Forward iterator over the defining-access chain of a MemoryDef or MemoryUse.
Declared in <llvm/Analysis/MemorySSA.h>
template<
class T,
bool UseOptimizedChain = false>
struct def_chain_iterator
: iterator_facade_base<def_chain_iterator<T, UseOptimizedChain>, std::forward_iterator_tag, MemoryAccess*>Stops after we hit something that has no defining use (e.g. a MemoryPhi or liveOnEntry). Note that, when comparing against a null def_chain_iterator, this will compare equal only after walking said Phi/liveOnEntry.
The UseOptimizedChain flag specifies whether to walk the clobbering access chain, or all the accesses.
Normally, MemoryDef are all just def/use linked together, so a def_chain on a MemoryDef will walk all MemoryDefs above it in the program until it hits a phi node. The optimized chain walks the clobbering access of a store. So if you are just trying to find, given a store, what the next thing that would clobber the same memory is, you want the optimized chain.
| Name | Description |
|---|---|
iterator_facade_base<def_chain_iterator<T, UseOptimizedChain>, std::forward_iterator_tag, MemoryAccess*> | CRTP base class which implements the entire standard iterator facade in terms of a minimal subset of the interface. |
| Name | Description |
|---|---|
difference_type | Signed type used to express the distance between iterators. |
iterator_category | Iterator category tag for this facade. |
pointer | Pointer type returned by the iterator. |
reference | Reference type returned by the iterator. |
value_type | Value type produced by the iterator. |
| Name | Description |
|---|---|
Unnamed enum | Capability flags for the iterator category. |
| Name | Description |
|---|---|
def_chain_iterator [constructor] | Constructors |
operator* | Return the current memory access in the chain. |
operator+ | Advance the iterator by n and return the result. |
operator++ | Increment operators |
operator- | Retreat the iterator by n and return the result. |
operator-- | Decrement operators |
operator-> | Return a proxy pointer to the current element. |
operator[] | Return a proxy to the element at offset n. |
operator== | Return true if this iterator refers to the same access as O. |
operator<= | Return true if this iterator is less than or equal to RHS. |
operator> | Return true if this iterator is greater than RHS. |
operator>= | Return true if this iterator is greater than or equal to RHS. |
| Name | Description |
|---|---|
PointerProxy | Proxy that yields a pointer from a copied reference. |
ReferenceProxy | Proxy that yields a reference from a copied iterator. |
| Name | Description |
|---|---|
def_chain | Return a range walking defining accesses from MA up to UpTo. |
optimized_def_chain | Return a range walking the optimized clobbering-access chain from MA. |