionConvertibleToType(I->getOperand(0), Ty, CTMap, TD))
return false;
break;
case Instruction::Load: {
LoadInst *LI = cast<LoadInst>(I);
if (!ExpressionConvertibleToType(LI->getPointerOperand(),
PointerType::get(Ty), CTMap, TD))
return false;
break;
}
case Instruction::PHI: {
PHINode *PN = cast<PHINode>(I);
// Be conservative if we find a giant PHI node.
if (PN->getNumIncomingValues() > 32) return false;
for (unsigned i = 0; i < PN->getNumIncomingValues(); ++i)
if (!ExpressionConvertibleToType(PN->getIncomingValue(i), Ty, CTMap, TD))
return false;
break;
}
case Instruction::Malloc:
if (!MallocConvertibleToType(cast<MallocInst>(I), Ty, CTMap, TD))
return false;
break;
case Instruction::GetElementPtr: {
// GetElementPtr's are directly convertible to a pointer type if they have
// a number of zeros at the end. Because removing these values does not
// change the logical offset of the GEP, it is okay and fair to remove them.
// This can change this:
// %t1 = getelementptr %Hosp * %hosp, ubyte 4, ubyte 0 ; <%List **>
// %t2 = cast %List * * %t1 to %List *
// into
// %t2 = getelementptr %Hosp * %hosp, ubyte 4 ; <%List *>
//
GetElementPtrInst *GEP = cast<GetElementPtrInst>(I);
const PointerType *PTy = dyn_cast<PointerType>(Ty);
if (!PTy) return false; // GEP must always return a pointer...
const Type *PVTy = PTy->getElementType();
// Check to see if there are zero elements that we can remove from the
// index array. If there are, check to see if removing them causes us to
// get to the right type...
//
std::vector<Value*> Indices(GEP->idx_begin(), GEP->idx_end());
const Type *BaseType = GEP->getPointerOperand()->getType();
const Type *ElTy = 0;
while (!Indices.empty() &&
Indices.back() == Constant::getNullValue(Indices.back()->getType())){
Indices.pop_back();
ElTy = GetElementPtrInst::getIndexedType(BaseType, Indices, true);
if (ElTy == PVTy)
break; // Found a match!!
ElTy = 0;
}
if (ElTy) break; // Found a number of zeros we can strip off!
// Otherwise, we can convert a GEP from one form to the other iff the
// current gep is of the form 'getelementptr sbyte*, long N
// and we could convert this to an appropriate GEP for the new type.
//
if (GEP->getNumOperands() == 2 &&
GEP->getType() == PointerType::get(Type::SByteTy)) {
// Do not Check to see if our incoming pointer can be converted
// to be a ptr to an array of the right type... because in more cases than
// not, it is simply not analyzable because of pointer/array
// discrepancies. To fix this, we will insert a cast before the GEP.
//
// Check to see if 'N' is an expression that can be converted to
// the appropriate size... if so, allow it.
//
std::vector<Value*> Indices;
const Type *ElTy = ConvertibleToGEP(PTy, I->getOperand(1), Indices, TD);
if (ElTy == PVTy) {
if (!ExpressionConvertibleToType(I->getOperand(0),
PointerType::get(ElTy), CTMap, TD))
return false; // Can't continue, ExConToTy might have polluted set!
break;
}
}
// Otherwise, it could be that we have something like this:
// getelementptr [[sbyte] *] * %reg115, long %reg138 ; [sbyte]**
// and want to convert it into something like this:
// getelemenptr [[int] *] * %reg115, long %reg138 ; [int]**
//
if (GEP->getNumOperands() == 2 &&
PTy->getElementType()->isSized() &&
TD.getTypeSize(PTy->getElementType()) ==
TD.getTypeSize(GEP->getType()->getElementType())) {
const PointerType *NewSrcTy = PointerType::get(PVTy);
if (!ExpressionConvertibleToType(I->getOperand(0), NewSrcTy, CTMap, TD))
return false;
break;
}
return false; // No match, maybe next time.
}
case Instruction::Call: {
if (isa<Function>(I->getOperand(0)))
return false; // Don't even try to change direct calls.
// If this is a function pointer, we can convert the return type if we can
// convert the source function pointer.
//
const PointerType *PT = cast<PointerType>(I->getOperand(0)->getType());
const FunctionType *FT = cast<FunctionType>(PT->getElementType());
std::vector<const Type *> ArgTys(FT->param_begin(), FT->param_end());
const FunctionType *NewTy =
FunctionType::get(Ty, ArgTys, FT->isVarArg());
if (!ExpressionConvertibleToType(I->getOperand(0),
PointerType::get(NewTy), CTMap, TD))
return false;
break;
}
default:
return false;
}
// Expressions are only convertible if all of the users of the expression can
// have this value converted. This makes use of the map to avoid infinite
// recursion.
//
for (Value::use_iterator It = I->use_begin(), E = I->use_end(); It != E; ++It)
if (!OperandConvertibleToType(*It, I, Ty, CTMap, TD))
return false;
return true;
}
