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//===- RegionIterator.h - Iterators to iteratate over Regions ---*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// This file defines the iterators to iterate over the elements of a Region.
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_REGIONITERATOR_H
#define LLVM_ANALYSIS_REGIONITERATOR_H
#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/Analysis/RegionInfo.h"
#include <cassert>
#include <iterator>
#include <type_traits>
namespace llvm {
class BasicBlock;
class RegionInfo;
//===----------------------------------------------------------------------===//
/// Hierarchical RegionNode successor iterator.
///
/// This iterator iterates over all successors of a RegionNode.
///
/// For a BasicBlock RegionNode it skips all BasicBlocks that are not part of
/// the parent Region. Furthermore for BasicBlocks that start a subregion, a
/// RegionNode representing the subregion is returned.
///
/// For a subregion RegionNode there is just one successor. The RegionNode
/// representing the exit of the subregion.
template <class NodeRef, class BlockT, class RegionT> class RNSuccIterator {
public:
using iterator_category = std::forward_iterator_tag;
using value_type = NodeRef;
using difference_type = std::ptrdiff_t;
using pointer = value_type *;
using reference = value_type &;
private:
using BlockTraits = GraphTraits<BlockT *>;
using SuccIterTy = typename BlockTraits::ChildIteratorType;
// The iterator works in two modes, bb mode or region mode.
enum ItMode {
// In BB mode it returns all successors of this BasicBlock as its
// successors.
ItBB,
// In region mode there is only one successor, thats the regionnode mapping
// to the exit block of the regionnode
ItRgBegin, // At the beginning of the regionnode successor.
ItRgEnd // At the end of the regionnode successor.
};
static_assert(std::is_pointer<NodeRef>::value,
"FIXME: Currently RNSuccIterator only supports NodeRef as "
"pointers due to the use of pointer-specific data structures "
"(e.g. PointerIntPair and SmallPtrSet) internally. Generalize "
"it to support non-pointer types");
// Use two bit to represent the mode iterator.
PointerIntPair<NodeRef, 2, ItMode> Node;
// The block successor iterator.
SuccIterTy BItor;
// advanceRegionSucc - A region node has only one successor. It reaches end
// once we advance it.
void advanceRegionSucc() {
assert(Node.getInt() == ItRgBegin && "Cannot advance region successor!");
Node.setInt(ItRgEnd);
}
NodeRef getNode() const { return Node.getPointer(); }
// isRegionMode - Is the current iterator in region mode?
bool isRegionMode() const { return Node.getInt() != ItBB; }
// Get the immediate successor. This function may return a Basic Block
// RegionNode or a subregion RegionNode.
NodeRef getISucc(BlockT *BB) const {
NodeRef succ;
succ = getNode()->getParent()->getNode(BB);
assert(succ && "BB not in Region or entered subregion!");
return succ;
}
// getRegionSucc - Return the successor basic block of a SubRegion RegionNode.
inline BlockT* getRegionSucc() const {
assert(Node.getInt() == ItRgBegin && "Cannot get the region successor!");
return getNode()->template getNodeAs<RegionT>()->getExit();
}
// isExit - Is this the exit BB of the Region?
inline bool isExit(BlockT* BB) const {
return getNode()->getParent()->getExit() == BB;
}
public:
using Self = RNSuccIterator<NodeRef, BlockT, RegionT>;
/// Create begin iterator of a RegionNode.
inline RNSuccIterator(NodeRef node)
: Node(node, node->isSubRegion() ? ItRgBegin : ItBB),
BItor(BlockTraits::child_begin(node->getEntry())) {
// Skip the exit block
if (!isRegionMode())
while (BlockTraits::child_end(node->getEntry()) != BItor && isExit(*BItor))
++BItor;
if (isRegionMode() && isExit(getRegionSucc()))
advanceRegionSucc();
}
/// Create an end iterator.
inline RNSuccIterator(NodeRef node, bool)
: Node(node, node->isSubRegion() ? ItRgEnd : ItBB),
BItor(BlockTraits::child_end(node->getEntry())) {}
inline bool operator==(const Self& x) const {
assert(isRegionMode() == x.isRegionMode() && "Broken iterator!");
if (isRegionMode())
return Node.getInt() == x.Node.getInt();
else
return BItor == x.BItor;
}
inline bool operator!=(const Self& x) const { return !operator==(x); }
inline value_type operator*() const {
BlockT *BB = isRegionMode() ? getRegionSucc() : *BItor;
assert(!isExit(BB) && "Iterator out of range!");
return getISucc(BB);
}
inline Self& operator++() {
if(isRegionMode()) {
// The Region only has 1 successor.
advanceRegionSucc();
} else {
// Skip the exit.
do
++BItor;
while (BItor != BlockTraits::child_end(getNode()->getEntry())
&& isExit(*BItor));
}
return *this;
}
inline Self operator++(int) {
Self tmp = *this;
++*this;
return tmp;
}
};
//===----------------------------------------------------------------------===//
/// Flat RegionNode iterator.
///
/// The Flat Region iterator will iterate over all BasicBlock RegionNodes that
/// are contained in the Region and its subregions. This is close to a virtual
/// control flow graph of the Region.
template <class NodeRef, class BlockT, class RegionT>
class RNSuccIterator<FlatIt<NodeRef>, BlockT, RegionT> {
using BlockTraits = GraphTraits<BlockT *>;
using SuccIterTy = typename BlockTraits::ChildIteratorType;
NodeRef Node;
SuccIterTy Itor;
public:
using iterator_category = std::forward_iterator_tag;
using value_type = NodeRef;
using difference_type = std::ptrdiff_t;
using pointer = value_type *;
using reference = value_type &;
using Self = RNSuccIterator<FlatIt<NodeRef>, BlockT, RegionT>;
/// Create the iterator from a RegionNode.
///
/// Note that the incoming node must be a bb node, otherwise it will trigger
/// an assertion when we try to get a BasicBlock.
inline RNSuccIterator(NodeRef node)
: Node(node), Itor(BlockTraits::child_begin(node->getEntry())) {
assert(!Node->isSubRegion() &&
"Subregion node not allowed in flat iterating mode!");
assert(Node->getParent() && "A BB node must have a parent!");
// Skip the exit block of the iterating region.
while (BlockTraits::child_end(Node->getEntry()) != Itor &&
Node->getParent()->getExit() == *Itor)
++Itor;
}
/// Create an end iterator
inline RNSuccIterator(NodeRef node, bool)
: Node(node), Itor(BlockTraits::child_end(node->getEntry())) {
assert(!Node->isSubRegion() &&
"Subregion node not allowed in flat iterating mode!");
}
inline bool operator==(const Self& x) const {
assert(Node->getParent() == x.Node->getParent()
&& "Cannot compare iterators of different regions!");
return Itor == x.Itor && Node == x.Node;
}
inline bool operator!=(const Self& x) const { return !operator==(x); }
inline value_type operator*() const {
BlockT *BB = *Itor;
// Get the iterating region.
RegionT *Parent = Node->getParent();
// The only case that the successor reaches out of the region is it reaches
// the exit of the region.
assert(Parent->getExit() != BB && "iterator out of range!");
return Parent->getBBNode(BB);
}
inline Self& operator++() {
// Skip the exit block of the iterating region.
do
++Itor;
while (Itor != succ_end(Node->getEntry())
&& Node->getParent()->getExit() == *Itor);
return *this;
}
inline Self operator++(int) {
Self tmp = *this;
++*this;
return tmp;
}
};
template <class NodeRef, class BlockT, class RegionT>
inline RNSuccIterator<NodeRef, BlockT, RegionT> succ_begin(NodeRef Node) {
return RNSuccIterator<NodeRef, BlockT, RegionT>(Node);
}
template <class NodeRef, class BlockT, class RegionT>
inline RNSuccIterator<NodeRef, BlockT, RegionT> succ_end(NodeRef Node) {
return RNSuccIterator<NodeRef, BlockT, RegionT>(Node, true);
}
//===--------------------------------------------------------------------===//
// RegionNode GraphTraits specialization so the bbs in the region can be
// iterate by generic graph iterators.
//
// NodeT can either be region node or const region node, otherwise child_begin
// and child_end fail.
#define RegionNodeGraphTraits(NodeT, BlockT, RegionT) \
template <> struct GraphTraits<NodeT *> { \
using NodeRef = NodeT *; \
using ChildIteratorType = RNSuccIterator<NodeRef, BlockT, RegionT>; \
static NodeRef getEntryNode(NodeRef N) { return N; } \
static inline ChildIteratorType child_begin(NodeRef N) { \
return RNSuccIterator<NodeRef, BlockT, RegionT>(N); \
} \
static inline ChildIteratorType child_end(NodeRef N) { \
return RNSuccIterator<NodeRef, BlockT, RegionT>(N, true); \
} \
}; \
template <> struct GraphTraits<FlatIt<NodeT *>> { \
using NodeRef = NodeT *; \
using ChildIteratorType = \
RNSuccIterator<FlatIt<NodeRef>, BlockT, RegionT>; \
static NodeRef getEntryNode(NodeRef N) { return N; } \
static inline ChildIteratorType child_begin(NodeRef N) { \
return RNSuccIterator<FlatIt<NodeRef>, BlockT, RegionT>(N); \
} \
static inline ChildIteratorType child_end(NodeRef N) { \
return RNSuccIterator<FlatIt<NodeRef>, BlockT, RegionT>(N, true); \
} \
}
#define RegionGraphTraits(RegionT, NodeT) \
template <> struct GraphTraits<RegionT *> : public GraphTraits<NodeT *> { \
using nodes_iterator = df_iterator<NodeRef>; \
static NodeRef getEntryNode(RegionT *R) { \
return R->getNode(R->getEntry()); \
} \
static nodes_iterator nodes_begin(RegionT *R) { \
return nodes_iterator::begin(getEntryNode(R)); \
} \
static nodes_iterator nodes_end(RegionT *R) { \
return nodes_iterator::end(getEntryNode(R)); \
} \
}; \
template <> \
struct GraphTraits<FlatIt<RegionT *>> \
: public GraphTraits<FlatIt<NodeT *>> { \
using nodes_iterator = \
df_iterator<NodeRef, df_iterator_default_set<NodeRef>, false, \
GraphTraits<FlatIt<NodeRef>>>; \
static NodeRef getEntryNode(RegionT *R) { \
return R->getBBNode(R->getEntry()); \
} \
static nodes_iterator nodes_begin(RegionT *R) { \
return nodes_iterator::begin(getEntryNode(R)); \
} \
static nodes_iterator nodes_end(RegionT *R) { \
return nodes_iterator::end(getEntryNode(R)); \
} \
}
RegionNodeGraphTraits(RegionNode, BasicBlock, Region);
RegionNodeGraphTraits(const RegionNode, BasicBlock, Region);
RegionGraphTraits(Region, RegionNode);
RegionGraphTraits(const Region, const RegionNode);
template <> struct GraphTraits<RegionInfo*>
: public GraphTraits<FlatIt<RegionNode*>> {
using nodes_iterator =
df_iterator<NodeRef, df_iterator_default_set<NodeRef>, false,
GraphTraits<FlatIt<NodeRef>>>;
static NodeRef getEntryNode(RegionInfo *RI) {
return GraphTraits<FlatIt<Region*>>::getEntryNode(RI->getTopLevelRegion());
}
static nodes_iterator nodes_begin(RegionInfo* RI) {
return nodes_iterator::begin(getEntryNode(RI));
}
static nodes_iterator nodes_end(RegionInfo *RI) {
return nodes_iterator::end(getEntryNode(RI));
}
};
template <> struct GraphTraits<RegionInfoPass*>
: public GraphTraits<RegionInfo *> {
using nodes_iterator =
df_iterator<NodeRef, df_iterator_default_set<NodeRef>, false,
GraphTraits<FlatIt<NodeRef>>>;
static NodeRef getEntryNode(RegionInfoPass *RI) {
return GraphTraits<RegionInfo*>::getEntryNode(&RI->getRegionInfo());
}
static nodes_iterator nodes_begin(RegionInfoPass* RI) {
return GraphTraits<RegionInfo*>::nodes_begin(&RI->getRegionInfo());
}
static nodes_iterator nodes_end(RegionInfoPass *RI) {
return GraphTraits<RegionInfo*>::nodes_end(&RI->getRegionInfo());
}
};
} // end namespace llvm
#endif // LLVM_ANALYSIS_REGIONITERATOR_H
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