Viewing file:  GenericLoopInfo.h (26.54 KB) -rw-r--r--
Select action/file-type:
 (+) |  (+) |  (+) | Code (+) | Session (+) |  (+) | SDB (+) |  (+) |  (+) |  (+) |  (+) |  (+) |
//===- GenericLoopInfo - Generic Loop Info for graphs -----------*- 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 LoopInfoBase class that is used to identify natural
// loops and determine the loop depth of various nodes in a generic graph of
// blocks. A natural loop has exactly one entry-point, which is called the
// header. Note that natural loops may actually be several loops that share the
// same header node.
//
// This analysis calculates the nesting structure of loops in a function. For
// each natural loop identified, this analysis identifies natural loops
// contained entirely within the loop and the basic blocks that make up the
// loop.
//
// It can calculate on the fly various bits of information, for example:
//
// * whether there is a preheader for the loop
// * the number of back edges to the header
// * whether or not a particular block branches out of the loop
// * the successor blocks of the loop
// * the loop depth
// * etc...
//
// Note that this analysis specifically identifies *Loops* not cycles or SCCs
// in the graph. There can be strongly connected components in the graph which
// this analysis will not recognize and that will not be represented by a Loop
// instance. In particular, a Loop might be inside such a non-loop SCC, or a
// non-loop SCC might contain a sub-SCC which is a Loop.
//
// For an overview of terminology used in this API (and thus all of our loop
// analyses or transforms), see docs/LoopTerminology.rst.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_GENERICLOOPINFO_H
#define LLVM_SUPPORT_GENERICLOOPINFO_H
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetOperations.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/GenericDomTree.h"
namespace llvm {
template <class N, class M> class LoopInfoBase;
template <class N, class M> class LoopBase;
//===----------------------------------------------------------------------===//
/// Instances of this class are used to represent loops that are detected in the
/// flow graph.
///
template <class BlockT, class LoopT> class LoopBase {
LoopT *ParentLoop;
// Loops contained entirely within this one.
std::vector<LoopT *> SubLoops;
// The list of blocks in this loop. First entry is the header node.
std::vector<BlockT *> Blocks;
SmallPtrSet<const BlockT *, 8> DenseBlockSet;
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
/// Indicator that this loop is no longer a valid loop.
bool IsInvalid = false;
#endif
LoopBase(const LoopBase<BlockT, LoopT> &) = delete;
const LoopBase<BlockT, LoopT> &
operator=(const LoopBase<BlockT, LoopT> &) = delete;
public:
/// Return the nesting level of this loop. An outer-most loop has depth 1,
/// for consistency with loop depth values used for basic blocks, where depth
/// 0 is used for blocks not inside any loops.
unsigned getLoopDepth() const {
assert(!isInvalid() && "Loop not in a valid state!");
unsigned D = 1;
for (const LoopT *CurLoop = ParentLoop; CurLoop;
CurLoop = CurLoop->ParentLoop)
++D;
return D;
}
BlockT *getHeader() const { return getBlocks().front(); }
/// Return the parent loop if it exists or nullptr for top
/// level loops.
/// A loop is either top-level in a function (that is, it is not
/// contained in any other loop) or it is entirely enclosed in
/// some other loop.
/// If a loop is top-level, it has no parent, otherwise its
/// parent is the innermost loop in which it is enclosed.
LoopT *getParentLoop() const { return ParentLoop; }
/// Get the outermost loop in which this loop is contained.
/// This may be the loop itself, if it already is the outermost loop.
const LoopT *getOutermostLoop() const {
const LoopT *L = static_cast<const LoopT *>(this);
while (L->ParentLoop)
L = L->ParentLoop;
return L;
}
LoopT *getOutermostLoop() {
LoopT *L = static_cast<LoopT *>(this);
while (L->ParentLoop)
L = L->ParentLoop;
return L;
}
/// This is a raw interface for bypassing addChildLoop.
void setParentLoop(LoopT *L) {
assert(!isInvalid() && "Loop not in a valid state!");
ParentLoop = L;
}
/// Return true if the specified loop is contained within in this loop.
bool contains(const LoopT *L) const {
assert(!isInvalid() && "Loop not in a valid state!");
if (L == this)
return true;
if (!L)
return false;
return contains(L->getParentLoop());
}
/// Return true if the specified basic block is in this loop.
bool contains(const BlockT *BB) const {
assert(!isInvalid() && "Loop not in a valid state!");
return DenseBlockSet.count(BB);
}
/// Return true if the specified instruction is in this loop.
template <class InstT> bool contains(const InstT *Inst) const {
return contains(Inst->getParent());
}
/// Return the loops contained entirely within this loop.
const std::vector<LoopT *> &getSubLoops() const {
assert(!isInvalid() && "Loop not in a valid state!");
return SubLoops;
}
std::vector<LoopT *> &getSubLoopsVector() {
assert(!isInvalid() && "Loop not in a valid state!");
return SubLoops;
}
typedef typename std::vector<LoopT *>::const_iterator iterator;
typedef
typename std::vector<LoopT *>::const_reverse_iterator reverse_iterator;
iterator begin() const { return getSubLoops().begin(); }
iterator end() const { return getSubLoops().end(); }
reverse_iterator rbegin() const { return getSubLoops().rbegin(); }
reverse_iterator rend() const { return getSubLoops().rend(); }
// LoopInfo does not detect irreducible control flow, just natural
// loops. That is, it is possible that there is cyclic control
// flow within the "innermost loop" or around the "outermost
// loop".
/// Return true if the loop does not contain any (natural) loops.
bool isInnermost() const { return getSubLoops().empty(); }
/// Return true if the loop does not have a parent (natural) loop
// (i.e. it is outermost, which is the same as top-level).
bool isOutermost() const { return getParentLoop() == nullptr; }
/// Get a list of the basic blocks which make up this loop.
ArrayRef<BlockT *> getBlocks() const {
assert(!isInvalid() && "Loop not in a valid state!");
return Blocks;
}
typedef typename ArrayRef<BlockT *>::const_iterator block_iterator;
block_iterator block_begin() const { return getBlocks().begin(); }
block_iterator block_end() const { return getBlocks().end(); }
inline iterator_range<block_iterator> blocks() const {
assert(!isInvalid() && "Loop not in a valid state!");
return make_range(block_begin(), block_end());
}
/// Get the number of blocks in this loop in constant time.
/// Invalidate the loop, indicating that it is no longer a loop.
unsigned getNumBlocks() const {
assert(!isInvalid() && "Loop not in a valid state!");
return Blocks.size();
}
/// Return a direct, mutable handle to the blocks vector so that we can
/// mutate it efficiently with techniques like `std::remove`.
std::vector<BlockT *> &getBlocksVector() {
assert(!isInvalid() && "Loop not in a valid state!");
return Blocks;
}
/// Return a direct, mutable handle to the blocks set so that we can
/// mutate it efficiently.
SmallPtrSetImpl<const BlockT *> &getBlocksSet() {
assert(!isInvalid() && "Loop not in a valid state!");
return DenseBlockSet;
}
/// Return a direct, immutable handle to the blocks set.
const SmallPtrSetImpl<const BlockT *> &getBlocksSet() const {
assert(!isInvalid() && "Loop not in a valid state!");
return DenseBlockSet;
}
/// Return true if this loop is no longer valid. The only valid use of this
/// helper is "assert(L.isInvalid())" or equivalent, since IsInvalid is set to
/// true by the destructor. In other words, if this accessor returns true,
/// the caller has already triggered UB by calling this accessor; and so it
/// can only be called in a context where a return value of true indicates a
/// programmer error.
bool isInvalid() const {
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
return IsInvalid;
#else
return false;
#endif
}
/// True if terminator in the block can branch to another block that is
/// outside of the current loop. \p BB must be inside the loop.
bool isLoopExiting(const BlockT *BB) const {
assert(!isInvalid() && "Loop not in a valid state!");
assert(contains(BB) && "Exiting block must be part of the loop");
for (const auto *Succ : children<const BlockT *>(BB)) {
if (!contains(Succ))
return true;
}
return false;
}
/// Returns true if \p BB is a loop-latch.
/// A latch block is a block that contains a branch back to the header.
/// This function is useful when there are multiple latches in a loop
/// because \fn getLoopLatch will return nullptr in that case.
bool isLoopLatch(const BlockT *BB) const {
assert(!isInvalid() && "Loop not in a valid state!");
assert(contains(BB) && "block does not belong to the loop");
return llvm::is_contained(inverse_children<BlockT *>(getHeader()), BB);
}
/// Calculate the number of back edges to the loop header.
unsigned getNumBackEdges() const {
assert(!isInvalid() && "Loop not in a valid state!");
return llvm::count_if(inverse_children<BlockT *>(getHeader()),
[&](BlockT *Pred) { return contains(Pred); });
}
//===--------------------------------------------------------------------===//
// APIs for simple analysis of the loop.
//
// Note that all of these methods can fail on general loops (ie, there may not
// be a preheader, etc). For best success, the loop simplification and
// induction variable canonicalization pass should be used to normalize loops
// for easy analysis. These methods assume canonical loops.
/// Return all blocks inside the loop that have successors outside of the
/// loop. These are the blocks _inside of the current loop_ which branch out.
/// The returned list is always unique.
void getExitingBlocks(SmallVectorImpl<BlockT *> &ExitingBlocks) const;
/// If getExitingBlocks would return exactly one block, return that block.
/// Otherwise return null.
BlockT *getExitingBlock() const;
/// Return all of the successor blocks of this loop. These are the blocks
/// _outside of the current loop_ which are branched to.
void getExitBlocks(SmallVectorImpl<BlockT *> &ExitBlocks) const;
/// If getExitBlocks would return exactly one block, return that block.
/// Otherwise return null.
BlockT *getExitBlock() const;
/// Return true if no exit block for the loop has a predecessor that is
/// outside the loop.
bool hasDedicatedExits() const;
/// Return all unique successor blocks of this loop.
/// These are the blocks _outside of the current loop_ which are branched to.
void getUniqueExitBlocks(SmallVectorImpl<BlockT *> &ExitBlocks) const;
/// Return all unique successor blocks of this loop except successors from
/// Latch block are not considered. If the exit comes from Latch has also
/// non Latch predecessor in a loop it will be added to ExitBlocks.
/// These are the blocks _outside of the current loop_ which are branched to.
void getUniqueNonLatchExitBlocks(SmallVectorImpl<BlockT *> &ExitBlocks) const;
/// If getUniqueExitBlocks would return exactly one block, return that block.
/// Otherwise return null.
BlockT *getUniqueExitBlock() const;
/// Return true if this loop does not have any exit blocks.
bool hasNoExitBlocks() const;
/// Edge type.
typedef std::pair<BlockT *, BlockT *> Edge;
/// Return all pairs of (_inside_block_,_outside_block_).
void getExitEdges(SmallVectorImpl<Edge> &ExitEdges) const;
/// If there is a preheader for this loop, return it. A loop has a preheader
/// if there is only one edge to the header of the loop from outside of the
/// loop. If this is the case, the block branching to the header of the loop
/// is the preheader node.
///
/// This method returns null if there is no preheader for the loop.
BlockT *getLoopPreheader() const;
/// If the given loop's header has exactly one unique predecessor outside the
/// loop, return it. Otherwise return null.
/// This is less strict that the loop "preheader" concept, which requires
/// the predecessor to have exactly one successor.
BlockT *getLoopPredecessor() const;
/// If there is a single latch block for this loop, return it.
/// A latch block is a block that contains a branch back to the header.
BlockT *getLoopLatch() const;
/// Return all loop latch blocks of this loop. A latch block is a block that
/// contains a branch back to the header.
void getLoopLatches(SmallVectorImpl<BlockT *> &LoopLatches) const {
assert(!isInvalid() && "Loop not in a valid state!");
BlockT *H = getHeader();
for (const auto Pred : inverse_children<BlockT *>(H))
if (contains(Pred))
LoopLatches.push_back(Pred);
}
/// Return all inner loops in the loop nest rooted by the loop in preorder,
/// with siblings in forward program order.
template <class Type>
static void getInnerLoopsInPreorder(const LoopT &L,
SmallVectorImpl<Type> &PreOrderLoops) {
SmallVector<LoopT *, 4> PreOrderWorklist;
PreOrderWorklist.append(L.rbegin(), L.rend());
while (!PreOrderWorklist.empty()) {
LoopT *L = PreOrderWorklist.pop_back_val();
// Sub-loops are stored in forward program order, but will process the
// worklist backwards so append them in reverse order.
PreOrderWorklist.append(L->rbegin(), L->rend());
PreOrderLoops.push_back(L);
}
}
/// Return all loops in the loop nest rooted by the loop in preorder, with
/// siblings in forward program order.
SmallVector<const LoopT *, 4> getLoopsInPreorder() const {
SmallVector<const LoopT *, 4> PreOrderLoops;
const LoopT *CurLoop = static_cast<const LoopT *>(this);
PreOrderLoops.push_back(CurLoop);
getInnerLoopsInPreorder(*CurLoop, PreOrderLoops);
return PreOrderLoops;
}
SmallVector<LoopT *, 4> getLoopsInPreorder() {
SmallVector<LoopT *, 4> PreOrderLoops;
LoopT *CurLoop = static_cast<LoopT *>(this);
PreOrderLoops.push_back(CurLoop);
getInnerLoopsInPreorder(*CurLoop, PreOrderLoops);
return PreOrderLoops;
}
//===--------------------------------------------------------------------===//
// APIs for updating loop information after changing the CFG
//
/// This method is used by other analyses to update loop information.
/// NewBB is set to be a new member of the current loop.
/// Because of this, it is added as a member of all parent loops, and is added
/// to the specified LoopInfo object as being in the current basic block. It
/// is not valid to replace the loop header with this method.
void addBasicBlockToLoop(BlockT *NewBB, LoopInfoBase<BlockT, LoopT> &LI);
/// This is used when splitting loops up. It replaces the OldChild entry in
/// our children list with NewChild, and updates the parent pointer of
/// OldChild to be null and the NewChild to be this loop.
/// This updates the loop depth of the new child.
void replaceChildLoopWith(LoopT *OldChild, LoopT *NewChild);
/// Add the specified loop to be a child of this loop.
/// This updates the loop depth of the new child.
void addChildLoop(LoopT *NewChild) {
assert(!isInvalid() && "Loop not in a valid state!");
assert(!NewChild->ParentLoop && "NewChild already has a parent!");
NewChild->ParentLoop = static_cast<LoopT *>(this);
SubLoops.push_back(NewChild);
}
/// This removes the specified child from being a subloop of this loop. The
/// loop is not deleted, as it will presumably be inserted into another loop.
LoopT *removeChildLoop(iterator I) {
assert(!isInvalid() && "Loop not in a valid state!");
assert(I != SubLoops.end() && "Cannot remove end iterator!");
LoopT *Child = *I;
assert(Child->ParentLoop == this && "Child is not a child of this loop!");
SubLoops.erase(SubLoops.begin() + (I - begin()));
Child->ParentLoop = nullptr;
return Child;
}
/// This removes the specified child from being a subloop of this loop. The
/// loop is not deleted, as it will presumably be inserted into another loop.
LoopT *removeChildLoop(LoopT *Child) {
return removeChildLoop(llvm::find(*this, Child));
}
/// This adds a basic block directly to the basic block list.
/// This should only be used by transformations that create new loops. Other
/// transformations should use addBasicBlockToLoop.
void addBlockEntry(BlockT *BB) {
assert(!isInvalid() && "Loop not in a valid state!");
Blocks.push_back(BB);
DenseBlockSet.insert(BB);
}
/// interface to reverse Blocks[from, end of loop] in this loop
void reverseBlock(unsigned from) {
assert(!isInvalid() && "Loop not in a valid state!");
std::reverse(Blocks.begin() + from, Blocks.end());
}
/// interface to do reserve() for Blocks
void reserveBlocks(unsigned size) {
assert(!isInvalid() && "Loop not in a valid state!");
Blocks.reserve(size);
}
/// This method is used to move BB (which must be part of this loop) to be the
/// loop header of the loop (the block that dominates all others).
void moveToHeader(BlockT *BB) {
assert(!isInvalid() && "Loop not in a valid state!");
if (Blocks[0] == BB)
return;
for (unsigned i = 0;; ++i) {
assert(i != Blocks.size() && "Loop does not contain BB!");
if (Blocks[i] == BB) {
Blocks[i] = Blocks[0];
Blocks[0] = BB;
return;
}
}
}
/// This removes the specified basic block from the current loop, updating the
/// Blocks as appropriate. This does not update the mapping in the LoopInfo
/// class.
void removeBlockFromLoop(BlockT *BB) {
assert(!isInvalid() && "Loop not in a valid state!");
auto I = find(Blocks, BB);
assert(I != Blocks.end() && "N is not in this list!");
Blocks.erase(I);
DenseBlockSet.erase(BB);
}
/// Verify loop structure
void verifyLoop() const;
/// Verify loop structure of this loop and all nested loops.
void verifyLoopNest(DenseSet<const LoopT *> *Loops) const;
/// Returns true if the loop is annotated parallel.
///
/// Derived classes can override this method using static template
/// polymorphism.
bool isAnnotatedParallel() const { return false; }
/// Print loop with all the BBs inside it.
void print(raw_ostream &OS, bool Verbose = false, bool PrintNested = true,
unsigned Depth = 0) const;
protected:
friend class LoopInfoBase<BlockT, LoopT>;
/// This creates an empty loop.
LoopBase() : ParentLoop(nullptr) {}
explicit LoopBase(BlockT *BB) : ParentLoop(nullptr) {
Blocks.push_back(BB);
DenseBlockSet.insert(BB);
}
// Since loop passes like SCEV are allowed to key analysis results off of
// `Loop` pointers, we cannot re-use pointers within a loop pass manager.
// This means loop passes should not be `delete` ing `Loop` objects directly
// (and risk a later `Loop` allocation re-using the address of a previous one)
// but should be using LoopInfo::markAsRemoved, which keeps around the `Loop`
// pointer till the end of the lifetime of the `LoopInfo` object.
//
// To make it easier to follow this rule, we mark the destructor as
// non-public.
~LoopBase() {
for (auto *SubLoop : SubLoops)
SubLoop->~LoopT();
#if LLVM_ENABLE_ABI_BREAKING_CHECKS
IsInvalid = true;
#endif
SubLoops.clear();
Blocks.clear();
DenseBlockSet.clear();
ParentLoop = nullptr;
}
};
template <class BlockT, class LoopT>
raw_ostream &operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) {
Loop.print(OS);
return OS;
}
//===----------------------------------------------------------------------===//
/// This class builds and contains all of the top-level loop
/// structures in the specified function.
///
template <class BlockT, class LoopT> class LoopInfoBase {
// BBMap - Mapping of basic blocks to the inner most loop they occur in
DenseMap<const BlockT *, LoopT *> BBMap;
std::vector<LoopT *> TopLevelLoops;
BumpPtrAllocator LoopAllocator;
friend class LoopBase<BlockT, LoopT>;
friend class LoopInfo;
void operator=(const LoopInfoBase &) = delete;
LoopInfoBase(const LoopInfoBase &) = delete;
public:
LoopInfoBase() = default;
~LoopInfoBase() { releaseMemory(); }
LoopInfoBase(LoopInfoBase &&Arg)
: BBMap(std::move(Arg.BBMap)),
TopLevelLoops(std::move(Arg.TopLevelLoops)),
LoopAllocator(std::move(Arg.LoopAllocator)) {
// We have to clear the arguments top level loops as we've taken ownership.
Arg.TopLevelLoops.clear();
}
LoopInfoBase &operator=(LoopInfoBase &&RHS) {
BBMap = std::move(RHS.BBMap);
for (auto *L : TopLevelLoops)
L->~LoopT();
TopLevelLoops = std::move(RHS.TopLevelLoops);
LoopAllocator = std::move(RHS.LoopAllocator);
RHS.TopLevelLoops.clear();
return *this;
}
void releaseMemory() {
BBMap.clear();
for (auto *L : TopLevelLoops)
L->~LoopT();
TopLevelLoops.clear();
LoopAllocator.Reset();
}
template <typename... ArgsTy> LoopT *AllocateLoop(ArgsTy &&...Args) {
LoopT *Storage = LoopAllocator.Allocate<LoopT>();
return new (Storage) LoopT(std::forward<ArgsTy>(Args)...);
}
/// iterator/begin/end - The interface to the top-level loops in the current
/// function.
///
typedef typename std::vector<LoopT *>::const_iterator iterator;
typedef
typename std::vector<LoopT *>::const_reverse_iterator reverse_iterator;
iterator begin() const { return TopLevelLoops.begin(); }
iterator end() const { return TopLevelLoops.end(); }
reverse_iterator rbegin() const { return TopLevelLoops.rbegin(); }
reverse_iterator rend() const { return TopLevelLoops.rend(); }
bool empty() const { return TopLevelLoops.empty(); }
/// Return all of the loops in the function in preorder across the loop
/// nests, with siblings in forward program order.
///
/// Note that because loops form a forest of trees, preorder is equivalent to
/// reverse postorder.
SmallVector<LoopT *, 4> getLoopsInPreorder() const;
/// Return all of the loops in the function in preorder across the loop
/// nests, with siblings in *reverse* program order.
///
/// Note that because loops form a forest of trees, preorder is equivalent to
/// reverse postorder.
///
/// Also note that this is *not* a reverse preorder. Only the siblings are in
/// reverse program order.
SmallVector<LoopT *, 4> getLoopsInReverseSiblingPreorder() const;
/// Return the inner most loop that BB lives in. If a basic block is in no
/// loop (for example the entry node), null is returned.
LoopT *getLoopFor(const BlockT *BB) const { return BBMap.lookup(BB); }
/// Same as getLoopFor.
const LoopT *operator[](const BlockT *BB) const { return getLoopFor(BB); }
/// Return the loop nesting level of the specified block. A depth of 0 means
/// the block is not inside any loop.
unsigned getLoopDepth(const BlockT *BB) const {
const LoopT *L = getLoopFor(BB);
return L ? L->getLoopDepth() : 0;
}
// True if the block is a loop header node
bool isLoopHeader(const BlockT *BB) const {
const LoopT *L = getLoopFor(BB);
return L && L->getHeader() == BB;
}
/// Return the top-level loops.
const std::vector<LoopT *> &getTopLevelLoops() const { return TopLevelLoops; }
/// Return the top-level loops.
std::vector<LoopT *> &getTopLevelLoopsVector() { return TopLevelLoops; }
/// This removes the specified top-level loop from this loop info object.
/// The loop is not deleted, as it will presumably be inserted into
/// another loop.
LoopT *removeLoop(iterator I) {
assert(I != end() && "Cannot remove end iterator!");
LoopT *L = *I;
assert(L->isOutermost() && "Not a top-level loop!");
TopLevelLoops.erase(TopLevelLoops.begin() + (I - begin()));
return L;
}
/// Change the top-level loop that contains BB to the specified loop.
/// This should be used by transformations that restructure the loop hierarchy
/// tree.
void changeLoopFor(BlockT *BB, LoopT *L) {
if (!L) {
BBMap.erase(BB);
return;
}
BBMap[BB] = L;
}
/// Replace the specified loop in the top-level loops list with the indicated
/// loop.
void changeTopLevelLoop(LoopT *OldLoop, LoopT *NewLoop) {
auto I = find(TopLevelLoops, OldLoop);
assert(I != TopLevelLoops.end() && "Old loop not at top level!");
*I = NewLoop;
assert(!NewLoop->ParentLoop && !OldLoop->ParentLoop &&
"Loops already embedded into a subloop!");
}
/// This adds the specified loop to the collection of top-level loops.
void addTopLevelLoop(LoopT *New) {
assert(New->isOutermost() && "Loop already in subloop!");
TopLevelLoops.push_back(New);
}
/// This method completely removes BB from all data structures,
/// including all of the Loop objects it is nested in and our mapping from
/// BasicBlocks to loops.
void removeBlock(BlockT *BB) {
auto I = BBMap.find(BB);
if (I != BBMap.end()) {
for (LoopT *L = I->second; L; L = L->getParentLoop())
L->removeBlockFromLoop(BB);
BBMap.erase(I);
}
}
// Internals
static bool isNotAlreadyContainedIn(const LoopT *SubLoop,
const LoopT *ParentLoop) {
if (!SubLoop)
return true;
if (SubLoop == ParentLoop)
return false;
return isNotAlreadyContainedIn(SubLoop->getParentLoop(), ParentLoop);
}
/// Create the loop forest using a stable algorithm.
void analyze(const DominatorTreeBase<BlockT, false> &DomTree);
// Debugging
void print(raw_ostream &OS) const;
void verify(const DominatorTreeBase<BlockT, false> &DomTree) const;
/// Destroy a loop that has been removed from the `LoopInfo` nest.
///
/// This runs the destructor of the loop object making it invalid to
/// reference afterward. The memory is retained so that the *pointer* to the
/// loop remains valid.
///
/// The caller is responsible for removing this loop from the loop nest and
/// otherwise disconnecting it from the broader `LoopInfo` data structures.
/// Callers that don't naturally handle this themselves should probably call
/// `erase' instead.
void destroy(LoopT *L) {
L->~LoopT();
// Since LoopAllocator is a BumpPtrAllocator, this Deallocate only poisons
// \c L, but the pointer remains valid for non-dereferencing uses.
LoopAllocator.Deallocate(L);
}
};
} // namespace llvm
#endif // LLVM_SUPPORT_GENERICLOOPINFO_H
|