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//===- GenericDomTreeUpdaterImpl.h ------------------------------*- 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 implements the GenericDomTreeUpdater class. This file should only
// be included by files that implement a specialization of the relevant
// templates. Currently these are:
// - llvm/lib/Analysis/DomTreeUpdater.cpp
// - llvm/lib/CodeGen/MachineDomTreeUpdater.cpp
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_ANALYSIS_GENERICDOMTREEUPDATERIMPL_H
#define LLVM_ANALYSIS_GENERICDOMTREEUPDATERIMPL_H
#include "llvm/Analysis/GenericDomTreeUpdater.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
namespace llvm {
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
template <typename FuncT>
void GenericDomTreeUpdater<DerivedT, DomTreeT, PostDomTreeT>::recalculate(
FuncT &F) {
if (Strategy == UpdateStrategy::Eager) {
if (DT)
DT->recalculate(F);
if (PDT)
PDT->recalculate(F);
return;
}
// There is little performance gain if we pend the recalculation under
// Lazy UpdateStrategy so we recalculate available trees immediately.
// Prevent forceFlushDeletedBB() from erasing DomTree or PostDomTree nodes.
IsRecalculatingDomTree = IsRecalculatingPostDomTree = true;
// Because all trees are going to be up-to-date after recalculation,
// flush awaiting deleted BasicBlocks.
derived().forceFlushDeletedBB();
if (DT)
DT->recalculate(F);
if (PDT)
PDT->recalculate(F);
// Resume forceFlushDeletedBB() to erase DomTree or PostDomTree nodes.
IsRecalculatingDomTree = IsRecalculatingPostDomTree = false;
PendDTUpdateIndex = PendPDTUpdateIndex = PendUpdates.size();
dropOutOfDateUpdates();
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
void GenericDomTreeUpdater<DerivedT, DomTreeT, PostDomTreeT>::applyUpdates(
ArrayRef<typename DomTreeT::UpdateType> Updates) {
if (!DT && !PDT)
return;
if (Strategy == UpdateStrategy::Lazy) {
PendUpdates.reserve(PendUpdates.size() + Updates.size());
for (const auto &U : Updates)
if (!isSelfDominance(U))
PendUpdates.push_back(U);
return;
}
if (DT)
DT->applyUpdates(Updates);
if (PDT)
PDT->applyUpdates(Updates);
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
void GenericDomTreeUpdater<DerivedT, DomTreeT, PostDomTreeT>::
applyUpdatesPermissive(ArrayRef<typename DomTreeT::UpdateType> Updates) {
if (!DT && !PDT)
return;
SmallSet<std::pair<BasicBlockT *, BasicBlockT *>, 8> Seen;
SmallVector<typename DomTreeT::UpdateType, 8> DeduplicatedUpdates;
for (const auto &U : Updates) {
auto Edge = std::make_pair(U.getFrom(), U.getTo());
// Because it is illegal to submit updates that have already been applied
// and updates to an edge need to be strictly ordered,
// it is safe to infer the existence of an edge from the first update
// to this edge.
// If the first update to an edge is "Delete", it means that the edge
// existed before. If the first update to an edge is "Insert", it means
// that the edge didn't exist before.
//
// For example, if the user submits {{Delete, A, B}, {Insert, A, B}},
// because
// 1. it is illegal to submit updates that have already been applied,
// i.e., user cannot delete an nonexistent edge,
// 2. updates to an edge need to be strictly ordered,
// So, initially edge A -> B existed.
// We can then safely ignore future updates to this edge and directly
// inspect the current CFG:
// a. If the edge still exists, because the user cannot insert an existent
// edge, so both {Delete, A, B}, {Insert, A, B} actually happened and
// resulted in a no-op. DTU won't submit any update in this case.
// b. If the edge doesn't exist, we can then infer that {Delete, A, B}
// actually happened but {Insert, A, B} was an invalid update which never
// happened. DTU will submit {Delete, A, B} in this case.
if (!isSelfDominance(U) && Seen.count(Edge) == 0) {
Seen.insert(Edge);
// If the update doesn't appear in the CFG, it means that
// either the change isn't made or relevant operations
// result in a no-op.
if (isUpdateValid(U)) {
if (isLazy())
PendUpdates.push_back(U);
else
DeduplicatedUpdates.push_back(U);
}
}
}
if (Strategy == UpdateStrategy::Lazy)
return;
if (DT)
DT->applyUpdates(DeduplicatedUpdates);
if (PDT)
PDT->applyUpdates(DeduplicatedUpdates);
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
DomTreeT &
GenericDomTreeUpdater<DerivedT, DomTreeT, PostDomTreeT>::getDomTree() {
assert(DT && "Invalid acquisition of a null DomTree");
applyDomTreeUpdates();
dropOutOfDateUpdates();
return *DT;
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
PostDomTreeT &
GenericDomTreeUpdater<DerivedT, DomTreeT, PostDomTreeT>::getPostDomTree() {
assert(PDT && "Invalid acquisition of a null PostDomTree");
applyPostDomTreeUpdates();
dropOutOfDateUpdates();
return *PDT;
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
LLVM_DUMP_METHOD void
GenericDomTreeUpdater<DerivedT, DomTreeT, PostDomTreeT>::dump() const {
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
raw_ostream &OS = llvm::dbgs();
OS << "Available Trees: ";
if (DT || PDT) {
if (DT)
OS << "DomTree ";
if (PDT)
OS << "PostDomTree ";
OS << "\n";
} else
OS << "None\n";
OS << "UpdateStrategy: ";
if (Strategy == UpdateStrategy::Eager) {
OS << "Eager\n";
return;
} else
OS << "Lazy\n";
int Index = 0;
auto printUpdates =
[&](typename ArrayRef<typename DomTreeT::UpdateType>::const_iterator
begin,
typename ArrayRef<typename DomTreeT::UpdateType>::const_iterator
end) {
if (begin == end)
OS << " None\n";
Index = 0;
for (auto It = begin, ItEnd = end; It != ItEnd; ++It) {
auto U = *It;
OS << " " << Index << " : ";
++Index;
if (U.getKind() == DomTreeT::Insert)
OS << "Insert, ";
else
OS << "Delete, ";
BasicBlockT *From = U.getFrom();
if (From) {
auto S = From->getName();
if (!From->hasName())
S = "(no name)";
OS << S << "(" << From << "), ";
} else {
OS << "(badref), ";
}
BasicBlockT *To = U.getTo();
if (To) {
auto S = To->getName();
if (!To->hasName())
S = "(no_name)";
OS << S << "(" << To << ")\n";
} else {
OS << "(badref)\n";
}
}
};
if (DT) {
const auto I = PendUpdates.begin() + PendDTUpdateIndex;
assert(PendUpdates.begin() <= I && I <= PendUpdates.end() &&
"Iterator out of range.");
OS << "Applied but not cleared DomTreeUpdates:\n";
printUpdates(PendUpdates.begin(), I);
OS << "Pending DomTreeUpdates:\n";
printUpdates(I, PendUpdates.end());
}
if (PDT) {
const auto I = PendUpdates.begin() + PendPDTUpdateIndex;
assert(PendUpdates.begin() <= I && I <= PendUpdates.end() &&
"Iterator out of range.");
OS << "Applied but not cleared PostDomTreeUpdates:\n";
printUpdates(PendUpdates.begin(), I);
OS << "Pending PostDomTreeUpdates:\n";
printUpdates(I, PendUpdates.end());
}
OS << "Pending DeletedBBs:\n";
Index = 0;
for (const auto *BB : DeletedBBs) {
OS << " " << Index << " : ";
++Index;
if (BB->hasName())
OS << BB->getName() << "(";
else
OS << "(no_name)(";
OS << BB << ")\n";
}
#endif
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
void GenericDomTreeUpdater<DerivedT, DomTreeT,
PostDomTreeT>::applyDomTreeUpdates() {
// No pending DomTreeUpdates.
if (Strategy != UpdateStrategy::Lazy || !DT)
return;
// Only apply updates not are applied by DomTree.
if (hasPendingDomTreeUpdates()) {
const auto I = PendUpdates.begin() + PendDTUpdateIndex;
const auto E = PendUpdates.end();
assert(I < E && "Iterator range invalid; there should be DomTree updates.");
DT->applyUpdates(ArrayRef<typename DomTreeT::UpdateType>(I, E));
PendDTUpdateIndex = PendUpdates.size();
}
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
void GenericDomTreeUpdater<DerivedT, DomTreeT,
PostDomTreeT>::applyPostDomTreeUpdates() {
// No pending PostDomTreeUpdates.
if (Strategy != UpdateStrategy::Lazy || !PDT)
return;
// Only apply updates not are applied by PostDomTree.
if (hasPendingPostDomTreeUpdates()) {
const auto I = PendUpdates.begin() + PendPDTUpdateIndex;
const auto E = PendUpdates.end();
assert(I < E &&
"Iterator range invalid; there should be PostDomTree updates.");
PDT->applyUpdates(ArrayRef<typename DomTreeT::UpdateType>(I, E));
PendPDTUpdateIndex = PendUpdates.size();
}
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
bool GenericDomTreeUpdater<DerivedT, DomTreeT, PostDomTreeT>::isUpdateValid(
typename DomTreeT::UpdateType Update) const {
const auto *From = Update.getFrom();
const auto *To = Update.getTo();
const auto Kind = Update.getKind();
// Discard updates by inspecting the current state of successors of From.
// Since isUpdateValid() must be called *after* the Terminator of From is
// altered we can determine if the update is unnecessary for batch updates
// or invalid for a single update.
const bool HasEdge = llvm::is_contained(successors(From), To);
// If the IR does not match the update,
// 1. In batch updates, this update is unnecessary.
// 2. When called by insertEdge*()/deleteEdge*(), this update is invalid.
// Edge does not exist in IR.
if (Kind == DomTreeT::Insert && !HasEdge)
return false;
// Edge exists in IR.
if (Kind == DomTreeT::Delete && HasEdge)
return false;
return true;
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
void GenericDomTreeUpdater<DerivedT, DomTreeT, PostDomTreeT>::eraseDelBBNode(
BasicBlockT *DelBB) {
if (DT && !IsRecalculatingDomTree)
if (DT->getNode(DelBB))
DT->eraseNode(DelBB);
if (PDT && !IsRecalculatingPostDomTree)
if (PDT->getNode(DelBB))
PDT->eraseNode(DelBB);
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
void GenericDomTreeUpdater<DerivedT, DomTreeT,
PostDomTreeT>::tryFlushDeletedBB() {
if (!hasPendingUpdates())
derived().forceFlushDeletedBB();
}
template <typename DerivedT, typename DomTreeT, typename PostDomTreeT>
void GenericDomTreeUpdater<DerivedT, DomTreeT,
PostDomTreeT>::dropOutOfDateUpdates() {
if (Strategy == UpdateStrategy::Eager)
return;
tryFlushDeletedBB();
// Drop all updates applied by both trees.
if (!DT)
PendDTUpdateIndex = PendUpdates.size();
if (!PDT)
PendPDTUpdateIndex = PendUpdates.size();
const size_t dropIndex = std::min(PendDTUpdateIndex, PendPDTUpdateIndex);
const auto B = PendUpdates.begin();
const auto E = PendUpdates.begin() + dropIndex;
assert(B <= E && "Iterator out of range.");
PendUpdates.erase(B, E);
// Calculate current index.
PendDTUpdateIndex -= dropIndex;
PendPDTUpdateIndex -= dropIndex;
}
} // namespace llvm
#endif // LLVM_ANALYSIS_GENERICDOMTREEUPDATERIMPL_H
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