/// %res = cmpxchg [weak] T* %ptr, T %old, T %new, memory_order_success
/// memory_order_failure
/// %val = extractvalue { T, i1 } %res, 0
/// %success = extractvalue { T, i1 } %res, 1
/// becomes:
/// %val = call T @llvm.nacl.atomic.cmpxchg.i<size>(
/// %object, %expected, %desired, memory_order_success,
/// memory_order_failure)
/// %success = icmp eq %old, %val
/// Note: weak is currently dropped if present, the cmpxchg is always strong.
void AtomicVisitor::visitAtomicCmpXchgInst(AtomicCmpXchgInst &I) {
PointerHelper<AtomicCmpXchgInst> PH(*this, I);
const NaCl::AtomicIntrinsics::AtomicIntrinsic *Intrinsic =
findAtomicIntrinsic(I, Intrinsic::nacl_atomic_cmpxchg, PH.PET);
checkSizeMatchesType(I, PH.BitSize, I.getCompareOperand()->getType());
checkSizeMatchesType(I, PH.BitSize, I.getNewValOperand()->getType());
auto Order =
freezeMemoryOrder(I, I.getSuccessOrdering(), I.getFailureOrdering());
Value *Args[] = {PH.P, I.getCompareOperand(), I.getNewValOperand(),
Order.first, Order.second};
replaceInstructionWithIntrinsicCall(I, Intrinsic, PH.OriginalPET, PH.PET,
Args);
}
void GraphBuilder::visitAtomicCmpXchgInst(AtomicCmpXchgInst &I) {
if (isa<PointerType>(I.getType())) {
visitInstruction (I);
return;
}
//
// Create a DSNode for the dereferenced pointer . If the DSNode is NULL, do
// nothing more (this can occur if the pointer is a NULL constant; bugpoint
// can generate such code).
//
DSNodeHandle Ptr = getValueDest(I.getPointerOperand());
if (Ptr.isNull()) return;
//
// Make that the memory object is read and written.
//
Ptr.getNode()->setReadMarker();
Ptr.getNode()->setModifiedMarker();
//
// If the result of the compare-and-swap is a pointer, then we need to do
// a few things:
// o Merge the compare and swap values (which are pointers) with the result
// o Merge the DSNode of the pointer *within* the memory object with the
// DSNode of the compare, swap, and result DSNode.
//
if (isa<PointerType>(I.getType())) {
//
// Get the DSNodeHandle of the memory object returned from the load. Make
// it the DSNodeHandle of the instruction's result.
//
DSNodeHandle FieldPtr = getLink (Ptr);
setDestTo(I, getLink(Ptr));
//
// Merge the result, compare, and swap values of the instruction.
//
FieldPtr.mergeWith (getValueDest (I.getCompareOperand()));
FieldPtr.mergeWith (getValueDest (I.getNewValOperand()));
}
//
// Modify the DSNode so that it has the loaded/written type at the
// appropriate offset.
//
Ptr.getNode()->growSizeForType(I.getType(), Ptr.getOffset());
Ptr.getNode()->mergeTypeInfo(I.getType(), Ptr.getOffset());
return;
}